[Gunnair]

[Gunnair]

West rim of the Endeavour Crater - Mars

[Gunnair]

Santa Maria Crater - Mars

[Strutz]

Some amazing pics Gunnair! A few are obvious but it would be informative if you added captions to them to tell us what we are actually seeing...

Just for those of us not quite as savvy as you are .

[Gunnair]

Strutz Strutz:

Some amazing pics Gunnair! A few are obvious but it would be informative if you added captions to them to tell us what we are actually seeing...

Just for those of us not quite as savvy as you are .

Oops, my bad. I'll fix them

[Gunnair]

Nope, not Bart's reaction to an Obama win in 2012.

This is sunrise with Venus.

[Gunnair]

Mars Rover looking backwards

[Gunnair]

wiki wiki:

21 Lutetia is a large main-belt asteroid of an unusual spectral type. It measures about 100 kilometers in diameter (120 km along its major axis). It was discovered in 1852 by Hermann Goldschmidt, and is named after Lutetia, the Latin name of the city that stood where Paris was later built.

Lutetia has irregular shape and is heavily cratered with the largest impact crater reaching 45 km in diameter. The surface is geologically heterogeneous and is intersected by system of groves and scarps, which are thought to be fractures. It has a high average density meaning that it is made of metal rich rock.
The Rosetta probe passed within 3,162 km (1,965 mi) of Lutetia in July 2010.[7] It was the largest asteroid visited by a spacecraft until the Dawn mission arrived at 4 Vesta in July 2011.

Discovery and exploration

Lutetia was discovered on November 15, 1852, by Hermann Goldschmidt from the balcony of his apartment in Paris.[8][9] A preliminary orbit for the asteroid was computed in November–December 1852 by German astronomer Georg Rümker and others.[10] In 1903, it was photographed at opposition by Edward Pickering at Harvard College Observatory. He computed an opposition magnitude of 10.8.[11]

There have been two reported stellar occultations by Lutetia, observed from Malta in 1997 and Australia in 2003, with only one chord each, roughly agreeing with IRAS measurements.[citation needed]

On July 10, 2010, the European Rosetta space probe flew by Lutetia at a minimum distance of 3168 ± 7.5 and a velocity of 15 kilometres per second on its way to the comet 67P/Churyumov-Gerasimenko.[3] The flyby provided images of up to 60 meters per pixel resolution and covered about 50% of the surface, mostly in the northern hemisphere.[2][7] The 462 images were obtained in 21 narrow and broad band filters extending from 0.24 to 1 μm.[7] Lutetia was also observed by the visible–near-infrared imaging spectrometer VIRTIS, and measurements of the magnetic field and plasma environment were taken as well.[2][7]

Characteristics

Orbit

Lutetia orbits the Sun at the distance of approximately 2.4 AU in the inner asteroid belt. Its orbit lies almost in the plane of ecliptic and is moderately eccentric. The orbital period of Lutetia is 3.8 years.[12]

Mass and density

The Rosetta flyby demonstrated that the mass of Lutetia is (1.700 ± 0.017)×1018 kg,[3] smaller than the pre-flyby estimate of 2.57×1018 kg.[13] It has one of the highest densities seen before in asteroids at 3.4 ± 0.3 g/cm3.[2] Taking into account possible porosity of 10–15%, the bulk density of Lutetia exceeds that of a typical stony meteorite.[3]

Composition

The composition of Lutetia has puzzled astronomers for some time. While classified among the M-type asteroids,[1] most of which are metallic, Lutetia is one of the anomalous members that do not display much evidence of metal on their surface. Indeed, there were various indications of a non-metallic surface: a flat, low frequency spectrum similar to that of carbonaceous chondrites and C-type asteroids and not at all like that of metallic meteorites,[14] a low radar albedo unlike the high albedos of strongly metallic asteroids like 16 Psyche,[6] evidence of hydrated materials on its surface,[15] abundant silicates,[16] and a thicker regolith than most asteroids.[17]

The Rosetta probe actually found that the asteroid has a moderately red spectrum in the visible light and essentially flat spectrum in the near infrared. No absorption features were detected in the whole wavelength range covered by observations—0.4–3.5 μm. Thus previous reports of hydrated minerals and organic compounds on the surface of Lutetia has been disproven. The surface also does not contain any olivine. Together with the high density of Lutetia these results indicate that it is either made of the enstatite chondrite material or may be related to metal-rich and water-poor carbonaceous chondrite of classes like CB, CH, or CR.[4][18]

Rosetta observations revealed that the surface of Lutetia is covered with a regolith made of loosely aggregated dust particles 50–100 μm in size. It is estimated to be 3 km thick and may be responsible for the softened outlines of many of the larger craters.[2][7]

Shape and axial tilt

21 Lutetia's orbit, and its position on 01 Jan 2009 (NASA Orbit Viewer applet).
The Rosetta probe's photographs confirmed the results of a 2003 lightcurve analysis that described Lutetia as a rough sphere with "sharp and irregular shape features".[19] A study carried out by I.N. Belskaya et al. in 2004–2009 had proposed that "Lutetia has a non-convex shape, probably due to a large crater";[20] it is not yet clear whether Rosetta's findings support this claim.

The analysis of Rosetta images in combination with photometric light curves yielded the position of the north rotational pole of Lutetia: RA= – 51.8 ± 0.4; Dec= – +10.8 ± 0.4°. This gives an axial tilt of 96° (retrograde rotator), meaning that the axis of rotation is approximately parallel to the ecliptic, similar to the planet Uranus.[2]

Surface features and nomenclature

Surface features

The surface of Lutetia is covered by numerous impact craters and intersected by fractures, scarps and grooves thought to be surface manifestations of internal fractures. On the imaged hemisphere of the asteroid there are a total of 350 craters with diameters ranging from 600 m to 55 km. The most heavily cratered surfaces (in Achaia region) have a crater retention age of about 3.6 ± 0.1 billion years.[2]

The surface of Lutetia has been divided into seven regions based on their geology. They are Baetica (Bt), Achaia (Ac), Etruria (Et), Narbonensis (Nb), Noricum (Nr), Pannonia (Pa), and Raetia (Ra). The Baetica region is situated around the north pole (in the center of the image) and includes a cluster of impact craters 21 km in diameter as well as their impact deposits. It is the youngest surface unit on Lutetia. Baetica is covered by a smooth ejecta blanket approximately 600 m thick that has partially buried older craters. Other surface features include landslides, gravitational taluses and ejecta blocks up to 300 m in size. The landslides and corresponding rock outcrops are correlated with variations of albedo, being generally brighter.[2]

The two oldest regions are Achaia and Noricum. The former is a remarkably flat area with a lot of impact craters. The Narbonensis region coincides with the largest impact crater on Lutetia—Massilia. It includes a number of smaller units and is modified by pit chains and grooves formed at a later epoch. Other two regions—Pannonia and Raetia are also likely to be large impact craters. The last Noricum region is intersected by a prominent groove 10 in length and about 100 m deep.[2]

The numerical simulations showed that even the impact that produced the largest crater on Lutetia, which is 45 km in diameter, seriously fractured but did not shatter the asteroid. So, Lutetia has likely survived intact from the beginning of the Solar System. The existence of linear fractures and the impact crater morphology also indicate that the interior of this asteroid has a considerable strength and is not a rubble pile like many smaller asteroids. Taken together, these facts suggest that Lutetia should be classified as a primordial planetesimal.[2]

Nomenclature

In March, 2011, the Working Group for Planetary Nomenclature at the International Astronomical Union agreed on a naming scheme for geographical features on Lutetia. Since Lutetia was a Roman city, the asteroid's craters are named after cities of the Roman Empire and the adjacent parts of Europe during the time of Lutetia's existence. Its regions are named after the discoverer of Lutetia (Goldschmitt) and after provinces of the Roman Empire at the time of Lutetia. Other features are named after rivers of the Roman Empire and the adjacent parts of Europe at the time of Lutetia.[21]

[Freakinoldguy]

Gunnair Gunnair:

Santa Maria Crater - Mars

Kinda looks like my backyard

[2Cdo]

Gunnair Gunnair:

Nope, not Bart's reaction to an Obama win in 2012.

This is sunrise with Venus.

That is an amazing shot!

[Gunnair]

$1:

Deimos (moon)
Wikipedia, the free encyclopedia
Deimos

Discovery

Discovered by Asaph Hall
Discovery date 12 August 1877
Designations
Adjective Deimosian
Orbital characteristics[1]
Semi-major axis 23,460 kilometres (14,580 mi)
Eccentricity 0.000 2
Orbital period 1.262 44 d (30.30 hours)
Average orbital speed 1.35 km/s
Inclination 0.93° (to Mars' equator)
1.793° (to the local Laplace plane)
27.58° (to the ecliptic)
Satellite of Mars
Proper orbital elements

Physical characteristics

Dimensions 15 × 12.2 × 10.4 km[2]
Mean radius 6.2 kilometres (3.9 mi) [3]
Mass 1.48×1015 kg[4]
(2.5×10−10 Earths)
Mean density 1.471 g/cm³[3]
Equatorial surface gravity 0.003 9 m/s² (3.9 mm/s²)
0.000 40 g (400 µg)
Escape velocity 5.6 m/s (20 km/h)[4]
Rotation period synchronous
Albedo 0.068[3]
Temperature ≈233 K
Apparent magnitude 12.4 [3][5]

Deimos ( /ˈdaɪməs/ dy-məs; also /ˈdiːməs/ dee-məs; Greek: Δείμος; also DAY-moce or DEE-moce) is the smaller and outer of Mars's two moons (the other being Phobos). It is named after Deimos, a figure representing dread in Greek Mythology.[6] Its systematic designation is Mars II.[6]

Deimos was discovered by Asaph Hall, Sr. at the United States Naval Observatory in Washington, D.C on August 12, 1877, at about 07:48 UTC (given in contemporary sources as "August 11 14:40" Washington mean time, using an astronomical convention of beginning a day at noon, so 12 hours must be added to get the actual local mean time).[7][8][9][10] Hall also discovered Phobos on August 18, 1877, at about 09:14 GMT, after deliberately searching for Martian moons.
The names, at first spelled Phobus and Deimus, were suggested by Henry Madan (1838–1901),[6] Science Master of Eton, from Book XV of the Iliad, where Ares (the Roman god Mars) summons Dread (Deimos) and Fear (Phobos).[11]

Deimos, like Mars' other moon Phobos, has spectra, albedos and densities similar to those of a C- or D-type asteroid. Like most bodies of its size, Deimos is highly non-spherical with dimensions of 15 × 12.2 × 10.4 km. Deimos is composed of rock rich in carbonaceous material, much like C-type asteroids and carbonaceous chondrite meteorites. It is cratered, but the surface is noticeably smoother than that of Phobos, caused by the partial filling of craters with regolith. The regolith is highly porous and has a radar estimated density of only 1.1 g/cm³.[13] The two largest craters, Swift and Voltaire, each measure about 3 kilometres across.

Orbital

Deimos' orbit is nearly circular and is close to Mars' equatorial plane. Deimos, Mars' outer moon, is possibly an asteroid that was perturbed by Jupiter into an orbit that allowed it to be captured by Mars, though this hypothesis is still controversial and disputed.[14] Both Deimos and Phobos have very circular orbits which lie almost exactly in Mars' equatorial plane, and hence a capture origin requires a mechanism for circularizing the initially highly eccentric orbit, and adjusting its inclination into the equatorial plane, most likely by a combination of atmospheric drag and tidal forces,[15] although it is not clear that sufficient time is available for this to occur for Deimos.[14]
As seen from Mars, Deimos would have an angular diameter of no more than 2.5 minutes (sixty minutes make one degree) and would therefore appear almost star-like to the naked eye.[16] At its brightest ("full moon") it would be about as bright as Venus is from Earth; at the first- or third-quarter phase it would be about as bright as Vega. With a small telescope, a Martian observer could see Deimos' phases, which take 1.2648 days (Deimos' synodic period) to run their course.[16]

Unlike Phobos, which orbits so fast that it actually rises in the west and sets in the east, Deimos rises in the east and sets in the west. However, the Sun-synodic orbital period of Deimos of about 30.4 hours exceeds the Martian solar day ("sol") of about 24.7 hours by such a small amount that 2.7 days elapse between its rising and setting for an equatorial observer.

Orbits of Phobos and Deimos (to scale)

Because Deimos’ orbit is relatively close to Mars and has only a very small inclination to Mars’ equator, it cannot be seen from Martian latitudes greater than 82.7°.

Solar transits

Deimos transits the Sun, as seen by Mars Rover Opportunity

Main article: Transit of Deimos from Mars

Deimos regularly passes in front of the Sun as seen from Mars. It is too small to cause a total eclipse, appearing only as a small black dot traveling across the Sun. Its angular diameter is only about 2.5 times the angular diameter of Venus during a transit of Venus from Earth. On March 4, 2004 a transit of Deimos was photographed by Mars Rover Opportunity, and on March 13, 2004 a transit was photographed by Mars Rover Spirit.

Origin

The origin of the Martian moons is still controversial.[14] The main hypotheses are that they formed either by capture or by accretion. Because of the similarity to the composition of C- or D-type asteroids, one hypothesis is that the moons may be objects captured into Martian orbit from the asteroid belt, with orbits that have been circularized either by atmospheric drag or tidal forces,[15] as capture requires dissipation of energy. The current Mars atmosphere is too thin to capture a Phobos-sized object by atmospheric braking.[14] Geoffrey Landis has pointed out that the capture could have occurred if the original body was a binary asteroid that separated due to tidal forces.[17] The main alternative hypothesis is that the moons accreted in the present position. Another hypothesis is that Mars was once surrounded by many Phobos- and Deimos-sized bodies, perhaps ejected into orbit around it by a collision with a planetesimal.[18][19]

[GreenTiger]

Thank You for this thread. I love it.

[Strutz]

Me too GT!

I was going through some of my archives of pics. I still find this one awesome... Remember when this happened?

0:

Space - August 2003 - Blackout - NE USA & Ontario.JPG

[Gunnair]

$1:

Cassini Sees Tropical Lakes on Saturn Moon

PASADENA, Calif. – NASA's Cassini spacecraft has spied long-standing methane lakes, or puddles, in the "tropics" of Saturn's moon Titan. One of the tropical lakes appears to be about half the size of Utah's Great Salt Lake, with a depth of at least 3 feet (1 meter).

The result, which is a new analysis of Cassini data, is unexpected because models had assumed the long-standing bodies of liquid would only exist at the poles. The findings appear in this week's issue of the journal Nature.

Where could the liquid for these lakes come from? "A likely supplier is an underground aquifer," said Caitlin Griffith, the paper's lead author and a Cassini team associate at the University of Arizona, Tucson. "In essence, Titan may have oases."

Understanding how lakes or wetlands form on Titan helps scientists learn about the moon's weather. Like Earth's hydrological cycle, Titan has a "methane" cycle, with methane rather than water circulating. In Titan's atmosphere, ultraviolet light breaks apart methane, initiating a chain of complicated organic chemical reactions. But existing models haven't been able to account for the abundant supply of methane.

"An aquifer could explain one of the puzzling questions about the existence of methane, which is continually depleted," Griffith said. "Methane is a progenitor of Titan's organic chemistry, which likely produces interesting molecules like amino acids, the building blocks of life."

Global circulation models of Titan have theorized that liquid methane in the moon's equatorial region evaporates and is carried by wind to the north and south poles, where cooler temperatures cause methane to condense. When it falls to the surface, it forms the polar lakes. On Earth, water is similarly transported by the circulation, yet the oceans also transport water, thereby countering the atmospheric effects.

The latest results come from Cassini's visual and infrared mapping spectrometer, which detected the dark areas in the tropical region known as Shangri-La, near the spot where the European Space Agency's Huygens probe landed in 2005. When Huygens landed, the heat of the probe's lamp vaporized some methane from the ground, indicating it had landed in a damp area.

Areas appear dark to the visual and infrared mapping spectrometer when liquid ethane or methane are present. Some regions could be shallow, ankle-deep puddles. Cassini's radar mapper has seen lakes in the polar region, but hasn't detected any lakes at low latitudes.

The tropical lakes detected by the visual and infrared mapping spectrometer have remained since 2004. Only once has rain been detected falling and evaporating in the equatorial regions, and only during the recent expected rainy season. Scientists therefore deduce the lakes could not be substantively replenished by rain.

"We had thought that Titan simply had extensive dunes at the equator and lakes at the poles, but now we know that Titan is more complex than we previously thought," said Linda Spilker, the Cassini project scientist based at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "Cassini still has multiple opportunities to fly by this moon going forward, so we can't wait to see how the details of this story fill out."

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. NASA's Jet Propulsion Laboratory manages the mission for NASA's Science Mission Directorate, Washington. The visual and infrared mapping spectrometer team is based at the University of Arizona, Tucson.

Very exciting news!!!!!!!!!!!!!!!

[2Cdo]

Strutz Strutz:

Me too GT!

I was going through some of my archives of pics. I still find this one awesome... Remember when this happened?

0:

Space - August 2003 - Blackout - NE USA & Ontario.JPG

We were lucky as I had just bought a generator a couple of weeks prior and had the house wired for it. I had lights, fridge, stove, washer, and TV and radio while my neighbours had candles.