Last week the spacecraft OSIRIS-REx performed a final review of all the maneuvers it would need to touch down on the Bennu asteroid and obtain a sample from it in the fall.
The sampling would take place on 20 October, making it the first NASA mission to collect a sample from an asteroid and return it to Earth.
The OSIRIS-REx will depart Bennu in 2021 and return to Earth in September 2023 bringing about 30 packets of asteroid material worth of sugar.
The NASA's OSIRIS-REx spacecraft has been circling the asteroid and mapping its surface since it arrived in December 2018.
Bennu is 179 million miles from Earth but it is considered an asteroid near Earth. For even near approaches possible in 2175 and 2195, the asteroid could come close to Earth, near than the moon, in 2135. A direct impact is impossible, but the data obtained during this mission will help determine the best ways to avoid asteroids close to Earth.
Bennu's samples will help scientists learn not only more about asteroids that could have an effect on Earth but also how planets developed and life began.
Environment Etiquette
The spacecraft worked through its TAG, or Touch-and-Go sequence, on Tuesday, which is how it would collect samples from the asteroid.
OSIRIS-REx performed its sampling sequence on Bennu, nicknamed Nightingale, about 131 feet above the selected spot. The site is on the northern hemisphere of the planet, within a crater. OSIRIS-REx then backed off site.
This training took about four hours to complete, as three of the four maneuvers that will be needed to collect a sample were working.
Essentially, to get closer to the surface of the asteroid's surface, the spacecraft had to perform burns, or fire its thrusters — leaving its orbit 0.6 miles from the asteroid.
NASA 's mission to collect the first asteroid sample finds its destination
Then at 410 feet it conducted a "checkpoint" fire. OSIRIS-Rex will autonomously test its location and velocity during this maneuver to see if it needs to make any changes before moving closer to the asteroid.
OSIRIS-REx then accomplished its "Matchpoint" burn, where the spacecraft matches the rotation of the asteroid to allow it to fly above the sample site.
The delicate dance of a NASA mission to collect samples from a rugged asteroid
This brought the spacecraft closer to the surface of the asteroid than it has ever been, at 131 feet.
OSIRIS-REx unfolded its Touch-and-Go-Sample Acquisition System during this close encounter, or sampling arm to test it in the setup it will be using in October.
Instruments on the spacecraft also took further measurements for the purposes of science and navigation, which is also part of the selection programme. The new high-resolution images obtained from these instruments will help the Natural Feature Tracking Guidance System for the spacecraft target the small sample collection site.
This guidance system allows OSIRIS-REx to use its on-board danger map and to avoid areas which could damage the spacecraft.
The proposed approach to enter and explore the Nightingale site indicates the likelihood of a successful touchdown in October.
This training took about four hours to complete, as three of the four maneuvers that will be needed to collect a sample were working.
Essentially, to get closer to the surface of the asteroid's surface, the spacecraft had to perform burns, or fire its thrusters — leaving its orbit 0.6 miles from the asteroid.
NASA 's mission to collect the first asteroid sample finds its destination
Then at 410 feet it conducted a "checkpoint" fire.
OSIRIS-Rex will autonomously test its location and velocity during this maneuver to see if it needs to make any changes before moving closer to the asteroid.
OSIRIS-REx then accomplished its "Matchpoint" burn, where the spacecraft matches the rotation of the asteroid to allow it to fly above the sample site.
The delicate dance of a NASA mission to collect samples from a rugged asteroid
This brought the spacecraft closer to the surface of the asteroid than it has ever been, at 131 feet.
OSIRIS-REx unfolded its Touch-and-Go-Sample Acquisition System during this close encounter, or sampling arm to test it in the setup it will be using in October.
Instruments on the spacecraft also took further measurements for the purposes of science and navigation, which is also part of the selection programme. The new high-resolution images obtained from these instruments will help the Natural Feature Tracking Guidance System for the spacecraft target the small sample collection site.
This guidance system allows OSIRIS-REx to use its on-board danger map and to avoid areas which could damage the spacecraft.
The proposed approach to enter and explore the Nightingale site indicates the likelihood of a successful touchdown in October.
The spacecraft would finally hit the surface of the asteroid in October, and use its measuring arm to touch down for five seconds. It releases a pressurized nitrogen charge to disrupt the asteroid's surface and retrieve samples from that material. Instead, on September 24, 2023, it will return the samples to Earth.
Another spacecraft, Hayabusa-2 from Japan, has obtained samples from the Ryugu asteroid — that may have originated from the same parent body as Bennu — and is already on its way back to Earth. As of December 2020, samples are expected back.
How we know till now
OSIRIS-REx has revealed intriguing details about the asteroid since it entered Bennu in 2018.
In September 2016, the project — which stands for History, Spectral Interpretation, Asset Detection, Security-Regolith Explorer — began.
Bennu is covered with boulders instead of the large areas of fine-grain material that scientists were anticipating.
According to NASA, Bennu is the smallest object ever orbited by a spacecraft, only a little smaller than the height of the Empire State Building.
Bennu 's form is similar to that of a spinning disk, and it's an asteroid named "rubble pile," which is a collection of rocks kept together by gravity rather than a single entity.
The instruments of OSIRIS-REx have confirmed that hydrated minerals, including magnetite, prevail on the asteroid and are widespread. The asteroid is full of precious materials and can also provide clues as to how life began. Bennu is, in fact, a legacy of the origin of our solar system billions years ago.
The spacecraft observed mysterious plumes of material ejected from the asteroid into space early in the mission.
Bennu possibly originated from the main asteroid belt, having split off from a larger asteroid in the Mars-Jupiter belt a few billion years ago. It knocked it into space until it was locked in place by an orbit near Earth.