http://www.spaceflightnow.com/news/n1009/06asteroid/
Asteroids are back in vogue
SPACEFLIGHT NOW
September 5, 2010
Responding to President Obama's call for a manned asteroid mission by
2025, brainstorming scientists and engineers say NASA could start
exploring nearby space rocks with robotic probes in four years, followed
by a bare-bones human expedition by the end of the decade.
The target dates require a quick agreement on a space exploration
strategy between Congress and the White House, notwithstanding
ever-present budget and technical challenges.
Asteroid exploration would meet key scientific, economic and national
security objectives, according to the plan's proponents. It would also
serve as a waypoint to Mars, NASA's ultimate destination.
Human visits to nearby asteroids could collect hundreds of pounds of
samples, shedding light on the formation of the solar system, valuable
minerals that could be harvested for commercial pursuits, and the threat
of these objects to civilization on Earth.
Congress continues to debate the White House plan, which also cancels
NASA's program to return humans to the moon and turns over crew
transportation to low Earth orbit to commercial operators.
When legislators return to Washington Sept. 13, there will be less than
three weeks until fiscal year 2011 begins, meaning NASA will likely be
forced to get by on a continuing budget resolution for at least some time.
The continuing resolution would freeze next year's funding at or near
fiscal year 2010 levels, putting any asteroid exploration dreams on the
backburner.
Despite the climate of uncertainty, an engineering team from Lockheed
Martin Corp. is proposing using two Orion capsules to stage a roundtrip
mission to an asteroid as soon as 2016.
The Orion spacecraft is the centerpiece of the Constellation program,
which would be scrapped under the Obama administration's proposed 2011
NASA budget.
President Obama announced his intention in April to salvage the Orion
capsule for use as an International Space Station lifeboat. The
president set the 2025 goal for humanity's first trip to an asteroid
during the same speech at the Kennedy Space Center in Florida.
Presented in a white paper this summer, the Plymouth Rock mission would
send two or three astronauts to accessible small asteroids with orbits
closely shadowing Earth's.
The Plymouth Rock concept identifies eight near-Earth asteroids for a
quick five-day visit by astronauts.
A dual-Orion configuration probably represents the minimum capability
necessary to perform an asteroid mission, a Lockheed Martin team led by
Josh Hopkins wrote in the white paper.
The Lockheed Martin proposal says the most feasible opportunity to
explore an asteroid before President Obama's deadline would be in 2019
and 2020, when an object named 2008 EA9 passes within reach of rockets
launched from Earth.
Crude estimates of the asteroid's size indicate it is less than 40 feet
in diameter.
Other launch opportunies from 2016 until 2030 have drawbacks or occur
after President Obama's 2025 goal.
The Plymouth Rock paper charts a mission scenario using two launches
from Earth.
Under the mission concept, an unpiloted Orion spaceship and high-energy
Earth departure rocket stage would blast off on a heavy-lift booster
like the Ares 5 rocket. The crew would launch on a smaller Ares 1 or
Delta 4-Heavy rocket, dock their capsule to the waiting Orion spacecraft
in orbit, then fire the Earth departure stage into deep space.
Once at the asteroid, the astronauts would conduct spacewalks to collect
samples and possibly leave behind permanent experiments. After a
five-day visit, the crew would jettison one of the Orion capsules and
return to Earth.
The Plymouth Rock mission could be accomplished in 200 days or less in
the 2019 launch opportunity. That duration is within the Orion's design
life and comparable to the length of current space station expeditions,
reducing the need for major spacecraft modifications and placing the
asteroid journey within NASA's experience base.
The crew's exposure to radiation and constrained living volume inside
the Orion vehicles would be limiting factors for longer voyages using
the Plymouth Rock architecture, according to the white paper.
The initial step in an asteroid exploration program would be to send
robotic spacecraft to sample, survey and study the objects, some of
which would be favorable destinations for human voyages. A scout mission
is crucial because scientists don't have much experience with asteroids.
The earliest robotic missions to scout potential asteroid destinations
could be ready to launch by 2014. Scientists at the Johns Hopkins
University Applied Physics Laboratory have a plan for an unmanned
spacecraft to depart for an asteroid around the same time.
There have only been two missions that have ever operated near an
asteroid and stayed there a long time, said Andrew Cheng, the chief
scientist of the Applied Physics Laboratory's
