The touch-and-go (TAG) sample collection from the asteroid 101955 Bennu will be discontinued on Tuesday, October 20 at around 3:12 p.m. PT. NASA will broadcast the TAG maneuver live on NASA television and on the agency’s website starting Tuesday at 2 p.m. You can find the livestream link below.
When did the mission start?
Osiris-Rex as a concept has existed since at least 2004 when a team of NASA astronomers first proposed the idea. After more than a decade of development, the spaceship ison an Atlas V rocket from the United Launch Alliance, a joint venture between Lockheed Martin and Boeing. The spaceship spent the next 26 months cruising to Bennu and officially arrived on December 3, 2018.
Since then, the mission team has spent nearly two years orbiting the diamond-shaped space rock, surveying and mapping its surface in order to select the best sampling point. For the past few months, rehearsals have started ahead of the upcoming sampling attempt, and now the team says they are ready to play TAG with Bennu.
Bennu is a so-called “debris pile” asteroid, which means that it was formed in the deep cosmic past when gravity slowly compressed the remains of an old collision. The result is a body in the shape of a top with a diameter of about 500 meters and a surface strewn with large stones and boulders.
Bennu is said to be a window into the solar system’s past: a flawless, carbon-rich body that carries the building blocks of planets and life. Some of these resources, such as water and metals, could also be worth mining at some point in the future for use on Earth or in space exploration.
The asteroid has another property that makes it particularly interesting for scientists and humans in general – it has the chance to affect Earth in the distant future. Bennu ranks second on NASA’s list of impact risks. Current data shows dozens of potential impacts in the last quarter of the 22nd century, though all of them have a tiny chance of actually occurring.
How will TAG work?
For anyone who has ever looked into robots, or maybe even entered a robotics competition, the Osiris Rex mission seems to be the ultimate culmination of a young robot’s dreams. The touch-and-go sampling process is a complex, high-stakes task that has been developing into an important climatic moment for years. If it succeeds, it will play a role in history and our future in space.
The basic plan is for Osiris-Rex Bennu to land on a rock. The van-sized spacecraft has to negotiate building-sized boulders around the landing area to land in a relatively free space that is only as large as a few parking spaces. However, a robotic sampling arm will be the only part of Osiris-Rex that will actually be deposited on the surface. One of the three pressurized nitrogen canisters is fired to stir up a sample of dust and small stones which can then be caught in the arm’s collection head for safe storage and return to earth.
The descent to Bennu’s surface takes about four hours, about as long as the asteroid needs a full revolution. Remarkably, after this slow approach, the actual TAG sampling process takes less than 16 seconds.
The preparation for the TAG did not go exactly as planned. The mission organizers initially hoped that Bennu’s surface would have many potential landing sites, mostly covered with fine materials comparable to sand or gravel. It turns out that Bennu’s surface is extremely rough and doesn’t have any really inviting landing pads.
After spending much of the time reevaluating the mission over the past two years, the team decided to “thread the needle” through the boulder-filled landscape in Nightingale and a few other sample backup locations. It is still possible that the surface will turn out to be too rocky to receive a good sample. If this turns out to be the case, the team can try again at a different location. Osiris-Rex is equipped with three nitrogen canisters to fire and destroy the surface. This means that the team will make up to three attempts to take a sample.
Immediately after collecting the sample, Osiris-Rex will fire its engines to retreat from Bennu. The spaceship will hang around Bennu for the rest of 2020 before finally performing a takeoff maneuver next year and embarking on a two-year journey back to Earth.
On September 24, 2023, Osiris-Rex is expected to drop its sample recovery capsule, which will land in the Utah desert and be recovered for study purposes.
Hasn’t that been done yet?
Yes. Japan’s Hayabusa spaceship successfully brought tiny grains of asteroid 25143 Itokawa back to Earth in 2010. Its successor Hayabusa-2 was successfuland then took part of the splinter. This sample is currently on its way back to Earth.
How can I watch?
Follow NASA’s livestream, which begins Tuesday at 2 p.m. You can also follow Osiris-Rex’s Twitter feed for the latest updates.