Chair Force Engineer

You aren't going to stick people on that thing, are you?

2009-07-11T07:26:00.000-07:00

During the Augustine Commission hearings, the side-mount, shuttle-derived vehicle has emerged as a surprising dark horse. Compared to Ares and even DIRECT, a side-mount can be developed quicker and cheaper than its shuttle-flavored competitors. It also does the most complete job of preserving more of the STS workforce within the first few years after the orbiters retire.

The most startling aspect of the side-mount SDV presentation is the option to mount a crew capsule and escape system. Because the crew capsule would be located laterally to the external tank, most observers feel it would not be a great improvement over the shuttle when it comes to launch aborts. Precise guidance and thrust-vectoring would be required in the escape system to pull the capsule away from the ET, even if the abort was triggered while the ET was structurally intact. In a Challenger-like situation where the ET rapidly disintegrates, there may be little or no chance of protecting the capsule from ET-produced shrapnel.

Another abort scenario worth considering is the shuttle's Return to Launch Site maneuver. The shuttle stack would flip end-over-end and fire the engines in the opposite direction to cancel out the forward velocity and head home. The orbiter would then separate and glide in for a landing. On a side-mount crew launcher, the capsule doesn't have the same cross-range as the shuttle orbiter. Hopefully the escape tower would be able to pull it away from the stack and set it down somewhere in the Atlantic ocean for recovery. The bigger question is the point at which the escape tower is going to be jettisoned for a side-mount crew launcher. Will the service module engine have the thrust and steering necessary to pull free from the ET during late-boost aborts?

The side-mount SDV has been given extensive study since the days before the first shuttle launch, and it remains a valid approach for transporting large unmanned payloads to space. But is it suitable as a crew launcher? It's probably no less safe than the existing shuttle, but it would still give me a high pucker-factor if I was an astronaut. The cynic in me suspects that NASA doesn't take the side-mount crew launcher seriously, but is pitching it as a means of undermining the rationale for EELV or DIRECT. After all, DIRECT may be a more difficult and expensive development than a side-mount SDV, but it's much more suitable for manned aborts during all phases of flight.

The approach I favored during the early days of Project Constellation was a Delta IV crew launcher and side-mount SDV for unmanned cargo. It's the cheapest crew launcher paired with the cheapest heavy lifter design. I would not be surprised if the Augustine Commission seriously considers this combination.

Shuttle-Derived Fratricide

2009-06-12T21:23:00.000-07:00

Rocketman, in his uniquely-unforgettable style, is taking a look at the race to replace Ares I. He thinks the writing is on the wall for the current Ares I, but continues to hint at a return to the original "Shaft" from the ESAS report using a stock SRB and an air-start Space Shuttle Main Engine on stage 2. At the same time, he thinks that the proponents of Ares, DIRECT and Shuttle-C are taking aim at each other, with the taxpayers getting caught in the crossfire.

After reading the presentation on DIRECT 3.0 from the International Space Development Conference, I can't help but agree with Rocketman. I must first congratulate the DIRECT team for pulling out all the stops to present their concept as a more sensible alternative to NASA’s technically-challenged and budgetarily-bloated plans for Ares I & V. The presentation is incredibly slick, and it’s the best apples-to-apples comparison between the two plans to date.

But near the end of the slides is an unnecessary slap in the face of Shuttle-C, trying to fend off competition from the easiest shuttle-derived option of all. I find their arguments to be a bit of a strawman, because even the most ardent Shuttle-C supporters do not see Shuttle-C as a crew launcher (they often leave that task to EELV’s.) And there’s no reason that Shuttle-C couldn’t be adapted to the clean-pad concept that DIRECT touts for their vehicle.

I have to confess some sympathy towards Shuttle-C or a similar design (perhaps using stock RS-68's instead of SSME's.) It would be the cheapest shuttle-derived rocket of all, at least from a development budget standpoint. But it doesn't offer a lot of room for future evolution, and it inherits the same inefficiencies that are ingrained into any shuttle-derived rocket.

Is the re-opening of the launcher debate good for the taxpayers? To some point I'd agree, because Ares I is a very expensive and a very behind-schedule vehicle that offers little benefit over the Delta IV Heavy (which has already been paid for.) The debate we're expecting from the Augustine Commission is one which should have been taken to the public in 2005. But there's also the risk posed by getting mired in continual debate and wasting taxpayer dollars on a succession of aborted development projects like Shuttle II, X-33, Space Launch Initiative, and Orbital Space Plane.

For both Shuttle-C and DIRECT, time is not on their side. The infrastructure of the shuttle program, particularly at the Michoud plant where the ET's are built, is being dismanted as the blue-ribbon panels busily debate. Unless the dismantling is halted, the panel may be left with no other choice than to put its rubber-stamp on "Plan Griffin." I would still argue for Delta IV Heavy as the fastest, cheapest and lowest-risk method for getting Orion into space. To retain the shuttle workforce, LC-39 could be converted for EELV use. One pad would go to the Delta crew launcher, while the other would be reserved for a future EELV variant capable of 55-tonne payloads (as per the Northrop-Grumman Crew Exploration & Refinement study of 2004.)

The Augustine Commission absolutely has to get this right. NASA has lost a lot of credibility with its string of past failures in developing manned launch systems, and it's hard to see how the agency can sustain a manned spaceflight program after another embarassing cancellation. It's not too late to change ships and abandon Ares, but the successor system cannot afford to be cancelled during its development.

Hubble Disposal Revisited

2009-05-25T09:35:00.000-07:00

With the crew of shuttle Atlantis having completed the last servicing mission on the venerable space telescope, I've revisited the question of what happens to the large Hubble spacecraft when its mission finally ends in a few years. A piece of space debris the size of post-shutdown Hubble poses an increased risk to people on earth during an uncontrolled re-entry.

The original Hubble disposal plan called for a shuttle mission to retrieve it and send it back to earth. But the winding down of the shuttle program ensured that Hubble would out-last the spacecraft that delivered her to orbit in 1990. Besides, the risk to astronauts in order to deliver Hubble to a museum on earth really can't be justified for most people.

Back when Sean O'Keefe supported a robotic servicing mission to Hubble, the addition of a deorbit stage was considered. At least a deorbit motor would permit Hubble to control its re-entry and minimize the risk to people on the ground. The deorbit motor was also considered for the current mission before being dropped. Instead, the STS-125 astronauts added the Soft Capture Mechanism, which should allow future spacecraft to pay Hubble a visit. A deorbit stage could also be launched, although it would require some form of terminal propulsion and gudance to safely dock with Hubble.

It's always possible that a future Orion spacecraft could dock with Hubble, re-boost it, and perform maintenance. But Orion is ill-suited for the task at hand. It has no payload bay for delivering spare parts to Hubble, and there's no arm to reposition spacewalking astronauts who would repair Hubble.

The long-term Hubble situation reminds me much of the fate of Skylab. While the first American space station was boosted into a higher orbit in hopes that it would still be around when the Space Shuttle first flew, it ended up re-entering and breaking apart over the Australian outback two years before the first Space Shuttle mission. Hopefully NASA will have an executable plan to safely deorbit Hubble at the end of it's life, unlike Skylab. And if anybody's holding out hope for Orion giving Hubble another reprieve, I think they'll be sorely mistaken.

Amateurs talk rocket tactics, professionals talk rocket logistics

2009-05-19T21:28:00.000-07:00

The DIRECT rebuttal to NASA’s analysis of their concept includes some very telling observations of NASA’s mentality in creating and defending the existing infrastructure. Perhaps the most telling NASA observation comes on slide 64:

-More detail on Launch Infrastructure than on vehicle design.

--This is a design that is sized by infrastructure as they note in their paper.

--However to date Launch Infrastructure is not on the critical path of Ares-V or Ares-I

To which DIRECT responds by saying:

-The fact that the infrastructure is not being considered by Ares is one of the reasons why that architecture costs as much as it does.

--Cost of all supporting systems, not just infrastructure must be one of the many factors considered as part of the critical path.

All I can say in response is “Wow.” Are we to believe that ESAS was designed with little or no consideration of what the supporting infrastructure would cost? It would certainly explain why we’re stuck with the unaffordable Ares I and Ares V.

Further NASA statements such as “Ares I + Ares V uses 15 SRB segments, while two Jupiter 232’s use 16 segments” also reveal an incredibly simplistic approach to cost estimation. Such simple methods might be appropriate for pre-algebra students. Professional cost estimators ought to know better. That's why cost estimation is so difficult; there may literally be thousands of dependent and independent variables that make up the true cost of the system over its lifetime. Saving a few million in rocket hardware may have bigger reprocussions with development dollars, standing army costs, and infrastructure costs. It’s best summed up on Slide 26, where Jupiter’s higher launch costs (measured in tens of millions per launch) are offset by the savings of billions in development costs.

The DIRECT rebuttal also points out a problem the EELV advocates have encountered. In estimating upper stage masses, NASA has become excessively reliant on software tools like INTROS, which give fairly high estimates for upper stage dry masses. When INTROS cannot match the values for real, flight-proven hardware (like the EELV upper stages,) it might be time to revise the INTROS code. If nothing else, NASA’s impartial estimators should defer to the real values of flight hardware when the numbers conflict with the computer estimates.

All-in-all, DIRECT appears to be a more affordable architecture for a shuttle-derived lunar transportation system. I say this as somebody who earned a BS in Aerospace Engineering and actually did some serious study of solid-rocket internal ballistics during senior design class, giving me a first-order feel for how lengthy a new SRB development program will be for ATK and NASA.

With that being said, DIRECT still faces an uphill battle against “the unknown unknowns.” How well will the Centaur balloon-tank structure scale up to the larger diameter of the Jupiter rockets? What new guidance and rendezvous techniques and docking systems are required to mate the Earth Departure Stage to the Altair-Orion stack once on-orbit? What other previously-unknown problems, such as SRB heating of the core engines, will affect DIRECT once development begins?

At this point, a swap of Ares for DIRECT will result in little net gain from a schedule or technical risk perspective. While Ares proponents might argue that the last four years have seen the design mature, Ares is still years away from flying significant flightworthy hardware. The maturity of Ares today is comparable to where DIRECT’s predecessor, National Launch System (aka New Launch System) was in 1991. The only potential crew launcher with any maturity is Delta IV Heavy. If SpaceX is lucky, Falcon IX will have a successful flight before the Augustine Commission completes its report.

The Heat is On

2009-05-18T17:16:00.000-07:00

If you want some interesting technical reading, do yourself a favor and check out the DIRECT Launcher rebuttal to NASA's review of their concept. I'll go into depth about the review tomorrow, but the most exciting (or shocking, depending on your point of view) development comes on Slide 112 of the presentation:

DIRECT has come to the conclusion that the ablative nozzle of the RS-68A/B will not be sufficiently robust for a cluster application in such close proximity to the exhaust from a pair of SRB’s, and a regeneratively cooled nozzle is necessary to survive this extreme base heating environment.

The takeaway: RS-68 isn't going to cut it for DIRECT or for Ares V without some MAJOR modifications. The DIRECT team believes that a regen nozzle is necessary, and they're advocating the Space Shuttle Main Engine as a replacement. NASA is conducting a trade study between SSME and a regenerative RS-68 for Ares V. This is consistent with reports from earlier this year that SSME was back in the trade space.

We've been down this road before. During the days of ESAS, before the "Ares" name was official, there was Cargo Launch Vehicle (CaLV.) Much like the Jupiter 232 of DIRECT, it used Shuttle-derived tankage and an upper stage. It also used five SSME's on the core. Over the next year, the RS-68 replaced SSME because it would be too expensive to throw away five SSME's per flight. The consequence was a wider, all-new core with more propellant to compensate for the lower specific impulse of the less-efficient RS-68.

NASA faces the choice of switching back to SSME, or trying to create a regen RS-68. Both choices are fraught with many unknowns. How easy will it be to restart SSME production? Can any incremental changes to the SSME result in cost savings? After all, Wayne Hale has said that if the shuttle program continued past 2010, the next upgrade might have been a channel-wall nozzle to replace the thousands of welded coolant tubes in the current SSME nozzle. But a regen nozzle for RS-68 won't be trivial, and it will add to Ares V schedule and development costs. And if NASA is going to pay for a regen nozzle on RS-68, it should also reconsider the expansion ratio of the new nozzle to ensure an optimal balance between thrust level and specific impulse.

When I look at the design problem created by SRB heating of the core engines, I wonder whether "SSME vs. RS-68 Regen" is a false choice. For starters, could an ablative RS-68 be viable if the outer nozzle was thicker and absorbed more heat? For that matter, could RS-68 work if its position on the booster changed? Remember that on the shuttle, the main engines aren't mounted between the two SRB's. A similar arrangment could work on Ares V if the six engines were mounted in two separate pods. If the base of Ares looked like a clock with SRB's mounted at three and nine, one engine pod would mount at twelve and the second pod would attach at six.

Just when it might have seemed like the design of Ares V was set in stone, it's all open for debate again. Perhaps the sixty days of ESAS studies weren't enough to thoroughly review all of the underlying assumptions behind the study. At least the DIRECT guys deserve credit for laying all of their assumptions out in the open. Let's hope that NASA gets it right this time around.

My Military Acquisition Rant

2009-05-05T18:43:00.000-07:00

After a recent chat with a friend who is working on the F-22 program, I've decided that it's time for me to unleash my rant about the biggest problems I've observed with the way that the Pentagon and Congress deal with military acquisition. I make my case from the perspective that I hope we'll get smarter about the way we spend defense dollars, getting a good value for the taxpayer and ensuring that our fighting forces get the weapon systems that they need.

I think the poster-children for all the problems with military acquisition are the Seawolf-class and Virginia-class submarine programs. The Seawolf-class was designed during the 80's as a class of subs that could autonomously track and destroy Soviet ballistic missile subs. When the Soviet Union fell, the Seawolf-class was seen as a relic, and dropped after only three boats were authorized. But there was a problem; namely, how do you replace all the aging Los Angeles-class subs in the US Navy fleet? Rather than building more Seawolf-class boats, the Navy authorized the Virginia-class submarines. In comparison, the Virginia-class was smaller and slower than the Seawolf-class, with fewer torpedo tubes. After a lengthy and costly development program, the Virginia class proved to be only marginally cheaper per boat than the Seawolf-class.

Another case-in-point is the F-22 fighter program. I will be the first to admit that it would have been wise to cancel the F-22 back in 1992 when the Soviet Union dissolved. But that didn't happen, and the F-22 development program slogged on, logging its first flight in 1997 and Initial Operational Capability by late 2005. Now it appears that F-22 production will soon end at 187 airframes. While the F-22 is undoubtedly an expensive plane, much of that can be attributed to its protracted and expensive development. Now that the development costs have been sunk, the marginal cost of each F-22 is a steal compared to what the F-35 will cost early in its production run. By comparison, the F-22 is faster, stealthier, and more maneuverable than the F-35. Even the F-35's touted advantages in attack capabilities are largely moot, because the F-22 can also carry two Joint Direct Attack Munitions internally. The F-35's only advantage is the novel lift fan which allows the Marine Corps' variant to land vertically.

The F-35 Joint Strike Fighter is another example of a program that has pressed on in spite of its questionable value to the taxpayers. It's supposed to replace the Air Force F-16 and A-10, Navy F/A-18 (and the A-6 long-range strike plane, which has been retired for the last 12 years,) and Marine Corps AV-8 Harrier. But is it really necessary to build an all-new fighter possessing "an affordable degree of stealth"? Stealth is overrated after the enemy's air defenses have been wiped out, and it constrains how much ordinance you can carry. The F-16 and F/A-18 are still very capable airplanes, and will remain on-top with avionics upgrades and integration of the newest weapon systems. Even the venerable A-10 is becoming less relevant, with F-15E Strike Eagles performing much of the close air support work in Iraq and Afghanistan. While the Harrier brings some very unique capabilities to the battlefield with its ability to operate from short airstrips and amphibious assault ships, it's worth asking whether the costs of Harrier acquisition and operations were superior compared to using Marine AH-1 Cobra attack choppers to meet the mission requirements.

So the F-22 production will soon end, while troubled programs like Global Hawk are kept on life support. Global Hawk is five years behind schedule, while the Predator series of tactical unmanned aerial vehicles continues pressing on at a remarkable pace. Originally used for recon in the Balkans, the baseline Predator has become a vital weapon for taking out high-value terrorists in Afghanistan and Pakistan. The bigger Predator-B was re-christened as the "Reaper," and it's living up to its name in dishing out laser-guided death to Jihad Joe. The new Predator-C introduces stealth and higher speeds to the successful Predator formula. While Global Hawk is more of a strategic intelligence asset than the tactical Predator, its myriad delays have motivated the defense department to find interim solutions that get results.

The big lesson for Congress and the military acquisition bureaucracy is that major development programs may take a decade or more and will require billions of dollars. They should never be undertaken lightly. And once we commit to them, we have a duty to see them through to production and build as many weapon systems from that program as we can to meet our mission requirements. It is a complete waste of taxpayer dollars and a dangerous disservice to our fighting men and women if we go back to the drawing board every time that we balk at the unit cost of a major weapon system.

Orion Takes a Backseat to Nobody

2009-05-02T09:51:00.000-07:00

NASA recently announced that the Orion Spacecraft will be initially limited to a crew of four, even for ISS missions. This is another step backwards from the ESAS Study which called for a crew of six on ISS missions and four on lunar missions.

There is a very clear reason why ESAS had a requirement for six crew to the ISS on Orion. The ISS has a crew of six, and it makes sense for Orion to deliver a full crew compliment to ISS and return them to earth. The alternative, in the post-shuttle era, is to send two Soyuz capsules (or one Dragon, if SpaceX ever sees COTS-D funding.) Apparently NASA is counting on one Orion and one Soyuz being docked at ISS at all times. If the station had to be evacuated in an emergency, NASA will have to hope that both capsules work properly to get the full crew compliment home.

Officially, NASA is justifying the smaller crew because it will eliminate the need for two different seat configurations in Orion. Development costs and mass savings have nothing to do with it. Yet this argument is pretty weak when considering that Apollo supported three crew for lunar missions and five crew in the Skylab Rescue configuration. The difference between 1973 and today is that NASA was willing to seat its astronauts in two rows during the Apollo era. Orion is significantly bigger than Apollo, in part because NASA is unwilling to have astronauts sitting in two rows during a hard landing. Only time and testing will validate this safety fear.

With the growing likelihood that ISS will see a life extension to 2020 or beyond, it doesn't make a lot of sense to take seats out of Orion and prevent it from serving as an ISS lifeboat.

Test like you fly

2009-04-25T10:22:00.000-07:00

In the business of aerospace, the phrase "test as you fly" can never be repeated too often. All hardware should be tested on the ground in as realistic fashion as possible. Flight testing should come as close to the environments where the hardware will be flown. Traditionally, new rocket designs have been tested one stage at a time, using dummy upper stages. Why then would NASA reject this test strategy for Ares I?

Perhaps it's because Project Apollo abandoned incremental testing in favor of all-up testing. Nowhere was this more pronounced than Apollo 4, the first Saturn V flight, which was the first instance when the S-IC and S-II stages had ever flown before. Of course, NASA and its contractors had extensively tested the stages on the ground before, and S-IVB had been tested on Saturn IB launches. Project Apollo is often held up as a model for how a space program should be conducted, but it's really an exception rather than the rule. Apollo was the unique product of its circumstances, and its "crash the schedule" approach should not be viewed as standard industry practice.

The current Ares test schedule calls for Ares I-X this year, a test of a 4-segment SRB with a dummy fifth segment, dummy upper stage, and avionics that don't represent Ares flight avionics. The next step is Ares I-Y in 2012. I-Y will be the first flight of the real Ares I SRB, plus an inert upper stage that, minus the engine, resembles the real Ares I upper stage. Ares I-Y will also test the Orion escape system.

As I've said many times before, Ares I-X has little to no bearing on the Ares I flight hardware and should be terminated. Ares I-Y is a far better test because it does involve Ares flight hardware, but I'm not certain there's much to be gained from flying an engine-less second stage in place of a dummy upper stage.

Recently there's been talk of an "Ares I-X Prime" which would actually test a five-segment SRB with dummy upper stage. Now we're actually getting serious about "testing like we fly." This is what Ares I-X should have looked like all along. The problem with the "Prime" test flight, in my view, is that it's being considered as a replacement for Ares I-Y instead of Ares I-X.

At this point, Ares I-X doesn't really buy NASA anything, aside from positive PR if it works correctly. Ares I-Y isn't doing much more than Ares I-X Prime would do, aside from testing the supper stage structure under flight loads and allowing for the high-altitude abort test. A wiser and more fiscally-responsible strategy would be cancelling both Ares I-X and Ares I-Y, skipping ahead to Ares I-X Prime, and then making Orion 1 (the first in-flight ignition of the upper strage and first on-orbit test of the Orion spacecraft) the last test flight before humans fly on Ares-Orion.

Spiral Development: The Chair Force Engineer Plan for Closing the Gap and Enabling Human Lunar Exploration

2009-04-21T21:36:00.000-07:00

Today's big news for Project Constellation comes in the form of Aerospace Corporation's independent study of using Heavy EELV's to launch the Orion spacecraft. The short of it: there are no problems with black zones, and the launchers can launch Orion with performance to spare. But the costs of doing so won't be trivial, and EELV+Orion won't be operational until 2014 or later. That's not much of an improvement over Ares I.

Right now NASA faces two challenges that are often opposed to each other. The first is fielding a human space launch capability in a minimal amount of time after the shuttle is retired. The second is the political consideration of retaining as many shuttle jobs as possible after the shuttle retires. Ares retains shuttle jobs, but it won't be ready for another six years or more. EELV and COTS-D might be able to shorten the post-shuttle gap, but they don't retain the shuttle workforce.

Since everybody seems to have their own ideas about how Project Constellation should run, I'd like to share mine. My ground rules are simple:
1) Get a manned spacecraft flying to ISS as soon as possible
2) Whenever possible, minimize development costs
3) Take a spiral approach to development, sacrificing the arbitraty 2020 moon landing date in favor of incremental and affordable advancements.

The first step would be halting all work on the Ares launch systems to evaluate which elements are applicable to the spiral development program that I propose, albeit on a longer time schedule than the current NASA plan. Once that's been accomplished, the Chair Force Engineer plan for manned spaceflight can begin in earnest.

1) Fully fund SpaceX's COTS-D effort
This is a no-brainer. Dragon is a simple capsule designed for one mission: deliver humans and cargo to ISS. It's the furthest system along the path that can shorten the gap.

2) Replace the current Space Shuttle system with a block I Shuttle C
Shuttle C shouldn't be hard to develop, as much of the work was completed prior to 1993. Even the leftover engines from the shuttle program can be expended on Shuttle C missions. While Shuttle C would be tasked with delivering cargo to ISS, we have to face reality: it's really there as an interim measure for retaining the shuttle workforce over the long haul while not endangering astronauts on further shuttle missions.

3) Make block upgrades to Shuttle C as the budget permits
The first order of the day is to find a replacement for the finite supply of space shuttle engines. RS-68 is a good canddiate, but it needs upgrades to even come close to SSME performance levels. The new injector plate and turbopumps from RS-68A&B are a good start, but a regeneratively-cooled nozzle would be really nice.

Shuttle C is also expandable in the SRB department. If NASA insists on paying ATK to develop longer SRB's than the current ones used byu the shuttle, they can be integrated with Shuttle C fairly easily.

4) Create a manned capsule capable of returning to earth from lunar trajectories
Perhaps Dragon could be upgraded for lunar missions. Certainly SpaceX has been discussing circumlunar Dragon missions, and I wouldn't rule out a "Block 2" variant with a beefier heat shield and enough consumables for a lunar mission. If Dragon Block 2 doesn't pan out, the Orion spacecraft could be revived using Falcon 9 Heavy or a Heavy EELV as a launcher.

5) Create an Altair lander and other elements of a lunar transit system, designed for launch on Shuttle C.
I'm agnostic on whether rendezvous in earth orbit is superior to rendezvous at an earth-moon Lagrange point. The important thing about my plan is that decisions such as EML vs. LEO are deferred until the budget exists to develop lunar-capable hardware. Certainly both would be possible using Shuttle C, in-space assembly, and on-orbit refueling. It's certain that a competent lunar mission could be staged using a capsule launched on a Heavy EELV, a lander and propulsion stage that are launched unfueled by a Shuttle C, and a load of propellant delivered by a second Shuttle C.

In closing, NASA has gotten itself into a lot of trouble by avoiding the "pay as you go" approach in favor of redoing Apollo on a shuttle-era budget. Unless the agency changes direction very soon, there will be a long gap and a brain drain in central Florida. The solution is the time-honored technique of spiral development. NASA should accelerate Dragon, fly an interim Shuttle C, and upgrade Shuttle C for sustainable operations before devloping lunar hardware in earnest. Such an approach gives policymakers enough options to ensure that the US stays in the manned spaceflight business even if the lunar goal is abandoned or replaced with more ambitious exploration targets.

Shaky Math

2009-04-20T22:17:00.000-07:00

SpaceX is delaying its next Falcon 1 launch because of "dynamic interactions" between the launcher and its RazakSat payload. A lot of commenters are coming down hard on SpaceX or wondering how this issue could have been left to simmer until the very last minute. Having observed a spaceflight program dealing with serious launch vibration issues, it's pretty easy for me to see how this happened.

Every launch vehicle users' manual contains a vibration profile for the launcher across the range of frequencies at which the rocket is expected to vibrate. SpaceX has been publishing users' guides since at least 2005, three years before the vehicle made its first successful flight. Furthermore, the flight configuration is somewhat different from the original one in the first users guides, after the change from a Merlin 1 to a Merlin 1C engine on the first stage.

The most likely scenario is that RazakSat was designed to the old vibe specs that were published for Falcon 1 several years ago (after all, RazakSat wasn't designed, fabricated, and integrated overnight.) It wasn't until all the data came back from the successful September 2008 Falcon launch that the vibe problem was discovered with RazakSat. Perhaps it affected certain structural modes of RazakSat, or maybe the vibe profile was more intense across the spectrum. Either way, it's time to go back to the drawing board.

The vibe problem doesn't require any drastic solutions. By placing a series of Softride isolators between the launcher and the payload separation system, vibrations can be damped down to a survivable level. A coupled loads analysis is absolutely necessary to examine the full launcher-softride-payload stack and determine how the isolators can be tuned for the RazakSat mission. I don't know how much time CSA Engineering would need to solve the RazakSat issue, but it would seem like the quickest possible option for getting the next Falcon 1 successfully off the pad.

Silent Eagle

2009-03-18T21:09:00.000-07:00

Boeing recently unveiled its concept for the “Silent Eagle,” the next model in the F-15 family designed to keep the venerable super-fighter in production for a few years more. In the Silent Eagle design, Boeing is hoping to offer foreign air forces an “affordable” degree of stealth. While the specifics are highly classified, the basic concepts behind designing a stealth aircraft aren’t hard to grasp:

--Introduce as few protuberances or angles as possible in the overall layout.

--Utilize radar-absorbing materials in the aircraft’s structure

--Submerge the engines in a way that protects the compressors from exposure to radar

--Reduce the noise and infra-red signatures produced by the engines through cooling, shielding the nozzles, sound dampening, and other methods.

The F-15 is still a world-class fighter aircraft, especially in the hands of a highly-trained pilot. Continuous avionics upgrades could keep it competitive with super-fighters like the F-22. But the F-22’s distinct advantage is that the airframe was designed to be stealthy from the start. While Boeing has done a few things to the F-15 airframe to reduce its radar return (submerged weapons carriage, an exportable radar-absorbent material coating on the airframe, and outward-canted fins,) it’s still a decidedly non-stealthy airplane.

Friendly foreign air forces have to face the question of whether they need stealthy combat aircraft in their arsenals. In scenarios like Afghanistan and the 2003 invasion of Iraq, stealth was not as vital a factor as it was in Operation Desert Storm because of the enemy’s degraded air defenses. Stealth often becomes a hindrance because internal weapons carriage reduces the overall payload the aircraft can carry.

I’m interested to see if anybody is interested in buying the F-15 “Silent Eagle,” especially with the price of the F-35 rising. The F-35 was designed with an “affordable” degree of stealth in mind, but it’s quickly becoming as expensive as the F-22 (an airplane which is faster, stealthier, more maneuverable, and just a better all-around air-to-air fighter aircraft.) "Silent Eagle" is the poor man's F-35, sacrificing the F-35's level of stealthiness for affordability, superior maneuverability, a higher top speed, a dual crew, and twin-engine reliability.

Japan is likely to be the target of Boeing's "Silent Eagle" marketing. The Japanese already fly F-15's but really want the F-22. With the US Congress prohibiting F-22 exports, Japan will likely settle for the F-35 unless Boeing can make a better offer (i.e., one that includes a higher degree of the plane's production in Japan) with the "Silent Eagle."

A Jem of an administrator?

2009-03-18T19:31:00.000-07:00

The hunt for a NASA administratorgot even messier today, with the nomination of retired Major General Scott Gration to the position of envoy to Sudan. Formerly the rumored front-runner for the job, his position has been taken by astronaut Mae Jemison in the rumor mill's pool of candidates.

I take the Jemison rumor with more than a grain of salt. My personal preference is still for Lester Lyles or Steve Isakowitz, of the people whose names have been floated. But with that being said, I'm interested in the Jemison rumors because I've actually met Dr. Jemison during a lecture and a Q&A session. I came away highly impressed with her intellect, but she definitely struck me as a scientist moreso than a manager or a leader. Maybe it was just the subject of her lecture which blinds me to the possibility of her as an administrator, but she strikes me as somebody who takes a very global view of utilizing human technological prowess to solve social problems and alleviate human suffering. These goals are very admirable, but they're not completely aligned with the NASA mission.

Service as an astronaut does not qualify one to be NASA administrator. At best, it should be viewed neutrally for an administrator candidate. Management acumen is the key here, and that's the reason why I view General Lyles or Steve Isakowitz so highly compared to the other rumored candidates. That might not mean the others are bad managers, it's just that they haven't had the opportunities to demonstrate it on a large scale. With the agency in a precarious position, I'd like to see a proven track record before supporting a candidate.

Meet the new boss?

2009-02-09T17:27:00.000-08:00

Of all the people having been previously mentioned for the position of NASA Administrator, the name of retired Air Force General Lester Lyles gives me the best feeling from my cursory knowledge of his resume. His experience as a commander and director of Launch Vehicle programs, and his experiences as commander of Space & Missile Systems Center and Air Force Materiel Command should be more than adequate experience for a potential NASA Administrator. It doesn’t hurt that a trusted confidante from my office met General Lyles at a convention and came away highly impressed.

It must be stressed that serving as an astronaut or earning an engineering Ph.D. should not substitute for automatic qualifications for the NASA Administrator job. It's not to say that either of these qualities should disqualify a potential candidate, but they have very little to do with what the administrator is tasked with. He or she has to manage a multi-billion dollar agency and "herd the cats" in a massive bureaucracy. Controlling costs and schedule while meeting performance targets is the name of the game.

The two biggest unknowns here are 1) what does the Obama Administration want the NASA Administrator to accomplish, and 2) what approach will the NASA Administrator take towards carrying out that goal? During the second Bush term, the direction was clearly laid out within the Vision for Space Exploration. Mike Griffin’s approach to VSE, known as ESAS, was an unknown at the time Griffin was appointed and confirmed (although one need only look at Griffin’s work from the First Lunar Outpost study and his work with the Planetary Society to see where he was going with ESAS.) Things are far more uncertain this time around. Without a space policy white paper from the White House, it’s very uncertain if the Obama Administration will endorse the general direction of Mike Griffin’s NASA, or if it will “change” towards currently-unknown goals in the exploration of space. It’s always possible that the White House could defer to the next NASA Admin, giving the new boss a lot of leverage over the overall goals of the agency.

Flight of the Griffin

2009-01-27T09:08:00.000-08:00

Last week, Michael Griffin departed his post as NASA administrator to considerable controversy, surrounded by a legacy that will remain tenuous and uncertain for many years to come. Mike Griffin is ESAS, and ESAS is Mike Griffin. The two of them will never be separable, and the success or failure of ESAS will likely mold the verdict that historians deliver on the Griffin administration of the agency.

With that being said, the positive accomplishments of Mike Griffin and his team have often gone neglected. The agency was responsible and courageous in the way it conducted the shuttle program as it returned to flight following the Columbia disaster. Griffin also deserves credit for the way NASA handled the COTS program, or at least for its sponsorship of SpaceX. At this point in time, SpaceX remains America's best hope for closing the spaceflight gap within a reasonable period after the shuttle retires.

At the heart of Mike Griffin's relationship with ESAS and Project Constellation is a fundamental misunderstanding of what the person in the position of "NASA Administrator" is supposed to do. For any management figure, the keys to success are cost, schedule & performance. Specifically, Mike Griffin was tasked with performing the following responsibilities during his 2005-2009 tenure with NASA:
--Keep his agency on-budget in meeting its mission
--Keep his agency on schedule as it meets its goals
--Ensure the agency's performance meets the thresholds & goals that have been set by the national leadership

During his tenure, Mike Griffin's NASA largely abandoned the presidentially-directed 2014 date for getting Orion operational ("operational" being the key term here, although further slips in the Orion schedule are highly likely,) and coalesced around an architecture which requires unplanned budget increases. The result is that the agency's ability to meet its goals, performance, is much less likely.

I would be remiss today if I did not mention Paul Spudis's excellent piece about why Project Apollo was an exception to the rules that traditionally govern national space programs. Apollo's success was due to an unsustainably large development budget. Mike Griffin's challenge, back in 2005, was to figure out how to get back to the moon while operating on a shuttle-sized budget that would only grow to keep pace with inflation. Rather than making cost-control a top priority, he signed on to "Apollo on Steroids" with a shuttle budget. Development would be stretched as long as possible in order to stay within the yearly budgets, which puts the schedule at risk.

If America fails to land a man on the moon by 2020, an argument will be made that if cost was a more serious factor during the ESAS studies, the original program schedule could have been maintained. The counter-argument is that cost-control cannot be used to justify an architecture that does not meet minimum safety requirements. At this point, I believe that NASA can do far more to reduce costs without compromising safety. It begins with a detailed analysis of the baseline mission requirements of how many man-days are required on the lunar surface, and how much volume each crew member requires to make the journey. These requirements are given as Gospel truth in ESAS with little or no justification.

The buck ultimately stopped with him, but Griffin in many ways served as "chief engineer" while forgetting all that is entailed with being an administrator. I would contend that Mike Griffin spent far too much time dictating an architecture to his own employees and then defending it to the world, instead of focusing on letting the engineers develop an architecture which fit within the cost, schedule & performance constraints placed by the nation's leaders. Mike Griffin should have been steering his agency towards meeting its cost, schedule & performance goals. Instead, he took the helm of a stalled Vision for Space Exploration and steered it firmly off-course with his engineers being keel-hauled underneath.

In spite of all the Beltway rumors surrounding the possible choices of the next administrator, I would hope that NASA's next chief comes to the job with experience as a capable manager of successful big-budget programs. His or her success should not be measured by what the changes to the architecture look like, but rather by how much cost and schedule they save the taxpayers.

A Reprieve for SSME?

2009-01-21T17:25:00.000-08:00

Rob Coppinger suggests that the days of the Space Shuttle Main Engine may not be over when the shuttle system is retired in 2010. When the shuttle program ends, there will be a number of engines that have not exceeded their lifetimes. It’s conceivable that a commercial rocket could use them on a single-use basis, although it’s unlikely that anybody would want to sink millions of dollars into developing a rocket if the supply of engines is finite.

Another (remote) possibility is that the SSME’s may find their way back onto the Ares V, as per the original ESAS studies of Summer 2005. The thought of recovering the SSME’s in a fashion similar to that proposed for the Atlas V engines had occurred to me. It’s harder to pull off a recovery of this nature on a cluster of six SSME’s, but it’s certainly worthy of study. It would improve Ares V’s performance to orbit (SSME has higher specific impulse than the RS-68,) but the thrust levels would drop off. The change to a six-engine cluster (versus the five engines on the original Ares V) might help offset that. Conversely, it might allow a switch back to the shuttle-derived 8.4-meter tankage instead of the all-new 10 meter tankage of the current design, and avoid the expense of changing the spacing between the SRB cut-outs on the Mobile Launch Platforms.

On a related note, NASA is looking at other uses of Ares V, especially for science missions. I must admit that the prospect of a massive space telescope, used to spot earth-like worlds around distant stars in our galaxy, is too exciting to ignore. At the same time, it's not realistic to think that Ares science missions will appreciably increase the Ares launch rate and amortize the big booster's massive standing army costs. Big-budget science missions on the scale of Hubble Space Telescope only launch once every few years. The obvious way to double the Ares launch rate is to dump both Ares I and Ares V in favor of two launches of an intermediate-capability rocket. You know, something that looks kinda like Jupiter-232. Or you can further amortize the existing standing army costs for the existing Delta or Atlas rockets by using six EELV's or so per lunar mission. The point is that the inherent fiscal inefficiencies of the Ares system will not be fixed through the addition of an occasional science mission to the manifest. Only a marked reduction in fixed costs or a steep increase in flight rate will make the system more efficient.

Boundary Conditions

2009-01-15T19:20:00.000-08:00

The staff of LaunchSpace wants everybody who cares about the fate of Project Constellation to keep quiet and let the big boys at NASA get on with business of going back to the moon. It's a nice sentiment, if you buy into the belief that NASA is nigh-infallible and that their plan will get us back to the moon with a reasonable amount of time and money.

At the same time, the most visible of the alternatives to Project Constellation is getting exposure in Popular Mechanics and even got a meeting with the Obama transition team. The promoters of DIRECT may see the change in administrations as their best (and perhaps final) chance to salvage Project Constellation from the budget and schedule nightmares that lie ahead.

We have a situation where multiple groups all believe they have the best solution to the challenge of going back to the moon. For what it's worth, twelve industry contractors submitted Crew Exploration & Refinement studies in Fall 2004, and their results were drastically different from either DIRECT or the NASA baseline.

How could fourteen different studies result in fourteen different conclusions about the best way to go back to the moon? The answer can simply be summed up as a difference in assumptions and evaluation criteria for what is truly best. How big of a crew are you sending to the moon? How many days will the mission last? What sites on the lunar surface will be accessible? How much volume does each crew member need in the capsule?

The criteria and assumptions that went into the ESAS study of Summer 2005 have been widely and justifiably criticised. The expendible SSME and air-start SSME which formed the basis of the early Ares designs were unrealistic. It was assumed that the existing Atlas and Delta rockets could not tailor their trajectories to enable aborts during all flight phases. On-orbit assembly and orbital refueling were viewed as highly undesirable, at best. It's enough to make one wonder what other flawed assumptions and judgement criteria went into the study.

While Ross Tierney relied on post-Challenger design studies for his original “DIRECT 1.0” concept, it should be noted that the Jupiter design was independently validated by Stephen Metschan using his FrameWork CT optimization software. FrameWork CT evaluated numerous configurations in a fashion similar to ESAS, but with different ground rules and assumptions. Neither approach is perfect, but I’m inclined to believe that ESAS is heavily flawed based on its low-balling of the cost for the five-segment SRB and other invalid assumptions.

The subjectivity of evaluation criteria is clear from the simple question whether Ares I is safer than Jupiter 120. The answer is conceivably yes, because it has less engines. But Jupiter 120 mitigates this by lighting both RS-68’s on the ground prior to igniting the SRB’s (which have an incredibly reliable ignition system.) Jupiter 120 gives you the confidence that all engines have been tested at liftoff. By contrast, Ares I relies on a staging event in which you hope and pray your second-stage engine ignites. Additionally, Jupiter 120 has more performance, allowing for greater redundancy to be added to the Orion capsule. This is the area where evaluators have to look at the probability of a staging failure on Ares I versus a loss of engines early in the Jupiter 120's ascent, or the probability that extra redundancy in certain capsule systems will allow the crew to survive in an emergency scenario. The analysis of these probabilities, and the weights given to predicted reliability numbers, present plenty of room for the experts to debate until they are blue in the face.

Every design will also possess unintended consequences that must be worked out once it has been chosen. Prediction of these consequences is a reflection of how valid and effective the original design trade was. For Ares I, launch drift and thrust oscillation are the challenges that we’ve bought. Jupiter would certainly have its own challenges, although it’s hard to see them being worse than launch drift or thrust oscillation.

I would like for the next NASA Administrator to call time-out and order a re-evaluation of crew and cargo launch strategies that takes development costs into account with infrastructure and operational costs for the expected duration of Project Constellation (from now until at least 2025.) The agency should look at permutations of all realistic crew launch & cargo launch designs. Examine Ares I, Jupiter 120, Atlas V Heavy, Delta IV Heavy, and Wide-Body Atlas for crew launch. Take a gander at Ares V, Jupiter 232, and a side-mount Shuttle Derived Vehicle similar to Shuttle-C. Take a realistic look at the assumptions which are driving the Orion capsule weight (especially the amount of volume available to each crew member) and the number of man-days the Altair lander is expected to support on the lunar surface.

The Atlas of LC-39

2009-01-12T16:35:00.000-08:00

Sir Sydney Camm famously observed that “All modern aircraft have four dimensions: span, length, height and politics. TSR-2 simply got the first three right.” He was referring to Britain’s stillborn attempt to design a medium jet bomber during the 1960’s, but the same could be said about using Atlas or Delta for space launch during the post-shuttle era. If we accept that NASA must retain government jobs, Atlas & Delta will not be acceptable solutions to the problem of manned space launch after the shuttle retires.

An option I have thought about (and I certainly was not the first) is whether the shuttle’s launch complex could be converted to launch Atlas or Delta rockets while retaining much of the shuttle workforce. Such an option is not economical, from the perspective that it’s not leveraging the infrastructure & personnel investments that United Launch Alliance has already made. But the idea of a NASA-run space launch program is inherently un-economical already.

From a technical perspective, it would not be too difficult to convert the shuttle launch facilities over for Atlas or Delta operations. It was already accomplished once, when the mothballed SLC-6 at Vandenberg was rebuilt from a Titan IIIM pad to a Shuttle pad and to a Delta IV pad. Prior to the conversion for Delta IV, Athena rockets were launched from a specially-designed stand placed over the flame trench for the shuttle SRB. It’s not hard to imagine a single-core Atlas or Delta being supported over an SRB flame-trench at Kennedy Space Center, using a modified version of the current pad’s crew elevator and access tunnel supported from the umbilical tower.

The Atlas V launch pad is designed with the umbilical tower already mounted to the transporter. One would conceivably need to be added to the Mobile Launch Platform if Atlas is flown from LC-39. Delta IV is transported horizontally, so the MLP would need some mechanism to erect the rocket at the launch site. Neither issue is non-trivial. But the alternative of modifying the MLP’s for Ares I also involves significant work.

I can see the Defense Department supporting the idea of establishing separate EELV pads at LC-39. It is always nice to have a backup launch pad in the event that an exploding rocket damages one of the existing launch pads on the east coast (LC-37B or LC-41.) Assuming that Ares V survives the anticipated cuts to Project Constellation, one of the pads at LC-39 will likely be reserved for the new super-rocket. The other launch complex could conceivably be designed for both Atlas and Delta operations, but the Mobile Launch Pads would be drastically different. I would anticipate that only one of the EELV’s will make the cut. My preferred configuration would be a wide-body Atlas with two RD-180 engines on the first stage, but a three-core Heavy EELV would be cheaper from a development perspective.

Recent rumors have indicated that the Obama Administration plans to euthanize Ares I in favor of Atlas, Delta or both. If the rumblings are true, the space community should be warned that the substitution will not be a simple slam-dunk. NASA will have to re-examine its workplace retention issues and its relations with United Launch Alliance. Ultimately NASA will find a way to retain as many existing jobs as possible through re-use of LC-39, regardless of how expensive and unnecessary it may be.

Final Rest

2008-12-30T19:40:00.000-08:00

NASA's release of the Columbia Crew Survival Investigation Report answers the lingering questions in my mind regarding the final moments of the Columbia disaster and what the astronauts must have experienced. Some of the questions arise from morbid curiosity while others are the product of a desire to build better crew survival systems into future spacecraft.

The report paints a picture of a rapidly-snowballing disaster. Control was lost and the orbiter began breaking up less than a minute after Columbia's last radio contact with Mission Control. With the hydraulics lost in the left wing, Columbia pitched into a nose-high attitude prior to ballistic flight and breakup. The crew module depressurized through a fairly small rupture, and the crew would have been unconscious prior to the point where the module completely disintegrated. Depending on how long crew consciousness was maintained, they may have felt the violent tumbling of the crew module as it began a multi-axis rotation after separating from the orbiter.

By concluding this investigation with a lengthy and detailed report, NASA has laid the groundwork for enhancing crew survivability during a re-entry accident. For starters, the parachutes should be rigged to deploy automatically (although, in the shuttle's case, they'd only be used during a subsonic, level glide.) NASA should also quantify the current performance envelope for bailing out while wearing the current ACES suit. Of course, there's no substitute for making the shuttle, Orion, and other spacecraft so safe that the escape system will be irrelevant.

That Other Anniversary

2008-12-14T15:49:00.000-08:00

Every space enthusiast seems to have some way of commemorating July 20th, the anniversary of when humans first walked on the surface of the moon. But few seem to mark that other anniversary: December 14, 1972, when humans last walked on the moon. For all of the jubilation on Apollo's success in landing a man on the moon before the decade was out, there is very little introspection on why Apollo gave us a tease of a space-faring future that has yet to come to fruition.

The success of Apollo can be credited to a well-run program packed with technical and management genius, flush with cash from a cold-war defense buildup. Conversely, the end of Apollo can be attributed to a decline in national will to continue the lunar effort, making it impossible to justify the human risk and national expenditures that were required to continue sending humans to the moon. Even after the risk was reduced and the development costs were sunk, a majority of Americans didn't want to keep cranking out Saturn rockets and launching them to further our understanding of our moon.

As NASA again embarks on the Apollo adventure, the questions of how we will sustain the lunar program have not been adequately addressed. If the cold war wasn't justification enough for a nationally-funded effort at sustained lunar missions, what is? I doubt that the use of NASA as a government jobs program can justify it alone. With regards to keeping people on the government payroll, sustained lunar missions don't have much advantage over, say, a sustained earth-orbital program such as the shuttle.

It's difficult to see Project Constellation sustaining itself beyond a few sortie missions, if it even achieves the lunar goal to begin with. Humans will only sustain a presence on the moon if a profit motive exists to do so. It doesn't matter if we're talking about the United States, Russia, China, or any other spacefaring world power. If the economic justification does not exist, the lunar landings will be an unsustainable stunt. Until a profitable reason to put humans on the moon exists, a sustained human presence on the moon will have to wait.

DynaSoar Extinction

2008-12-09T19:07:00.001-08:00

No single name curdles the blood of space enthusiasts like that of Jeffrey Bell. The University of Hawaii professor and "recovering pro-space activist" often lends a cynical commentary that douses water on the dreams of NASA-lovers and NewSpacers alike. While I can't say that I always agree with Dr. Bell, he crafts a rational argument and often serves to inject a dose of harsh reality into the kool-aid drinkers who deal effective setbacks to space programs by peddling unrealistic fantasies.

In his new piece, Jeffrey Bell strikes back at the “Cult of the DynaSoar,” the aviation enthusiasts who lament the cancellation of the Air Force spaceplane program of the 50’s and 60’s. I will admit that I would probably be labeled as a member of the DynaSoar cult, based on my past polemics about how we needed the X-20, or something like it, to blaze the trail for the operational Space Shuttle. Part of it stems from a desire I share with Dr. Bell, the belief that a small-scale spaceplane demo would have steered decision-makers away from many ill-fated design choices during the Space Shuttle program. Another part of it stemmed from my lack of appreciation for how ineffective the DynaSoar thermal management system was. I didn’t read about the silicon coatings or the liquid hydrogen tank that was essential to keep the cabin cool until Jeff Bell brought attention to them.

Admittedly, DynaSoar was clearly an extreme example of undisciplined requirements creep leading to the death of an acquisition program. Conceived as a suborbital bomber, it evolved through four stages into an orbital spaceplane. The personnel who set goals for the DynaSoar program must have been unaware of the materials science realities of the time. It was a shining example of how a bad acquisition program is run.

If DynaSoar would have served as an example of how not to build a reusable spacecraft, and if the Space Shuttle has served as an example of how not to build a reusable spacecraft, then what approaches are left to try? The shuttle’s thermal protection system is effective but fragile. DynaSoar’s thermal protection system was impractical but robust. But Shuttle and DynaSoar are both examples of what would be called “dense” reentry vehicles. Perhaps the solution is to design a vehicle that carries its propellant tanks to orbit, ensuring that it will have a low wing loading (and low heat loading) when it hits the atmosphere. It would be able to get away with a robust metallic thermal protection system because it would be so “fluffy” that heating would be reduced. That was one of many goals in the X-33 program. And because I brought up X-33, that will undoubtedly be the subject of Jeff Bell’s next polemic.

The Incredible Shrinking Orion

2008-11-29T09:45:00.000-08:00

The NASA transition team is asking the agency to look at several options in order to craft the Obama Administration's space exploration policy. To wit, these options include:
1. Acceleration of Ares & Orion
2. Cancellation of Ares I while retaining Ares V
3. Shrinking Orion to fit on an Atlas V or Delta IV
4. Shrinking Orion to fit on a foreign launcher (H-2A or Ariane 5)
5. Accelerate COTS-D (SpaceX Dragon, perhaps other vehicles)

Before discussing any of these options, it's worth asking the question of how big Orion needs to be in the first place. While the ESAS report cited 22.5 tonnes and a diameter of 5.5 meters (later reduced to 5 meters,) there is no discussion of exactly how much volume a crew needs for a lunar mission, and the diameter seems to be an arbitrary number with zero justification. My preference is to look at historical examples (chiefly, Apollo,) and use that to determine the requirements for the next manned spacecraft.

The Apollo capsule had a diameter of 3.9 meters and afforded a 3-man crew an adequate amount of room for a two-week lunar voyage. That same volume was adequate to deliver a crew of five or six on a shorter trip to Skylab (as studied during the Skylab rescue planning and the shuttle escape study.) For earth-orbit missions, Apollo weighed as little as 14.7 tonnes. For lunar missions, the additional consumables and propellant brought that weight to 30 tonnes. Apollo also required nearly seven years to move from contract award to first manned flight.

In ESAS, NASA dismissed the stock Atlas and Delta on the grounds of crew safety during mission aborts. While those fears were shown to be spurious during the Atlas man-rating study performed by Lockheed Martin, the performance of both rockets leaves much to be desired. NASA should budget no less than 30 tonnes for Orion. While the new spacecraft won't need propellant to perform a lunar-orbit insertion burn, and it trades the mass of fuel cells for lighter solar arrays, the capsule will need to be heavier to accomodate a larger crew, and the spacecraft will have to carry more consumables.

If Orion shrinks to the point where it can fly on an existing launcher, the lunar goal will be deferred or cancelled entirely. Perhaps a two-man Orion would be light enough to launch on an EELV and still be capable of a lunar journey, at the expense of higher crew workload and diminished science return from a lunar sortie.

Most disturbingly, if Orion is limited to earth-orbit missions, it destroys the rationale for Dragon and COTS-D. What incentive will NASA have to buy commercial launches for ISS if Orion does the job? While Bob Bigelow's space hotel plans might give SpaceX some incentive, the real near-term prize is COTS-D. The chicken-and-egg dilemma here is that a COTS-type vehicle must be ready before the Bigelow space hotel can go into operation.

Getting back to the meat of the post, I wanted to take a quick look at the four scenarios being examined by the Obama transition team:

1. Acceleration would be difficult to achieve with the existing Ares and Orion vehicles. It may have to come at the expense of testing, which is rarely a sound strategy (except in the case of all-up testing in Apollo.) Based on the 2006 contract award for Orion and a seven-year development time, we can't expect the capsule to be ready for manned flight any sooner than early 2013. That figure is optimistic, assuming that Orion is at a similar level of completion to where Apollo was in early 1964. An infusion of added cash into Ares and Orion will probably not accelerate the schedule; rather, they will serve to prevent the schedule from slipping further to the right as unanticipated problems rear their ugly heads.

2. This is my favored option, when paired with #5. Ares I will take too long to develop and has no real chance of closing the gap. Ares V and Orion can be kept going as a jobs-retention program. Perhaps NASA can adopt a two-Ares V mission profile, avoiding the tight mass margins currently encountered by the current architecture.

3. Again, I think there's nothing to be gained by stripping Orion down to the point where it can no longer perform a practical, safe lunar mission. The EELV option should be a non-starter.

4. The foreign launchers option is an interesting one, even though it suffers the same flaws as the Atlas/Delta option. It's interesting to note that Ariane 5 was designed with a manned spacecraft (the Hermes spaceplane) in mind. Even if the foreign boosters had the performance required to lift Orion in its current form, I think that "not invented here" and jobs-retention issues will scuttle the idea.

5. As many NewSpacers have pointed out before, the most cost-effective use of manned spaceflight dollars would be cancelling Ares I and using the savings to fund the unfunded COTS-D program. If I were advising the president-elect, this is exactly the advice I'd give him. An accelerated Dragon program gives America the best shot to have a manned spacecraft flying by 2012 or 2013.

I'd also recommend keeping Orion, Altair and Ares V going at a slower schedule and a lower spending profile until "the gap" was closed. At that point, a decision could be made on whether to proceed with manned lunar missions. NASA could retain "Apollo on Steroids" using two Ares V's per mission, or an "Apollo Redux" which would perform a more limited mission with a single Ares V launch.

Air Launch Revisited

2008-11-22T12:24:00.000-08:00

The Selenian Boondocks blog has, since its inception, been one of the best sources for discussion of space transport ideas on the internet. Some of the ideas have been downright inventive, while others have only been shot down after much serious discussion. Nevertheless, it represents the kind of thinking we need to truly solve the problems of making space access routine and affordable. While already a great blog under the meticulous care of Jon Goff and Ken Murphy, Selenian Boondocks just got even better with the addition of John Hare to the team. Hopefully he will dispel the notion of a “Hare-brained” scheme as a bad thing. (Pardon the pun.)

My eye was recently caught by a discussion of an optimized carrier aircraft to serve as the first stage for a reusable launch vehicle. During Jon Goff’s previous air-launch discussions, I came out in favor of using unmodified military cargo planes for air-launching small vehicles with scissor-wings. While I still favor this idea based on tight development budgets, discussion of an optimized mothership has merit if somebody is willing to pay for one.

It should be noted that the most successful mothership in recent memory, the Lockheed Tristar operated by Orbital Sciences, was chosen because it was cheap to obtain second-hand, and because it had fairly tall landing gear which allowed for adequate ground clearance. While the option exists for captive-carry on top of the mothership, it has fallen out of favor because of incidents like the D-21 collision with its Blackbird mothership. While the idea worked for the Enterprise glide testing, it’s probably a much different story if the separation involves igniting a rocket.

John Hare’s idea for a “flying wing” mothership does have some historical basis. One of the Northrop-Grumman concepts for Space Launch Initiative, released in 2002, used a six-engined flying wing as its first stage. A large winged rocket would provide most of the delta-V from subsonic cruise to orbit, and the crew would ride in a small lifting body. The biggest problem with the design is the amount of money required to develop it. The second biggest problem is whether the large winged rocket could accelerate from Mach 0.8 to orbital velocity, especially when burdened with the structural requirements of its own wings and landing gear. Problem three is how you’d get the winged rocket back to base after it’s expended all of its propellants.

One of the big assumptions here is that the mothership need only carry the vehicle to a speed around Mach 0.8. In fact, Boeing twice patented a two-stage system with a supersonic mothership. The 1982 iteration used eight turbojets, while the 1993 version used six. Both designs made use of a Space Shuttle Main Engine for acceleration during climb, prior to staging. The mothership would be nearly 200 feet long. The problem is that multiple studies have shown that subsonic launch is a pretty efficient solution. The challenges of supersonic flight erode the benefits of a higher separation speed. Supersonic launch doesn’t break even with subsonic launch until hitting mach 3 or higher. The Boeing idea isn’t bad if your goal is to ignite a scramjet, but it seems like engineering and budgetary overkill for the space launch problem. The primary benefit of the Boeing patents was their addition to the lore of mythical craft like Aurora and Blackstar.

The challenge of a custom air-launch system is the need to develop both the rocket and the mothership aircraft. Systems that have utilized existing aircraft for motherships have been able to spare themselves the development of one element of the system. But the inverse paradigm has not been attempted: use of a newly-designed mothership aircraft to boost the performance of an existing rocket. Structurally, this may not be feasible due to the changes to bending and other loads encountered by the change to air launch. At the same time, it has been studied before (such as the Crossbow concept) and is worthy of further consideration. Even though the payload boost may be small, it reduces the facilities costs and the weather-related delays that have accompanied traditional ground-launched rockets. Air-launch makes space launches more flexible in terms of launch azimuths, launch sites, and reduced launch delays. The concept's advantages should draw the interest of the Defense Department as a solution to the problems of Operationally-Responsive Space.

The Shuttle Legacy

2008-11-11T11:04:00.000-08:00

When Project Apollo was shut down, the most tragic aspect of it was all of the useful technologies that were lost as tooling was destroyed and experts were reassigned to other programs. The mighty F-1 engine was relegated to museums, ceding the kerosene-engine market to the Russians. The demise of the J-2 engine has led to an expensive development program for the new J-2X that will be used on the Ares launchers. Even the exact formulation and processes for creating the Apollo capsule's ablative heat shield were lost to time, complicating the effort to develop the Orion heat shield.

As the Space Shuttle winds down, it appears that the same mistake is not being repeated, at least not on the same scale. In taking stock of the program's technical accomplishments, many of them are being preserved or leveraged for the Ares and Orion systems. Of the ones being discarded, they have served as lessons for ways that a reusable launch vehicle should not be built.

When NASA transitioned from Saturn to Shuttle, significant propulsion elements had to be re-developed. While Space Shuttle Main Engine owes a lot to the J-2 program, it is a much bigger engine with higher specific impulse and thrust, a more complex staged combustion cycle, and built-in reusability. The solid rockets were a massive undertaking in many ways, eclipsing any solid rocket with flight history up to that point in time.

Some elements of the propulsion system will remain relevant for the Ares generation. The shuttle solid rocket boosters will be leveraged for the boosters on the Ares rockets. While the new boosters are a leap beyond the current SRB, it's not as far of a leap as the original SRB was when compared to its predecessors. Additionally, the shuttle's maneuvering engines are being re-used for Orion. This may be the only element of the shuttle system that is reused with no changes.

For other shuttle developments, they will best serve as lessons learned in the development of equivalent systems. Perhaps the shuttle's most remarkable achievement was its main engines. Nevertheless, the SSME's taught us a lot of the ways not to design an engine for producibility or reliability. The high chamber pressure and staged combustion cycle ensured high performance, but required lots of ground support equipment. Thousands of tiny welded tubes in the nozzle and chamber for cooling? It was state of the art for the 70's, but channel-wall cooling is the preferred method nowadays. The RS-68 benefited from the lessons of SSME, sacrificing specific impulse in favor of producibility. Its gas-generator cycle, lower chamber pressure, and channel-wall chamber with ablative nozzle make for a much cheaper engine. Its only drawbacks when compared to SSME are specific impulse (which can be increased with a redesigned injector and regen-cooled nozzle) and lack of reusability. In fact, a channel-wall nozzle was planned as a shuttle upgrade until the program's 2010 retirement was announced.

At the same time, a lot of the shuttle's pioneering achievements in the field of re-usability are being discarded as dead-ends which taught us how not to build a reusable launcher. Case in point is the shuttle's thermal protection system. While the blankets will likely find use on the cooler surfaces of a future reusable launcher, the other heat shield materials will likely be dismissed. The ceramic tiles still are remarkable, but they form a complex system that is difficult to maintain. Reinforced carbon-carbon had incredible abilities to stand up to high temperatures on the shuttle's nose cap and leading edges, but they were too brittle to reliably ensure safe reentry. A future reusable launcher will likely be a "fluffier" design along the lines of X-33, which can get by using a robust, metallic thermal protection system.

Overall, NASA and the industry are taking a wiser approach to the end of the shuttle program than was taken at the end of Apollo. Many critical technologies are being reused, albeit in expendable rockets. The clear succession from Shuttle to Ares is mainly in the field of propulsion, where breakthroughs during the shuttle's development have reduced the risk for Ares. The enduring challenge from the shuttle program is to learn the correct lessons from the reusability concepts that proved so difficult to implement on the operational shuttle.

Reports of The Stick's Death Are Greatly Exaggerated

2008-11-06T20:06:00.000-08:00

The speculation of Rocketman notwithstanding, I don't think that the recent election will have much effect on the development of the Ares I launch vehicle and Orion Spacecraft. Anybody who claims otherwise is broadcasting wishful thinking to the rest of the world.

There are many reasons why I believe that Ares I will continue to plod along. Most prominently, it's a jobs-retention vehicle. The political impacts of shutting down the shuttle facilities and laying off the workforce will make any politician think twice. The political ramifications of Ares cancellation would be felt prominently in Florida, Louisiana and California. While President-Elect Obama was able to win without the support of Louisiana or Florida's Brevard County (home to Kennedy Space Center,) I still doubt that many politicians want to tell thousands of people that they're getting laid off.

While shuttle program extension is talked about, particularly by the GAO, there's no compelling reason for adding any more missions to the current manifest (aside from the possibility of an Alpha Magnetic Sprectrometer mission, STS-134.) I do accept the possibility that unexpected delays will extend the current manifest to 2011 or even 2012. But the shuttle's lack of lifeboat capabilities ensures that it will not fill the gap.

At this point, we have no idea who the new administrator will be, or what his or her whims are. For all we know, the President-Elect might convince Michael Griffin to stay aboard. Much more will be known once the NASA Administrator situation shakes out.

The biggest threat to Ares I comes not from the next president or next administrator, but from Elon Musk and his outstanding team at SpaceX who are working on the Falcon IX rocket and Dragon spacecraft. The American public will be justifiably angry if a private firm like SpaceX can launch a manned, orbital spaceflight on a shorter schedule and smaller budget than NASA received for Ares-Orion. The shock of such an event might be able to overcome Congressional resistance to changing the NASA status-quo. It really doesn't matter to the public or Congress if Orion is a more able spacecraft capable of lunar flight. The spiral-development model should have taken this into account and worked on closing the gap first, worrying about the moon later.

While Ares V, Altair, and lunar hardware are a distant future whose continued funding is verymuch in doubt, it's clear that Orion and Ares I have significant momentum heading into the next administration. At this point, only a Dragon can break The Stick.

Morale Stops Here

2008-10-22T18:07:00.000-07:00

Michael Griffin blames anonymous weblogs, critical of Project Constellation, for harming the morale of NASA engineers. Further, he claims that engineering disagreements between NASA insiders and the weblogs have escalated into personal vendettas. The message of the strawman argument is that bloggers should just shut their mouths and let the big boys get on with the serious business of Project Constellation.

I don't know if Mike Griffin has ever known how it feels to be completely demoralized, but I feel demoralized on a daily basis. I have also seen firsthand the ways that professional disagreements over engineering judgments have turned into passive-aggressive behavior in the workplace. There is no virtue in schadenfreude, and I certainly don't wish those things upon anybody. With that being said, none of my experience can be attributed to anything I've read in a weblog (although there's plenty of intelligent criticism to go around.)

In my years as a critic of Mike Griffin's NASA, I have never intended to criticize the engineers who have been tasked to make this plan a reality. They're doing the best they can with the plan they were handed by their management. The engineering staff at NASA-Marshall and the other NASA centers who are working Project Constellation are putting in long days and making great personal sacrifices in order to ensure the success of the Constellation program.

While my critics may disagree, I have no personal vendetta against Mike Griffin, either. I don't think he's done anything illegal, immoral, or scandalous. I'm convinced that he believes 100% in Project Constellation as he's implemented it. The problem is one of vision, and one of pride. Mike Griffin had his own vision for how to implement the Vision for Space Exploration, and his agency rushed a 60-day study based on multiple flawed assumptions. While the Griffin vision is now the law of the land, many of us are disappointed. We want to believe in things like afforability and sustainability. We haven't seen any evidence that "Apollo on Steroids" will be able to avoid the same fate as its namesake.

NASA's engineers are smart people, and they're plenty capable of making their own value judgements about the programs they work on. They don't need anybody's blog to help them make an educated decision. I want NASA’s engineers to be happy. If working on Ares makes them happy, they should keep plugging away. If they can’t stand the work they’re doing, they should try to get reassigned, or find a job outside of NASA that's more rewarding.

Along similar lines, I have made my own value judgments about the worthless nature of the work I have performed for the US Air Force. This miserable experience has soured me towards the engineering profession, the aerospace industry, and government bureaucracy. Next August I bid the Air Force "good riddance" and look for a non-engineering job that promises a rewarding experience of immediate benefit to humanity.

Over the last few months, I have kept a lid on criticism of the Ares I configuration, which should make Mike Griffin and his engineers happy. Fighting The Shaft is futile, as Ares I has progressed far enough where it will probably survive into the next administration. The argument should not be over whether it should be killed, but on ways to make it as safe as possible. But ending all criticism of the Griffin plan won’t fix the problem of NASA morale.

The morale of engineers is directly tied to the work they are given by their management. If you want to keep engineers happy, give them tasks that are worthy of their efforts. When management fails to do that, they have nobody to blame for poor morale but themselves.