SPACE NEWS
In new space race, scientists propose geoarchaeology can aid in preserving space heritage
LAWRENCE, KANSAS — As a new space race heats up, two researchers from the Kansas Geological Survey at the University of Kansas and their colleagues have proposed a new scientific subfield: planetary geoarchaeology, the study of how cultural and natural processes on Earth’s moon, on Mars and across the solar system may be altering, preserving or destroying the material record of space exploration.
“Until recently, we might consider the material left behind during the space race of the mid-20th century as relatively safe,” said Justin Holcomb, postdoctoral researcher at the Kansas Geological Survey, based at the University of Kansas, and lead author on a new paper introducing the concept of planetary geoarchaeology in the journal Geoarchaeology. “However, the material record that currently exists on the moon is rapidly becoming at risk of being destroyed if proper attention isn’t paid during the new space era.”
Since the advent of space exploration, humans have launched more than 6,700 satellites and spacecraft from countries around the globe, according to the Union of Concerned Scientists. The United States alone accounts for more than 4,500 civil, commercial, governmental and military satellites.
“We’re trying to draw attention to the preservation, study and documentation of space heritage because I do think there’s a risk to this heritage on the moon,” Holcomb said. “The United States is trying to get boots on the moon again, and China is as well. We’ve already had at least four countries accidentally crash into the moon recently. There are a lot of accidental crashes and not a lot of protections right now.”
Holcomb began considering the idea of planetary geoarchaeology during the COVID-19 lockdown. Applying geoarchaeological tools and methods to the movement of people into space and the solar system is a natural extension of the study of human migration on Earth, the focus of the ODYSSEY Archaeological Research Program housed at KGS and directed by Holcomb’s co-author, Rolfe Mandel, KGS senior scientist and University Distinguished Professor in the Department of Anthropology.
“Human migration out of Africa may have occurred as early as 150,000 years ago, and space travel represents the latest stage of that journey,” Mandel said. “Although the ODYSSEY program is focused on documenting the earliest evidence of people in the Americas, the next frontier for similar research will be in space.”
How planetary geoarchaeologists will determine whether an item is worth preserving is an open question.
“We feel that all material currently existing on extraterrestrial surfaces is space heritage and worthy of protection,” Holcomb said. “However, some sites, such as the very first footprints on the moon at Tranquility Base or the first lander on Mars, Viking 1, represent the material footprint of a long history of migration.”
Beyond those “firsts,” sifting through the hundreds of thousands of bits of material currently in orbit or strewn across the surfaces of the moon and Mars — what many call “trash” but Holcomb and his colleagues regard as heritage — will require case-by-case decision making.
“We have to make those decisions all the time with archaeological sites today,” Holcomb said. “The moon has such a limited record now that it’s totally possible to protect all of it. Certainly, we need to protect space heritage related to the Apollo missions, but other countries, too, deserve to have their records protected.”
With resources for protecting space heritage limited, Holcomb and his colleagues advocate for developing systems to track materials left in space.
“We should begin tracking our material record as it continues to expand, both to preserve the earliest record but also to keep a check on our impact on extraterrestrial environments,” he said. “It’s our job as anthropologists and archaeologists to bring issues of heritage to the forefront.”
Beyond the moon, Holcomb wants to see planetary geoarchaeology extend to issues related to exploration and migration to Mars. He points to NASA’s Spirit Rover as an example. The rover became stuck in Martian sand in 2008 and now risks being completely covered by encroaching sand dunes.
“As planetary geoarchaeologists, we can predict when the rover will be buried, talk about what will happen when it’s buried and make sure it’s well documented before it’s lost,” he said. “Planetary scientists are rightfully interested in successful missions, but they seldom think about the material left behind. That’s the way we can work with them.”
Holcomb believes geoarchaeologists should be included in future NASA missions to ensure the protection and safety of space heritage. Meanwhile, geoarchaeologists on Earth can lay the foundation for that work, including advocating for laws to protect and preserve space heritage, studying the effects extraterrestrial ecosystems have on items space missions leave behind and conducting international discussions regarding space heritage preservation and protection issues.
As for being part of a space mission himself?
“I’ll leave that to other geoarchaeologists,” Holcomb said. “There’s plenty to do down here, but I do hope to see an archaeologist in space before it’s all over.”
JOURNAL
Geoarchaeology
ARTICLE TITLE
Planetary geoarchaeology as a new frontier in archaeological science: Evaluating site formation processes on Earth's Moon
Two planets sharing same orbit around their
star? Astronomers find strongest evidence yet
Wed, July 19, 2023
CAPE CANAVERAL, Fla. (AP) — Astronomers reported Wednesday the discovery of what could be two planets sharing the same orbit around their star.
They said it’s the strongest evidence yet of this bizarre cosmic pairing, long suspected but never proven.
Using a telescope in Chile, the Spanish-led team spotted a cloud of debris in the same orbit as an already confirmed planet circling this star, 370 light-years away in the constellation Centaurus. They suspect it’s either a planet in formation or remnants of a planet that once was.
Asteroids are known to accompany planets around their star — for example, Jupiter and its so-called Trojan asteroids. But planets in the same orbit “have so far been like unicorns,” noted study co-author Jorge Lillo-Box of Madrid’s Center for Astrobiology.
“They are allowed to exist by theory, but no one has ever detected them,” he said in a statement.
The scientists said they will need to wait until 2026 in order to properly track the two objects around the star known as PDS 70.
The confirmed planet with the suspected tagalong takes 119 years to complete a lap. A gas giant, it’s three times the size of Jupiter. Another gas giant is known to circle this star, albeit from a much greater distance.
Lead author Olga Balsalobre-Ruza of the Center for Astrobiology in Madrid, said the findings, published in the journal Astronomy and Astrophysics, are “the first evidence” that such double worlds might exist.
“We can imagine that a planet can share its orbit with thousands of asteroids as in the case of Jupiter, but it is mind-blowing to me that planets could share the same orbit," she said in a statement.
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Marcia Dunn, The Associated Press
To stick or to bounce: Size determines the stickiness of cosmic dust aggregates
IMAGE: MICROMETER-SCALE DUST PARTICLES FROM PROTOPLANETARY DISKS, OR SITES AROUND STARS WITH PARTICLES AND HYDROGEN AND/OR OTHER GASSES, AGGREGATE TO FORM PLANETESIMALS, OR KILOMETER-SCALE BUILDING BLOCKS OF PLANETS. PLANETESIMALS, IN TURN, MERGE DUE TO MUTUAL GRAVITY. view more
CREDIT: JAMSTEC
Microparticle dust aggregates, which are thought to play a role in the formation of new planets, are less likely to stick together after a collision when the aggregates are larger.
Current evidence suggests that microparticles of cosmic dust collide and stick together to form larger dust aggregates that may eventually combine and develop into planets. Numerical models that accurately characterize the conditions required for colliding microparticle aggregates to stick together, rather than bounce apart, are therefore paramount to understanding the evolution of planets. Recent modeling suggests that dust aggregates are less likely to stick together after a collision as the size of the aggregates increases.
A team of astrophysicists performed numerical simulations of dust aggregate collisions, with equal-mass aggregates varying between 10,000 and 140,000 microns (one to 14 cm) in size, using soft-sphere discrete element methods. The discrete modeling system accounted for each particle within the aggregate rather than treating the aggregate as a single entity, and soft-sphere simulation assumed the rigidity of each particle of the aggregate but allowed for deformations that may occur during collision. Their modeling indicated that increasing the radius of microparticle dust aggregates decreased the sticking probability, or likelihood that two aggregates would stick together and form a larger aggregate after collision.
The team published the results of their study in The Astrophysical Journal Letters.
"The formation process of kilometer-sized bodies, planetesimals, from cosmic dust, which is the initial stage of planet formation, has been one of the biggest problems in the theory of planet formation," said Hidekazu Tanaka, one of the authors of the study and professor at the Astronomical Institute in the Graduate School of Science at Tohoku University in Sendai, Japan. "The present study showed that the dust clumps that are the material for planets stop growing when they grow to a certain size, as large clumps are difficult to adhere to each other. Our results made the problem of planetesimal formation even more difficult. The adhesive growth of dust clumps is a key process in the planet-formation process."
The simulations suggest that collisional bouncing between large microparticle aggregates would decrease the formation of planetesimals, or the building blocks of planets. Kilometer-scale planetesimals form planets through collisional merging via mutual gravity.
Earlier modeling simulations and laboratory experiments characterizing the threshold for the sticking/bouncing barrier of dust aggregate collisions often produced conflicting results, which the research team and others hypothesized was due to varying sizes of aggregates. The results of the current study support this hypothesis.
It is currently unclear why the size of aggregates affects the sticking probability during a collision. Future studies aimed at dissecting the packing structure of aggregates over time may help scientists understand how aggregates can approach the scale of planetesimals. Studies of the contact sites between aggregates, where most energy is dissipated, after a collision may also unveil how larger aggregates eventually stick together.
Additionally, the simulations performed by the research team suggest that the sticking probability of particle aggregates may also be affected by the size of the individual particles that make up the aggregate and not just the radius of the entire aggregate.
The team acknowledges that the simulations they have performed in this study are far from comprehensive. Simulations that include aggregates that can be prepared by realistic procedures and that address acceleration will be performed, and laboratory experiments that will fine-tune the model are also planned.
Beyond these simulations, the team has their sights set on larger aggregates, which may fundamentally change current theories of planet development. "We will use a supercomputer to perform large-scale numerical simulations of collisions between even larger dust clumps in order to investigate how difficult it is for large dust clumps to attach to each other. This will help to settle the question of whether the formation of planetesimals is possible through the adhesion of dust clumps or not," said Tanaka.
JOURNAL
The Astrophysical Journal Letters
DOI
Hubble images a starstruck galaxy
Reports and ProceedingsIMAGE: THE IRREGULAR GALAXY ARP 263 LURKS IN THE BACKGROUND OF THIS IMAGE FROM THE NASA/ESA HUBBLE SPACE TELESCOPE, BUT THE VIEW IS DOMINATED BY A STELLAR PHOTOBOMBER, THE BRIGHT STAR BD+17 2217. ARP 263 – ALSO KNOWN AS NGC 3239 – IS A PATCHY, IRREGULAR GALAXY STUDDED WITH REGIONS OF RECENT STAR FORMATION, AND ASTRONOMERS BELIEVE THAT ITS RAGGED APPEARANCE IS DUE TO ITS HAVING FORMED FROM THE MERGER OF TWO GALAXIES. IT LIES AROUND 25 MILLION LIGHT-YEARS AWAY IN THE CONSTELLATION LEO. TWO DIFFERENT HUBBLE INVESTIGATIONS INTO ARP 263, USING TWO OF HUBBLE’S INSTRUMENTS, CONTRIBUTED DATA TO THIS IMAGE. THE FIRST INVESTIGATION WAS PART OF AN EFFORT TO OBSERVE THE SITES OF RECENT SUPERNOVAE, SUCH AS THE SUPERNOVA SN 2012A THAT WAS DETECTED JUST OVER A DECADE AGO IN ARP 263. ASTRONOMERS USED HUBBLE’S POWERFUL WIDE FIELD CAMERA 3 TO SEARCH FOR LINGERING REMNANTS OF THE COLOSSAL STELLAR EXPLOSION. THE SECOND INVESTIGATION IS PART OF A CAMPAIGN USING HUBBLE’S ADVANCED CAMERA FOR SURVEYS TO IMAGE ALL THE PREVIOUSLY UNOBSERVED PECULIAR GALAXIES IN THE ARP CATALOG, INCLUDING ARP 263, IN ORDER TO FIND PROMISING SUBJECTS FOR FURTHER STUDY USING THE NASA/ESA/CSA JAMES WEBB SPACE TELESCOPE. THE INTERLOPING FOREGROUND STAR, BD+17 2217, IS ADORNED WITH TWO SETS OF CRISSCROSSING DIFFRACTION SPIKES. THE INTERACTION OF LIGHT WITH HUBBLE’S INTERNAL STRUCTURE MEANS THAT CONCENTRATED BRIGHT OBJECTS, SUCH AS STARS, ARE SURROUNDED BY FOUR PROMINENT SPIKES. SINCE THIS IMAGE OF BD+17 2217 WAS CREATED USING TWO SETS OF HUBBLE DATA, THE SPIKES FROM BOTH IMAGES SURROUND THIS STELLAR PHOTOBOMBER. THE SPIKES ARE AT DIFFERENT ANGLES BECAUSE HUBBLE WAS AT DIFFERENT ORIENTATIONS WHEN IT COLLECTED THE TWO DATASETS. view more
CREDIT: TEXT CREDIT: EUROPEAN SPACE AGENCY (ESA) IMAGE CREDIT: ESA/HUBBLE & NASA, J. DALCANTON, A. FILIPPENKO
Space telescope detects supernova blast so bright instruments couldn’t keep up
Rob Waugh
·Contributor
Wed, July 19, 2023
The explosion was so bright instruments struggled to keep up (University of Alabama in Huntsville)
A space telescope has detected a gamma ray burst (GRBs) so bright instruments couldn’t keep up with it, triggered by the collapse of a massive, distant star.
Gamma ray bursts are hugely energetic explosions – and this is believed to be the brightest ever observed.
It was accompanied by a huge supernova explosion, leaving behind a black hole.
Dr Peter Veres, an assistant professor with CSPAR, said: "During a GRB, we see the death of a massive star, approximately 30 times more massive than the sun, and the formation of a black hole."
"The black hole launches a very fast jet close to the speed of light, and the jet will produce the gamma-ray burst. At later times, GRBs are visible at other wavelengths as well, from radio, or optical through very high-energy gamma-rays, which is called the afterglow of the GRB.
"This GRB was so bright, the afterglow showed up in the gamma ray burst monitor, which is very uncommon, and we could follow it for almost three hours.”
Read more: Mysterious “rogue planet” could be even weirder than we thought
The explosion came from 2.4 billion light-years away in the constellation Sagitta.
GRB 221009A is also one of the nearest and possibly most energetic GRBs ever found, as detailed in a paper on the arXiv preprint server, which has been accepted for publication in The Astrophysical Journal Letters.
The GBM is an instrument in low-Earth orbit aboard the Fermi Gamma-ray Space Telescope that can see the entire gamma-ray sky not blocked by the Earth and hunts for GRBs as part of its main programme.
Read more: Astronomers find closest black hole to Earth
"This gamma-ray burst was extremely bright. We expect to see one like this only every 10,000 years or so," says Dr Veres.
"We routinely detect GRBs at a rate of about five per week and keep an eye out if any of the GRBs are special in some way.
“This one was so bright, the instrument couldn't keep up with the large number of incoming photons. Most of the work, led by Stephen Lesage, was to figure out how to reconstruct the lost counts."
When the gamma rays enter these detectors, they interact with crystals in the instrument. The more energetic the gamma ray, the more light is produced.
By seeing which crystals light up, the GBM can tell the direction of the bursts. In all, the Fermi instrument has discovered over 3,500 GRBs, and 221009A is by far the brightest ever detected.
