GSAT-4 , ISRO venture

Two portions of GSLV-D3 fairing on either side of GSAT-4.

GSAT-4 with one of its solar arrays deployed (developmental stage).

COURTESY : ISRO
http://www.isro.org/gslv-d3/Imagegallery/satellite.aspx
DOWNLOAD brochure and images of GSAT-4 from tha above address.

Solar-Electric Propulsion System (image)

 

This image provides a close-up on the jets of ionised gas ejected by BepiColombo’s solar-electric propulsion (SEP) system.

In its cruise configuration, BepiColombo consists of: a transfer module, the Mercury Planetary Orbit (MPO), the sun shield and the Mercury Magnetospheric Orbiter (MMO).

The transfer module is provided with both solar-electric propulsion and chemical propulsion units. The former will be used during the cruise to destination; the latter will be used to boost the initial launch orbit out to the Moon for a gravity assist manoeuvre.

Mars’ northern polar regions in transition

A newly released image from ESA’s Mars Express shows the north pole of Mars during the red planet’s summer solstice. All the carbon dioxide ice has gone, leaving just a bright cap of water ice.

This image was captured by the orbiter’s High-Resolution Stereo Camera on 17 May 2010 and shows part of the northern polar region of Mars during the summer solstice. The solstice is the longest day and the beginning of the summer for the planet’s northern hemisphere. The ice shield is covered by frozen water and carbon dioxide ice in winter and spring but by this point in the martian year all of the carbon dioxide ice has warmed and evaporated into the planet’s atmosphere.

Only water ice is left behind, which shows up as bright white areas in this picture. From these layers, large bursts of water vapour are occasionally released into the atmosphere.

The polar ice follows the seasons. In winter, part of the atmosphere recondenses as frost and snow on the northern cap. These seasonal deposits can extend as far south as 45°N latitude and be up to a metre thick.

Another phenomenon occurs on the curved scarps of the northern polar cap, such as the Rupes Tenuis slope (on the left of this image). During spring, the seasonal carbon dioxide layer is covered by water frost. At certain times, winds remove the the millimetre-thick top layer of frozen water, revealing the carbon dioxide ice below.

These processes bear witness to a dynamic water cycle on Mars and may lead to the varying accumulation of water ice over the polar cap.

Other noticeable features in this image include the Chasma Boreale canyon, coloured deposits and a large dune field.

Chasma Boreale is about 2 km deep, 580 km long and about 100 km wide. Its walls allow a perfect view into the strata within the deposits. There are impact craters on the canyon floor, some heavily covered by sand and some partly exhumed.

Dark and light-toned deposits can be seen as a fine and regular covering. The darker sediments have been dropped by the winds during spring dust storms. The patterns are created when the deposits change in quantity according to the seasons.

The polar cap is surrounded by a large dune field, parts of which extend 600 km to the south.

Mars Express will soon be using its radar to probe the northern polar cap in three dimensions. Since the radar antenna was deployed in mid-2005, the team have been waiting for the right conditions to observe the region.

The radar works best at night when the electrical interference from the planet’s atmosphere is at a minimum. An excellent opportunity to observe the cap’s shape, depth and composition occurs in August and September 2011.

COURTESY: ESA.

Astronomers searching for oxygen can breathe more easily.

ESA’s Herschel space observatory has found molecules of oxygen in a nearby star-forming cloud. This is the first undisputed detection of oxygen molecules in space. It concludes a long search but also leaves questions unanswered.

The oxygen molecules have been found in the nearby Orion star-forming complex. While atomic oxygen has been long known in warm regions of space, previous missions looking for the molecular variety – two atoms of oxygen bonded together – came up largely empty-handed.

Even the observed amount of atomic oxygen is far less than that expected and this created an oxygen ‘accounting problem’ that can be roughly voiced as “where is all the oxygen hiding in the cold clouds?”

NASA’s Submillimetre Wave Astronomy Satellite and Sweden’s Odin mission have both searched for molecular oxygen and established that its abundance is dramatically lower than expected.

One possibility put forward to explain this was that oxygen atoms freeze onto tiny dust grains found floating in space and are converted to water ice, effectively removing them from sight.

If this is true, the ice should evaporate in warmer regions of the cosmos, returning water to the gas and allowing molecular oxygen to form and to be seen.  They used Herschel's HIFI far-infrared instrument and targeted Orion, where they reasoned that the forming stars would heat the surrounding gas and dust.

Using three infrared frequencies of the instrument, the Herschel Oxygen Project team were successful. They found there to be one molecule of oxygen for every million hydrogen molecules.

"This explains where some of the oxygen might be hiding," said Dr Goldsmith. "But we didn't find large amounts of it, and still don't understand what is so special about the spots where we find it. The Universe still holds many secrets."

Oxygen, in all its forms, is the third most abundant element in the Universe and a major ingredient of our planet. It is found in our atmosphere, oceans and rocks, and is critical for life itself because we breathe the molecular form.

Although the search continues for it in space, Göran Pilbratt, ESA’s Herschel Project Scientist, believes this is a breakthrough moment: “Thanks to Herschel, we now have an undisputed confirmation that molecular oxygen is definitely out there. There are still many open questions but Herschel’s superior capabilities now enables us to address these riddles.”