Mars (zbiorczo)

[kanarkusmaximus]

Zgadzam się - ten wątek to najlepsze miejsce na tego typu dyskusje!

[kretus5]

Ciekawe ile innych cennych i nowych informacji uda się uzyskać z meteoroidów powiedzmy za 50 lat, gdy tego typu metoda analizy składu tych ciał sie upowszechni...  Na razie korzystamy głównie z tych co dotarły do ziemi, ale jak będzie można docierać do tych z kosmosu w większych ilościach ...  Rozmarzyłem się...

[kanarkusmaximus]

Meteoroidy są chyba za małe by dotarły do powierzchni Ziemi, bo wówczas stają się meteorytami. Żeby zebrać meteoroidy to bardziej trzeba polecieć w przestrzeń kosmiczną.

Na Marsie są meteoryty, niektóre z nich pewnie mają tam lepsze warunki do zachowania niż te odnajdywane na powierzchni lodów Antarktydy. Z nich pewnie sporo można by się nauczyć.

[Orionid]

Silne erupcje słoneczne w postaci wiatru słonecznego docierając w okolice Marsa mogą dodatkowo generować powstawanie ładunków na powierzchni  jego księżyców, co może stanowić zagrożenie dla astronautów tam przebywających oraz dla aparatury elektronicznej.

Solar Eruptions Could Electrify Martian Moons
Oct. 18, 2017 RELEASE 17-23

Powerful solar eruptions could electrically charge areas of the Martian moon Phobos to hundreds of volts, presenting a complex electrical environment that could possibly affect sensitive electronics carried by future robotic explorers, according to a new NASA study. The study also considered electrical charges that could develop as astronauts transit the surface on potential human missions to Phobos.

Phobos has been considered as a possible initial base for human exploration of Mars because its weak gravity makes it easier to land spacecraft, astronauts and supplies. The idea would be to have the astronauts control robots on the Martian surface from the moons of Mars, without the considerable time delay faced by Earth-based operators. "We found that astronauts or rovers could accumulate significant electric charges when traversing the night side of Phobos - the side facing Mars during the Martian day," said William Farrell of NASA's Goddard Space Flight Center, Greenbelt, Maryland. "While we don't expect these charges to be large enough to injure an astronaut, they are potentially large enough to affect sensitive equipment, so we would need to design spacesuits and equipment that minimizes any charging hazard." Farrell is lead author of a paper on this research published online Oct. 3 in Advances in Space Research.

https://www.nasa.gov/press-release/goddard/2017/mars-electric-moons

[Orionid]

Pojawiło się wytłumaczenie dlaczego mimo tego , że wg klimatycznych teorii temperatura w przeszłości była poniżej topnienia, to istnieją ślady geologiczne  świadczące o dużym udziale wody w rzeźbieniu powierzchni planety. Po prostu latem wyższe temperatury prowadziły do topnienia lodu na obrzeżach lodowców. Niewielka ilość wody działająca okresowo przez długi czas odcisnęła trwałe ślady na powierzchni Czerwonej Planety.

Study shows how water could have flowed on ‘cold and icy’ ancient Mars
October 17, 2017  Kevin Stacey


Martian Valleys
Extensive valley networks spidering through the southern highlands of Mars suggest that the planet was once warmer and wetter, but new research shows that water could still have flowed intermittently on a cold and icy early Mars.
NASA/JPL-Caltech/Arizona State University

(...)In order for this mechanism to possibly explain the valley networks, it must produce the correct volume of water in the time duration of valley network formation, and the water must run off on the surface at rates comparable to those required for valley network incision. A few years ago, Head and Eliot Rosenberg, an undergraduate at Brown at the time who has since graduated, published an estimate of the minimum amount of water required to carve the largest of the valleys. Using that as a guide, along with estimates of necessary runoff rates and the duration of valley network formation from other studies, Palumbo showed that model runs in which the Martian orbit was highly eccentric did indeed meet these criteria. That degree of eccentricity required is well within the range of possible orbits for Mars 4 billion years ago, Palumbo says. (...)

https://news.brown.edu/articles/2017/10/icyhighlands

[ekoplaneta]

Kolejne dowody wspierające hipotezę, że Mars od długiego czasu jest zimny i suchy.

Paul Niles of NASA’s Johnson Space Center is the lead author of a paper that discusses how sulfate minerals on Mars, previously thought to indicate a warm past climate, could actually form at extremely cold temperatures similar to those now present at the surface. Niles’ co-authors on the paper are Douglas Ming, also of NASA’s Johnson Space Center; Joseph Michalski, a scientist formerly from the Natural History Museum, London; and D.C. Golden with the Engineering and Science Contract Group at Jacobs Technology.

Sulfate deposits on Earth are generally thought to occur due to evaporation of water bodies. This has led researchers to conclude that sulfate minerals found in equatorial regions on Mars indicate that it was warm and wet even after losing its magnetic field. Niles and his co-authors, however, are suggesting that sulfate-rich deposits on Mars could have been formed at much colder temperatures without water.  They believe that the deposits actually come from a period of intense volcanic outgassing in a cold, dry climate, where ash and dust were exposed to thin films of acidic solutions at temperatures well below 0 degrees Celsius.

The researchers’ experiment subjected fine-grained particles, similar to what would have been found on Mars, to an acidic solution that had been cooled to temperatures well below zero-degrees Celsius. Instead of just slowing down the reaction rate, the cold temperatures actually created a concentrated acid solution that enhanced dissolution rates despite the cold temperatures.

“When you combine the results of our experiments with studies of sulfates in ice deposits in Greenland and Antarctica and the polar regions on Mars, you get a compelling argument that sulfate formation at super cool temperatures is not only possible, but would likely be unavoidable on Mars,” said Niles. “The evidence clearly shows that cryogenic weathering can operate, even under the extremely cold current Martian conditions.”

https://www.nasa.gov/feature/mars-may-have-been-colder-longer-than-originally-thought

Żeby wesprzeć ten scenariusz musiały by być odkryte zasoby siarczanów bez odznak obecności wody w okolicy. Może coś takiego już znaleziono? Przynajmniej na Meridiani Planum gdzie jeździ łazik Opportunity ślady wody, w tym wód gruntowych są obecne przy siarczanowych osadach, które łazik badał już podczas pobytu w kraterze Eagle:



https://en.wikipedia.org/wiki/Eagle_(Meridiani_Planum_crater)

[Orionid]

Wg eksperymentów sublimujący CO2 jest odpowiedzialny za kształtowanie powierzchni Czerwonej Planety.

Winters on Mars are shaping the Red Planet’s landscape
27 October 2017

Researchers based millions of kilometres from Mars have unveiled new evidence for how contemporary features are formed on the Red Planet.

Their innovative lab-based experiments on carbon dioxide (CO2) sublimation – the process by which a substance changes from a solid to a gas without an intermediate liquid phase – suggest the same process is responsible for altering the appearance of sand dunes on Mars. (...)


Linear gullies on a dune in Matara Crater, Mars, Red and white arrows point to pits. Image credit: NASA/JPL/University of Arizona

The researchers designed and built a low humidity chamber and placed CO2 blocks on the granular surface. The experiments revealed that sublimating CO2 can form a range of furrow morphologies that are similar to those observed on Mars.

Linear gullies are another example of active Martian features not found on Earth. They are long, sometimes sinuous, narrow carvings thought to form by CO2 ice blocks which fall from dune brinks and ‘glide’ downslope.

Lauren Mc Keown said: “The difference in temperature between the sandy surface and the CO2 block will generate a vapor layer beneath the block, allowing it to levitate and maneuver downslope, in a similar manner to how pucks glide on an ice-hockey table, carving a channel in its wake. At the terminus, the block will sublimate and erode a pit. It will then disappear without a trace other than the roughly circular depression beneath it.”

“While gullies on Earth are commonly formed by liquid water, they almost always terminate in debris aprons and not pits. The presence of pits therefore provides more support for a hypothesis whereby CO2 blocks are responsible for linear gullies.”
(...)
http://www.tcd.ie/news_events/articles/winters-on-mars-are-shaping-the-red-planet-s-landscape/8305

[ekoplaneta]

Bardzo ciekawa wiadomość. Czyli nie wszędzie gdzie są kanały na kraterach czy innych wyniosłościach nie musi to wskazywać że ciurkała tam woda. Polecam artykuł w oryginale:

https://www.nature.com/articles/s41598-017-14132-2

Teraz pytanie jak odróżnić żleby i wąwozy powstałe przy udziale wody od tych co powstały bez jej wpływu? Czy wystarczy obecność uwodnionych minerałów?

[mars76]

Chyba tak

[mars76]

https://www.nasa.gov/press-release/nasa-selects-instrument-for-future-international-mission-to-martian-moons
Ciekawa misja się zapowiada

[ekoplaneta]

https://www.nasa.gov/press-release/nasa-selects-instrument-for-future-international-mission-to-martian-moons
Ciekawa misja się zapowiada

Przecież założyłem wątek o tej misji.

http://www.forum.kosmonauta.net/index.php?topic=2875.0

Czemu nikt tam nie dopisuje postów? 

[kanarkusmaximus]

Raczej na Marsie obecnie nie ma za dużo wody (gotowej do doprowadzenia do formy ciekłej, blisko powierzchni). To raczej ruch cząstek/ziarenek.

USGS: "Dark features previously proposed as evidence for significant liquid water flowing on Mars now identified as granular flows, according to the U.S. Geological Survey. These new findings indicate that present-day Mars may not have a significant volume of liquid water."

[ekoplaneta]

Kolejne empiryczne argumenty, że Mars mógł być dłużej suchy i chłodny niż wcześniej myśleliśmy.

The Red Planet has widespread deposits of clay minerals, which are formed via the interaction of volcanic rock and water. This fact has led some researchers to suspect that liquid water covered much of the Martian surface for extended stretches long ago — perhaps during the Noachian period, which lasted from about 4.1 billion to 3.7 billion years ago. But a new study suggests that these clays could have formed even longer ago, right after the planet's formation — meaning the Noachian may well have been a mostly dry and chilly time,  as other scientists have posited.

Otóż wg autorów nowego artykułu w Nature większość glinokrzemianów, które wskazują na ciepły i wilgotny klimat mogło się uformować i to w pokładach sięgających 3 km grubości podczas 10 milionów lat istnienia wilgotnego i ciepłego klimatu, podczas kontaktu bazaltów z gorącą parą wodną.

"I'd say, right now, it's sort of leaning more toward the idea that Mars was mostly cold and dry during that time, and that you just had these 100- or 1,000-year periods where temperatures got a little bit warmer — enough to have melting and runoff, but maybe not enough to significantly alter the crust and form a bunch of clays and things like that," Cannon told Space.com.

In those very early days, Mars was likely covered by a scorching-hot ocean of liquid rock (as were the other rocky planets, including Earth), scientists say. As this rock melted, it released water vapor, carbon dioxide and other gases, generating a steamy, superhot, high-pressure atmosphere on the Red Planet.

The study team synthesized rock similar to Martian basalt, then exposed the stuff to the steam-bath conditions that likely prevailed on the Red Planet's surface way back when. After a mere two weeks, the researchers found, a lot had happened.

"It was really remarkable how quickly and extensively this basalt was altered," Cannon said in a statement. "At the highest temperatures and pressures, it ate completely through the basalt particles. It's a really intense degree of alteration."

The steam atmosphere may have persisted for up to 10 million years — long enough to create a global clay layer 1.9 miles (3 kilometers) thick, the researchers said. So they modeled what would happen to such a layer over the ensuing 4.5 billion years of Martian history, as volcanic eruptions covered many clay deposits and asteroid and comet impacts unearthed others. 

The modeling results accord well with what orbiters and rovers actually see on the Red Planet, Cannon said.

Na przykład, gazy szlachetne, takie jak krypton i ksenon, były prawdopodobnie dość powszechne w pierwotnej atmosferze odgazowanej, - powiedział Cannon. com. Tak więc znalezienie wielu z tych pierwiastków w glinach marsjańskich podparłoby hipotezę kąpieli parowej wysuniętą w nowym opracowaniu.


Autprzy wysuwają też argument wspierający wysłanie misji sample return, która mogłaby wesprzeć lub osłabić teorię krótkiego ,,łaźniowego" klimatu na Marsie

Such measurements probably can't be made from orbit, Cannon added: They would require the work of a sophisticated rover on site or, even better, analysis of returned Martian samples in well-equipped labs here on Earth.

Pytanie tylko, kiedy taka misje wreszcie wyruszy?  Chińczycy obiecują nam start po próbki marsjańskiego gruntu do 2030 roku, oby ich marsjańskie plany nie uległy zmianom i opóźnieniom.... 

[kanarkusmaximus]

Ha! A czy potrafimy obecnie technologicznie wykonać takie badania? Wydaje mi się, że nie do końca!

[ekoplaneta]

Ha! A czy potrafimy obecnie technologicznie wykonać takie badania? Wydaje mi się, że nie do końca!

Zebrać próbki przecież możemy, tylko nie ma nikogo kto by za to zapłacił  Nawet NASA nie kwapi się do takiej imprezy