Geologen auf Spurensuche in den Jeetze-Wiesen - Salzwedel. Was flog am Abend des 3. Juni 1883 über den Horizont der Hansestadt?
Und wo ist es geblieben? Das Salzwedeler Wochenblatt berichtete 1883: „Einen prachtvollen Anblick gewährte uns gestern Abend zur elften Stunde ein langsam niedergehender Meteorstein von ziemlicher Größe. “ Fest steht, diese Himmelserscheinung gab es. Und das nicht nur über der Hansestadt, weiß der Salzwedeler Amateur-Geologe Ulrich Sperberg.
Dogs have been man’s best friend for tens of thousands of years. Their superior tracking abilities, combined with man’s superior killing abilities, made them invaluable to early hunter-gatherers.
This relationship persists to today, but the apex of the bond of friendship between the two species may have come in 1957, when a three-year-old mongrel named Kudryavka (“Little Curly”) was picked up on the streets of Moscow. She weighed about six kilograms, was part husky and part terrier, and had survived through several harsh Russian winters.
That made her the perfect candidate for an experimental programme being run by the Soviet government. Vladimir Yazdovsky was a medical scientist in the space program, who’d launched a number of dogs to altitudes of more than 450km in pressurised rockets.
While the US test rocket programme used monkeys, about two thirds of whom died, dogs were chosen by the Soviets for their ability to withstand long periods of inactivity, and were trained extensively before they flew. Only stray female dogs were used because it was thought they’d be better able to cope with the extreme stress of spaceflight, and the bubble-helmeted spacesuits designed for the programme were equipped with a device to collect feces and urine that only worked with females.
Training included standing still for long periods, wearing the spacesuits, being confined in increasingly small boxes for 15-20 days at a time, riding in centrifuges to simulate the high acceleration of launch, and being placed in machines that simulated the vibrations and loud noises of a rocket.
Some of the spacesuit designs used by the canine cosmonats // National Space Centre
The first pair of dogs to travel to space were Dezik and Tsygan (“Gypsy”), who made it to 110km on 22 July 1951 and were recovered, unharmed by their ordeal, the next day. Dezik returned to space in September 1951 with a dog named Lisa, but neither survived the journey. After Dezik’s death, Tsygan was adopted by Anatoli Blagronravov, a physician who later worked closely with the United States at the height of the Cold War to promote international cooperation on spaceflight.
They were followed by Smelaya (“Brave”), who defied her name by running away the day before her launch was scheduled. She was found the next morning, however, and made a successful flight with Malyshka (“Babe”). Another runaway was Bolik, who successfully escaped a few days before her flight in September 1951. Her replacement was ignomoniously named ZIB — the Russian acronym for “Substitute for Missing Bolik”, and was a street dog found running around the barracks where the tests were being conducted. Despite being untrained for the mission, he made a successful flight and returned to Earth unharmed.
“Despite being untrained for the mission, he made a successful flight and returned to Earth unharmed.”
In June 1954, Another dog named Lisa flew to an altitude of 100km with a companion named Ryzhik (“Ginger”), returning successfully. But they didn’t have to deal with the trauma of a mid-air ejection at an altitude of 85km, as Albina and Tsyganka (“Gypsy Girl”) did. The pair landed safely, and it was noted in particular by the scientists how well Albina had coped with the journey.
In 1957, Soviet scientists were ready to attempt something rather more audacious — an orbital flight. Sputnik was launched on 4 October 1957, in a storm of publicity, sparking something of a crisis in the United States. This triggered the space race, and eventually led not only to the creation of NASA and eventually the Apollo programme and Moon landings, but also a vast increase in the funding of science.
Soviet leader Nikita Khrushchev, in full thaw, decided to increase that pressure on the US and so Sputnik was followed up a mere month later by Sputnik 2 — a mission to put a living creature into orbit. The Soviets didn’t have the time to build the technology to bring the craft back, so it was known from the start that whichever animal was chosen would perish in space.
A longlist of ten canine cosmonauts was drawn up, which was then reduced to a shortlist of three. They were Albina — who’d already ejected from 85km, a dog named Mushka (“Little Fly”), and the aforementioned Kudryavka, who’d been collected on the streets of Moscow and impressed her trainers with her calm and quiet demeanour in the face of simulated stresses.
That even temperament won her the honour of being the first animal in orbit, and she was renamed Laika (“Barker”). In the days before launch she was kept in the module she would fly in — it was padded, had enough room for her to stand or lie down as she wanted to, and gave her access to a specially-designed nutritious jelly that was high in fibre for her to eat.
Dogs were housed in padded boxes like this for their voyage, allowing them space to stand or sit, and giving them access to food.
Before launch, she was covered in an alcohol solution and painted with iodine in the places where sensors were connected to her skin, which monitored her heartbeat, blood pressure and other biological variables.
On 3 November 1957, Laika blasted off from the Baikonur Cosmodrome and became the first creature to orbit the Earth. The launch went smoothly, and her capsule entered an elliptical orbit, circling the planet at 29,000 km/h and completing a full rotation every hour and forty-two minutes.
While Laika certainly made it into space alive, it’s not entirely clear how long she lived after that. It was originally announced that she was euthanised with poisoned food several days into the mission, then it was said she died when her oxygen supply ran out, on the sixth day of her journey.
Laika on a Romanian postage stamp
But in October 2008, fifty-one years after her journey and after a monument had been erected in her honour near the facility in which she was trained, it was finally revealed that she had most likely perished a few hours after launch from overheating and stress caused by the failure of a rocket component to separate from the capsule.
“We did not learn enough from this mission to justify the death of the dog.”
Oleg Gazenko, one of the scientists working on the mission, said in 1998 that he regretted sending Laika to her death:
Work with animals is a source of suffering to all of us. We treat them like babies who cannot speak. The more time passes, the more I’m sorry about it. We shouldn’t have done it… We did not learn enough from this mission to justify the death of the dog.
Laika in training and her memorial in Moscow // Soviet Space Program
But the mission was another great success for the Soviets, and the space programme continued. One of the most-travelled dogs was named Otvazhnaya (“Brave One”), who accompanied a dog named Snezhinka (“Snowflake”) into sub-orbital space on 2 July 1959 before making five more successful flights that year.
On 28 July 1960, Bars (“Snow Leopard”) and Lisichka (“Little Fox”) were chosen to follow Laika into orbit, but both perished after their rocket explosively disintegrated just twenty-eight seconds into the launch sequence. This crash caused considerable uproar within the Soviet space programme, as the problem that caused the explosion had supposedly been fixed.
Belka (“Squirrel”) and Strelka (“Arrow”) were the next successful orbiters, spending a day in space on 19 August 1960 aboard Sputnik 5, which was a veritable Noah’s Ark of animals. The craft contained Belka, Strelka, a grey rabbit, forty-two mice, two rats, flies, and several plants and fungi, as well as some slightly creepy strips of human flesh.
All the animals survived the spacecraft’s return to Earth on 20 August, though telemetry showed that one of the dogs had suffered a seizure during the fourth orbit. That led directly to the decision to limit Yuri Gagarin’s legendary flight the following year to just three orbits before returning to Earth.
Strelka subsequently had six puppies with Pushok, a male dog kept around the research base, who participated in many of the ground-based experiments but didn’t travel to space. One of the puppies was named Pushinka (“Fluffy”) and was given to US president John F Kennedy’s daughter, Caroline, by Khrushchev in 1961.
The dog was initially kept away from the White House by Kennedy’s staff over fear that its body may have been implanted with microphones, but after a medical check she was brought into the home and won the heart of another of Kennedy’s dogs — a Welsh Terrier named Charlie. They had a litter of puppies together themselves, which Kennedy affectionately referred to as “pupniks”. Their descendents are still living today, and Belka and Strelka were celebrated in 2010 with an animated feature film named Space Dogs.
Left: A model of Strelka in Australia in 1993 // Right: Pushinka and her pupniks
On 1 December 1960, tragedy struck. Mushka — who was shortlisted for Laika’s mission but lost out after — finally made it into space aboard Sputnik 6, accompanied by Pchyolka (“Little Bee”) and other animals, plants and insects. They were in good health when the rocket began its re-entry, but at the last minute a navigation error meant that the craft would have landed outside of Soviet borders.
The CIA intercepted and decoded this image of one of the dogs aboard Sputnik 6 in December 1960
Fear of foreign agents inspecting the capsule trumped the lives of the dogs aboard the spacecraft, and so it was intentionally destroyed, killing everything aboard.
On 22 December 1960, the team tried once more. Damka (“Queen of Checkers”) and Krasavka (“Little Beauty”) were selected from the pool and prepared for launch.
Almost immediately after taking off, however, the rocket encountered difficulties. The upper stage booster failed, causing the craft to re-enter the atmosphere after reaching a maximum altitude of 214km. The back-up plan in this situation was to eject the dogs and then self-destruct, but the ejector seat failed to operate, leaving the dogs stuck in the capsule as the self-destruct sequence ticked down.
Then something incredible happened. The self-destruct module also shorted out — aborting the sequence, and the capsule plummeted back to Earth intact, landing in deep snow in Siberia. A backup self-destruct timer had been set for 60 hours, so a team was scrambled to quickly locate the craft. They found it on the first day, but without sufficient daylight to disarm the self-destruct sequence and open the capsule. They were only able to report that the window of the capsule had frosted over in the -45C temperatures of the landing site, and no signs of life were heard from inside.
The next day, at dawn, they returned to the capsule fearing the worst. As it was opened, however, barking was heard — Damka and Krasavka were alive, though the mice that had accompanied them on the mission had frozen to death in the freezing temperatures of Siberia.
The dogs were wrapped in sheepskin coats immediately, and flown to Moscow, where they were thawed out and given the best medical care. Both survived, and Krasavka was adopted by Oleg Gazenko, a Lieutenant General who’d fought in World War II and the Korean War, and supervised the mission. Krasavka went on to have a litter of puppies, before dying at home 14 years later.
Damka and Krasavka narrowly escaped tragedy, before living long and healthy lives.
As the Soviet spaceflight programme ramped up towards its first human launch in 1961, the dogs began to be accompanied by dummy cosmonauts.
Chernushka (“Blackie”) flew on Sputnik 9 on 9 March 1961 with a dummy named Ivan Ivanovich, some mice and a guinea pig. To test the spacecraft communications, they placed a recording of a choir in Ivanovich’s chest, so that any radio stations picking up the signal would understand he wasn’t real. He was ejected at altitude, and parachuted to the ground, while Chernushka was recovered unharmed from the capsule.
Zvyozdochka (“Starlet”, named by Gagarin himself) flew on Sputnik 10 on the final practice flight before Gagarin’s voyage on 25 March 1961, again accompanied by Ivanovich and his choir recording — which this time had been augmented with a recipe for cabbage soup to confuse anyone listening in. Again, both the dummy and the dog returned safely to Earth, and Ivanovich was auctioned in 1993 for $189,500, still in his spacesuit. Today he lives in the US National Air and Space museum.
Ugolyok and Veterok in space. 1966
Following Gagarin’s triumphant mission on 12 April 1961, the Soviets slowly dismantled their dogs-in-space programme as it was no longer required. Its final flight, the Cosmos 110 mission, came five years later on 22 February 1966. It carried two dogs — Veterok (“Light Breeze”) and Ugolyok (“Coal”), who spent a record-breaking 22 days in orbit, testing whether life could survive for longer durations in orbit. As well as Veterok and Ugolyok, it carried yeast cells, blood cells and live bacteria.
The long-duration mission was a success, and the dogs were safely landed back on Earth. However, in their medical checkups afterward, it was discovered that their muscle and bone structures had sustained some damage from spending such a long time zero gravity, paving the way for later discoveries on the biological effects of spaceflight on the human body. Veterok and Ugolyok held the record for spaceflight duration until Skylab 2 in 1973, and still hold the record for the longest spaceflight by dogs.
A number of other dogs flew on sub-orbital flights, including Dymka (“Smoky”), Modnitsa (“Fashionable”) and Kozyavka (“Little Gnat”), as well as at least four others whose names don’t survive to this day. Almost all survived, with the exception of two of the unnamed dogs who perished in failed launches.
Without their contributions, and those of their canine colleagues, Russia would never have been able to launch Sputnik in 1957 and Gagarin in 1961, and the space race may never have taken off. Their heroism and bravery fuelled the earliest space exploration missions, paving the way for humans to later follow.
So to Dezik and Tsygan, Smelaya, Malyshka, ZIB, Ryzhik, Albina and Tsyganka, Mushka, Otvazhnaya, and Snezhunka, Bars and Lisichka, Belka and Strelka, Pushok, Pchyolka, Damka and Krasavka, Chernushka, Zvyozdochka, Veterok and Ugolyok, Dymka, Modnitsa, Kozyavka — and, most of all, Laika — I’d like to thank you for everything that you’ve done for mankind.
Хорошая собака, or as we say in the West…Good dog.Quelle:
MAUNA KEA, HAWAII – A team of researchers led by Justin R. Crepp, the Freimann Assistant Professor of Physics at the University of Notre Dame, has directly imaged a very rare type of brown dwarf that can serve as a benchmark for studying objects with masses that lie between stars and planets. Their paper on the discovery was published recently in Astrophysical Journal.
Initial data came from the TRENDS (TaRgetting bENchmark-objects with Doppler Spectroscopy) high-contrast imaging survey that uses adaptive optics and related technologies to target older, faint objects orbiting nearby stars, and precise measurements were made at the W. M. Keck Observatory on the summit of Mauna Kea, Hawaii. Brown dwarfs emit little light because they do not burn hydrogen and cool rapidly. Crepp said they could provide a link between our understanding of low-mass stars and smaller objects such as planets.
HD 19467 B, a T-dwarf, is a very faint companion to a nearby Sun-like star, more than 100,000 times as dim as its host. Its distance is known precisely, and the discovery also enables researchers to place strong constraints on important factors such as its mass, orbit, age, and chemical composition without reference to the spectrum of light received from its surface.
Precise radial velocity measurements were obtained using the HIRES instrument installed on Keck Observatory's 10-meter, Keck I telescope. The observations, which span 17 years starting from 1996, show a long-term acceleration, indicating that a low-mass companion was "tugging" on the parent star. Follow-up high-contrast imaging observations were then taken in 2012 using the NIRC2 instrument on the Keck II telescope with the adaptive optics system revealing the companion as shown above. Observations were granted through each of the Keck Observatory consortium members, including NASA, the California Institute of Technology, and the University of California.
While scientists understand the light received from stars relatively well, the spectra from planets is complicated and little understood. Understanding brown dwarfs, such as HD 19467 B, could be a step towards a fuller understanding of exoplanets.
“This object is old and cold and will ultimately garner much attention as one of the most well-studied and scrutinized brown dwarfs detected to date,” Crepp said. “With continued follow-up observations, we can use it as a laboratory to test theoretical atmospheric models. Eventually we want to directly image and acquire the spectrum of Earth-like planets. Then, from the spectrum, we should be able to tell what the planet is made out of, what its mass is, radius, age, etc., basically all relevant physical properties.”
HIRES (the High-Resolution Echelle Spectrometer) produces spectra of single objects at very high spectral resolution, yet covering a wide wavelength range. It does this by separating the light into many "stripes" of spectra stacked across a mosaic of three large CCD detectors. HIRES is famous for finding planets orbiting other stars. Astronomers also use HIRES to study distant galaxies and quasars, finding clues to the Big Bang.
NIRC2 (the Near-Infrared Camera, second generation) works in combination with the Keck II adaptive optics system to obtain very sharp images at near-infrared wavelengths, achieving spatial resolutions comparable to or better than those achieved by the Hubble Space Telescope at optical wavelengths. NIRC2 is probably best known for helping to provide definitive proof of a central massive black hole at the center of our galaxy. Astronomers also use NIRC2 to map surface features of solar system bodies, detect planets orbiting other stars, and study detailed morphology of distant galaxies.
The W. M. Keck Observatory operates the largest, most scientifically productive telescopes on Earth. The two, 10-meter optical/infrared telescopes on the summit of Mauna Kea on the Island of Hawaii feature a suite of advanced instruments including imagers, multi-object spectrographs, high-resolution spectrographs, integral-field spectroscopy and world-leading laser guide star adaptive optics systems. The Observatory is a private 501(c) 3 non-profit organization and a scientific partnership of the California Institute of Technology, the University of California and NASA.
Quelle: W. M. Keck Observatory
On reading a new paper by Stephen Hawking that appeared online this week, you would have been forgiven in thinking the world-renowned British physicist was spoofing us. Hawking’s unpublished work — titled “Information Preservation and Weather Forecasting for Black Holes” and uploaded to the arXiv preprint service — declares that “there are no black holes.”
Keep in mind that Hawking’s bedrock theory of evaporating black holes revolutionized our understanding that the gravitational behemoths are not immortal; through a quantum quirk they leak particles (and therefore mass) via “Hawking radiation” over time. What’s more, astronomers are finding new and exciting ways to detect black holes — they are even working on an interferometer network that may, soon, be able to directly image a black hole’s event horizon!
Has Hawking changed his mind? Are black holes merely a figment of our collective imaginations? Are all those crank theories about “alternative” theories of the Cosmos true?!
Stephen Hawking hasn’t changed his mind about the whole black hole thing, but he has thrown a complex physics paradox into the limelight, one that has been gnawing at the heart of theoretical physics for the last 18 months.
Black Hole Fight Club
It all boils down to a conflict between two fundamental ideas in physics that control the very fabric of our Universe; the clash of Einstein’s general relativity and quantum dynamics. And it just so happens that the extreme environment in and around a black hole makes for the perfect “fight club” for the two theories to duke it out. But what’s the first rule of the black hole fight club? Don’t talk about the firewall, lest you get sucked into an argument with a theoretical physicist.
At a California Institute of Technology (Caltech) lecture in April 2013, Hawking and other prominent theoretical physicists had an opportunity to describe the problem at hand. Caltech’s Kip Thorne, for example, described the firewall paradox as “a burning issue in theoretical physics.”
The very basis of this burning issue is the thing that makes black holes black — the event horizon. In its most basic form, the event horizon of a black hole is the point at which even light cannot escape the gravitational clutches of the massive black hole singularity. If light cannot escape, it stands to reason that it will appear as a black sphere in space. It is a cosmic one-way street: everything goes in, nothing comes out.
An Unlucky Astronaut
In the general relativity universe, for an astronaut who had the misfortune to fall toward a black hole, he or she wouldn’t notice anything untoward as they passed across the event horizon. It would be a fairly peaceful event, no drama. “Although later on you’re doomed and you’ll encounter very strong gravitational forces that will pull you apart,” noted Caltech physicist John Preskill at the 2013 Caltech event.
However, the quantum universe contradicts this “no drama” event horizon idea as predicted by general relativity.
In 2012, a group of physicists headed by Joseph Polchinski of the University of California in Santa Barbara revealed their finding that if black holes truly do not destroy information — a standpoint that Hawking himself reluctantly advocates — and that information can escape from the black hole through Hawking radiation, there must be a raging inferno just inside the event horizon they dub the “firewall.”
In this case, rather than falling into a “no drama” event horizon, our unlucky astronaut gets burnt to a crisp before getting ripped apart by tidal shear. This is the very antithesis of “no drama” and, therefore, a paradox.
This apparent conflict between what general relativity predicts and what quantum dynamics predicts — two very established fields in physics — is precisely what theoretical physicists are trying to understand. This appears to be yet another situation where gravity and quantum dynamics don’t play nice, the solution of which may transform the way we view the Universe.
So, when Hawking, one of the key players in the great firewall debate, writes a short paper on the topic (regardless of whether or not it has been published) the world takes note.
Hawking’s solution to the paradox removes the black hole’s event horizon, thereby removing the paradox; no event horizon, no firewall. But we’re told all black holes have event horizons — the line you cannot cross or be forever lost inside the black hole — what gives?
Hawking thinks that the idea behind the event horizon needs to be reworked. Rather than the event horizon being a definite line beyond which even light cannot escape, Hawking invokes an “apparent horizon” that changes shape according to quantum fluctuations inside the black hole — it’s almost like a “grey area” for extreme physics. An apparent horizon wouldn’t violate either general relativity or quantum dynamics if the region just beyond the apparent horizon is a tangled, chaotic mess of information.
“Thus, like weather forecasting on Earth, information will effectively be lost, although there would be no loss of unitarity,” writes Hawking. This basically means that although the information can escape from the black hole, its chaotic nature ensures it cannot be interpreted, sidestepping the firewall paradox all together.
Needless to say, this paper has done little to convince Polchinski. “It almost sounds like (Hawking) is replacing the firewall with a chaos-wall, which could be the same thing,” he told New Scientist.
Much of the theoretical debate is hard to fathom and the result of calculations of physical events that we cannot possibly experience in our day to day lives. But don’t mistake this particular debate as solely a high-brow argument in the theoretical physics community. Its foundations are rooted in the growing discomfort we are feeling with the mismatch of general relativity and quantum dynamics (particularly what role gravity plays in the quantum world), a problem that cannot be solved with our current understanding of the universe.
It is, after all, these science problems that we build multi-billion dollar particle accelerators for.
Astronomen finden heraus, wie sich unsere Heimatgalaxie entwickelte
Ein Team von Wissenschaftlern unter der Leitung von Ivan Minchev vom Leibniz-Institut für Astrophysik Potsdam (AIP) hat einen Weg gefunden die Entstehungsgeschichte der Milchstraße in neuer Detailtiefe zu rekonstruieren. Maßgeblich für die jetzt publizierten Ergebnisse ist die Untersuchung eines Datensets von Sternen im Umkreis der Sonne.
Die Astronomen untersuchten wie die Bewegung von Sternen senkrecht zur galaktischen Scheibe von ihrem Alter abhängt. Da eine direkte Bestimmung des Alters von Sternen schwierig ist, analysierten sie zunächst die chemische Zusammensetzung der Sterne: Das Verhältnis von Magnesium zu Eisen (Mg/Fe) weist auf ein hohes Alter hin. Für Ihre Studie nutzte das Team von Ivan Minchev hochaufgelöste Daten des RAdial Velocity Experiments (RAVE) über Sterne im weiteren Umkreis der Sonne. Die Wissenschaftler stellten fest, dass die Faustformel „je älter ein Stern ist, desto schneller bewegt er sich senkrecht zur galaktischen Scheibe" nicht für jene Sterne mit dem höchsten Magnesium-Eisen-Verhältnis zutrifft. Bei diesen ist ganz im Gegenteil ein extremer Abfall der vertikalen Geschwindigkeit zu beobachten.
Die Wissenschaftler verglichen daraufhin die Beobachtungsdaten mit astronomischen Simulationen. Eine Erklärung für ihre Beobachtungen fanden sie in den sogenannte "Merger-Effekte“, bei denen kleinere Galaxien in den Galaxienorbit eintreten. Astronomen gehen von Hunderten solcher Kollisionen in der Entstehungsgeschichte der Milchstraße aus. Merger-Effekte wirken sich insbesondere auf die Sterne am Galaxienrand aus, da diese den Kräften der eindringenden Körpern unmittelbar ausgesetzt sind. Dies führt zu einer Geschwindigkeitssteigerung der betroffenen Sterne und zu einer Erhöhung ihres Bewegungsradius senkrecht zur galaktischen Scheibe. Sterne, die sich eher im Zentrum der Milchstraße befinden, sind hingegen nur wenig beeinflusst von eindringenden Galaxien und keiner zusätzlichen Bewegungsenergie ausgesetzt. Sie migrieren erst zeitversetzt, bedingt durch von Mergern ausgelöste Spiralkräfte, vom Galaxienzentrum weg Richtung Sonne und verfügen über eine vernachlässigbare senkrechte Bewegungsgeschwindigkeit. Dies erklärt warum wir heute Sterne im Umkreis der Sonne beobachten können, die zwar ein ähnliches Alter haben, sich in ihrer Geschwindigkeit jedoch stark voneinander unterscheiden.
AIP-Wissenschaftler Ivan Minchev: „Mit unseren Ergebnissen wird es möglich sein, die Entwicklung unserer Heimatgalaxie genauer als zuvor nachzuzeichnen und zwar indem wir uns anschauen, welche Sterne um uns herum sind und wie sich diese bewegen. Darüber können wir ableiten, welche Sterne wann und von wo ihren Weg vom Zentrum der Milchstraße in die äußere Galaxis angetreten haben. Unser Verständnis der Entwicklung der Milchstraße wird dadurch ein besseres werden."
Die Studieist am 20. Januar in den Astrophysical Journal Letters erschienen.
Bilderklärung (englisch): Three stages of the evolution of the galaxy simulation used to model the Milky Way. Face-on (top) and edge-on (bottom) stellar density contours are shown for each time. Each square panel has a side of about 117,500 light years. The mass and frequency of satellites galaxies interacting with the disc decrease with time. (Credit: AIP)
Quelle: Leibniz-Institut für Astrophysik Potsdam (AIP)
Interplanetary dust particles carry water generated with hydrogen solar wind. Credit: John Bradley.
Researchers from the University of Hawaiʻi at Mānoa's School of Ocean and Earth Science and Technology (SOEST), Lawrence Livermore National Laboratory, Lawrence Berkeley National Laboratory, and University of California – Berkeley discovered that interplanetary dust particles (IDPs) could deliver water and organics to the Earth and other terrestrial planets.
Interplanetary dust, dust that has come from comets, asteroids, and leftover debris from the birth of the solar system, continually rains down on the Earth and other Solar System bodies. These particles are bombarded by solar wind, predominately hydrogen ions. This ion bombardment knocks the atoms out of order in the silicate mineral crystal and leaves behind oxygen that is more available to react with hydrogen, for example, to create water molecules.
“It is a thrilling possibility that this influx of dust has acted as a continuous rainfall of little reaction vessels containing both the water and organics needed for the eventual origin of life on Earth and possibly Mars,” said Hope Ishii, new Associate Researcher in the Hawaiʻi Institute of Geophysics and Planetology (HIGP) at UH Mānoa's SOEST and co-author of the study. This mechanism of delivering both water and organics simultaneously would also work for exoplanets, worlds that orbit other stars. These raw ingredients of dust and hydrogen ions from their parent star would allow the process to happen in almost any planetary system.
Implications of this work are potentially huge: Airless bodies in space such as asteroids and the Moon, with ubiquitous silicate minerals, are constantly being exposed to solar wind irradiation that can generate water. In fact, this mechanism of water formation would help explain remotely sensed data of the Moon, which discovered OH and preliminary water, and possibly explains the source of water ice in permanently shadowed regions of the Moon.
“Perhaps more exciting,” said Hope Ishii, Associate Researcher in HIGP and co-author of the study, “interplanetary dust, especially dust from primitive asteroids and comets, has long been known to carry organic carbon species that survive entering the Earth’s atmosphere, and we have now demonstrated that it also carries solar-wind-generated water. So we have shown for the first time that water and organics can be delivered together.”
It has been known since the Apollo-era, when astronauts brought back rocks and soil from the Moon, that solar wind causes the chemical makeup of the dust’s surface layer to change. Hence, the idea that solar wind irradiation might produce water-species has been around since then, but whether it actually does produce water has been debated. The reasons for the uncertainty are that the amount of water produced is small and it is localized in very thin rims on the surfaces of silicate minerals so that older analytical techniques were unable to confirm the presence of water.
Using a state-of-the-art transmission electron microscope, the scientists have now actually detected water produced by solar-wind irradiation in the space-weathered rims on silicate minerals in interplanetary dust particles. Futher, on the bases of laboratory-irradiated minerals that have similar amorphous rims, they were able to conclude that the water forms from the interaction of solar wind hydrogen ions (H+) with oxygen in the silicate mineral grains.
This recent work does not suggest how much water may have been delivered to Earth in this manner from IDPs.
“In no way do we suggest that it was sufficient to form oceans, for example,” said Ishii. “However, the relevance of our work is not the origin of the Earth’s oceans but that we have shown continuous, co-delivery of water and organics intimately intermixed.”
In future work, the scientists will attempt to estimate water abundances delivered to Earth by IDPs. Further, they will explore in more detail what other organic (carbon-based) and inorganic species are present in the water in the vesicles in interplanetary dust rims.
Quelle: University of Hawaiʻi