The OSIRIS-REx spacecraft has been orbiting the asteroid Pennu since late 2018. This task – refers to the origin, spectral interpretation, resource identification, and Security-Recolith Explorer launched in September 2016.
Since arriving in Penn, the spacecraft and its cameras have been collecting and returning data and images, helping to learn more about asteroid composition and map the best landing sites to collect samples.
The main event of this trip, also known as the Touch-and-Go Sample Collection Event or TAG, is scheduled for October 20 at 5 p.m.
The asteroid and spacecraft are currently about 207 million miles from Earth, causing a communication delay of about 18.5 minutes. The team at NASA will do livestream animation depicting what is happening based on commands already sent to OSIRIS-REx for the sample collection queue.
Since direct commands from Earth are not possible, the spacecraft will approach the asteroid and make the entire sequence of collecting samples autonomously.
Based on the data provided by the spacecraft, the mission team can confirm whether Touchdown was successful on Tuesday.
The spacecraft has actually conducted two rehearsals without touching the asteroid, so its crew is ready for this much-anticipated event.
However, this is not what scientists expected. The Nightingale landing site is surrounded by dangers, so this task must be carried out very accurately.
The OSIRIS-REx spacecraft must detect hazards and delay its own mission if there are any obstacles in the way of sample collection. But if everything goes smoothly, the spacecraft and its valuable model will embark on a long journey to Earth next year and land the model on Earth in 2023.
Tapping building-sized boulders
Imagine a van flying 15 passengers in space and approaching a cliff the height of the Empire State Building and spinning fast. This is the OSIRIS-REx task for Pennu.
Penn has an orbit that brings it closer to Earth, which is why it is considered an asteroid close to Earth. One of its future approaches is to bring it closer to Earth in the next century; This is one of the 2,700 opportunities that will affect our planet.
Pennu’s models will help scientists understand not only the asteroids that could affect Earth, but also how planets formed and how life began. In total, the spacecraft will collect about 2 ounces or 30 packets of sugar, valuables from the asteroid.
Although it may seem small, NASA says it is the largest sample revenue from space since the Apollo program.
But first, you need to take a short, narrow path to the Nightingale landing site in a ravine in the northern hemisphere of the OSIRIS-REx asteroid.
The touchdown area has been reduced to one tenth of the original plan, so accuracy is important. At the eastern edge of the abyss lies a building-sized boulder that threatens the spacecraft and retreats from the asteroid as soon as the sample is collected.
Penn was “not the sandy beach we had hoped for and expected,” Thomas Surbuchen, co-executive director of the Science Mission Directorate at NASA, told a news conference in September.
Instead, scientists discovered that the asteroid was covered by house-sized rocks. The team used the spacecraft to determine the entire asteroid map and four landing sites. Nightingale was eventually chosen as one of the best.
“We chose Nightingale because it has the best material from all four sample site candidates,” said Dante Loretta, the mission’s primary investigator and professor at the Arizona Lunar and Planetary Laboratory in September.
“We did low-altitude spy surveillance on this site in early 2020, eventually capturing an eighth of an inch per pixel. We basically have incredibly detailed images covering the entire abyss, and we counted all of those rocks.”
Goes inside Touch Town
The Nightingale landing site is 52 feet in diameter, about the size of a few parking spaces, where the van-sized spacecraft briefly touches for a few seconds. There is no room for error; The building-sized boulders are a few steps away.
The event takes about 4.5 hours to launch, and the spacecraft will run three maneuvers to collect the sample.
The spacecraft will first leave its safe orbit around the asteroid at a distance of about 2,500 feet from the surface and travel for four hours before reaching a distance of 410 feet. Then, the spacecraft adjusts its position and speed to continue landing.
Next, OSIRIS-REx slows down its descent to target a path, so it is compatible with asteroid rotation during contact. Its solar panels fold the Y-Wing locally above the spacecraft to protect them.
Finally, OSIRIS-REx will touch down in less than 16 seconds. The spacecraft will inject a compressed nitrogen bottle into the asteroid using gas as a means of lifting objects from the surface of the pen.
The spacecraft’s collector catches the headless object. Located in the hands of an 11-foot-long robotic model, the head touches only one part of the spacecraft, the pen. The panel compares it to the air filter in an older model car, which is better suited for collecting items.
If part of the model maneuver does not go according to plan, small disks that can collect dust, such as sticky pads, are also located on the head.
A camera on the spacecraft will take footage of the collection event.
“We can tell if we are leaning, if the gas is blown to the side, if the material is stirred enough,” Loretta said. “We also have a good indication of the exact location of the Nightingale we are in contact with, and can compare it to our sample map, to assess if we touch an area with lots of sample objects or one of the rocker spots.”
Then, the spacecraft’s triggers move away from the surface of the pen and help it reach a safe distance again.
The OSIRIS-REx spacecraft must go its own way with these maneuvers and ultimately determine whether it is safe or not. The spacecraft relies on its natural feature tracking navigation system to take pictures seriously during descent and compare them to a list of logged images to ensure they are on the right track. It affects every step of the lineage and attitude.
If it certainly leaves, the spacecraft will stop this attempt.
The navigation system also has a danger map of the landing site, and if it finds that the spacecraft is approaching a danger, it will stop at an altitude of 16 feet above the asteroid and will not pursue that attempt.
This means OSIRIS-REx can be safe and try another sample collection in the future.
Checks with earth
At each step, the spacecraft will return data to NASA researchers on Earth, which will allow Touchdown to determine whether or not it was successful. Due to the epidemic only a limited number of teams will be on site in the mission support area of Lockheed Martin Space, while others will be on site at different locations to monitor the event.
To confirm whether the spacecraft actually collected a sample, one of the OSIRIS-REx cameras will take pictures of the collection leader on October 22nd. Also on October 24, the spacecraft will conduct a rotation to determine the mass of material it has collected.
Although the 2 ounce target, OSIRIS-REx can hold up to 4 pounds.
If the sample collection goes as planned, the head and sample will be placed in the return capsule for return to earth and sealed.
If the collection fails or there is not enough material, there are two more nitrogen charges for future efforts at a second site called Ospray in January 2021.
Overall, the team members will spend a week evaluating what they have collected and ensuring that the spacecraft and its equipment survive unscathed.
“So far, the result we get on October 20th is that we will come up with a great model that will touch the surface and meet our needs. But Pennu has already thrown a number of curved balls, which is why we are fully ready to mark Ospray (salvage site) if necessary,” said NASA in Maryland. Mike Morey, deputy project manager at the Goddard Space Center, said in a statement.
Scientists have recently discovered that the finest material on the Nightingale site has recently been exposed to the space environment. This means that the object collected by OSIRIS-REx will be the most beautiful object on the asteroid.
Pennu’s return to Earth will not be like the meteorites we have on Earth, NASA scientists say, because much of what they have learned about Pennu is unexpected.