OSIRIS-REx mission will meet with asteroid “Bennu” in 2018, collect samples and return back to Earth. What can we learn from this mission and how important it is? What’s the next best object to collect samples from?

Morgan Rehnberg (PhD student at University of Colorado, works with Cassini to study Saturn’s rings)


Samples from an asteroid like Bennu will help us understand the conditions out of which planets like Earth formed in the early Solar System. With each new exoplanet discovery, we find more evidence that confounds the traditional model of planetary formation, so this is vital information. If I could sample from elsewhere in the Solar System, I’d pick either Meecury or Mars. We need additional samples from cratered bodies in order to refine our dating methods. Today, the ages of pretty much everything are calibrated solely by the rocks returned from the Moon by the Apollo astronauts!

Paul Carr (Space Systems engineer at NASA, podcaster, blogger, investigator)


OSIRIS-Rex is not the first asteroid sample return. In fact, when it returns to Earth in 2023, it should be the third sample return, with the Japanese Hayabusa and Hayabusa 2 missions ahead of it. Hayabusa only returned a tiny sample from an S-class asteroid, but it was confirmed to be asteroidal in nature. The NEAR mission launched in the mid 1990s was the first asteroid rendezvous mission, but did not return samples. From my perspective, the most important aspect of studying asteroids is to determine if they are ore-bearing, and I’m not clear if sample return does a whole lot better for that purpose than instruments like an X-ray spectrometer (OSIRS-REX is flying one called REXIS), which can measure the elemental composition. My understanding is that the asteroid Bennu was picked as a target because it is a C type asteroid, and may contain some organic material, which would be of great scientific interest. A sample return will of course provide tremendous detail about the material composing the asteroid’s regolith, and I always hope there will be interesting surprises – maybe even water bearing minerals. So far, the closest look we have had to a C type asteroid was in 1999, when NEAR flew by the main belt asteroid Mathilde. What NEAR saw was surprising – two huge craters in comparison to the size of the body. To absorb impacts that large, Mathilde must be quite low density – a sort of spongy texture. It will be interesting to see if Bennu is similar, and its laser altimeter should enable some precise measurements of its gravity field.

Antonio Paris (Astronaut Candidate, Astronomy Professor, Planetary Scientist, Space Science Author)


Asteroid Bennu, like all asteroids, is a “time capsule” loaded with vital information regarding the formation of the Solar System. More importantly, the Osiris-Rex mission to Bennu is centered on studying the surface of the asteroid, which is covered in carbonaceous material. This material is a critical element in organic molecules required for life. It is possible, therefore, that the Osiris-Rex mission could finally unlock the secrets to how life on Earth began, and, more importantly, could provide clues for the search for life elsewhere in the Solar System!