It’s been in the works for more than a decade.
And now, the time has finally come: NASA’s getting ready to launch its first asteroid
sampling mission, called OSIRIS-REx.
On September 8th — that’s this coming Thursday!
— OSIRIS-REx is set to blast off and begin its journey to the asteroid 101955 Bennu.
The probe will collect a small sample from Bennu to help researchers learn more about
how life could have begun here on Earth.
Of the 500,000 known asteroids orbiting the sun, Bennu was chosen because its orbit takes
it close to Earth — it passes within 450,000 kilometers of us — and because of its size
and chemical composition.
Asteroids smaller than about 200 meters across spin so fast that any loose material we’d
want to study might have already been thrown into space.
But Bennu is about 500 meters in diameter, so it’s large enough that it doesn’t spin
too quickly to take a sample.
More importantly, though, Bennu is rich in carbon and other organic material.
Asteroids like Bennu haven’t changed much since they formed more than 4 billion years
ago, meaning the material they’re made of is the same stuff that was floating around
when Earth formed.
By analyzing the regolith, the loose, rocky material on the surface of the asteroid, NASA
hopes to uncover elements and amino acids that might have been the building blocks for
life on Earth.
Since we’ve already found these molecules in meteorites and on comets, we know the elements
for life can be created in space, but this time, we’re hoping to learn even more.
NASA has been visiting asteroids since the Galileo mission 1991, and we’ve even sampled
a comet with the 1999 Stardust mission, but OSIRIS-REx will be the first American spacecraft
to take and return samples from an asteroid.
The Japanese Space Agency, JAXA, completed a similar asteroid sampling mission in 2010,
so OSIRIS-REx will contribute to a growing body of research.
And after more than ten years of planning, it’s almost ready to go!
OSIRIS-REx is scheduled to launch from Cape Canaveral, Florida in only six days!
Once in orbit, it will slingshot around Earth in a gravity assist, using Earth’s gravitational
pull to help generate speed.
Then it’s off to Bennu, where it will arrive in 2018.
For almost two years, the spacecraft will travel with the asteroid, creating maps, checking
out its geology, and selecting a final target for sampling, using five top-notch scientific instruments.
The OSIRIS-REx Camera Suite contains cameras that will map the asteroid.
That’ll also help the sampling process go more smoothly.
The laser altimeter will create a topographical map of the asteroid, and the visible and infrared
spectrometer will map Bennu’s composition.
Meanwhile, the OSIRIS-REx Thermal Emission Spectrometer will check out the asteroid’s
mineralogy and surface temperatures.
Finally, there’s REXIS, the Regolith X-Ray Imaging System.
This is an experiment created by students from MIT and Harvard, and its goal is to track
the different elements on the asteroid’s surface.
After nearly two years, the asteroid sampling part of the mission will finally begin in
July 2020.
Instead of landing on Bennu, OSIRIS-REx will use the Touch-and-Go Sample Acquisition Mechanism
to basically give the asteroid a high-five.
To collect a sample, the craft will reach out with a mechanical arm and touch the asteroid
for only five seconds.
In those five seconds, it’ll release a puff of nitrogen gas to loosen material from the
asteroid’s surface, and pop it off into space.
And then it will just sort of hope that some of that stuff falls into its capsule where
it will close up and keep all the asteroid samples.
It’s pretty cool!
In case there are any issues, OSIRIS-REx will carry enough nitrogen for three attempts.
Depending on how the process goes, it could collect anywhere between 60 grams and 2 kilograms
of material – the most we’ve returned from a mission since the Apollo days.
Eight months later, OSIRIS-REx will leave the asteroid and head back toward Earth.
Once it gets close, it’ll eject the capsule carrying the sample, then enter an orbit around the sun.
The sample capsule has heat shields and parachutes, which will help it land in the Utah desert
in 2023 — seven years after the mission started.
Some of the material from Bennu will be shared with other space agencies or set aside for
future research, and the rest will be examined all the way down to the atomic level.
Bennu is like a time capsule of our early solar system.
Hopefully, our visit will give us a much better idea of what was floating around the solar
system as it formed.
Thanks for watching this episode of SciShow Space News, and thanks especially to our patrons on Patreon.
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