Moon Smasher: Expert Q&A
On August 3, 2009, Dan Andrews answered viewer questions about excavating water on the moon, how amateur astronomers can watch the impact of the LCROSS satellite, and other aspects of the mission.
Q: I've heard that NASA wants to build a lunar outpost by 2024. If you guys are unable to find ice, will that render the [lunar outpost] mission unaffordable? And even if you find ice, where will you get the power you need to utilize it? (solar, nuclear, PEM fuel cells?) Kennedy Junior High School - 8th grade, Naperville, Illinois
Dan Andrews: Finding lunar ice would be a great discovery in that water (and its constituents, hydrogen and oxygen) is a requirement for sustaining human life. Wherever humans go, they need this resource. If lunar ice were discovered, it could make human sorties and habitation easier since a major resource would not have to be brought to the moon from Earth. However, at the same time technologies would have to be developed to harvest this resource, capture what is harvested, and convert it into useable form. This is where your second question comes in. There is clearly a need for surface power systems on the moon for not only water-ice processing needs, but for all the other reasons we humans need power. There are a number of different developments ongoing at NASA for just such surface power systems.
Q: Do you like your job as LCROSS Project Manager? Cathie Peddie, Greenbelt, Maryland
Andrews: A great question! I have very much enjoyed being the Project Manager for the LCROSS Mission. I am surrounded by some of the most impressive people I've known in my professional career, doing something that few people have the chance to enjoy—a mission to the moon. The folks on the LCROSS team from both Ames Research Center and Northrop-Grumman have an amazing work ethic because of a mutual desire to do right by everyone else on the team and, frankly, to prove this approach to missions works.
I also have to say that my job on LCROSS has been made much easier by having a great sibling mission in LRO (the Lunar Reconnaissance Orbiter with which we launched). The LRO team worked very constructively with the LCROSS team since we shared similar hardware. We shared test results and findings along the way, which benefited both missions. I very much appreciate the chance to work beside the LRO team.
Q: If water is found to exist, how long will it take for practical applications on the moon to be realized? Thanks! Kay Knowles, San Jose, California
Andrews: Water ice excavation will be a significant engineering challenge for future engineers as the temperature in those permanently-shadowed neighborhoods is quite cold. Robust, complex harvesting means will be required to bake, dig, or drill the water out without failures under those conditions. This will be the challenge for the next generation of explorers. For this reason, it is likely that the early human sorties will utilize Earth-provided water and recycling of existing waters to support astronaut stays while the harvesting means are developed and tested.
Q: After the shepherd craft passes through the plume, what, if any, data do you expect to get from its collision with the moon's surface? And how would it be collected? LRO? Jerry Maddox, Riverside, California
Andrews: The primary mission of LCROSS is to learn from the impact of the Centaur, but we are interested in extracting scientific value from the impact of the shepherding spacecraft. We should get a valuable ejecta cloud from each impact, but since the shepherding spacecraft's primary role is to measure the products of the Centaur impact, we don't steer the shepherding spacecraft to a particular location.
Regolith (or moon dirt) is fairly well understood in the equatorial regions of the moon thanks to the Apollo missions, but the polar locations, both inside and outside of the craters, are largely an unknown. Since the polar regions on the moon represent a favorable location for an outpost, whether or not water is found, it would be good to understand what future building materials might be available, and that begins with understanding this regolith.
As for how the second impact will be monitored, Lunar-orbital assets (e.g. LRO) should be able to see the shepherding spacecraft impact, as well as some Earth-orbital (e.g. Hubble) and Earth-ground assets (Great Earth observatories). In the end, all the science from this second impact is truly "bonus" science. With the large number of eyes watching both impacts, we'll have plenty of materials with which to study to help define what it will be like to "live off the land."
Q: What is the payload of the rocket we're impacting on the moon, and how does that compare to the missiles we use today? Thomas Gomez, Norfolk, Virginia
Andrews: The LCROSS impactor is the spent upper stage of the Atlas-V rocket that delivered LRO and LCROSS to the moon. That upper stage is called a Centaur rocket, and it has a long history dating back decades. However, we are not shooting it like a missile into the moon, and it has no explosive ordinance within it. It is simply a large, heavy piece of metal (about the size of a school bus with the weight of an SUV) that will be naturally pulled toward the moon by its gravity and create a spectacular impact. We just steer it on the way in. As for its impact potential, we expect it will excavate ~350 metric tons of regolith with a substantial amount of kinetic energy.
Q: When you look at the exploding of the moon's surface and the particles in the atmosphere, how do you know if there is moisture in the particles and whether that moisture is water or not? Do you use a special lighting or filter? I've watched footage on asteroid collisions and don't see anything that helps me know what it is made of. Anonymous
Andrews: The suite of instruments outfitted on the LCROSS shepherding spacecraft was specifically chosen by NASA-Ames scientists and engineers to look for water in all its forms. Our mission design relies on both looking at the lunar impact itself and the material that gets kicked-up into the sunlight to search for the presence of water-ice. We have visible cameras, IR cameras, and spectrometers that utilize optical filters on them to specifically look for water signatures. The fact that we fly right through the ejecta plume makes our measurement sensitivities quite good for a definitive measurement of the ejecta.
Q: If water is proven to exist on the moon, what do you think the next steps will be, and within what timeframe do you think those steps will happen? Paul George, Bristow, Virginia
Andrews: LCROSS discovering water on the moon would be a great enabler as it could enable astronauts to "live off the land" with one of the required constituents for human life: water. The next likely steps would be to better understand the locations where this water exists in order to map this resource, followed by developing ideas and devices for extracting the water for its many uses. This may prove to be quite an engineering challenge given the extreme temperatures in the permanently-shadowed craters. It is really no different than early prospecting in the Old West—you survey the land and you develop tools to live off it.
Q: How will water be "split" to yield fuel for space vehicles, and where will the energy come from for this process? P. Cunningham, Toronto, Ontario, Canada
Andrews: I am not an expert in surface energy systems, but you've got it right—there needs to be an energy source to provide heat from which ice can be broken down and captured into water, steam, and the elements of oxygen and hydrogen, each of which has critical value. NASA is already studying different surface energy systems for exactly this and additional reasons.
Q: If water is found, how could it be recovered from under the surface as it encounters the airless vacuum of the moon? Lawrence Zendler, Las Cruces, New Mexico
Andrews: Good observation. In a vacuum, water ice sublimes directly into water vapor—there is no liquid water phase. What this means is harvesting the water ice would require some engineering creativity. There would have to be some form excavation since ice, if it exists on the moon, would have been protected under some depth of lunar regolith. However, we can't just scoop it out like earth and sift through it, because any ice presented would be inclined to turn to water vapor, so this would need to be done in a containment system of some sort. These ideas and engineering challenges are being explored by NASA right now.
Q: When is LCROSS scheduled to do everything? Or, where can I find the schedule? Lynn Higgins, Fleming Island, Illinois
Q: What is the expected date and time for the LCROSS probe impact on the moon? Ed Holt, Etowah, Tennessee
Andrews: The entire LCROSS mission is explained and spelled-out on the NASA website: www.nasa.gov/LCROSS. If you go there you can see a countdown clock to the impact date/time, as well lots of photos and videos about the mission and even some educational materials about the moon and our history of exploring it.
Q: Will we be able to see one of the two impacts of the LCROSS mission? I have a telescope and can view from the Portland, Oregon area. If I am able to view the event, what day and time will LCROSS impact? James, Milwaukie, Oregon
Q: When will we be able to view the dust plume (or how can we track the progress), and what sort of telescope would be best? Thank you. Eric W., Fort Worth, Texas
Andrews: One of the great things about the LCROSS mission is that the public can, with the right equipment, participate in the impact activities directly. Your ability to view the impact of course depends on where you are located on Earth and the equipment you have (telescope). We estimate that a 10"-12" diameter telescope is what would minimally be required to view the impact ejecta cloud. Most of the continental U.S. should be in early morning darkness during impact, enabling direct viewing. I recommend for further details you go to the LCROSS website at: www.nasa.gov/LCROSS.