A group of University of Colorado Boulder researchers is readying for
NASA’s Sept. 8 launch of a spacecraft to a near-Earth asteroid named
Bennu, thought to harbor primordial material left over from the
formation of the solar system 4.5 billion years ago.
The main mission goal is to pluck a sample of rocks and surface soil
from the asteroid, then return it to Earth for analysis. CU Boulder
Distinguished Professor Daniel Scheeres of the Department of Aerospace Engineering Sciences is the team leader for the mission’s radio science team, which will use spacecraft tracking data to probe Bennu.
“We essentially will be weighing the asteroid to see how the mass is
distributed within it," he said. "We need to know the mass and gravity
field of the asteroid before the spacecraft comes in contact with it and
to understand the sample we will collect."
The mission, called the Origins, Spectral Interpretation, Resource
Identification, Security- Regolith Explorer (OSIRIS-REx), will launch
from Cape Canaveral, Florida. After its two-year journey to Bennu, the
spacecraft will make observations and measurements for the following two
years, ending in the collection of a surface sample of up to 4 pounds
of material.
“Bennu has what we believe to be some of the most primitive,
organic-rich material that exists in our solar system,” said Scheeres.
“We think it was initially distilled out of gas during the dawn of the
solar system, which is the main reason it was chosen for the mission.”
Other CU Boulder researchers from aerospace sciences involved in the
mission include Assistant Professor Jay McMahon, Senior Research
Associate Paul Sanchez, postdoctoral researcher Siamak Hesar and
graduate students Daniel Brack and Samantha Rieger. CU Boulder is
expected to receive about $3 million from NASA over the course of the
mission.
Scheeres and his colleagues will use the Deep Space Network (DSN), a
group of large antennas and ground stations in the United States, Spain
and Australia that support interplanetary missions, to help them measure
the speed of the spacecraft. Scheeres and his team also will bounce
periodic “blips” between the DSN and OSIRIS-REx, using the time lags to
determine the spacecraft’s precise distance from Earth.
In addition to its pristine nature, Bennu also was selected because
it is fairly easy to get to, at least by space exploration standards,
said Scheeres. The spacecraft will fly roughly 1.2 billion miles,
circling the sun several times over the two-year journey, including one
flyby of Earth before catching up to and eventually nestling alongside
the asteroid.
Bennu is believed to be a rubble pile of primitive boulders, rocks
and gravel as well as organic compounds like amino acids that are rich
in carbon, Scheeres said. Scientists believe such compounds may have
contributed to the evolution of life on Earth and are important factors
in determining the potential for life elsewhere in the solar system.
A third motivation to visit Bennu is the tiny chance it could smack
Earth in the coming centuries. As a near-Earth asteroid, Bennu will
cross Earth’s orbit in about 160 years.
“By visiting Bennu we can very precisely determine its orbit,
determine the physical forces affecting it, and do a much better job of
predicting where it will be in the next couple of hundred years,”
Scheeres said. “By then we should know if we need to start building a
giant space tugboat.”
Bennu is roughly spherical with an equatorial bulge and has a
diameter of about 1,600 feet – larger than that of the U.S. Pentagon
building in Arlington County, Virginia.
The mission has a strong Colorado connection: In addition to CU
Boulder’s radio science role, the spacecraft was designed and built by
Lockheed Martin Space Systems in Littleton, Colorado, which also will
operate the spacecraft. OSIRIS-REx will be launched on an Atlas V rocket
built by United Launch Alliance in Centennial, Colorado.
In addition to the radio science equipment, OSIRIS-REx is carrying a
suite of cameras, spectrographs, a laser altimeter for mapping and the
Touch-And-Go Sample Acquisition Mechanism (TAGSAM). TAGSAM is a long,
jointed arm with a collection box that will reach from the moving
spacecraft to scoop up surface material that will be placed in a small,
cone-shaped container that later will be launched back to Earth,
arriving in 2023.
Scheeres was also a project scientist on NASA’s NEAR-Shoemaker
mission that visited the asteroid Eros in 2000 and the Japan Aerospace
Exploration Agency (JAXA) Hayabusa mission that visited the asteroid
Itokawa in 2005.
“When the first images come back and we see what Bennu’s surface
looks like and how the material is distributed, it will change our whole
perspective,” he said. “It will have features we never would have
imagined, which will be a joyful scientific experience.”
The OSIRIS-REx mission is being led by the University of Arizona
under Principal Investigator Dante Lauretta. NASA’s Goddard Spaceflight
Center in Greenbelt, Maryland is managing the mission
No comments:
Post a Comment