Posted on October 4th, 2016

Reaching Orbit – To Bennu and Beyond!

Humans have a love/hate relationship with asteroids. They can spell out our untimely demise or unlock the mysteries of the Universe. Since our Sun hypothetically has many, many more years’ worth of fuel left the most imminent risk, outside of our own self-destructive behavior, is an asteroid strike. The Kepler and K-2 missions focus on finding asteroids that could be potentially hazardous to life on Earth, i.e. those objects that could be on a direct path to the planet. Getting funding for this kind of work is relatively easy as Congress has seen Armageddon enough to consider this a real possibility and they can’t be sure they are on the list for the underground bunker.

bennuThis handy pyramid show the elimination process for choosing a suitable asteroid for the OSIRIS-REx mission. (Credit: NASA and The University of Arizona)

Outside of our awesome fear of going the way of the dinosaur, asteroids contain material that many consider to be the building blocks of our Universe. There are three general categories of asteroids, of these C-type or carbon-rich asteroids are believed to be the most primitive, flying through space relatively unscathed for 4 billion years. Many scientist hypothesize that carbon-rich asteroids brought the building blocks of life to Earth, from amino acids to other organic molecules. Getting a sample from one of these asteroids is an astronomers dream, borne from this dream is the OSIRIS-REx mission.

The Rosetta mission was the last time a probe visited an asteroid and touched down, but it didn’t bring back any samples. Prior to that, Japan’s Hayabusa 1 attempted to land on an asteroid, Itokawa, to collect samples and return to Earth. However it lost communication and crashed into the asteroid, the sampling mechanism didn’t operate and the only particles that made it back to Earth were mostly contaminated. OSIRIS-REx launched on September 8, 2016 with the illustrious goal of bringing a sample back for in-depth analysis into the composition of asteroids and their origins.

Picking the best candidate for another asteroid mission is a process of elimination. First, the asteroid needs to be orbiting close to Earth but also not too close, and also easily accessible for a spacecraft. The asteroid also can’t be too small due to rapid rotation when the asteroid is less than 200 meters in diameter. Last on the list is composition, some were removed since their composition was unknown or they weren’t carbon-rich asteroids. In the end, an asteroid called Bennu was selected for the OSIRIS-REx mission.

The OSIRIS-REx spacecraft is assembled for environmental testing. (Credit: Lockheed Martin Corporation)

After 2 years of travel, OSIRIS-REx will rendezvous with the Bennu asteroid. For the next year the satellite will orbit and map the surface of the asteroid. The OLA instrument onboard will use scanning LiDAR (these are lasers that measure distances) to create a 3-D model of the asteroid’s surface. These measurements will help select the best sampling site for the instrument. OSIRIS-REx also includes a number of cameras for imaging the asteroid and the surrounding area, as well as an infrared spectrometer and an X-ray imaging spectrometer. Once a suitable site is chosen, the satellite will approach the area and collect a sample with its Touch-And-Go Sample Acquisition Mechanism (TAGSAM). The spacecraft will then return to Earth with its sample in tow for eager astronomers to inspect. The successful completion of the missions on September 24th 2023 will leave researchers with a plethora of data to analyze with the hope that some of the mysteries of our Universe will be unraveled.

Katie Nelson
Geospatial Ninja
(303) 718-7163

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