Johnson Space Center Campus 31 does not have the grandeur and history of any Tower of London. There is no royal guard outside. However, it is here, in a 60s era building, that NASA keeps the jewels of its space program. Inside various clean rooms, curators track meteorites from Mars and the asteroid belt, cosmic dust, solar wind samples, comet particles and, of course, hundreds of kilograms of lunar rocks. Ars Technica took a tour of this secret NASA repository and brought out a lot of interesting things, which we will talk about.
At the end of December, representatives of this resource spent the day touring the collections of Object 31, including the rarely visited Genesis Lab. And although they were not given a lunar pebble as a keepsake, they took an unprecedented tour of each and every astromaterial that NASA collected from other bodies in the solar system and beyond. We now have the opportunity to study how NASA protects its rarest and most valuable examples from other worlds. Further in the first person, the story of Ars.
Antarctic meteorites
First we wanted to take a look at the famous Martian rock.
Before getting to NASA's meteorite laboratory, we took off our wedding rings, and then put on shoe covers, surgical caps and white vestments. After the locker room, we were transferred to a small chamber, in which an air shower took free particles from us - a kind of hurricane simulator. Finally, we find ourselves in a brightly lit sterile room in which NASA stores asteroids that scientists have collected in Antarctica.
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This collection contains about 20,000 stones, but the most famous of them is ALH84001. About 16 million years ago, a large meteorite or asteroid 0.5 to 1 kilometer across fell to the surface of Mars and lifted a row of rocks into space at a speed exceeding the planetary escape velocity. One of them flew through space and 13,000 years ago fell into Antarctica. A team of scientists, funded by the National Science Foundation, discovered it in the winter of 1984, but did not know at the time that the asteroid was home to Mars.
Americans were far from the first to realize that Antarctica is the best place in the world to search for meteorites. Japanese explorers have walked and collected them there since the 60s. When University of Pittsburgh geologist William Cassidy learned of their successful finds of all kinds of meteorites in 1973, he convinced the National Science Foundation to fund American expeditions. By 1976, the Americans had caught up with Japanese scientists in this area; and two years later, a NASA laboratory was created to store these samples.
Although the stream of meteorites in Antarctica is no different from streams anywhere else in the world, the climate on this continent is arid and cold, with almost no people, which helps the meteorites remain intact. Geography helps too. As massive sheets of ice float from the South Pole, they collide with the Transantarctic Mountains, a 3500-kilometer high ridge that stretches across the continent. Meteorites fall into the wide and flat polar region and are absorbed by this stream, which stops after reaching the mountains.
“When this ice appears, the right combination of altitude and temperature creates an ablation zone for the ice, and the meteorites remain beneath it,” explains Kevin Reiter, planetary scientist and curator of the Antarctic meteorite. "There are areas on the ridge with an incredible concentration of meteorites."
The rocks remain frozen until they reach the laboratory in Houston. This prevents rusting and mineral alteration that can occur at higher temperatures. Once in the laboratory, stones melt in a warm, dry environment, from which moisture is quickly removed. The stones are then stored in nitrogen cabinets to prevent further oxidation.
Ten years after scientists discovered ALH84001, they realized that this and a dozen other similar meteorites almost certainly came from Mars, since they contain traces of gas inherent in the atmosphere of Mars.
This led to an unexpected surge of interest from laboratories. When Dave McKay and other scientists at Johnson Space Center examined the rock, they discovered tiny, strange features that resembled worm-like fossils. Based on this finding, an article was published in Science in 1996 in which scientists announced the discovery of evidence of the existence of ancient life on Mars. Overnight, the Antarctic Meteorite Research Laboratory became one of the hottest places in the world. Scientists and journalists vied with each other to get inside.
Today, with NASA's rovers scratching the entire surface of Mars, it might seem like the search for new Martian rocks in Antarctica, where they were exposed to the Earth's atmosphere for thousands of years, would be useless for science. But that's not true, says Reiter.
“Martian meteorites are of great interest,” he explains. - We have received a lot of useful information about Mars from rovers, and a lot of attention is paid to finding evidence of the existence of liquid water, volatiles and everything that may be associated with life. However, when we collect Martian rocks here on Earth, there is not much evidence in these meteorites to indicate such processes. Therefore, we believe that we are missing a significant part of the diversity of rocks from Mars in our collection. If we were to actually find a piece of sediment from Mars, there could be many more measurements on Earth in the laboratory than robotic missions would allow.”
In addition to the Martian rocks, NASA has hundreds of meteorites from the large asteroid West, and some are believed to have come from other bodies in the asteroid's belt. There are also meteorites from the Moon, and Reiter says they offer valuable variety over our sample of six lunar landing sites. There are also several dozen "stray" meteorites, the place of origin that scientists cannot trace. It is possible that one of them was born on Venus or Mercury. The search for interesting new meteorites is the reason scientists return to Antarctica every November.
As for ALH84001, Reiter received the packed meteorite in no time. “This is it,” he says so that we understand the scale of the delivery. "A large piece of rock." And there was a big piece of rock. Soon after being published in Science, the majority of the scientific community came up with a different, more acceptable explanation for the small fossil tunnels. This stone is lifeless today and probably always has been.
But the search continues. If the universe is going to bring pieces of other worlds to Earth, the least we can do is go and get them.
Comets and stardust
He was standing on the table, right in front of us. Eleven years ago, this array of 132 airgel-filled tiles shaped like a tennis racket flew through Comet Wilde's 2 coma. After passing 400 kilometers from the comet's nucleus, the array first captured tiny pieces of the comet. The Stardust spacecraft then successfully returned to Earth in 2006. Now, nearly ten years later, scientists continue to scrutinize each tile for dust particles that have trapped in the airgel.
The airgel itself is almost a magical substance. It looks like frozen smoke. With a density 1000 times less than that of glass, it is almost air. But it's perfect for stopping particles smaller than a grain of sand that travel six times faster than a rifle bullet. The particles create trails as they pass through the airgel until they stop but are completely destroyed.
Ron Bastien, Stardust Lab Manager, prepared one of the tiles to demonstrate during our visit. “If you look at it closely, you can see this line going through it, this is where a small particle hits the airgel and its way through it,” he says. "If you look at the bottom of this trail, there will be a particle." A comet particle now hundreds of millions of kilometers away.
The comet's material has been studied by dozens of research groups. To their surprise, they found that comets form simultaneously in icy and hot conditions. Scientists have long known that comet ice forms at the cold edge of the solar system beyond the orbit of Neptune, but now they realized that a rocky core forms much closer to the sun.
They are aware of this because some of the particles collected by Stardust were white and irregular. These calcium-aluminum inclusions are believed to have formed very close to the sun's surface in the fire of the solar system's creation. They are among the oldest materials in the solar system, which are close to 4.56 billion years old. And now scientists have found them in comets that have traveled to Pluto and beyond. This gives scientists additional confidence that the study of comets is the study of time capsules, which will tell a lot about the times of the formation of the solar system.
Since the airgel tray was provided to the comet for a relatively short time, the Stardust mission had a second tray of tiles, just in case of fire.
During its extended flight to and from Comet Wilde 2, the spacecraft used this second tray to collect interstellar dust. Unlike the powerful stream of cometary particles, scientists expected to collect only a few tiny interstellar particles, microns in size, rushing towards the solar system at different angles. So when the spacecraft returned to Earth, scientists were asked to find these particles.
The Stardust lab installed automatic scanning microscopes that took pictures of the interstellar collector, and scientists invited the public - "duster" - to help find traces of particles in individual tiles as part of the Stardust @ Home project.
In August 2014, seven interstellar dust particles were announced, the first samples of dust from stars outside the solar system. The dasters found two particles. Even now, scientists are just beginning to understand the nature of these particles, some of which are "fluffy" like snowflakes and may have come from a supernova explosion millions of years ago.
Genesis
We were preparing for the most delicious part of the walk for an hour and a half when Judine Alton asked if we needed to use the restroom (I forgot to ask earlier). Fortunately, not necessary.
NASA stores the most sensitive samples in the Genesis laboratory, which is kept clean according to the space center's strictest protocols. The Genesis Laboratory stores particles of the solar wind, tiny pieces of the Sun that contain clues about the composition of the solar nebula when the planets were just forming.
We were instructed that morning not to wear wedding rings or use deodorant. In the hallway we put on gloves, shoe covers and hairnets. In the “dressing room” we were put on masks, full body suits, hats, special boots and a second pair of gloves. They also took my notebook and gave me "clean" paper - and inside I also got a "clean" Sharpie pen. Our photography equipment went through a cleanup, too: we had to spend several minutes wiping lenses and tripods with alcohol wipes until scientists were sure that the devices were sufficiently free of dust.
After all this, we asked how many visitors the laboratory received. “I don't accept people,” said Alton, the laboratory's curator. - You guys are special. This is mainly because people are dirty."
In 2001, NASA's Genesis spacecraft went into space to the L1 Lagrange point, where the gravity between the Earth and the Sun is balanced. For more than two years, the arrays of the apparatus have been collecting ions flowing from the outer layer of the Sun. Filters have been developed in various purities of materials, including aluminum, sapphire, germanium, silicon, gold, and diamond-like amorphous carbon, to collect different types of solar wind.
It was believed that the spacecraft would be able to collect billions of solar particles, equal in weight to just a few grains of salt, and then go to Earth. But during the last phase of the return, the aircraft's parachute system failed, and it fell in the Utah desert at a catastrophic speed of 300 km / h.
This was supposed to be the end. For most experiments, this would mean the end of the game. But the captured solar wind particles were 40-100 nanometers below the surface. Scientists, including Alton, have found they can save some of the particles if they thoroughly clean the filters that survived the impact with the Earth.
In short, scientists have adapted. In a brightly lit, clean room, Carla Gonzalez showed us exactly how by placing a stream of ultrapure water over a sample filter rotating at several thousand revolutions per minute. After 15 minutes, the water cleared the earth's dirt and space debris from the filter. This process also left no solvents. In the ten years since the return of Genesis to Earth, Alton, Gonzalez and others have cleaned and classified more than 2,000 samples, many of which are available for study by scientists.
Scientists accomplished most of the mission's research goals, including the surprising discovery that the Sun has more oxygen-16, the most abundant isotope, than Earth. This divergence has led scientists to investigate how this oxygen left the Sun during the first few million years of its existence, leading to new findings about the nature and development of the early solar system.
As we came to the end of our tour in a spotless lab, Gonzalez pulled out a filter with ultrapure water samples. I asked if it was possible to eat it now if it was so clean. “I think you can,” Alton replied. "But you would break my heart if you did that."
Moon stones
Ryan Ziegler smiled broadly, his round face perfectly emphasized by the clean cap that covered his head as we found ourselves in front of the shiny, multi-ton door of the bank vault. “Well guys, I've saved the best for last,” he said. Ziegler is studying lunar rocks at Johnson Space Center to better understand how the moon formed. He also oversees Apollo samples and organized our tour of NASA's Astromaterials Laboratory.
We were now standing in front of the vault that held two-thirds of all moonstones in the world.
And then we entered. Built in 1979, this building houses the Apollo 11 through Apollo 17 collections, which are housed in separate stainless steel cabinets. Astronauts brought back about 2,200 samples during six Apollo missions. Although 85% of the collection remains in pristine condition, more than 100,000 moonstones are currently tracked. “NASA general surveillance allows a specific sample to be requested at any time and can be found,” explained Ziegler.
There was something extraterrestrial in the room itself. The stones themselves were not visible; they were carefully packed in metal containers in teflon bags, sealed three times in cabinets that were themselves filled with pure nitrogen. “There is a lot of effort going into keeping these lunar specimens safe for future generations,” says Ziegler. And although you can't see them, you can feel the presence of tons of stones. Once they lay on the surface of the moon for billions of years, and then were collected by a dozen human hands, lifted from the lunar surface and fell into the Pacific Ocean. And now they are lying quietly again, already in this room.
Despite the precautions taken, "open" samples cannot be stored indefinitely. Even inside triple-sealed airtight containers, ultrapure nitrogen contains 10 to 100 ppb water. The lunar rocks show no signs of corrosion, but still the top nanometer or two have already been contaminated. Ziegler leads us to one of the closets. “These have never been opened,” he says. "These are three of our seven undiscovered samples." They were collected in the vacuum of the lunar surface, housed in vacuum sealed tubes and remain so to this day. NASA is saving them for an uncertain theoretical future in which scientists will find great new ways to analyze.
70% of all lunar rocks are stored in this one room. About five percent have been destroyed during various research processes, and another 15% are stored in a spare storage facility at White Sands, New Mexico. Johnson Space Center is safe, and this facility is on the second floor. But the space center is across the street from Clear Lake, which flows into Galveston Bay, which flows into the Gulf of Mexico. A Category 5 hurricane could destroy this facility.
Ziegler leads us out of the vault into a similar-sized workroom where the rest of the moonstone is kept. Large pieces of the Moon are displayed in larger stainless steel cabinets. Samples are returned here after study - the laboratory distributes from 500 to 1000 lunar samples a year to scientists for research. VIPs are also brought here to show the moonstones.
Among the samples on display is the so-called Genesis rock, which seems to be covered with powdered sugar. The Apollo 15 crew was tasked with finding just one in anorthosite rock, and they found it near the Apennines. At 4.1 billion years old, born just a couple hundred million years after the formation of the solar system, the Genesis stone helped confirm the theory of the formation of the moon after the Earth collided with an object the size of Mars at the very beginning of the solar system.
Based on materials from Ars Technica