New pictures have been released of the Martian moon Phobos, acquired by the European Mars Express (Mex) probe during its recent flybys. The images reveal details down to a resolution of just 4.4m per pixel. Mex began a series of 12 close passes in mid-February. The observation schedule continues until 26 March. Read more
Martian moon's secrets to be revealed during flybys
The deepest secrets of Mars's moon Phobos are set to be revealed, following a series of 12 flybys by Europe's Mars Express spacecraft. Six have been completed, including the closest ever pass of the moon, at 67 km, last week. The flights will probe the moon's gravity better than ever before, revealing the distribution of material throughout its body. The MARSIS radar will also search for underground structures in the rubbly moon, which is probably riddled with caverns. The gravity data will help Russia's Phobos-Grunt mission, set to launch in 2011 or 2012, manoeuvre efficiently around the moon before coming in for a landing. Read more
First sighting of the Martian moons, Deimos and Phobos, was reported in 1877 by Asaph Hall, an astronomer of the Naval Observatory in Washington. The increasing interest in Phobos, the larger of the two Martian moons, is not only due to the steadily increasing number of space based and earth based observations but also to its low orbit about Mars. Its motion and rotation are thus effected by the Martian gravity field and variation may lead to further clues of its origin and evolution. Furthermore, Phobos was identified as potential target for sample return missions by different mission planning groups. The German Aerospace Center (DLR) was involved in an in-depth study of this natural satellite. Based on images of the multi-spectral line scanning High Resolution Stereo Camera (HRSC) and the Super Resolution Channel (SRC) - a frame camera - the department of Planetary Geodesy Read more
Phobos is doomed. It is gradually spiralling towards Mars and eventually could slam into the planet's surface, leaving a large crater as its parting gift. Believe it or not, this discovery led to the USA's President Eisenhower being briefed in 1960 that Phobos could be a space station launched by an advanced Martian civilization. At the time, calculations showed that the moon's orbit was decaying at around 5 cm per year. Phobos is in an unusually low orbit around Mars, and so it was thought that this drag could be caused by the upper atmosphere of the planet. Russian astrophysicist Iosif Samuilovich Shklovsky set about calculating whether the atmosphere could indeed be responsible. What he found surprised not only him, but many others too. Read more
The European Space Agency says its Mars Express spacecraft started a series of flybys of Phobos Tuesday, researching the origin of the mysterious Mars moon. The ESA said the study will include a March 3 record low pass, with the spacecraft passing just 31 miles above the moon's surface. Read more
In July of 1610 Galileo was still making discoveries faster than he could publish descriptions of them. On the 25th he discovered that Saturn was apparently situated between two smaller companions that always moved together. Wanting to establish his priority of discovery, but not yet ready to reveal what he had found, he sent to Kepler (and others) the following jumble of letters, which he informed them was a coded description of his latest discovery:
smaismrmilmepoetaleumibunenugttauiras
It was not uncommon in those days for scientists to communicate (or rather, to avoid communicating) their discoveries by means of coded expressions. Kepler, of course, was a born riddle solver, and made strenuous efforts to decipher Galileo's string of characters. It's fair to say that Kepler had an unusual aptitude for seeing patterns, to the extent that he sometimes saw patterns that weren't even there (as witness his perception that the planets were arranged in accord with the dimensions of circumscribed Platonic solids). A good example is that when he learned of Jupiter's four moons, and compared this with the Earth's one Moon, he concluded that Mars must have two moons (by the geometrical progression 1,2,4...). Read more
It was Johannes Kepler (1571-1630) who first predicted the existence of two satellites of Mars. In 1611 he misinterpreted an anagram by Galilei concerning Saturn as the announcement of Martian satellites: "Be greeted, double knob, children of Mars." Based on numerological arguments, he also noted that it seemed to him quite probable that Mars had two companions, since Mars orbits between Earth - a planet with one moon - and Jupiter, a planet with (at that time) four known moons. Read more
Mars Express animation of Phobos' shadow transiting Mars
For the first-time ever, VMC has imaged what we believe to be the shadow of Mars' moon Phobos crossing the surface of Mars. The shadow cast by Phobos as it passes between the Sun and Mars was photographed by VMC on 30 January, just as Mars Express approaches an intensive scientific observation campaign of Phobos. These events (called Phobos Transits) are similar to a solar eclipse on Earth but happen much more frequently. The shadow cast by the tiny moon has been seen by several spacecraft before, including by HRSC on Mars Express, but such a long sequence of images showing the shadow crossing the planet is very rare. Read more
An image of Phobos by the High-Resolution Stereo Camera on board Mars Express on 22 January 2007. The larger and inner of the two martian moons is seen here floating just above the martian limb. The image has been enhanced slightly to bring out the detail on the moon.