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 space department.
Those projects were APL’s Near Earth Asteroid Rendezvous mission, or NEAR Shoemaker, and Japan’s Hayabusa probe that completed the first roundtrip voyage to the surface of an asteroid in June.
In an interview Friday, Cheng said APL has already mapped out a new mission concept called Next Gen NEAR, which could launch in 2014 if Congress approves money to start design and development by next year.
Many of the proposed project’s architects worked on NEAR Shoemaker, a NASA research mission that spent a year closely studying asteroid Eros before landing on the rock in February 2001.
Eros is about the size of a large city, but the Next Gen NEAR craft would chase down a much more modest asteroid. Cheng said officials have identified five near-Earth objects for the mission: 1989 ML, 2001 SW169, 2001 US16, 2002 TD60 and 2004 EW.
All of the candidates are at least a few hundred meters in size and reside in orbits close to Earth, permitting relatively short transits between seven and 16 months after launching in 2014 or 2015. But scientists aren’t sure of the exact dimensions and composition of all the accessible Next Gen NEAR asteroids.
“We’ve worked together to design the Next Gen NEAR concept of operations to parallel, to the extent possible, operations of a future human mission,” said Rob Landis, a NASA mission operations specialist.
Near-Earth objects, or NEOs, are asteroids that commonly pass near Earth. They are the easiest to reach and pose the greatest threat to the planet.
“We’ve learned a lot about NEOs using telescopes, Earth-based radar and two robotic missions, but we’d have to get up close and personal with a specific asteroid again, and learn much more about its environment, before we could send human explorers,” said James Garvin, chief scientist at NASA’s Goddard Space Flight Center.
According to Cheng, all five candidates for the Next Gen NEAR mission would be ideal targets for a human sortie.
“Each of these is considerably larger than the space station, so there’s plenty of interesting stuff to go and explore when you get there,” Cheng said.
The $400 million Next Gen NEAR concept would lay the groundwork for a manned visit by analyzing the surface of the asteroid after a soft landing.
“Its purpose to help prepare for human spaceflight. For that reason, it’s also going to do something that…no one has ever done on an asteroid, which is not only just set down on the surface but actually do an experiment, interact with the surface and learn some basic information about what the surface is like,” Cheng said. “How hard is it? How easily does it come part? Does it create a lot of dust if you just touch it?”
Teams at Goddard and the Johnson Space Center, along with college interns, contributed to the Next Gen NEAR concept, according to Cheng.
NASA received 130 responses to a request for information in May on robotic precursor mission strategies, according to an Aug. 10 presentation by Mike Hecker, director of the Constellation systems division in NASA’s exploration directorate.
Precursor missions could also visit the moon and Mars, but NASA’s early focus is aimed squarely at near-Earth objects. NASA wants the projects to answer questions about the safety hazards, chemical resources and dimensions of potential asteroid destinations before humans visit.
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