You are looking at the successful landing and extraction of the largest rock sample from an asteroid that humanity has managed to transport back to Earth from space. Specifically, NASA managed to do it on Sunday, September 24 at 16:52 Central European Time (CET).
You can listen to and view information and footage in the introductory video report. It contains both available videos of the launch, sampling progress and landing of the mission, as well as additional animations.
It is estimated that the return capsule contains about 250 grams of particles that come from the asteroid Bennu, about 190 million kilometers away, that is about five hundred times farther than the Moon. The sun orbits once every 436 days, on average it is about 500 meters, so it does not rotate that fast, and that was one of the reasons why it was ideal for sampling.
“Bennu was chosen for a lot of reasons, but I’ll give you my three favorites. First, it is not far away. It is close to Earth, so we are able to get there easily and return with samples in a reasonable time frame,” says Michelle Thompson, Associate Professor of Earth, Atmospheric and Planetary Sciences from Purdue University, who is the first in the six-member team of scientists examining the samples, in the SZ Tech report.
“Secondly, it is a carbonaceous type of asteroid. That is, as we think, it is rich in organic molecules. And these organic molecules may have been around since Earth’s earliest days, so they can give us information about how life evolved on our planet. And the third reason is that in about 100 years Bennu will pass very close to Earth, even closer than the Moon is today. So we want to understand how its orbit works and how it evolves over time so that we can be prepared if there is ever an asteroid that needs to be deflected away from Earth in the future,” the expert continues.
Mission progress from gravity slingshot to asteroid impact
The mission to obtain unique samples from space took almost exactly seven years and was exciting not only during the actual collection of rocks from the asteroid, but also when they were unloaded on Earth. And it doesn’t even end there. But everything is in order.
The OSIRIS-REx spacecraft launched from Cape Canaveral, Florida on September 9, 2016. But due to fuel consumption, it could not fly directly to the planet Bennu, so it had to travel an astonishing 7.1 billion kilometers. And in order to overcome it as quickly as possible and survive at the same time, she had to master two main maneuvers.
The first was a gravitational slingshot around the Earth, with which it accelerated to 13,000 kilometers per hour after one year.
And the second was a series of four deceleration fires, after which on December 3, 2018, it reached a parallel speed with the asteroid, i.e. “only” 450 kilometers per hour at a distance of 20 kilometers from its surface. This was followed by a series of observation and mapping flights, among other things, to select and check the landing site, which itself came on October 21, 2020. The probe spent only six seconds on the surface after it.
“And we have Touch Down! Touch Down,” an enthusiastic cheer echoed through the control center at the time.
“We literally bumped into her. When the probe came into contact with it, the rocks apparently broke and shattered. We watched the images come in one by one. And at about two in the morning local time here in Denver. We got what I call bang for the buck,” Dante Lauretta, head of the OSIRIS-REx research team, described the landing at the time.
What is the probe equipped with and how did it take samples
The probe, manufactured by the American company Lockheed Martin for a total of one billion dollars, measuring up to 2.4 × 2.4 × 3.1 meters and weighing 2.1 tons, was equipped with six scientific instruments for this purpose. Of these, the camera system alone had three different types of lenses, followed by LIDAR for navigation, then three types of spectrometers to measure the radiation, temperature and composition of the asteroid, and then the most important of all – the sampling mechanism, which was said to be a real challenge to solve.
“OSIRIS-REx will collect samples from Bennu using the TAGSAM instrument, which is a Touch And Go Sample Acquisition Mechanism. It’s actually an arm connected to a head with a sampler that you see here. It’s similar in size to an air filter in a car,” Sandy Freund, probe development manager from Lockheed Martin, showed the key device in the SZ Tech report.
“The way the mechanism works is that there’s a compressed gas in it that, when released, stirs up the regolith on Bennu and stores it in this canister, which we then place in our storage return capsule and bring it back to Earth,” she added.
Door not closed
The aim of the probe was to collect at least 60 grams of samples from the planet Bennu, which, according to the enthusiasm at NASA, it managed to fulfill beyond expectations. Until it even seemed that the success of the probe could be fatal. Because of the larger fragments, the box door did not close and the samples leaked out.
Using the same arm, the scientists eventually had to rearrange the contents to seal it. And now they estimate that around 250 grams of material could have remained in it – plus or minus 101 grams. Due to unexpected complications, the devices could not weigh the sample.
Even if the Americans found the lower estimated limit of the quantity in the return capsule, it would still far exceed the previous transported samples. There were only two of them and both were acquired by the Japanese space agency JAXA. The Hayabusa 1 mission in June 2010 delivered less than a milligram from asteroid Itokawa, and Hayabusa 2 in December 2020 brought back over 5.4 grams of particles from asteroid Ryuga.
A difficult return. Thirty times the speed of sound and the temperature of the Sun
Returning to Earth wasn’t easy either. OSIRIS-REx launched it on May 10, 2021, and just today, September 24, 2023, it underwent its most difficult phase.
“We launch the capsule about 100 thousand kilometers away from Earth, which is a third of the distance to the Moon. And it must hit a corridor in the atmosphere about five kilometers wide. That’s like kicking a ball across a 110 kilometer pitch or something. It’s really amazing, but the navigators have been doing an equally amazing job all the time until now,” Mike Moreau, NASA team leader responsible for the capsule retrieval, described the landing maneuver in June.
The probe launched a capsule with samples of the asteroid at 12:42 Central European Time (CET) about 102 thousand kilometers from Earth.
The blunt cone with a diameter of 81 and a height of 50 centimeters entered the atmosphere four hours later, at an altitude of 132 kilometers and at a speed of up to 44.5 thousand kilometers per hour, during which it exposed its heat shield to a temperature of 2760 degrees Celsius.
In order to gradually slow down, he first opened the brake at a height of 31 kilometers, and then at 1.5 kilometers the main parachute, and thus reached a speed of 18 kilometers per hour. He hit the target area, an oval measuring 58 by 14 kilometers in the desert of the state of Utah, shortly before five o’clock in the afternoon.
Most of the samples taken will be saved for better times
From there, the capsule has already headed to the Johnson Space Center in Texas, where more than 200 scientists from 35 different institutions will get to work after a series of cleanings to ensure the samples are not contaminated.
They will be analyzing them for an estimated two years, hoping to understand what role these asteroids played in the formation of life on Earth. On Bennu, they found traces of the mentioned organic molecules and even water just from overflights. But they only get a quarter of the rocks to examine.
NASA wants to preserve 70 percent for the future when humanity has better technology. Four percent will then go to the Canadian Space Agency (CSA) for their LIDAR contribution, and half a percent to JAXA, which previously also gave part of its samples to the Americans for cooperation on the Hayabusa 2 mission.
“What we learn from this mission will likely revolutionize our understanding of objects in the early Solar System. So are these asteroids. It also required a lot of effort in engineering to make such a mission even possible. It was an extreme challenge to get it into orbit and retrieve a sample of the asteroid, which is less than 500 meters in diameter. And we will take such technology with us to all other planetary missions – be it explorations with robots or with a crew across the Solar System,” Michelle Thompson, who will examine the samples, adds again in the SZ Tech report.
Meanwhile, OSIRIS-REx has another journey ahead. After the capsule is released, it starts its engines again and sets off on a new mission to the planet Apophis. It is supposed to reach Earth at a distance of only 32,000 kilometers in 2029, and the renamed OSIRIS-APEX should just catch up with it. This time he won’t collect any more samples because he doesn’t have another container. Still, he tries to get close to her to find out her subsurface makeup. She should be examined for about 18 months.