NASA’s back to the Moon
adventure is being kick-started by the building of the Lunar
Reconnaissance Orbiter. That probe is the opening volley of spacecraft
in response to President George W. Bush’s multi-billion dollar Vision
for Space Exploration that he outlined in January 2004.
A goal of the Vision is returning humans to the Moon as early as 2015 and no later than 2020.
To
make that happen, starting no later than 2008, a series of robotic
missions will be sent to the lunar surface "to research and prepare for
future human exploration," Bush proclaimed.
This
week, the Lunar Reconnaissance Orbiter (LRO) begins a preliminary
design review. A process that is sure to reflect the financial stress
and strain status of NASA’s newly issued budget for fiscal year 2007.
Overarching goals
The
task ahead for engineers and scientists is to keep LRO on track in
order to achieve several goals: To characterize future robotic and
human lunar landing sites and to identify potential lunar resources,
with emphasis on applied science/engineering assessments. LRO is also
to investigate the lunar radiation environment in terms of impact on
humans.
LRO is
the first of the Robotic Lunar Exploration Program missions. After a
planned launch by late fall 2008, LRO will take four days to make its
way to the Moon and then orbit that chunk of "magnificent desolation"
for nominally one year.
Now
being competitively sought is a co-manifested "secondary" payload on
the LRO launch. One idea floating about is ejecting some type of
hardware from LRO to demonstrate a "first look" at the polar regions
from the Moon’s surface.
Challenging mission
The
mission remains an essential "first step back to the Moon for NASA and
its implementation of the Vision," said Jim Garvin, Chief Scientist at
NASA’s Goddard Space Flight Center in Greenbelt, Maryland, which is
managing the mission.
LRO’s
topographic mapping capabilities will, in Garvin’s view, "reveal for
all of us a ‘new Moon’ that we will be able to utilize on our path to
human return and eventual human missions to Mars."
The
NASA center is acquiring the launch system and spacecraft, as well as
providing payload accommodations, mission systems engineering,
assurance, and management.
"LRO,
in all respects, is a unique and challenging planetary mission," Jim
Watzin, Planetary Division Chief for the Flight Programs and Projects
Directorate at Goddard Space Flight Center explained to SPACE.com.
For example, LRO will fly within 31 miles (50 kilometers) of the lunar
surface for at least one year in order to conduct a comprehensive and
detailed mapping mission. That’s a feat that has never before been
attempted, he noted.
"Low
lunar orbit, at the precision mapping altitude of 50 kilometers, is
substantially different from our experiences at other planets," Watzin
said, underscoring the relatively stable and benign environments of
Mars orbit, or Earth orbit for that matter.
Active propulsion
Watzin
said that low lunar orbit is inherently unstable, due to the asymmetry
of the lunar gravitational field. LRO’s orbit would oscillate and
collapse to the point of collision in about two months time if not
properly maintained through active propulsive means, Watzin advised.
Furthermore,
Watzin said that as LRO swings around the Moon it will be exposed to
dramatic temperature shifts. Another tough duty for LRO is its
precision mapping mission, requiring large volumes of data that must be
collected and transmitted back to Earth.
"This
requires a data system with capacities similar to many low Earth
orbiting satellites…but exercised over a far greater distance with less
power and weight than typically allotted," Watzin said. "In almost all
aspects, this is a challenging mission," he reemphasized.
Down memory lane
Whisking
over the lunar landscape, LRO is slated to relay unique close-up
imagery. On the priority list is catching sight of small-scale features
that could be landing site hazards for both robotic and human
explorers. It also will survey the lunar poles to record changing
illumination conditions and potential resources at those locations.
On the
LRO camera-sweep agenda are trips down memory lane too, said Mark
Robinson of Northwestern University’s Center for Planetary Sciences in
Evanston, Illinois. He is Principal Investigator for the Lunar
Reconnaissance Orbiter Camera (LROC).
Take note. For you "Apollo landings were a hoax" believers LROC’s sightseeing abilities should set the record straight.
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VIDEO: A New Era of Space ExplorationLROC
is to image U.S. and Soviet landing sites on the Moon. That includes
NASA’s Ranger and Surveyor lunar probes, as well as the touch down
spots of Apollo expeditionary crews and the impact sites of spent
Saturn rocket stages that hurled astronauts moonward. Also on the LROC
see list are the Soviet Union’s Lunakhod automated rovers, Robinson
told SPACE.com.
"We
will image the Apollo sites and you will see the descent stages sitting
on the surface," Robinson said. LROC will clearly see the overall shape
of that landing hardware, but won’t be able to resolve such things as
the insignia on the side of the descent stage, or see the stripes on
astronaut-planted flags, he said.
Additionally,
Robinson noted, given a setting Sun in the lunar sky, LROC should spot
the long shadow of descent stages cast across the Moon’s crater-pocked
terrain.
New crater count
An
LROC duty is to better characterize the current impact rate on the Moon
of Near Earth Objects (NEOs) from very small impactors up to 33-feet
(10 meters) in size for hazard assessment.
In the
1960s, NASA’s Lunar Orbiter missions acquired meter scale imaging for a
small percentage of the Moon, Robinson said, mostly in equatorial
mare regions of the nearside. Later Apollo missions (Apollo 15 through
Apollo 17) carried very sophisticated high-resolution imaging
systems—panoramic cameras—that acquired meter to several meter scale
images.
"We
intend to re-image many of these [panoramic camera-scanned] sites to
accurately determine the current small impactor rate on the Moon,"
Robinson said. Over the stretch of time from Apollo 15-17 to when LRO
flies, hundreds of new craters in the 10-meter diameter size are
predicted to have been created, he said.
Hot-button topic
LRO will give extra special attention to the relatively unexplored polar regions on the Moon.
Unresolved
is the issue of polar volatiles as a resource—especially water-ice. The
hunt for water-ice on the cold Moon is a hot-button topic. Among a bevy
of sensors, LRO is outfitted with equipment to chip away at the
ice-on-the-Moon matter.
NASA’s
Lunar Prospector circled the Moon for over a year in 1998-1999,
charting levels of hydrogen in shadowed craters near the Moon’s south
and north poles. That hydrogen signal has been inferred by some
specialists as billions of tons worth of water-ice below a modest
covering of soil.
Earlier, the Pentagon’s Clementine spacecraft also hinted that water-ice may be found in sunlight-deprived polar craters.
If
present, water-ice would be a nifty resource. It could be processed
into oxygen, water, and rocket fuel for use by future lunar explorers.
Still, whether that icy material is truly tucked away at the Moon’s
poles is arguable.
"Diviner" intervention
"There’s
clearly something going on at the lunar poles that we don’t fully
understand," said David Paige, a space researcher at the University of
California, Los Angeles. He’s the lead scientist on LRO’s Diviner Lunar
Radiometer Experiment. It will chart the temperature of the entire
lunar surface at roughly 985 feet (300 meter) horizontal scales to
identify cold-traps and potential ice deposits.
Paige
said there’s one thing that’s bothersome in the search for lunar ice
saga. "It’s not a very strong signal" from Lunar Prospector in regards
to the enhancement of hydrogen in the Moon’s polar regions, he said.
"If
every place that was permanently shadowed was completely stuffed with
ice you’d expect a much bigger signature that we’ve seen," Paige said.
Paige
said his Diviner device will provide thermal data that can tell if ice
is on the surface, close to the surface, or deep. Coupled with data
sets from other LRO instruments the ice chests on the Moon issue can be
clarified, he said.
Seeing in the dark
"There’s
no one killer technique" that LRO carries to find ice, said Alan Stern,
a planetary scientist at the Southwest Research Institute in Boulder,
Colorado and Principal Investigator of the Lyman-Alpha Mapping Project,
or LAMP for short.
LRO’s
LAMP instrument will observe the entire lunar surface in the far
ultraviolet. "We call it seeing in the dark," Stern said. LAMP’s main
job is to spot surface ices and frosts in the polar regions and provide
images of permanently shadowed regions illuminated only by starlight.
"Nothing
like this has ever been done," Stern noted. "We’re using a clever trick
of nature. That is, permanently shadowed regions are dark to sunlight
and Earthshine. But in the ultraviolet, the sky is showering photons
down from the interplanetary hydrogen glow. So to LAMP…it’s not dark at
all."
Stern said that the whole idea behind LRO—in regards to the water-ice detection—is fly three or four different techniques.
"Each
has their own pluses and minuses. But the suite of them can let you get
the checkmate. They shore each other up in their weaknesses and they
strengthen each other with their own pluses," he said.
