International Workshop Starts Work on Moon Exploration
Aviation Week & Space Technology, 05/01/2006, page 26
Frank Morring, Jr., Washington
International symposium starts work on some lunar exploration scenarios
Participants in a closed-door NASA workshop aimed at starting to put together a "global strategy" for Moon exploration were dubious of the space shuttle-derived architecture the U.S. agency has developed to get there.
But NASA now has input from some 200 workshop participants who suggested ways their countries, companies and scientific disciplines could contribute to a long-term human presence on the lunar surface.
India, Ukraine and South Korea joined such traditional U.S. space partners as Britain, Canada, France, Germany, Italy, Japan, Russia and the European Space Agency in the sessions, which were conducted on a "not-for-attribution" basis to encourage discussion. Meanwhile, Administrator Michael Griffin has accepted a long-standing invitation to visit his counterparts in China to discuss cooperation in the wake of President Hu Jintao's summit with President Bush.
"We have developed the architecture," says Deputy Administrator Shana Dale. "We're planning on providing transportation to the surface of the Moon. That's where we want to have a lot of dialogue about what collectively can be done on the surface."
Companies attending the workshop included Boeing, EADS Space, Honeywell, Lockheed Martin and Northrop Grumman, as well as construction giant Bechtel; heavy machinery manufacturer Caterpillar; startups like Transformational Space Corp. and PoliSpace; spacesuit-maker Hamilton Sundstrand; and existing commercial space operations like Spacehab and the Spectrum Astro unit of General Dynamics.
The objective, Dale says, was to begin developing a long-term strategy for collaborative exploration of the lunar surface that would build on NASA's plans to use a shuttle-derived architecture to return humans to the Moon by about 2018.
In keeping with President Bush's space-exploration directives, the U.S. still plans to maintain control over all of the transportation elements required to get humans from the surface of the Earth to the surface of the Moon.
However, many participants wondered at the value of that architecture when the goal is to keep humans on the surface indefinitely. Instead of a rushed architecture to replace the space shuttle as soon as possible after it is retired in 2010, some experts at the workshop felt it would be better for the U.S. to develop a reusable launch system instead.
Other nations may also develop lunar-transportation capabilities in the years ahead, Dale concedes, mentioning Russia, in particular. "Industry-to-industry" international cooperation to develop redundant capability may also be possible, she says.
At the behest of NASA organizers, participants in seven breakout sessions where most of the discussions took place were not constrained by NASA's current lunar transportation architecture, and the sessions were described as free-wheeling. NASA's "Apollo-on-steroids" approach drew a fair amount of criticism, said one participant, but in general, "people buckled down and worked over the last three days and gave them their best effort at what they think NASA's going to the Moon for and what they think they should be doing there."
ONE THEME THAT drew a lot of agreement centered on the need to establish a lunar outpost early, instead of the series of sortie missions NASA has planned at the moment.
European participants were interested in how lunar exploration could benefit society at large, while Japan's delegates talked up the commercial possibilities on the lunar surface.
As laid out by Dale and Doug Cooke, deputy associate administrator for exploration systems, the U.S. space agency hopes to begin identifying strengths and requirements different nations and groups of nations might bring to exploring the Moon, and how those could be melded into a cooperative effort.
"We may get any number of scenarios," Cooke says. "Those from our standpoint tend to lead toward understanding of potential reference missions that we would lay out for what you do on the surface. That helps to drive requirements and understand the scale of activity that we've planned for."
At least two more lunar-exploration workshops are planned in Europe later this year, and NASA may organize a second international session to discuss the scientific work that would be possible on and from long-term Moon bases. At their summit here the week before, Bush told Hu he would send Griffin to China to discuss potential areas of cooperation, and last week Griffin told the Senate Commerce space subcommittee he will go.
"I think the United States always benefits from discussions, and I do not see how it can hurt us," he told the lawmakers Apr. 25. No date for a visit has been set, and Griffin has made clear space cooperation is only one element of U.S.-Chinese relations.
"NASA has not been able to engage in cooperative endeavors with the Chinese space agency, in part because aerospace technology is closely linked to missile and weapons proliferation in the world, and we control that technology very carefully," he says.
Lunar Workshops Are Making Some Connections to Mars Exploration
Aviation Week & Space Technology, 05/15/2006, page 80
Frank Morring, Jr., Washington
Lunar workshops are making some connections to Mars exploration
A new push to begin planning what humans will actually do on the Moon once NASA delivers them there late in the coming decade includes a requirement that lunar operations be tied to the eventual exploration of Mars.
While NASA's exploration outline to date has centered on using existing technology to replace the space shuttle with vehicles that can return humans to the lunar surface (AW&ST May 8, p. 46), the agency is beginning to shift focus to the new technologies that will be needed for long-duration expeditions to Mars. That is in keeping with the "Vision for Space Exploration" that President Bush announced Jan. 14, 2004, which saw the Moon as a stepping-stone to exploration deeper into the Solar System.
At the top of the technology list is a closed-loop life support system that can contain humans for multi-year excursions away from Earth.
Workable in-situ resource utilization techniques to allow future space explorers to "live off the land," and high-reliability hardware needed to explore Mars and perhaps the near-Earth asteroids safely also are prominently featured. All of that hardware will be tested first on the Moon, where failure can be covered with a relatively quick return to Earth.
"A series of activities are planned in 2006 to gain a better understanding of the role that human and robotic exploration and development of a sustained human presence on the Moon plays in supporting a broad exploration strategy that includes Mars and other destinations," NASA says in a broad-brush request for information on lunar exploration (AW&ST Apr. 17, p. 26).
In addition to that open search for new ideas, NASA began looking for connections between lunar and Mars exploration at a Washington workshop last month where hand-picked experts started to develop what the U.S. agency hopes will be a "global strategy" for lunar surface operations (AW&ST May 1, p. 26). Participants were briefed on scientific ties between exploration on the Moon and Mars, and given an overview of the technology and life-science research under way to support these exploits.
Scott Horowitz, NASA's associate administrator for exploration systems, listed space radiation, space medical skills, countermeasures to physiological effects of space environments, behavioral health, human factors and environmental standards as "major areas of investment" for human spaceflight research, along with research capabilities that will be afforded by the International Space Station (ISS) when it is completed.
Among "key technologies" Horowitz said need to be matured for the early phase of lunar exploration were structures, propulsion, power, thermal control, avionics and software, mechanisms for exploration, resource utilization, crew support and accommodations, and environmental control and life support systems.
NASA Administrator Michael Griffin has highlighted life support lately as one of the biggest challenges that must be met before humans go to Mars,
likening the problem to developing a closed system that could keep a nuclear submarine submerged for three years or more. Doug Cooke, Horowitz's deputy, says just getting machinery to operate that long will be another technology challenge that can be worked out on the Moon.
"We'll be sending people on trips from 500 to 1,000 days, and the hardware's going to have to be reliable to the extent that we have not done it before in space with human spaceflight hardware," Cooke says. "Between the space station and the Moon we're going to get experience on hardware that will help us understand that to a greater extent."
Concepts for operating on the Moon, and later Mars, came in for a lot of discussion at the lunar workshop, including the idea of using robots to stretch the productivity of human explorers as far as possible. Dave Beaty, assistant chief Mars scientist at the Jet Propulsion Laboratory, says participants saw the need for such human/robotic "partnerships" at all levels.
"One thought that came up repeatedly was the need to develop human/robotic synergies, or human/robotic partnerships at many different scales, from small-scale [items] directly associated with humans to larger-scale things that can be sent away from humans," Beaty says. "That's a functionality that can be demonstrated at the Moon [and] become very important at Mars."
Also discussed was the need to get away from tightly choreographed crew time lines that have characterized space shuttle operations and, to a slightly lesser extent, crew activities on the station.
"While we're on the surface of the Moon [it would be useful] to maybe be a little more autonomous, to have astronauts be able to explore and maybe have a little more unscripted time, because they're likely to have to do that when they go to Mars," says Laurie Lesin, director of sciences and exploration at Goddard Space Flight Center, who, like Beaty, conducted one of the breakout sessions at the lunar workshop where most of the discussion took place.
Overall, Lesin says, "in our group it was a consensus that almost everything we do at the Moon is going to teach us something relevant for going to Mars."
The Washington workshop marked the first chance NASA has had to solicit the views of potential international partners in lunar exploration, but it also served a purpose for lunar experts in other space agencies who do not have the top-level political support for an ambitious exploration program that NASA enjoys. Participants from more than one NASA partner-nation said afterward that concepts from the workshop would help them at least start to sell the ideas the U.S. is developing to their governments and elsewhere.
Indeed, the Japanese Aerospace Exploration Agency (JAXA) has formed a "lunar exploration promotion team" to push for a continuation of Japan's lunar program, which has received scant attention from the public over the years. One approach JAXA team members say may help them back home is putting forth exploration as a way to interest students in math and science.
"Those are related to the commercial side, the economic side, and also the educational side," says Junichiro Kawaguchi of the JAXA lunar team.
I think that a 500 to 1000 day mission is very challenging technologicly. So much so, that I am skeptical of the 1000 day mission altogether. Back in the 1980's some of the first baseline Mars 600 day missions looked risky enough, strictly from the point of view of hardware. The mission must be designed with field replaceable airlock seals, field mantainable hardware requires many spares. Then there are the tools that must be carried along to effect repairs. The there is the problem of expertise: what happens when if the primary mission 'engineer' is incapacitated followed by a major hardware failure: not just mission failure, but likely loss of crew in toto.
For a successful and reasonably safe mission, not only must the mission hardware be designed with ease of servicing in mind, but the duration of the mission must be small enough to reduce the probability of a major equipment failure to small levels of probability. An energy 'rich,' quick turn around mission utilizing nuclear propulsion allows for flexability and enough delta-v to manage contingincies that might otherwise be fatal to the crew. Otherwise the only responsible course would be to transport sufficient infrastructure to Mars to completely support a mission with enough contingency spares to get back--this likely means a well equipped machine shop, spare parts, and several skilled engineers supporting a large crew and a very costly mission. In essence, creating from scratch a Mars colony. While this should be the eventual goal, it is not a good idea for an initial exploration sortie to the Red Planet.
Nuclear propulsion can greatly shorten the total mission duration and still achieve valid scientific and exploration objectives with a responsible level of risk to the crew AND achieve a more reasonable total mission cost.
I suppose,1000Days are unaccepteable by recent technique.When we use a nuclear propulsion,NTR,(Gas- Core wuld be even better)or VASMIR,etc.mission time and costs would be shring and the reliability of the whole mission increases as well.With pure chemical propulsion it is nearly impossible,because we need about delta V=27KM/second or more inclusively return.To go over the Moon itīs even worse and more expensive.My opinnion is we need first a new post Space Shuttle,than a nuclear transfer shuttle and a Mars ferry. Maybe,if NTR engines are powerful enough,landing and restart with the whole nuclear transfer shuttle could be possible,because martianīs gravity is .35g only. What are you thinking about this? Regards : Martin
Certainly a nuclear transfer stage for TMI trajectory (Trans Mars Insertion) and return makes sense. A nuclear powered descent/ascent stage is certainly possible and desirable. Years ago someone proposed the MINRVA (Martian Indigenous Nuclear Rocket Vehicle) which would utilize a dual-mode NTR which was capable of generating onboard electric power. On the Martian surface electric power was used to operate atmosphereic compressors which would take in the thin Martian atmosphere (98% CO2) and compress and liquify it. The liquid CO2 would then be run through the NTR to heat it. The hot, expanding CO2 would be expelled out of the nozzle providing thrust. Such a vehicle could fly, land, and refuel at will just about anywhere on Mars (and without the need or complexity of processing local ground water to produce liquid methane and liquid oxygen for rocket fuel.
It's an interesting idea, but it does require some clever reactor engineering to deal with the hot corrosive gasses inherent in the cycle (CO2 at high temperature can actually be slightly oxidizing.) Still, I think Robert Zubrin's idea of synthesizing methane and oxygen makes sense--especially in light of the fairly abundant supplies of permafrost that a thought to probably exist on Mars. LCH4/LO2 offers very good performance on Mars, and with the reduced size of the gravity well of Mars, access to Mars orbit and Earth-Return trajectories are much better...
Shure, metane CH4 or carbonmonoxide CO or -dioxide CO2 are to aggressive to the reactor.I would prefer H2.With help the reactorīs energie frozen ice (water)could be seperated in oxigene and hydrogenium for crew and propellant for return or other use. In each case the reactor ist useful /unreplaceable fur the whole mission.Propulsion,heating,cooling the LH2,electric power,manufaction of fuel,oxigene production etc. could be done by the (same)reactor. When the responsibles are clever,they could save much money,enhence realibility and save time and it would be a big push for spaceflight in generally.A lost/failed mars-mission,caused by unsuitable/unsafely chemical rocket-technique could be the end of manned planet missions for 100years. Best Regards: Martin
The problem with the idea of using an NTR for hopping around Mars is of course the neutron radiation from the reactor, which would get reflected to the crew cabin from the ground below, on take-off.
Neutron shielding tends to be very heavy (because of the penetrating power of fission neutrons). But one might also make good use of the CO2 propellant tanks, using them as cabin shielding on take-off. Once high above the ground, I think that low-mass shadow-shielding would be quite effective, due to the very low density of the Martian atmosphere, which wouldn't reflect neutrons efficiently.
Of course the big problem comes during landing, once all the propellant (shielding material) is nearly gone from the tanks, but the NTR is still needed for a touch-down..... Lots of dose there !
Its probably better to use a smaller electricity-generating reactor for ISRU chemical propellant production, and then have an ordinary chemical rocket hopper for transportation.... Having such a small reactor on board would be much easier to design for, since the shielding would only need to protect against post-shutdown gammas, instead of the full-power neutron flux (plus gammas). Moreover, the post-shutdown radiation decays very quickly initially, so further shielding savings can be had if one doesn't mind waiting a day or two before boarding the craft for the next Mars hop....
An NTR hopper would be a challenge. I think the radiation back-scatter from the ground was why the author proposed the vehicle in two basic designs: the first used a conventional VTOL ballistic lander with a large LCO2 tank midline with the NTR at the base and crew cabin on top. A truncated conical configuration could attenuate much of the direct radiation backscatter from the ground, but as Jaro points out, sidescatter from rockts, nearby hills, canyon walls, etc. could be a problem. The second design focussed on a hypersonic waverider which was actually designed to cruise at about 1-2 km/s very high in the Martian atmosphere. It too was VTOL, but would actually cruise horizontally. Additional propellant supplied from drop tanks could give the vehicle an orbital capability.
The reactor would be located at the extreme aft end of the vehicle--but still as you point out, radiation shielding especially for neutron radiation, is a really tough thing to get a hold on... Then there is the center of gravity issue with so much mass so far to the back.
It starts to look a little like conventional chemical descent/ascent stages might end up being more practical. Long range excursions could probably be better accomplished by the use of large pressurized rovers which could tow a nuclear power pack in a trailer. Surface vehicles (in contrast to flight weight vehicles) can actually benefit from the additional weight of carrying radiation shielding because this tends to enhance traction. (Just ask any off road vehicle driver worth their salt!)
