OSIRIS would return a pristine sample of a scientifically priceless asteroid to Earth in 2017. Regents' Professor and UA Lunar and Planetary Laboratory (LPL) Director Michael Drake is principal investigator for the proposed $415 million mission.
Drake and LPL Associate Professor Dante Lauretta, who is OSIRIS deputy principal investigator, will direct the mission science. LPL will also provide OSIRIS' cameras. NASA's Goddard Space Flight Center in Greenbelt, Md., is responsible for overall mission management. Lockheed Martin Space Systems will build the flight system, the sampling mechanism, and the sample return capsule. Lockheed also will perform spacecraft operations.
The $1.2 million award is for the next seven months, when the team will prepare a more detailed engineering study of how it will accomplish mission science objectives.
OSIRIS would be the first spacecraft sent to explore a "carbonaceous" asteroid, a type of asteroid that contains primitive carbon compounds that have survived since solar system formation 4.5 billion years ago.
OSIRIS is both a mythological figure and an acronym. "O" stands for the scientific theme, origins. "SI" is for spectral interpretation, or taking images of the asteroid at wavelengths that will reveal its composition. "RI," or resource identification, is surveying the asteroid for such useful resources as water and metals. "S" stands for security, learning how to predict the detailed motion Earth-approaching asteroids.
OSIRIS of Egyptian mythology is the god of life and fertility, the god who taught Egyptians agriculture, Lauretta noted. There's an analogy to the proposed 21st century space mission, he added. "We're looking at the kind of object that we think brought life to Earth, that is, objects that seeded Earth with early biomolecules, the precursors of life."
Not only would OSIRIS delve into the evolution of our solar system and life, it would identify such resources as water, precious metals and other materials needed by future human explorers in near-Earth space, Drake and Lauretta said.
And, not least, OSIRIS would accurately measure the "Yarkovsky effect" for the first time.
Without understanding the Yarkovsky effect -- a force created by the uneven solar heating of an asteroid's surface -- humans can't defend Earth against potentially catastrophic asteroid impacts. There's no sure way to predict an Earth-approaching asteroid's orbit unless you can factor in how the Yarkovsky effect will change that orbit, Drake and Lauretta said.
Their targeted near-Earth asteroid was discovered in 1999 and is named RQ36. It is roughly 580 meters in diameter, or about two-fifths of a mile.
Asteroid RQ36 orbits between about 83 million and 126 million miles from the sun, swinging within about 280,000 miles of Earth orbit, or roughly 40,000 miles beyond the moon. The International Astronomical Union's Minor Planet Center has officially classified RQ36 as a "potentially hazardous asteroid."
Asteroid RQ36 is especially rare because it linked to other asteroids that are outgassing volatiles and organic molecules like a comet. Only four such comet-like asteroids have been found in the main asteroid belt between Mars and Jupiter, Lauretta said.
Asteroids in the main belt between Mars and Jupiter are the leftovers of terrestrial planet formation. Near-Earth asteroids are fragments of main belt asteroids that were sent careening out of the belt in collisions with larger asteroids millions of years ago. Those which move into Earth-approaching orbits present hazards -- hazards that Congress has mandated that NASA address.
But near-Earth asteroids also present great opportunities, Lauretta said. "The analogy is that, much the same way rocks and sediments in a river bed reveal information about the type of material found upstream, we can use near-Earth objects to discover a great deal about the nature of bodies found in the main belt," he said. "That's what we're doing in sampling a near-Earth object -- we're looking at the rocks that are tumbling in from the main asteroid belt, a place that's too expensive to sample with a Discovery-class mission."
If selected, OSIRIS would launch in fall 2011 and reach Asteroid RQ36 in February 2013. It would rendezvous with RQ36 for nearly 300 days, using scanning lidar, an instrument similar to radar but using light instead of radio, and LPL-designed cameras to map and photograph the asteroid at visible and infrared wavelengths.
Before departing no later than December 2013 for its 4-year journey back to Earth, OSIRIS would use a robotic arm and the asteroid's weak gravity to collect at least 150 grams (about 5 ounces) of primitive asteroid regolith (dirt) for analysis by scientists at Lauretta's LPL lab and around the world. NASA's Johnson Space Center in Houston will curate returned samples.
In a novel arrangement ideal for longer missions, each of OSIRIS' science and management teams partner lead senior personnel with mid-career and early-career team members. Drake is the senior scientist mentoring the younger Lauretta in directing OSIRIS science, for example. The LPL's Peter Smith heads the imaging team that will build OSIRIS' camera system, for another example. The LPL's Bashar Rizk, Professor Tim Swindle and Carl Hergenrother are younger or mid-career scientists on Smith's team.
NASA also selected two other proposed new Discovery-class missions, and three more Discovery-class proposals that would make use of existing NASA spacecraft, for concept development funding. The space agency is expected to review developed proposals next year and select the final winner, or winners, from currently competing Discovery class missions in summer 2008.
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