Chair Force Engineer

Friday, February 29, 2008

Quick-Fix Tankers

Much like the New York Giants slaying the dastardly Patriots, Airbus has beaten Boeing to build the Air Force's KC-45 refueling aircraft. The European consortium's A330 has emerged over the Seattle-based juggernaut's 767 like David Tyree clutching the football to his helmet while soaring over Rodney Harrison.

I can't speculate much on the selection of the A330 aside from the fact that it's a bigger plane than the 767, capable of refueling more aircraft per mission based on its larger internal reserves. Regardless of the Air Force's final decision, both planes represent a "quick fix" buy of old technology to fill an urgent requirement to replace aging KC-135E's.

While the current contract is potentially worth 179 aircraft, I hope it is capped well before that point. It should allow the Air Force to meet current operational needs while retiring the tired KC-135E's. In that sense, Boeing's original offer of a lease back in 2002 makes sense. The Air Force really needs to look ahead to the next generation of airliners and acquire an airplane that has a lower lifecycle cost than current jumbo jets.

The 787 will soon be gracing the skies, promising 20% less fuel burn compared to the 767. Airbus's A350XWB will offer similar advantages. While the Air Force of the 1950's was ambitious enough to sign on to the KC-135 before its civil equivalent (the 707) took flight, the service has taken a much more cautious approach to the next-gen airliners. With the need to replace aging KC-135R's becoming more apparent, a bit more urgency in starting a "KC-787" program becomes all the more prudent.

The Real Space Race

Recent advances in manned spaceflight (the Chinese manned program, the birth of commercial manned spaceflight, and NASA's challenge to travel to the moon and beyond) has prompted some observers to claim there is a new "space race" going on. President Bush, in unveiling his Vision for Space Exploration, likened it to a marathon rather than a sprint.

The question I pose to the people who use the term "space race" is whether this is a race between competitors, or merely an individual quest for personal achievement. This cannot be viewed as a Cold War analog of the USA versus China, because the Chinese program is plodding along at an even slower pace than the US program (and admittedly has much farther to go than the US program.)

The real race, in my estimation, is one of the US Government versus the US private sector. The dreams of lunar spaceflight probably have an even chance of being wiped out within the next year, depending on the way the political winds blow in Washington. But neither political party really wants to kill manned spaceflight (albeit one constrained to flight in earth orbit.) In the absence of a lunar goal, the scramble for funds will be a heated contest between NASA's Orion and SpaceX's Dragon.

SpaceX's current manifest calls for completion of their test series for their Commercial Orbital Transportation System to conclude by 2010. This does not include manned flights, but certainly sets the stage for them in the near future. I am not so naive as to believe that SpaceX's schedule will hold, and they will fly a human in space by 2010. But even a four-year delay is enough to beat NASA's current schedule for a manned Orion flight.

NASA's pacing item in the Ares-Orion development schedule is the development of the J-2X upper stage engine. What was supposed to be an Apollo-heritage engine has turned into a largely-new development that is forcing America to accept several years of making its astronauts ride on Russian rockets.

In a true competition for transporting astronauts to low earth orbit, NASA would be beaten hands-down by SpaceX at this stage in the game. SpaceX has a capsule with more astronauts (seven versus six,) a cheaper booster (Falcon 9 vs. Ares I,) and a faster schedule.

Imagine for a second that you're a Congress-critter. You can't get past the giggle-factor associated with landing a man on the moon, but you don't want to look like the Luddite who kept American astronauts grounded. So you've got to pick a system for sending your astronauts to the space station. Do you pick the privately-developed system which carries more astronauts, costs less to operate, and gets America back into orbit faster? Or do you keep shoveling money at the government-run program? The only thing NASA has going for itself right now, aside from the fading lunar dream, is the political implications of laying off the thousands of people whose jobs rely on NASA's manned spaceflight program.

If NASA is prohibited from flying to the moon, there will truly be a space race within the United States. And if NASA continues to fund COTS, it will be hoisted by its own petard.

Monday, February 25, 2008

Going to Pieces

The destruction of USA 193 by a US Navy SM-3 missile and LEAP impactor has worked a lot of people into a tizzy, for what is a tempest in a teapot for all intents and purposes.

On the US side, there was a lot of hype and hysteria about the spacecraft's fall from orbit and the consequences. There were several concerns about classified hardware surviving atmospheric entry, or the damage that could be caused by falling debris, or the health hazards posed by dispersion of hydrazine.

The most interesting aspect of this was the large quantity (estimated to be one ton) of frozen hydrazine that was expected to be entering the earth's atmosphere. I don't recall any spacecraft entering the atmosphere with such large quantities of frozen hydrazine aboard. The situation was unique in that the spacecraft had been powerless on-orbit for over a year, and the propellant was frozen solid. I'm not aware of any entering spacecraft going through similar conditions with such a large propellant load. The ballistic coefficient of the propellant tank(s) might be sufficient so that some quantity of the propellant could survive into the lower atmosphere.

While I can't say who the source of the hype over USA 193 was, it stands to reason that the news media has a duty to serve as a fact-check and defuse unjustified fears. But the history of news reporting in this country gives no reason to be so optimistic. The incredibly small risk that anybody would be harmed was definitely overblown in the media, and the testimony of experts in downplaying the risk was insufficient to stop the story from spiraling out of control.

Of course, the usual suspects (Russia & China) balked at the prospect of shooting down USA 193. The predictable complaints about the militarization of space were aired. But it must be emphasized that destroying a satellite in a low, decaying orbit does not represent the capability to destroy a satellite in a higher, stable orbit. The risk to other spacecraft was minimal as the debris largely continued to dip through denser regions of the upper atmosphere as it passed through perigee.

Moreover, the domestic missile-defense critics claimed the missile shot would not work. The destruction of USA 193 is also very different from missile defense tests. While satellites travel faster than reentry vehicles, their flight paths (or orbit tracks, in the satellite's case) are far more predictable and can be known with great precision several days from the planned intercept. In the case of shooting down USA 193, it was sufficient to launch the LEAP interceptor to the precise point in space at the precise point in time when USA 193 was expected to be there. It should be noted that the LEAP vehicle required new sensors which may not have any application to operational sea-based missile defenses.

The death of USA 193 is another strange twist in a secretive but tragic MilSpace story. The satellite's early failure was a massive waste of taxpayer dollars. Its death was a spectacular display of capabilities, but it may not have any military relevance.

Tuesday, February 19, 2008

I'm Full of Bull

My cynical prediction from earlier about NASA's choice for COTS hasn't come to fruition. But I'm happy that NASA made the right choice (in my view) by picking the Orbital Sciences team and their Taurus II launcher.

Orbital has never been a company to fit within a paradigm. They're too big to be considered "NewSpace" but too young and too small to fit in with the major aerospace giants. Likewise, Taurus-II is a paradigm-breaking vehicle. The engines were built for the Soviet lunar program but never flown. The tanks have heritage with the Ukrainian Zenit launcher. The upper stage is an all-new solid from ATK. It's a Delta II-class vehicle designed from the ground up with low costs in mind. Even the launch site (Wallops Island) breaks the business-as-usual paradigm.

In teaming with Alenia Spazio, Orbital hopes that the Cygnus spacecraft will be able to deliver and return cargo to and from the space station. My biggest question is how Orbital's team plans to provide thermal protection for Cygnus when it re-enters the earth's atmosphere, and how they intend to recover it after the mission is complete.

The selection of the Orbital team and the Taurus II + Cygnus system represents a bold gamble by a firm that has pulled off its fair share of tech miracles. While Orbital has a recent reputation for being risk-averse, the new vehicle hearkens back to the Pegasus days. I still think it represents less risk than Falcon 9 + Dragon (which admittedly has more performance potential than Taurus-II + Cygnus.)

NASA's COTS officials have also shown excellent judgement in their selections for COTS. The original pair of COTS contenders (Falcon 9 and K-1) was a mixture of moderate-to-high risk and extremely-high risk. By dropping Rocketplane-Kistler and picking up Orbital (although sticking with the same first stage engine, as fate would have it,) NASA traded a lot of risk for the experience of a seasoned team.

I wish the best of luck to both SpaceX and Orbital in engineering the future. America is going to need COTS sorely as the shuttle era draws to a close.

Sunday, February 17, 2008

A Solid Prediction

NASA will make an announcement this Tuesday, Feb 19, on which company or companies will be selected to receive the COTS funds vacated by RocketPlane-Kistler.

I'm going to go out on a limb and suggest that the PlanetSpace-LockMart-ATK team is going to get COTS money out of Tuesday's announcement. I'm not going on any insider info, but on very sound guesswork.

You see, ATK is smart, and they know the Ares solid rocket boosters are going to need a heck of a lot of development beyond what currently exists on the Space Shuttle. So they've designed a rocket, informally called Athena III, which uses an expendable "2.5-segment SRB" first stage.

Let's assume for a minute that ATK develops a new casing for their SRB using the COTS money received from NASA. A composite or filament-wound casing would probably not be reusable, but it would offer improved performance margins over the existing SRB casing. It would also help in damping the vibrations created when the SRB burns (which is currently the biggest technical risk facing the Ares I program.) So even if COTS never delivers a single kilo of payload to the space station, NASA is still going to see some benefit if ATK's team gets a COTS contract.

That's not to say that all will be rosy in Ares-land if ATK creates an expendible SRB casing. By throwing the casings away, the inherent safety that comes from retrieving the SRB's and analyzing their performance will be lost. Perhaps composite or filament-wound casings could be fished back from the ocean, but it's likely they will be damaged beyond repair (and probably be mangled beyond recognition.)

That's just my interpretation on NASA's reasoning going into the COTS selection. I've been burned in many of my predictions before, so don't be surprised if I get burned again.

Tuesday, February 12, 2008

From the Moon to Mars

This week, dissident scientists and space explorers meet at Stanford to discuss alternatives to NASA's mission of sending humans to "The Moon, Mars and Beyond." The group seems to have coalesced around the position that the Moon is an unneeded detour on the road to Mars, and prefer manned asteroid missions as precursors to a human Mars mission.

As critical as I have been of NASA during the "ESAS period" of exploration, I think the agency's priorities are in the right place. While Mars offers more benefit than the moon in terms of both science and exploration, I think there is still much to be gained from the Moon. (This should come as a surprise to the people who knew me in my younger days, as I used to be a hardcore disciple of Bob Zubrin and his Mars-first agenda.) I also believe that asteroid missions are a worthwhile pursuit during Project Constellation, but they pose many challenges beyond the complexity of manned moon landings. The moon is in our own backyard, and it should be the first step in a logical plan of exploring the solar system.

When the Vision for Space Exploration was first rolled out in Early 2004, I recognized that a "Moon first" approach ran the risk of establishing a "lunar quagmire" that would prevent NASA from later flights to Mars. I didn't think that the "Lunar Quagmire" was inevitable, but I knew that NASA had to be smart about its lunar plans in order to avoid it. I could forsee two approaches for avoiding it:
1) Develop a lunar architecture with obvious applications to Mars in future development spirals
2) Deeply involve the private sector in lunar missions, so they can take over the lunar base when NASA has progressed to Mars

As Bob Mahoney notes in his recent The Space Review article, NASA has done a poor job demonstrating how the ESAS architecture could be extended to Mars. Not that it can't be done, mind you. SpaceWorks Engineering did a study showing how Ares I, Ares V and Orion could be used for human missions to Mars. Unfortunately, the SpaceWorks architecture comes with a steep price tag and a high pucker-factor. Still, the applicability of a heavy-lift rocket and capsule to Mars missions is a sound idea.

One of the ideas presented in ESAS that I was actually fond of was the use of methane and oxygen propellants for the Orion service module and Altair ascent stage. Unfortunately, methane propulsion was one of the first things thrown out of ESAS due to its long development time. But cryogenic methane and oxygen do have applicability to Mars (because they can be produced in-situ,) and they offer better performance than storable propellants. Unfortunately, NASA has been reluctant to address the problem of long-term cryogen storage in space, an unresolved issue that could pay off with huge dividends in the long term.

It remains to be seen if any of the Altair hardware is applicable to a Mars mission. There's a vast difference between a cabin that can support four astronauts for seven days on the moon, and one that can support at least three astronauts for nearly 600 days on Mars. Further, is there anything from the Altair ascent & descent stages that can be applied to a Mars lander or ascent craft? Probably not, especially if Methane & Oxygen propellants are produced on Mars.

In The Case for Mars, Bob Zubrin suggests that his "Mars Direct" architecture could be used with minimal changes to support moon missions. The logic behind this is a bit dubious, as safety would dictate the astronauts travel in a craft capable of both direct landing on the moon, and direct ascent from the lunar surface to earth. A heavy-lift rocket in the same class as Saturn V could only deliver a two-man, direct-ascent spacecraft to the moon.

While such an architecture would not be very mass-efficient, it does have some unique operational benefits. The descent stage of the manned lander could also be applied to a long-duration lunar habitat. Such a habitat would enable longer surface stays than the cabin launched as part of Altair. While only two crew would arrive initially, one or two more direct landers could drop off additional astronauts to man the lunar surface base. Further, the long-duration lunar habitat would retire a lot of the technical risk facing a Mars habitat.

Admittedly, I'm more a fan of L1 rendezvous for human lunar missions. I'd eventually like to see propellant production on the lunar surface, and reusable landers shuttling humans and cargo between an L1 station and the lunar surface habitat. While such a task should be left to the private sector, there's nothing stopping NASA from adopting L1 rendezvous for the first generation of Constellation missions.

Still, the use of direct landing and surface rendezvous deserves to be explored in greater detail. While an Ares I and Ares V might be able to launch four humans to the moon for seven days on the surface, two Ares V's could put two humans on the moon for a much longer span. For a fairly low marginal cost, a third Ares V could deliver two more humans to the same lunar surface base, establishing the same crew size as the baseline ESAS architecture (with significantly more time on the surface to explore and perform research.)

Many Americans look at the moon and think "Been there, done that." The public needs to see why a lunar return is worthy of their tax dollars. Tying it into the success of a Mars mission is an important part of NASA's public relations campaign (and an aspect that NASA has not handled well.) If NASA can't "sell" the idea that its architecture will help us get to Mars, it should look ahead and tweak it, in order to bring the Red Planet a little bit closer to our reach.