The countdown has begun for NASA’s OSIRIS-REx mission to land on asteroid Bennu, a massive space rock zooming through the solar system at a distance of 334 million kilometers (over 200 million miles) from Earth.
The mission’s primary objective is to make its way to the surface of the asteroid, remain there for a few seconds, long enough for the spacecraft’s instruments to extend, collect surface samples from the asteroid before its thrusters take it back into space and orbit around Bennu.
The mission is of great importance since if it succeeds, it will mark the first time NASA will land a spacecraft on the surface of an asteroid, collect samples from it, and return it into space. If everything goes according to plan, the spacecraft is expected to begin its journey back home, carrying the alien samples with it.
Mission specialists have revealed that the spacecraft has been programmed to begin its descent onto the surface of the asteroid on Tuesday, October 20. The mission event, dubbed TAG, which stands for Touch-and-go, is expected to begin at 10:12 UTC when OSIRIS-REx begins its journey towards the asteroid’s rugged rocky surface.
This series of programmed maneuvers will take the spacecraft to the Nightingale site, an area of around 14 meters in diameter in the northern hemisphere of Bennu, where the spacecraft’s robotic sampling arm will attempt to collect some of the material from the asteroid’s surface.
The Nightingale site was selected as the mission’s primary sampling site because it contains the most fine-grained material free of obstructions. However, even though Nightingale contains materials that are likely easily collectible by the spacecraft’s robotic arm, NASA has revealed it is surrounded by building-sized rocks, which make this attempt at landing a daring one.
During the sampling event, the spacecraft which is the size of a large truck will attempt to land in an area that is only the size of a few parking spaces and only steps away from some of these largest boulders on the asteroid’s surface, NASA revealed in a statement.
The TAG event is expected to last 4.5 hours, which will see the spacecraft descend to the surface, collect the samples, and make its way back into space.
As explained by NASA, the spacecraft’s descent sequence begins with OSIRIS-REx firing up its thrusters for a maneuver to leave its safe-zone approximately 770 meters from the surface of Bennu.
The spacecraft will travel towards the asteroid’s surface for four hours, and before touching down, it will need to clear two checkpoints.
It will perform its first checkpoint maneuver at a distance of 125 meters above the surface. The spacecraft will adjust its position and speed relative to the asteroid to land on its designated position accurately.
Some 11 minutes after the first “checkpoint,” the spacecraft will perform its second maneuver doubled matchpoint, during which the spacecraft will be located at an altitude of 54 meters above the surface. It is during “matchpoint” when the spacecraft will begin to decelerate and make final adjustments in order to touch down smoothly on the surface.
You can see how all of the above will occur in the video animation below.
If, for some reason, things don’t go according to plan, and the descent towards Bennu is met with obstacles or the spacecraft fails to meet its landing criteria, there’s a backup plan that can be triggered with the spacecraft just 5 meters away from the surface. The navigation system of OSIRIS-REx is equipped with a hazard map of the landing site. This chart delineates areas within the sample site that can be potentially dangerous for the spacecraft.
If the NFT system detects that the spacecraft approaches an area that can damage the vehicle, it will abort the landing; this will keep the spacecraft safe and allow for another attempt at collecting samples to be made on a different date.
Nonetheless, we hope that everything goes to plan and that the mission will be another accomplishment by NASA in our effort to understand our solar system.
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