Posted on 01/21/2004 7:49:49 AM PST by presidio9
For the future of human space exploration, NASA may turn to retro spacecraft designs.
The spacecraft that is to take astronauts back to the Moon, called the crew exploration vehicle, may turn out to be more than passingly reminiscent of the old Apollo spacecraft. NASA is not about to start rummaging about museums for leftover equipment to fulfill President Bush's mandate, but many outside experts expect the space agency to turn away from sleek, winged, reusable designs like the shuttle and return to the simple capsules that parachute back to Earth. Such designs, updated with modern electronics, would also help the agency stay within the modest budgets that Mr. Bush has set out for the Moon shot.
"The concept has been very well proven out," said Dr. Jerry Grey, director of science and technology policy for the American Institute of Aeronautics and Astronautics. "It's a rumor that was kicking around that they were going to use Apollo-type hardware."
While getting back to the Moon may be straightforward, the further goals of establishing a permanent base and then going on to Mars are more complex. The president has not offered a timetable for either, but each will require many technologies not yet invented. No one knows, for example, how to run a construction site on the dusty, airless surface of the Moon, and at most locations, a base would require power systems that persevere through the two-week-long lunar nights.
While challenging, "I think those are all feasible," said Dr. Haym Benaroya, a professor of mechanical and aerospace engineering at Rutgers University, who has studied, out of his own curiosity, the construction challenges of a lunar base.
The tasks for a Mars mission are more challenging. A robotic factory would be sent ahead to make fuel for the astronauts' return trip. Water would have to be efficiently recycled for two and a half years. Perhaps a new propulsion system would be developed to shorten the duration of the 50-million-mile trip, which would take at least half a year with present-day chemical rockets.
A Mars spacecraft must also be rock-solid reliable, as a rescue mission would be neither swift nor simple.
But before NASA can consider ambitious lunar or Mars missions, it must first design and build the successor to the shuttle, a task it has repeatedly attempted and failed. Since the 1980's, the agency has produced a succession of futuristic concepts that fell short of reality.
For example, Lockheed Martin in 1996 contracted to build the chubby-finned X-33, which was to blast into space like a rocket and then glide back like the shuttle. It used innovative technologies like carbon composites for its fuel tanks to cut down on weight. But the carbon composites leaked, the project went over budget and NASA canceled it in 2001.
Even the second-to-last revision of NASA's post-shuttle plans, in November 2002, retained the winged motif: the orbital space plane, which was to ferry astronauts to and from the International Space Station.
Former Senator John Glenn and other members of an advisory council for NASA asked why the orbital space plane had to be a plane rather than a capsule like the Apollo command module.
A group of experts enlisted by NASA to study the capsule idea concluded it had merit. "The command module is simple," said Dale Myers, a former NASA deputy administrator who was a member of the group. "It has an easy heat shield design. You need all the simplicity and robustness you can get."
The crew exploration vehicle now replaces the orbital space plane in NASA's plans. The exploration vehicle is to be a modular design, able to carry astronauts to the space station as well as the Moon.
NASA has said it is too early to say what it may look at. "I think we've got to avoid getting fond of a design," Sean O'Keefe, the NASA administrator, said last week at a news conference.
But Mr. Myers is certain that the part that returns to Earth with the astronauts will be a capsule, not a plane. "There's no question it's going to be a capsule," Mr. Myers said. "Wings don't do any good on the Moon. They're just dead weight."
To develop the exploration vehicle, NASA has budgeted $5 billion through 2008, when unmanned testing is to start. The spacecraft is to become operational in 2014, and total costs through 2020 will be about $30 billion, NASA estimates.
To launch the exploration vehicle, NASA no longer has anything like the Saturn 5 of the Apollo program, which could lug 280,000 pounds of payload to low Earth orbit. The space shuttle, which will be retired in 2010, can lift about 60,000 pounds, and the current generation of expendable rockets lift only about 40,000 pounds.
But not everything would have to go up in one package. The lunar version of the exploration vehicle could consist of three components — a rocket to push the astronauts out of Earth orbit, a lunar lander and the capsule to bring the astronauts back. These could be brought up separately on expendable rockets and then autonomously dock together, much as the unmanned Russian Progress supply ships dock with the International Space Station. The joined spacecraft would then depart for the Moon.
A second option would be to revive plans shelved a decade ago for a cargo version of the space shuttle. It would use the same external fuel tank and solid rocket boosters as the shuttle, but instead of an orbiter, it would have a disposable cargo container strapped on to the tank capable of lifting up to 170,000 pounds.
"That's a dimension of what we're going to have to lay out here, of how you provide cargo capabilities," Mr. O'Keefe said at last week's news conference.
Cargo capacity will become even more important when NASA starts considering what it will do once it gets back to the Moon. An agency study in 1992 looked at establishing a simple Moon base, part of the Space Exploration Initiative that the elder President Bush proposed in 1989, and even that would cost $25 billion and require the use of Saturn 5-scale rockets to transport it.
"I wouldn't call it a lunar base," said Dr. Michael B. Duke, who worked at NASA's Johnson Space Center in Houston at the time. "It was single habitat and a capability to do a few things on the lunar surface."
Under that plan, astronauts were to stay for only 45 days before returning to Earth.
A follow-up study in 1993 concluded that if oxygen could be extracted from the lunar soil for use as fuel for the return trip, costs could be reduced by $5 billion and smaller, shuttle-size cargo ships would suffice.
Since then, there has been only a smattering of research on how to build a lunar base. "One has to build in a severe environment, something we've never done before," said Dr. Benaroya of Rutgers.
Lacking both air and a magnetic field, the Moon's surface is bombarded by radiation and sand-grain-size micrometeorites hitting at tens of thousands of miles per hour. For protection, a long-term habitat would probably need to be buried under 10 feet of soil, Dr. Benaroya said.
The ubiquitous dust that covers the Moon's surface will also pose problems, clogging up machinery and wearing it out.
The first structure might be something similar to one of the components of the space station, built on Earth or in space and then taken to the lunar surface. "Essentially, it's your mobile home," Dr. Benaroya said. "That first one will be a tin can."
Later additions might essentially be balloons that arrive folded up, then inflated and stiffened, perhaps with injected foam.
The most promising location for the first lunar base appears to be an area near the south pole continually bathed in sunlight, allowing the use of solar panels for power. Large amounts of frozen water are also believed to exist in deep craters there.
In his speech, Mr. Bush suggested that the eventual trip to Mars would start at the Moon, saying, "Spacecraft assembled and provisioned on the Moon could escape its far lower gravity using far less energy, and thus, far less cost."
Dr. Robert Zubrin, president of the Mars Society, who has been pushing for a goal of sending astronauts to Mars within 10 years, said the idea of building a spacecraft on the Moon was "technically nonsense."
Dr. Zubrin, who developed a plan for a direct Earth-to-Mars mission a decade ago while an engineer at Martin Marietta, applauded the decision to phase out the shuttle and roll back activities at the space station but said he thought the priorities in Mr. Bush's proposal were reversed.
"The right way to do Mars is to design a coherent set of hardware that can do Mars," he said. Along the way, a Moon mission employing some of the Mars equipment might be a worthwhile test.
The key would be developing a rocket with the lifting power of the Saturn 5, either a cargo version of the shuttle or a larger version of the Delta 6 or Atlas 5.
Dr. Zubrin said the mission could be done in two launchings. First, an empty spaceship for the return would be sent. Once it landed it would begin to produce fuel, combining carbon dioxide from the Martian air with hydrogen to produce water and methane, and then splitting the water into hydrogen and oxygen. A year later, a spacecraft with the astronauts would arrive.
That project, he said, could be accomplished in a decade, for about $50 billion.
Man rate an expendable? Most likely. But very expensive. By the time an existing expendable is man-rated, it may cost a sizable fraction of the shuttle launch.
I see the need to go, but our shortsightedness means we have to walk.
Actually, no - water is a byproduct of the fuel production process, the Sabatier reaction:
Mars In Situ Resource Utilization
First flight is this year. Can lift 50,000lbs to LEO - a real heavy lift capability. Manrating would be expensive, but cheaper than a new design.
Don't invest the money in developing new big dumb boosters... spend it on nuclear engines for the crew exploration vehicle.
My speculation regarding the CEV. (Open the above image in a new wndow to see it full-size.)
For large cargo - especially cargo the has large fareable dimension requirements - they may take a shuttle/fuel tank approach but it will be a wingless mostly dumb module.
What they really need to do is establish space-based, in orbit fabrication if not outright manufacturing and construction, and open that infrastructure up to commercial sat vendors. We would see a whole new generation of architectures if the designs did not have to be lifted into orbit and they could be service from space. I think that they were mum about this for some political reasons as some of these new architectures do not rely on solar power (if you know what I mean.)
Me myself, favor the approach where they are going (I think that it is derived from USAF thinking.) Lots of mid-sized EELVs, keep it cheap and dependable and have lots of launches. Incremetally improve things.
I like what I see with emerging smaller firm solutions like the FALCON.
I think that Bush actually got it right but it is seems to be a hard sell because the solution has such a comprehensive and long term vision to it. I sure hope they can bring it off.
There was a great design concept I saw a couple of years ago. A winged craft, looking very much like the old British Vulcan bomber, that had turbojet engines and one off-the-shelf russian rocket engine.
The concept was to take off with LOX and a bit of JP4 for the turbojets. Hit a tanker and top off with JP4 (kerosene), light the rocket and fly a sub-orbital mission around 60 miles high and mach 10.
For safety, you could build a "crew escape module", like the FB-111 has.
At the apogee, it opens hatches in the top of the vehicle, and kicks out an upper stage that goes on into orbit. That's the only "throw away" part of it.
Granted, you still need a bit of heavy lift for major components of big projects (man rating not necessary). But this thing you could fly litterally every day, boosting components and supplies for bigger missions.
But it would obviously also be able to be copied, or bought outright, by folks like the Saudi's, or whomever. Or even some private individuals. And THEN where would NASA be? Out of a job? Can't have that.
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