The OSIRIS-REx / Bennu Meeting Was Two Billion Kilometers in the Making

Bennu approach

It took a little over two years and more than two billion kilometers of cruising, but NASA’s OSIRIS-REx spacecraft made it. The asteroid Bennu, which measures about 1,600 feet across, will be OSIRIS-REx’s home for the next two years or so.

For the next 12 months, a suite of five scientific instruments will survey every inch of Bennu looking for the perfect place to grab a scoop of asteroid stuff. That’s right, the spacecraft will briefly touch the surface of Bennu to grab a sample of it. A sampling arm attached to the probe will rest on the surface for about five seconds. OSIRIS-REx will basically ‘tag’ Bennu.

But in these five seconds, one of the spacecraft’s most important mission objectives will be conducted. A burst of nitrogen gas will kick up rocks, and surface material that will be captured in the sampler head says NASA. OSIRIS-REx gets three tries to make it happen with the mission team hoping to collect anywhere between 2-70 ounces of Bennu stuff.

Even common measurements of Bennu like mass will be a big deal. That’s because there’s a chance the asteroid could hit Earth in the future.

Calculating its exact mass lets scientists get an even better handle on its future orbits according to OSIRIS-REx’s flight navigator Coralie Adam. Today, OSIRIS-REx will perform its first close flyby of Bennu as it soars above the surface at less than five miles away.

Wondering where the OSIRIS-REx name came from? It doesn’t have the same ring as New Horizons or Juno, but it does share a place in the New Frontiers program with them. OSIRIS-REx is an acronym of the mission objectives.

Asteroids like Bennu are such intriguing targets because they are the leftovers from the solar system’s birth. Once back on Earth, scientists will be able to study a sample untouched since the early Solar System. And it’s these chunks of rock and ice that scientists suspect may have given Earth some of its water.

If everything goes smoothly, OSIRIS-REx will deliver the largest sample to Earth since the Apollo moon rocks. And it’ll make that delivery in September 2023.