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Using the instrument aboard Cassini probe, scientists have confirmed that the 500km-wide Saturn moon Enceladus has an atmosphere. They have also seen a "hotspot" at the icy moon’s south pole, which is riven with cracks dubbed "tiger stripes".But they could not yet explain fully the energetic processes driving all the activity on Enceladus.
Enceladus orbits the ringed planet at a distance of approximately 237,400km and is described as the most reflective object in the Solar System; its icy surface throws back about 90% of the sunlight that hits it.
High-resolution imagery shows the southern polar region to be relatively smooth - usually a good indicator of recent activity - but cut by a number of long, dominant cracks. These are the so-called tiger stripes. They are about 130km long and roughly parallel to one another, spaced about 40km apart.
Cassini’s composite infrared spectrometer shows the region to be much warmer than expected.
Whereas temperatures near the equator are a frigid 80 Kelvin (minus 193C), the south polar average reaches 85K (minus 188C). Small areas of the pole, concentrated near the tiger stripe fractures, are even warmer: well over 110K (minus 163C) in some places. This is only the second place in the Solar System beyond Earth that we’ve seen signs of heat coming out of the interior - the other being Jupiter’s moon Io. The scientists think the cracks may act like vents, spewing out water vapour and very fine water-ice particles. Some have suggested there could be ice geysers and even ice volcanoes at the stripe locations - but these have not been imaged directly.
The puzzle for researchers is how to explain such an energetic system on Enceladus. As the moon moves around an eccentric orbit of Saturn, gravitational forces should subject the tiny world to some tidal heating. Radioactive isotopes in its rocky core may also be a source of some warming. But scientists are struggling to make the numbers add up and are frankly baffled as to why the activity they see should be so concentrated in just the one region. It’s hard for a body as small as Enceladus to hold onto the heat necessary to drive such large-scale geophysical phenomena, but it had done just that.
The finding moves Enceladus from being a small denizen of the outer Solar System - a frozen iceberg - to something that’s more of an active type world that we’re interested in exploring."
Cassini discoveries at Enceladus include:
The $3.2bn Cassini-Huygens mission is a joint venture between the US space agency (Nasa), the European Space Agency (Esa) and the Italian Space Agency (Asi).
Scientists are using the Hubble Space Telescope to scout out sites for potential human bases on the Moon.
Hubble can identify spectral features just 50 metres across over swathes of lunar terrain.
In particular, scientists hopes to be able to identify a mineral called ilmenite - or iron titanium oxide - which has previously been found in lunar soil samples. It has properties which would be useful in constructing a lunar base. It contains oxygen, which could be extracted for breathing, as well as hydrogen and helium absorbed from the solar wind. Heating the mineral would release the gases, which could then be used as a power source for the base.. Iron in the mineral might eventually be used to produce construction materials, such as steel, for lunar buildings.
Ilmenite was found in different concentrations in the several areas visited by the Apollo astronauts more than three decades ago. Hubble observed two of these sites - where Apollo 15 and Apollo 17 astronauts touched down in 1971 and 1972, respectively - as part of an observing run that finished on Sunday.
Hubble also looked at a third site - a 42 kilometre-wide crater called Aristarchus, near the Moon’s equator. The crater lies near the edge of a plateau that rises about 2 km above the vast lava plains that surround it.
NASA expects to release the results of the Hubble observations of the Moon by early October 2005.
Russian cosmonaut Sergei Krikalev and US astronaut John Phillips successfully completed a spacewalk outside the International Space Station.
The spacewalk was devoted to tending science experiments and maintenance tasks. Krikalev and Phillips were tasked with removing the Russian Biorisk experiment, which houses bacteria, and retrieving a suitcase-sized Japanese experiment which exposed various materials to the space junk, micro-meteors and radiation that zip through the harsh external environment. The pair also had to remove the Matroshka experiment – a human-like torso with layers of dosimeters intended to measure the radiation astronauts are exposed to while spacewalking.
The pair then installed a video camera to the hull of the Zvezda service module which will be used to aid the docking of the European Space Agency’s uncrewed cargo ship, the Jules Verne. The first launch of that craft is scheduled for early 2006.
NASA said there will be no shuttle flight at least until March 2006.
Engineers need to find a solution to the foam debris problem which re-emerged during Discovery’s launch.
During its close fly-bys of the ring system, instruments on Cassini have been able to determine that the environment around the rings is like an atmosphere, composed principally of molecular oxygen. This atmosphere is very similar to that of Jupiter’s moons Europa and Ganymede.
Saturn’s rings consist largely of water ice mixed with smaller amounts of dust and rocky matter. They are extraordinarily thin: though they are 250 000 kilometres or more in diameter they are no more than 1.5 kilometres thick. Despite their impressive appearance, there is very little material in the rings - if the rings were compressed into a single body it would be no more than 100 kilometres across.
The Russian cosmonaut Sergei Krikalev, the current commander of the International Space Station (ISS), has broken the record for the most cumulative time in space - clocking up 748 days in orbit on Tuesday. He beat a previous record of 747 days, 14 hours, 14 minutes and 11 seconds held by fellow Russian Sergei Avdeyev.
Now 46 years old, Sergei Krikalev was born in Leningrad (now St Petersburg), Russia, in 1958, selected as a cosmonaut in 1985 and made his first long-duration mission to the Russian Mir space station in 1988.
The cosmonaut flew aboard space shuttle Discovery on STS-60, the first joint US/Russian shuttle mission in 1994. He was also part of the first crew to stay aboard the International Space Station.
Krikalev and fellow astronaut Phillips are due to return to Earth on 7 October.
China is preparing to launch its first ever lunar orbiter in 2007. The expedition, christened Chang’e-1 after the Chinese Moon goddess, will map the moon in 3D in an effort to identify future landing sites. The satellite will also study the Moon’s composition and radiation environment and may use radar to probe below its surface.
NASA’s Mars Reconnaissance Orbiter (MRO). began its journey to Mars on 12 August 2005
The orbiter carries six scientific instruments for examining the surface, atmosphere and subsurface of Mars in unprecedented detail from low orbit of 150 miles. Researchers will use the instruments to learn more about the history and distribution of Mars’ water. That information will improve understanding of planetary climate change and will help guide the quest to answer whether Mars ever supported life. The orbiter will also evaluate potential landing sites for future missions. MRO will use its high-data-rate communications system to relay information between Mars surface missions and Earth.
Flying over both Martian poles, the new spacecraft will cover Mars’ entire surface for nearly two years during its $720 million mission, pinpointing features as small as a desk top and probing nearly half a mile deep beneath the planet’s shifting sands with specialized Italian-built radar.
Mars is 72 million miles from Earth today, but the spacecraft will travel more than four times that distance on its outbound-arc trajectory to intercept the red planet on March 10, 2006.
The orbiter’s primary mission ends about five-and-a-half years after launch, on December 31, 2010.
Nasa is planning two further Mars missions this decade: the Phoenix module, set for launch in 2007, and Mars Science Laboratory in 2009.
The shuttle started landing at 4:06 a.m. Pacific time by firing its engines over the Indian Ocean for more than two minutes in what is known as a de-orbit burn. About 30 minutes later, at an altitude of 76 miles, the shuttle entered the atmosphere at a maximum speed of more than 16,000 mph, guided at first by its steering jets and later, as the atmosphere became thicker, by its wing flaps and rudder.
During the computer-controlled descent, Discovery bled off excess energy and reduced its speed by performing a series of four banks. The shuttle streaked across the California coast from the southwest and flew north of Los Angeles on a course that took it between Oxnard and Ventura.
Once Discovery’s velocity dropped below the speed of sound, Collins took over the controls and brought the spacecraft - now essentially a brick with wings - in for its approach. She executed a 196-degree turn to line up with Edwards’ 15,000-foot concrete runway 2-2. Main gear touched down and the parachute was deployed; the nose gear touched down immediately after, at 5:11 a.m. PDT, one minute ahead of schedule.
Mo'nonymous on New companion of Nep...
Mo'nonymous on New companion of Nep...
Mo'nonymous on New companion of Nep...
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