|dan (67) myron (1) rich (61) shiloh (4) :: Contact|
Fri, 29 Dec 2006
NASA Goes Back To The Future
The latest Space Shuttle mission (STS-116) is back on the ground again after delivering supplies, equipment, and crew to the International Space Station. Preparations for the next launch (scheduled for March 2007) are already underway. The ISS itself continues to orbit the globe, changing crewmembers every three to six months, its ongoing assembly still several years from completion.
But the buzz around the aerospace community is not so much about the shuttles, or the ISS, or the couple of dozen robotic missions NASA currently has underway. Instead, the focus is quietly but perceptibly shifting to NASA's "next big thing": the Constellation program, a manned program designed "to take us back to the moon, then to Mars, and beyond", as the NASA spokespeople like to put it.
So just where did the Constellation program come from, and what's it all about anyway?
Project Constellation had its origins in the aftermath of the loss of the shuttle Columbia in February 2003. President Bush directed NASA's Administrator, Sean O'Keefe, to investigate the accident and understand its cause as quickly as possible. But the President was also concerned about NASA's future. He did not want to see public and congressional support for the space program completely disappear, nor did he want to put at risk the thousands government and contractor jobs NASA made possible (not to mention the several billion dollars a year NASA spends to do its work). Bush did not think very highly of the agency and how it operated -- he had seen the not-even-half-hearted efforts NASA made to work on the space initiatives proposed during his father's administration, and so believed that some radical restructuring of the way NASA did business was in order. "You've got to save your [NASA's] reputation, but don't break the bank," he reportedly told O'Keefe.
As O'Keefe kept the White House informed on the progress of the Columbia accident investigation, informal discussions between NASA brass and White House staffers began on future space initiatives. By the summer of 2003, Vice President Cheney chaired a formal committee with representatives from key federal agencies -- Defense, State, the CIA, NASA, and (importantly) the administration's Office of Management and Budget (OMB) -- which met weekly to review the possibilities for future space programs and to try to reach consensus on what should be done.
Somewhat unusually for a government committee, a consensus did indeed emerge from these meetings. A resumption of manned lunar exploration was agreed to be the core task of the new program. The Apollo program had been put together on somewhat of a "crash" basis, doing only what was absolutely necessary to achieve President Kennedy's goal of successfully accomplishing a manned lunar landing by the end of the 1960s. As such, expediency was its byword, and a fair amount of the program's eventual $24 billion cost was due to working against its tight time constraints. As far as Cheney's committee was concerned, Apollo's biggest drawback was its short-term focus -- NASA had no real plans for what to do next with all the Apollo hardware and technology after the initial moon landings were completed in 1972. (Skylab, and the Apollo-Soyuz Test Project with the Russians were mere afterthoughts, ways to use up hardware already paid for and built, and two complete, flyable Saturn V launch vehicles wound up as display exhibits at the Kennedy and Johnson Space Centers after budget cuts forced the cancellations of Apollos 19 and 20.) Returning to the moon would require the development of new, more advanced space technologies, as the goal would be not for two astronauts to explore for two or three days at a time, but for larger crews to stay for much longer missions. The committee believed that this approach was both affordable and, more importantly, sustainable. As more experience was gained in longer stays on the moon, the knowledge gained from these missions would allow the technology to be incrementally improved, leading over time to the development of a permanent lunar base, and eventually manned missions to Mars -- depending on how well things went, and how much it turned out things cost, of course.
Another important consensus the committee reached was to try to make maximum use of existing resources and programs, as a way to attempt to control costs. In an earlier article, I've noted how NASA always seems to get itself into trouble when presented with a blank sheet of paper and a less-than-Kennedyesque specific mandate. While much of the technology involved would be new, the committee felt that a deliberate effort to take advantage of what was already available would be important to keep the designs from going off on speculative tangents.
By the fall of 2003, the OMB was asked by the committee to develop a series of budget recommendations for next 5 to 15 years. They called for a ceiling on budget increases for NASA of 5% a year for 2005 through 2007, and about 3% a year for 2008 through 2010. While these would be the largest sustained budget increases NASA had been given in more than a decade, by themselves they would not amount to anywhere near enough money to fund the whole Moon-Mars exploration initiative. The rest of the money would have to come from restructuring and cutting within NASA itself -- and there were only a small number of major projects available that could possibly be cut to free up the billions of dollars required.
Seeing no real alternative, and looking to refocus NASA's energies in new directions in any case, the committee recommended that the two biggest expenses in NASA's current budgets -- the shuttle and the International Space Station -- be terminated. The shuttles would continue to fly to carry out the job of completing the construction of the ISS. The station would be completed by 2010, and the shuttle fleet would be retired as soon as that task was done. NASA plans for new vehicles to reach low earth orbit, including the hypersonic Orbital Space Plane, would be dropped, as would the spending currently underway as part of the Next-Generation Launch Technology program. Instead of a shuttle successor, Russian manned Soyuz and unmanned Soyuz-TM spacecraft would keep the ISS resupplied and crewed in the interregnum between the last shuttle flight and the launch of a new spacecraft called the Crew Exploration Vehicle (CEV), whose role would be akin to the Apollo Command and Service Modules in the new lunar missions; the CEV would initially serve to bring supplies and crews to the ISS.
While the ISS itself would continue to fly (since the U.S. is under international obligations to Russia, Japan, and the European Space Agency to do so), the research carried out there would be refocused from simply maintaining a permanent orbiting outpost ("Being there for the sake of being there," as one wag put it) to specific projects to investigate how long-term exposure in space affects astronaut health and capabilities, as well as developing countermeasures for any problems discovered in the course of the investigations. These findings would be fed into the ongoing manned lunar and Martian exploration programs. In addition, most or all of the physical science studies that would have been carried out on the ISS would be cancelled. Finally, NASA would end its involvement with and use of the ISS around the time that the new series of lunar landings would begin, around 2014 or 2015.
Cheney's committee met with President Bush on December 19th, 2003 to present and discuss the plan. Reading through it, Bush turned to his staff and asked, "This is about more than the moon, isn't it?" Cheney replied that this was a plan for exploration, not a way to reach a particular destination. Another member of the committee added that in order to accomplish the plans goals, NASA itself would have to be reinvented from the ground up. "Let's do it," Bush replied to the group.
On January 14th, 2004, President Bush, with NASA Administrator O'Keefe standing nearby, announced the committee's results as the national "Vision for Space Exploration". Manned exploration of the solar system became the central rationale for NASA's programs.What's It All About?
Since the president's announcement in January 2004, plans for Project Constellation have gone forward with surprising rapidity. As with Apollo before it, the president has mostly set the overall goals and objectives, leaving the millions of implementation details to NASA itself. While a great many details are still to be worked out, the first major pieces of hardware are coming into focus.
One important thing to note about the Project Constellation hardware announced to date is how much of it derives from development principles first formulated for Apollo. ("You have to hand it to those Apollo guys, they really knew what they were doing," one NASA engineer involved in designing the Constellation hardware recently remarked.)
The first key piece of Constellation hardware is the Crew Exploration Vehicle, now called the Orion spacecraft. An updated version of the Apollo Command and Service Modules (CSM), the Orion retains the basic cone-shaped crew capsule and cylindrical service structure. The habitable volume of the CEV is about two-and-a-half times larger than that of the Apollo Command Module -- necessary since the CEV will carry a crew of four for lunar missions, and six for missions to the ISS (compared to the Apollo crews of three). Unlike Apollo, which splashed down in the ocean and thus required a large support contingent from the Navy for recovery operations, the CEV is being designed to land on land, using parachutes, braking rockets that fire just before landing, and large airbags deployed on the underside of the craft beneath a detachable heat shield. The heat shield/airbag system derives from one used on robotic probes like the Mars Rovers, and the braking rocket system is not unlike that used for decades on the Russian Soyuz capsules, which have never splashed down at sea.
Two new launch vehicles are being developed for Project Constellation. In an homage to the Saturn I and Saturn V launchers developed for Apollo, the Constellation launchers are named Ares I and Ares V. (The names are also in keeping with the proclivities of NASA's first Boostermeister, Wernher von Braun, who tended to name his launchers after ancient gods and goddesses.)
The Ares I's job is to launch the Orion spacecraft into orbit. Its first stage is an extended version of one of the space shuttle's solid rocket boosters. As on the shuttle, this booster will parachute into the ocean after separation for recovery, refurbishment, and reuse. A new second stage uses a 1990s version of the Saturn's J-2 engine (now called the J-2X) to push Orion to orbital velocity.
The Ares V will be used to launch heavy payloads, like the lunar landing vehicle. Nearly the size of the Saturn V, the Ares V's first stage consists of an enlarged, modified version of the current shuttle's external fuel tank. It will have five RS-68 engines (currently used on the Delta rocket, a commercial satellite launcher), as well as two of the same reusable solid rocket boosters found on the Ares I. Another new second stage, called the Earth Departure Stage, will carry the lunar lander into earth orbit. The CEV will be launched separately by an Ares I and will dock with the Departure Stage. Then the Departure Stage will fire again, boosting the spacecraft out of orbit and onwards towards the moon.
The details of the lunar lander (somewhat clunkily called the Lunar Surface Access Module) are still somewhat vague. It is clearly an enlarged version of the Apollo Lunar Module, retaining the same basic two-stage design (a descent stage with legs and landing gear, and an ascent stage for returning from the lunar surface to the CEV), with a much larger crew compartment in the ascent stage. Interestingly, the current project documents describe the entire lunar crew leaving the CEV unattended in orbit around moon while they all explore the surface. One of the reasons the Apollo missions left one astronaut in the CSM in lunar orbit was that if anything should happen to the LM during the lunar ascent, the CSM pilot would be able to rendezvous with and rescue the LM even if it only managed to limp into a low or lopsided orbit. I guess NASA has more confidence today in automated its docking systems, or possibly they just believe this level of redundancy is not really needed.
So, besides being bigger and capable of staying on the moon longer, will this all work?
At the outset, it's clear that NASA has learned the error of its earlier ways, especially compared to the development of the space shuttle.
One of the great time and money wasters in the development of the shuttle was spent on the brand-new shuttle main engines, which, early on, had an alarming propensity for blowing up on the test stands. It took several years and many hundreds of millions of dollars to finally come up with a stable, workable design. On the other hand, a fair portion of the Constellation boosters consists of variants and combinations of existing boosters, tankage, and engines, so there should be considerable time and cost savings there.
The CEV itself, the lunar lander, and the second stages of the two Ares boosters are new, of course, but each seems to share the basic design of its Apollo predecessor, which should help contain the preliminary engineering costs, as their baseline configurations were put in place decades ago.
Another lesson learned from the shuttle has to do with the basic design of Ares launchers. Instead of the shuttle configuration with the spacecraft sitting astride the fuel tank and solid rocket motors, with a fair amount of the external tank towering above the shuttle orbiter itself, the Ares vehicles return to the basic pre-shuttle design of placing the crew capsule at the apex of the launcher, topped by an escape rocket to pull the capsule clear in an emergency. This makes damage to the spacecraft from debris like ice or insulating foam falling off the booster "very unlikely", as one NASA document put it with uncharacteristic understatement. (In the Apollo days, a Saturn V would routinely shed several tons of ice during a launch, but the CSM, sitting atop the 360-foot vehicle, was completely unaffected by it.) The escape rocket also gives the crew a fair chance to survive a Challenger-type catastrophe either on the launch pad or during the first few minutes of powered flight -- the shuttles have only a limited capability to abort during launch, and virtually no way for the crew to bail out in an emergency.
Finally, beyond all the hardware and infrastructure, is the rationale at the heart of the Constellation project -- a return to manned exploration of the moon as a springboard to manned expeditions to Mars and the other planets.
First of all, it's good to have a compelling theme at the heart of NASA's mission once again. While not having quite the same zip and pithiness of "I believe this nation should commit itself, before the decade is out, of achieving the goal of landing a man on the moon and returning him safely to the earth," the Constellation project's focus on human exploration of the solar system as the driving force behind the manned space program is a good one. As we close in on the 50th anniversary of Yuri Gagarin's first space flight, it's about time that we stop spending our time in space flying in circles and actually go someplace again.
Is a return to the moon the right goal? At this point, yes. Some people, like Robert Zubrin of the Mars Society, argue that the moon is essentially barren, that there's no real point in going back there, and that, if we had really wanted to, we could have landed men on Mars years ago. He makes the analogy of the moon and Mars being comparable to Greenland and North America in Viking times: "It might take a little more to travel to North America than to Greenland, but it is easier to sustain a colony there." While there is some validity to his points, the "on to Mars" argument glosses over a number of technical details, not the least of which is that the shortest possible flight to Mars using conventional rockets would take on the order of six months each way, assuming that you were willing and able to wait after landing on the Martian surface for eighteen months for the two planets to align themselves properly for the shortest return flight. Can we manufacture oxygen and rocket fuel there out of the tenuous Martian atmosphere, and extract water from the Martian ground? Zubrin takes these as given, although neither has been demonstrated yet. (Perhaps these would be good tasks for a future Mars robotic lander to try to accomplish.)
The moon's proximity does have important advantages in trying to learn to live in space, not the least of which is that you can always pack up and get home relatively quickly in an emergency (compared to being on Mars, anyway). It also seems more sensible to try to learn to survive in a harsher environment much closer to home than to attempt to survive in a somewhat more benign one much further away. Living on the airless, probably-waterless moon would be like living in New York -- if you can make it there, you can make it anywhere, as the song goes.
It's also clear that, even with the stated goals of "Mars and beyond", the current Orion spacecraft being developed for Project Constellation has nowhere near the capabilities of going anywhere close to Mars, let alone the moons of Jupiter or rendezvousing with an asteroid. This part of the plan is deliberately left in the vague, foggy future -- not a criticism so much as a statement of fact. There's just so much involved in these stages of exploring the solar system that we just don't know yet, it would be foolhardy to attempt to commit to anything concrete right now.
Finally, it's clearly politically expedient for President Bush to point the direction and set the goals, but to leave the detailed execution steps to his successors in the White House and to future Congresses. One could argue that that's no different than what President Kennedy did, but one important difference is that Kennedy asked Congress and the American people to "commit themselves to the goal" of reaching the moon by 1969. In fact, just a few paragraphs after his famous words, Kennedy also said that if Congress and the people were not willing to make this long-term commitment, it would be better if they did not even start, rather than killing the project partway through: "Let it be clear that I am asking the Congress and the country to accept a firm commitment to a new course of action -- a course which will last for many years and carry very heavy costs....If we are to go only halfway, or reduce our sights in the face of difficulties, in my judgment, it would be better not to go at all."
Will the new Vision for Space Exploration, of which Project Constellation is a major first step, wind up as the next Project Apollo? Or will it suffer from hamstrung pursestrings and wind up, as so many presidential space initiatives do, as nothing more than bold words on paper with no substance to back them up? NASA is working hard to do better and not repeat the mistakes it has made in the past. It would be a shame not to let them follow through and show what they're capable of doing, as they did in those heady days nearly forty years ago, when nearly a quarter of the world's population stopped to watch their televisions and hear an astronaut proclaim, "Houston, Tranquility Base here. The Eagle has landed."
Posted Dec 29, 2006 at 02:49 UTC, 3362 words, [/rich] Permalink