OSIRIS-REx, the hotly anticipated asteroid sample return mission bound for asteroid 101955 Bennu, has blasted off from Cape Canaveral Air Station’s SLC-41!
Rocketcam footage of liftoff:
Full launch through Centaur MECO-1:
The rocket coasted halfway around the Earth after that, then relit Centaur for a second burn, and about forty-five minutes after launch, MECO-2 left it on an Earth escape course. A fifteen minute coast then brought the vehicle within range of the tracking station in Canberra, Australia, and then the spacecraft was released. At this point, OSIRIS-Rex has a solar orbit actually not too much different than the Earth itself. This is by design; Bennu is an Earth-crossing asteroid, belonging to a class of bodies called Apollos. So they don’t want to get too far away from Earth orbit or they will be going far too quickly when they encounter Bennu. In about a year, OSIRIS-REx will briefly return for a gravity assist maneuver, stealing a tiny bit of the Earth’s momentum to propel it to a collision course with Bennu. Then, nearly a year after that, the spacecraft will arrive at Bennu.
OSIRIS-REx is spending a long time at Bennu; the window for Earth return will not open until 2021. So it will make good use of its time until then, mapping and investigating the carbonaceous (rocky) asteroid, selecting a site from which to collect a sample, and then gingerly flying up to the asteroid to collect the sample. Bennu is too light for a spacecraft to meaningfully land on it; its gravity is very slight. The concept is broadly similar to that of the Hayabusa spacecraft, which sampled the asteroid 25143 Itokawa in 2005 and returned the particles to Earth in 2010. However, the collection mechanism is different. Hayabusa had difficulties with its collector, and did not retrieve as much material as had been hoped; let’s cross our fingers for OSIRIS-REx to have better luck!
The mission does seem blessed so far — not only did the spacecraft survive the Falcon 9 pad explosion just a mile away, but the mission itself is $30 million under budget. During the cruise, the team will have the pleasure of deciding what to do with that extra money. Hire more scientists to make better use of the time they’ll have at Bennu? Additional studies during the cruise phases? A mission extension for the spacecraft after the canister is returned, a la Genesis? It will be fun to see what they come up with. 😉