http://www.aviationnow.com/publication/awst/loggedin/AvnowStoryDisplay.do?pubKey=awst&issueDate=2006-01-23&story=xml/awst_xml/2006/01/23/AW_01_23_2006_p44-48-02.xml&headline=NASA%27s+Lunar+Orbiter+Gets+A+Bigger+Boost

The LRO instruments that Chin oversees were picked to give Robotic Lunar Exploration Program planners the best shot at moving human space exploration out of low Earth orbit. The LRO mission has three goals for the data the instruments return -- to map potential landing sites; assess water and other lunar resources, including sunlight that can power surface systems; and characterize the radiation environment future astronauts will face.

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The Lunar Reconnaissance Orbiter, shown in this artist's concept, is designed to produce the most detailed Moon map yet starting in 2008.Credit: CHRIS MEANEY/GODDARD SPACE FLIGHT CENTER

"A lot of the instruments are very complementary," Chin says. "All are powerful in themselves, but when you put the data together, they supported each of the goals in different ways."

Lola, the laser altimeter already in work at Goddard, will split single laser pulses into five beams, and then measure the reflections from the surface below to determine range from the time delay. Lola will also measure surface roughness from the spreading of the beams, surface reflectance from the energy of the return and surface slope from the different return times of the five different beams.

"Because you get these digital elevation maps, you can model where the permanently shadowed regions or permanently illuminated regions might be," Chin says.

Working with the laser altimeter will be the Lunar Reconnaissance Orbiter Camera (LROC)--really two cameras, one narrow-angle and one wide-angle. The narrow-angle instrument will return panchromatic images with a resolution of about 50 cm. (20 in.), fine enough to pick up the Apollo landing sites and other spacecraft on the surface. While the narrow-angle camera will only be used 5-10 times per orbit, the wide-angle camera will provide a global lunar map with a resolution of about 100 meters (328 ft.) in seven wavelengths to characterize minerals on the surface.

The spacecraft's orbit will send it over the lunar poles about 10 times a day at a nominal altitude of 50 km. (31 mi.), allowing intensive imaging of the regions scientists and explorers find most interesting. And the high-resolution digital maps will guide the follow-on robotic lander -- and the human-piloted landers after that -- to the most promising regions for both ice and solar power.

"Using LROC, we'll be actually able to make motion picture images of the polar region that will tell us what the illumination scenario would be for a particular season, again, looking for areas of permanent shadows and permanent illumination," Chin says.

The LRO cameras will be built by Malin Space Sciences Systems, which has built cameras for Mars orbiters as well. Similarly, the Lola instrument has heritage in the Mola laser altimeter Goddard built for the Mars Global Surveyor. Chin says using instruments that draw on technology from other planetary spacecraft is one approach the LRO program is taking to meet its tight development schedule.

WORKING WITH THE multispectral wide-angle camera to map the surface composition will be the Lunar Exploration Neutron Detector (Lend), designed to measure neutrons kicked up by surface material reacting with cosmic rays. Hydrogen absorbs the neutrons, so a dip in the so-called neutron albedo means there is some form of hydrogen in the soil below.

NASA's Lunar Prospector orbiter used the technique to follow up on findings by the Pentagon's Clementine missile defense testbed that the permanently dark regions at the poles were rich in hydrogen, which could be water ice left when comets crashed into the Moon early in its history. With a 10-km. resolution--better than Prospector--the Lend instrument will further pinpoint promising locations in the permanently shaded regions to seek water.

An instrument called Diviner, a multi-channel solar reflectance and infrared filter radiometer, will work with Lend to take the temperature of the surface below. It will help locate shaded cold traps where ice may exist. Places registering 50K or below would be promising locations for ice, Chin says.

Also aiding in the search for water will be the Lyman-Alpha Mapping Project (Lamp), virtually a duplicate of an instrument flown on the European Space Agency's Rosetta comet-lander mission launched in March 2004. Using ultraviolet light from stars, the Lamp instrument will seek surface ice in the darkness of the deep polar craters. It will also map the permanently shaded regions, and serve as a testbed to demonstrate the use of starlight for future exploration in dark regions.

The final baseline LRO instrument is the Cosmic Ray Telescope for the Effects of Radiation (CRaTER), which will measure the radiation environment future astronauts will face at the Moon and characterize the shielding they will need for protection.

The orbiter also will carry a miniature synthetic aperture radar (SAR) supplied by the Johns Hopkins University Applied Physics Laboratory and funded by the U.S. Navy. Included as a technology demonstration, the instrument should be able to supplement LROC and Lola with imagery, and its ground-penetrating signal may pinpoint potential water-ice deposits with higher resolution than the Lend instrument.

Robotic Lunar Exploration Program (RLEP) planners at NASA are putting together options for a mission they call RLEP-2, which should launch by the beginning of 2011. They plan to pick a concept this spring. The 40-50 engineers agency-wide who are working on the task have a lot of ideas for tackling the mission, which has one overriding problem.

"We want to land where it's light almost all the time, and the interesting volatiles, the water, are probably where it's dark all the time," says John Horack, assistant director of the Science and Mission Systems Office at Marshall Space Flight Center, which will manage RLEP-2 development. "So I need to move some kind of sensor, package or payload off of the lander and down into the crater."

The lander's primary objective will be to check out the possibility that water ice left by primordial comet impacts remains unthawed in the eternal darkness at the bottoms of deep craters in the lunar polar regions. Data from lunar orbiters suggest that may be the case, and NASA is sending the Lunar Reconnaissance Orbiter (LRO) to scout good landing sites for a closer look (see p. 46). But scientists probably won't know for sure until they can analyze the soil directly using furnaces and mass spectrometers.

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Artist's concept of one idea for the RLEP-2 lunar lander, set for launch by 2011. NASA managers are scheduled to choose a final concept in March. Credit: NASA MARSHALL SPACE FLIGHT CENTER

The answer will influence the direction of future human space exploration. If water can be recovered from the permanently shaded regions at the Moon's poles, it can supply oxygen and hydrogen fuel for life support and rocket propulsion, sustaining lunar bases and easing the path for explorers bound for Mars and elsewhere.

"The No. 1 thing that almost everyone agrees is you want to go touch the water," says Scott Horowitz, associate administrator for exploration systems. "So depending on what LRO finds with its mapping and looking at the hydrogen, that would provide a tremendous amount of data on where you want to look, and where you want to look has a huge impact on the design of your spacecraft, especially for a place like the Moon."

The RLEP-2 project at Marshall is collecting design options for the lander and hopes to present them by the end of next month. Working within a cost limit of $400-750 million, the project is looking at lander design, mobility on the surface, communications, launch vehicles and extensibility -- whether a concept can evolve along with the growing lunar presence. Somewhat like the Mars Pathfinder mission of 1997, RLEP-2 probably will be a combination of a lander that remains stationary and something that moves away from it. In addition to rovers, other mobility options under consideration include shooting sensors into nearby craters with a mortar or using a free-flying "hopper" to descend into dark craters.

Engineers at Raytheon have proposed a hopper based on technologies originally developed for Defense Dept. missile programs as a generic way to move around the surface of the Moon. Initially called the Lunar Penguin, the robotic vehicle would descend into craters using the hypergolic propulsion system from the Exoatmospheric Kill Vehicle from the anti-missile Ground-Based Interceptor. Navigation would come from the Digital Scene-Matching Area Correlation system that guides the Tomahawk missile.

Karleen Seybold, system lead for Lunar Penguin at Raytheon's Tucson, Ariz., operation, says it could hop about 4 km. (2.5 mi.) horizontally and 1-2 km. down into a crater, with greater range possible if more fuel tanks are added. In lighted terrain, the navigation technology is as accurate as the map available, which should be about 50 cm. (20 in.) at the lunar poles, if the LRO camera works.

THE TECHNOLOGY would be extensible to other landers, says Mike Booen, vice president for Raytheon's advanced missile defense product line, and would be available much faster and at lower cost than a new development. Raytheon is also studying whether it could be used on a piggyback LRO ground-sensor payload, one possibility under a new request for information put out by Ames Research Center, home of the RLEP program office (see p. 44).

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Engineers are studying some sort of "hopper" to descend into permanently shadowed craters to look for water ice. Raytheon proposed this one, dubbed Penguin. Credit: RAYTHEON

If the secondary LRO payload is a lunar communications satellite, it could help solve the problem of communicating with sensors in deep craters, at least when the satellite is over the crater. Also being considered are trailing cables that would link the sensor with the lander on the crater rim. That, in turn, might help solve the problem of powering sensors in the dark crater bottoms. Other possibilities include batteries, fuel cells or a nuclear power source that converts heat from radioactive decay into electricity.

Like the Apollo Lunar Excursion Module (LEM), the lander will use rockets to lower itself to the surface. But also in the tradeoff is whether to use storable hypergolic fuel, as did the LEM, or tackle the problem of long-term storage of cryogenic propellants. For the launch vehicle itself, among the options under study are the Delta IV "with a few caveats," and the planned Crew Launch Vehicle--a single space shuttle solid-fuel booster with a cryogenic upper stage that might be flying in time for the lander mission. The latter could play into the go-as-you-can-pay approach NASA is taking to the whole exploration effort.

"If we're truly to be successful in going back to the Moon and going on to Mars, we need a systems approach to make that sustainable," Horack says. "So while NASA could invest in a point-solution lander, you don't get as much extensibility, sustainability and what I guess I'd call residual equity value out of a point solution, as you might get if you could take a more systems-based approach." [....sooo how about using a copy of the MSL on the moon ???]

NASA Developing Robotic Scouts For Lunar Exploration

Work on the Lunar Reconnaissance Orbiter (LRO) set for launch in 2008, and on the lander known only as RLEP-2 -- the second mission in the Robotic Lunar Exploration Program -- is being driven more by the need to find a place for humans to land again than by unfettered curiosity about Earth's huge satellite.

"When we compete instruments or missions on the science side, we ask people to describe the scientific investigation they wish to pursue, and it's important to reference things like National Academies' priority for science," says Laurie A. Leshin, director of sciences and exploration at NASA's Goddard Space Flight Center, Md. "In this case, these proposals were not written that way."

Leshin, a planetary scientist who joined NASA after serving on the presidential commission that advised the agency on implementing President Bush's exploration policy, stresses that the robotic program will produce important results for scientists and explorers. At the top of the list is a potential answer to questions raised by two earlier lunar orbiters, the Pentagon's Clementine and NASA's Lunar Prospector. Both found evidence of large quantities of hydrogen at the lunar poles, suggesting that water ice may exist there in the permanent deep-freeze of deep craters where sunlight can't reach.

It will also be a big deal for scientists studying the forces that shaped our Solar System, and that are shaping the planetary systems around other stars. Knowing the form of hydrogen spotted from lunar orbit will be a giant data point in understanding those forces. If it is water ice, deposited by comet impacts or some other process, the finding also would dramatically enable additional research. In a priority list established by the U.S. National Academies, the big Aitken Basin impact feature at the lunar south pole ranked right behind Pluto and the Kuiper Belt as a target for planetary exploration in the current decade.

Under present U.S. planning, samples in the basin are likely to be picked up by spacesuited humans. Getting them in place would be much easier if there are nearby deposits of frozen H2O that they could tap for life support and rocket propellant. NASA's early exploration plans include a focus on possible in situ resource utilization (ISRU) -- living off the land with local materials -- at the Moon as practice for more challenging expeditions to Mars (AW&ST Sept. 26, 2005, p. 22).

EVEN THOUGH "it's a requirements-driven mission rather than a science-driven mission," the robotic scouting should answer other scientifically interesting questions as well, says Chris McKay, RLEP program scientist. Those questions include: whether there are places in the Moon's polar regions where a solar-powered lander can get sunlight almost continuously, whether lunar dust is a health hazard and whether the combination of low lunar gravity and higher radiation levels will endanger human explorers in ways not yet clearly understood.

Engineers at Goddard Space Flight Center already are working on hardware for the Lunar Robotic Orbiter to meet the 2008 launch date. Coming up soon is a decision on the launch vehicle, which has been shifted from the Delta II to an Atlas V or Delta IV. The shift avoids stability problems with the smaller booster's spinning upper stage caused by the fuel load that will be needed to maintain the LRO's 50-km. (31-mi.) orbit.

"Because of the Moon's gravitational field, that is not a trivial exercise," says Mark Borkowski, program executive for robotic lunar exploration at NASA headquarters.

The orbiter design is basically set (see below), so the launch vehicle upgrade gives the program at least another 1,000 kg. (2,200 lb.) of capacity for a piggyback mission. Capped at $50 million, one potential secondary payload would be an orbiting communications satellite to serve future surface explorers. But engineers also are examining the possibility of actually sending a probe from the LRO to the surface to push the search for water at one of the poles (AW&ST Jan. 9, p. 15).

Regardless of whether or not the first U.S. scouting mission will be able to "touch the water," as Horowitz, a former space shuttle astronaut, puts it, the second will focus on doing just that. Set for launch in late 2010 or early 2011, the RLEP-2 lander will almost certainly be sent to one of the lunar poles to look for water ice there. The job will be operationally complicated, because the ice -- if it exists -- probably lies in permanent darkness down a deep hole, while the lander will need to draw its power from the Sun.

Possibilities include a rover with enough capability to get down the steep sides of a deep crater, or a separate "hopper" that could jump from a larger lander into a crater. Communications between Earth and the bottom of a crater would also be tricky, since the crater walls would block data signals.

In any event, RLEP-2 will need pinpoint navigation to be able to land at a spot within range of the hydrogen fields. Under the stepping-stone approach that characterizes NASA's overall approach to the new exploration goals, the LRO is being designed to provide as much of that sort of mapping data as possible to guide the robotic landing -- and future human landings as well. NASA managers hope to have a reference mission -- with cost options -- for the lander by the end of next month, based on trade studies that started in November 2005 (see p. 48).

"LRO is going to give us the overview, the map, that we need," McKay says. "The lander is going to start giving us the ground truth."

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