Today, an Atlas V rocket launches into space carrying NASA’s OSIRIS-REx spacecraft on the first U.S. mission to retrieve a pristine sample of an asteroid and return it to Earth for further study. The mission’s target is Bennu, a carbon-rich near-Earth asteroid that is also potentially hazardous to Earth. Have questions about the mission? I answer a few.
What is the OSIRIS-REx Mission?
It’s a lofty goal involving a little luck, a lot of foresight, and the potential for immense advances in human knowledge and our ability to survive. OSIRIS-REx is a spacecraft commissioned by NASA and built by aerospace firm Lockheed Martin. Powered by two large solar panels, the flying laboratory is home to a variety of instruments that will study and map many characteristics of Bennu for further study.
OSIRIS-REx is an Acronym
NASA loves acronyms with many meanings. When broken down, the various letters correspond to each of the mission’s primary science goals (in NASA’s words):
O – Origins: Return and analyze a sample of a pristine carbon-rich asteroid to study the nature, history, and distribution of its minerals and organic materials.
SI – Spectral Interpretation: Define the global properties of a primitive carbon-rich asteroid to allow for direct comparison with existing ground-based telescopic data for all asteroids.
RI – Resource Identification: Map the global properties, chemistry, mineralogy of a primitive carbon-rich asteroid to define its geologic and dynamic history and provide context for the returned sample.
S – Security: Measure the Yarkovsky Effect* on a potentially hazardous asteroid and learn which asteroid properties contribute to this effect. *A force caused by the emission of heat from a rotating asteroid that can change its orbit over time
REx – Regolith Explorer: Document the texture, morphology, geochemistry, and spectral properties of the regolith (surface material) at the sampling.
The acronym is also a reference to the mythical Egyptian god, Osiris; purveyor of life along the Nile Delta and guardian of the afterlife and underworld. In that regard, OSIRIS-REx is a fitting name as two of the primary mission goals are searching for organic molecules to advance our knowledge of how life began on Earth and to assess the risk of Bennu impacting planet Earth in the near future. Scientists do have a sense of humor.
Why was Bennu Chosen?
Bennu is an asteroid that meets some very specific criteria. In fact, out of all 500,000 asteroid candidates in our Solar System, Bennu was the only prospect that made sense. It has the right composition, size, and proximity to Earth. It approaches our planet every 6 years and completes an orbit around the Sun every 1.2 years. At around 500 meters in diameter, the asteroid is large enough to safely land a spacecraft on the surface and conduct the necessary sampling. Smaller asteroids rotate too quickly and occasionally discharge surface debris.
Bennu is a B-type asteroid. Great, what does that mean? B-type asteroids are both primitive and carbon-rich (and rare). Primitive means that it’s nearly unchanged from when it formed nearly 4.5 billion years ago. Because of that, scientists expect to find organic (means carbon-based) compounds and water-bearing minerals. These will be immensely helpful in answering more questions about how life originated on Earth.
Stay in your Lane
As a Near-Earth Object (NEO), Bennu is one of many asteroids we watch and study due to their potential threat to planet Earth. Bennu in particular is considered a high-risk threat for impact in the late 22nd century.
Its combination of size, composition, orbit, and impact-threat made Bennu the perfect target for the OSIRIS-REx mission.
When to Watch:
OSIRIS-REx is scheduled to be launched on September 8, 2016 from Space Launch Complex 41 at Cape Canaveral Air Force Station, Fla. The launch window opens at 7:05pm EDT and lasts for approximately 120 minutes. Watch online at NASA TV.