Return to the Moon
On July 20, 1969, man first set foot on the Moon.
Almost exactly forty years since Neil Armstrong and Buzz Aldrin made history on the dusty plains of the Sea of Tranquillity, NASA has returned to the Moon.
This time, we are going back to stay.
This vanguard for our return to the Moon – the Lunar Reconnaissance Orbiter – launched from Pad 41 at Cape Canaveral Air Force Station on Thursday, June 18. It slid, with little fanfare, into lunar orbit on Tuesday, June 23.
According to Richard Vondrak, Project Scientist for the LRO and Deputy Director of Solar System Exploration, the LRO spacecraft will spend several weeks maneuvering into its polar orbit. LRO’s camera is capable of imaging the lunar surface at such a high level of detail, it will be able to take pictures of the descent stages of the Apollo landers, the craters their descent engines made, and even items of hardware left behind by the men who walked there forty years ago.
The recent launch carried two missions: the LRO mission itself and the separate LCROSS mission. LCROSS (Lunar Crater Observation and Sensing Satellite) comprises the Centaur booster upper stage and the interstage adaptor ring (which joined the booster and the LRO payload during launch). The adaptor ring has been fitted with instruments that will observe the Centaur upper stage as it crashes into a permanently shadowed crater in the south polar region of the Moon on October 8, 2009. The impact of the booster will create a fresh ejecta plume from the lunar surface that will allow the instrumented adaptor ring following behind it to detect – using infrared and visible light spectrometers and cameras – whether the impact of the booster exposed traces of water ice.
LRO is one of the most ambitious and important experiments in the history of the scientific investigation of the Moon, according to Vondrak. “We want to identify whether there is hydrogen at the poles that is associated with water ice or the other volatiles,” he says. “Our goal is to locate them, measure their concentration and after that the question becomes: Is that material accessible in the quantities required for use?"
The Lunar Reconnaissance Orbiter’s photograph of the Apollo 14 landing site.
Credit: NASA/Goddard Space Flight Center/Arizona State University
Finding water ice on the Moon is important because, if there is enough water to access, future expeditions will be able to use it to support the habitation and eventual colonization of the Moon. Not only could the water be used for human consumption, but the hydrogen in the water could be converted into rocket propellant.
Vondrak sees the LRO mission as the first step in humankind’s journey to Mars and then beyond. “The official NASA goal of going to the Moon … is to get experience in living and working off of our home planet and living and working on another planetary surface, testing systems so that then we are better prepared to go to Mars,” he notes.
NASA’s LRO will use its six instruments collecting detailed information about the lunar environment from a low polar orbit.
However, Vondrak is clear that the merits of a Moon mission are sufficient on their own terms. “There are many interesting places on the Moon, there are many places we would like to go purely for science, and so I expect that developing the capability to return to the Moon safely will have many benefits both for exploration and for science.”
Farouk El-Baz, the geologist behind the site selection of the Apollo missions, is equally enthusiastic about the return to the Moon. “There are all kinds of questions about the Moon which remain to be answered,” he says. “I think to answer them in the best way is to send robotic missions. We already have all kinds of information from three missions sent to the Moon by India, Japan and China, and [the LRO and LCROSS missions] will add to that.”
However, El-Baz is less enthusiastic about the idea of sending humans back to the Moon. “Our objective in the long run should be an astronauts’ mission to Mars. That’s what we should concentrate on.”
But Vondrak points out that “the intent is not to build spacecraft [on the Moon], but to use it as a place to test systems and to learn how to live and work on another planetary surface”
NASA’s LCROSS mission will confirm the presence or absence of water ice in a permanently shadowed crater at the Moon’s South Pole.
Credit: NASA Ames
El-Baz emphasizes that the best place to launch a mission to Mars is from a stable, strategically-positioned, orbiting space station. “There is an L5 point between the Earth and the Moon [where the gravity is much less] than the gravitational pull of the Moon,” he notes. “If you want to put together a [human-carrying] spacecraft to send to Mars, you don’t need to go to the Moon at all.” El-Baz comments that President Obama has already appointed a committee, chaired by Norm Augustine, former CEO of Lockheed Martin, to consider these and other suggestions. As El-Baz says, “For the US to remain in the lead of space business, the US needs to send humans to Mars.”
Returning to the immediate drama of the LRO, however, another ardent supporter of the mission is Bill Hartmann, a lunar specialist since the days of Apollo and the co-developer of the impact theory of the origin of the Moon. Like Vondrak and El-Baz, Hartmann believes that the search for ice on the Moon is very important but – as an inveterate crater enthusiast – he is very excited about what the LRO and LCROSS mission will tell us about the rate at which small craters form on the Moon. This is important because, once that number has been established, he says it will be possible to work out the age of geomorphologic features on the Moon and elsewhere. Hartmann is intrigued by the notion that the LRO data – by telling us the rate of cratering in our part of the solar system – will eventually allow us to date the age of geologic formations on Mars.
On July 17, 2009, NASA released pictures of five of the six Apollo landing sites (images of the Apollo 12 landing site will be acquired next month). The resolution of the images will only get better as the LRO retrieves more data. The most detailed images so far released are from the Apollo 14 landing site at the Fra Mauro highlands – the site that ill-fated Apollo 13 had aimed for. The images from the Apollo 14 site are so detailed that the tracks left by the astronauts between the Lunar Module and the ALSEP instrument package are clearly discernable, “like going into an old building [where] the carpet is worn out down the middle of the hall” as LRO Camera principal investigator Mark Robinson of Arizona State University put it.
The traces of the Apollo 14 astronauts pulling a "shopping cart" while traversing the surface to reach Cone crater are clearly visible in the images. This indicates that the lunar dust layer is brightened by solar radiation, since the disturbed area by human activity exposed darker soil.
LRO and LCROSS will provide essential information for NASA’s return to the moon. NASA is currently developing a new fleet of spacecrafts and rockets in order to transport equipment and human explorers to the Moon. In the near future, humankind may once again spread its reach beyond our home planet.
El-Baz comments, “These are fabulous photographs in the highest resolution we have ever seen. They tell a great deal about the Apollo landing sites. For example, now we see how dramatic the large crater east (to the right) of Apollo 11’s landing looks. The lander would have crashed into it had Neil Armstrong not taken over the controls to move farther west. Similarly the photograph of the Apollo 16 landing site shows it is perilously close to a large crater pit.”
Hartmann, when asked (days before these images were published) whether he thought the Apollo landing site images would be the final rebuff for all those who claim the Moon landings were bogus, sighed wearily. “They’ll just say we faked the pictures.”
Now though, any space buff worth the name can compare these new images (http://www.nasa.gov/mission_pages/LRO/multimedia/lroimages/apollosites.html) with the fantastically detailed map of the Apollo 14 traverses available on Google Moon (http://www.google.com/moon/). A quick comparison shows the match is virtually perfect. So much for the conspiracy theorists!
But, in fact, we did not need these new data to rebuff those nay-sayers of one of humanity’s greatest achievements. Hartmann rightly points out that the science that came out of the Apollo landings is proof enough that America went to the Moon. “The Russians also went to the Moon with their robotic probes, and three of them returned samples to Earth. Do people really believe that the Soviets would have failed to publicize it if their scientific findings of the Moon’s geology had differed from those published by the Americans at the height of the Cold War?”
The real excitement of the LRO and LCROSS missions lies in the future rather than in nostalgia of past glories. It is already clear that the science that LRO and LCROSS will be doing in the next few months will impact directly on humanity’s plans to head for the planets of our solar system, and, ultimately, the stars.