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How do electrified gases penetrate through magnetosphere

The European Space Agency's Cluster spacecraft have helped answer a 17-year mystery about how the magnetosphere, a magnetic bubble that surrounds the Earth, keeps filling up with , when it should be acting as a barrier to keep them out. The four Cluster spacecraft found huge swirling vortices of gas at the outer edges of the magnetosphere caused by interacting flows of solar wind. As they collapse, they force material into the magnetosphere, filling it up.

posted by: kyawoo at 06:11 | link | comments |
unmanned missions, space science

Propelling without propellant

To travel to the moon and the planets most NASA spacecraft rely on some form of chemical propellant to push themselves through space. But at the Marshall-based center researchers are studying a range of future propulsion methods, including propellant-less systems.Among the more promising future propulsion technologies is aerocapture.

Much like aerobraking, which a number of NASA spacecraft including Mars Odyssey have used to slow themselves upon arriving at their target worlds, aerocapture is intended to allow a spacecraft use a planet's atmosphere to alter its flight trajectory. But where aerobraking requires multiple orbits and repeated burns by a spacecraft's engine, aerocapture is expected to put a vehicle in orbit after one pass without consuming one drop of fuel.

"With aerocapture, it's done all at once," explained Les Johnson, manager of NASA's In-Space Propulsion Technology Projects Office at MSFC. "You have a heat shield...you do the maneuver, and in 30 minutes you're in a circular orbit."

Letting a planet's gravity and physics direct a spacecraft could save about 40 percent of mass in propellant that would be better spent on scientific instruments, Johnson said.

The engineering foundation for an aerocapture system -- in terms of ablative materials, thermal protection systems and navigation control -- are not untested technologies, and a potential test vehicle could be ready in about two years, researchers said. In addition to a standard cone-shaped aeroshell approach to aerocapture, scientists have also looked using a protective nose ballute, and even dragging an inflatable, donut-like ballute behind a spacecraft during the flight maneuver.

"It's a matter of putting it all together and it all looks pretty doable," Johnson said, adding that the method is primary targeted for robotic missions. "There is a benefit to human exploration for aerocapture, from an incremental technology point of view."

posted by: kyawoo at 20:58 | link | comments |
space science

Mars Reconnaissance Orbiter in progress

Mars Reconnaissance Orbiter (MRO) - the next spacecraft from Earth to head for the Red Planet will be launched on August 10, 2005, the spacecraft will reach Mars 7 months later, and mapping the planet with the most powerful instruments ever sent to Mars; its camera will be so sensitive, it will be able to see objects as small as a metre (3 feet) across. The team building the spacecraft has completed integration and testing of most of the MRO's components, and nearly completed its software.

posted by: kyawoo at 01:14 | link | comments |
unmanned missions, mars

Honoring Apollo-11 crew

On July 20, 1969 humans first walked on the Moon and changed history forever. To honor the Apollo-11 crew I managed to present a slide show consisting 29 memorable images and sketches vividly highlighting their epic journey.

Please visit

http://photobucket.com/albums/v351/kyawoo/apollo%2011/ or

just click "apollo-11" link at the right side of this page.

Your comments are highly appreciated.

posted by: kyawoo at 22:26 | link | comments (1) |
manned missions

Our solar system could be unique

Although many more planets are being discovered outside the solar system, none of them looks anything like our own planets. And it is possible that they formed in a completely different way, making our planetary system rather unique.

In the traditional model of planet formation, the dust in a disc of gas around a star gradually clumps together into rocks, which eventually merge to make planetary cores. The cores then accumulate gaseous atmospheres. In this model, gas giants such as Jupiter form in the relatively cooler outskirts of the system.

But it is possible that one formation mechanism may not fit all planetary systems, as some Jupiter-like planets are found near the stars. Typically, these planets are much heavier than Jupiter, and most are so-called "hot Jupiters" that orbit closer to their star than does the Earth, or even Mercury. Some researchers have proposed that giant planets can form directly through sudden gravitational collapse of the gaseous discs around stars.

Some astronomers have argued that these giants formed far away from the star, just as Jupiter did, but then migrated inwards. However, they are struggling to explain why the planets do not simply plunge into the star.

It will take a few years to resolve this puzzle. The vast majority of extrasolar planets have been detected by measuring the way a star wobbles as a result of the gravity of an orbiting planet. This technique is inherently sensitive to heavy planets with short orbital periods, so those are the ones we are finding.

To see a planet as far away from its star as Jupiter is from the sun, astronomers would need to observe the star for at least 12 years.

It will be another five years or so before we know whether the solar system is truly different.

posted by: kyawoo at 19:56 | link | comments (1) |
astronomy

Cassini Makes Saturn Discoveries

Aug. 6, 2004
The U.S.-European Cassini spacecraft discovered a new radiation belt around Saturn and has found that lightning in the ringed planet's atmosphere is occurring much differently now than when NASA's Voyagers flew by in the early 1980s, scientists said.

"This is exactly the point of doing a mission like this," said Bill Kurth of the University of Iowa, the deputy principal investigator for Cassini's radio and plasma wave instrument, which detects "cracks" and "pops" from lightning like those that can be heard on an AM radio during a thunderstorm on Earth.

"Cassini now has evidence for changes in the thunderstorms that occur on Saturn over more than 20 years since we first started making measurements of these," Kurth said Thursday.

One difference is in the patterns in which lightning is occurring.

"Currently Cassini is seeing lighting on a very sporadic basis. It comes and goes," Kurth said. "Some days we see no lightning at all; other days we see evidence perhaps of more than one storm. Back in the early 1980s on Voyager such storms were detected extremely regularly."

The other major difference is that the thunderstorms observed by Cassini are taking a longer time to rotate around the giant gas planet, about 10 hours and 45 minutes, compared to the 10 hours and five minutes in the 1980s.

Voyager scientists associated those storms with "superrotational clouds" near the equator, where a high-velocity windstream can move them around Saturn faster than the planet itself rotates.

"The fact that Cassini is seeing a longer period suggests that the storms are coming from a higher latitude" where the winds don't move as fast, Kurth said.

Scientists suspect that cause of the difference in the lightning patterns may be due to the difference in the way shadows from Saturn's rings are falling on the planet now compared to when the observations were made in early '80s.

Then, the sun was nearly on the same plane as the rings, and their shadow fell along a narrow band close to the equator. Now, the sun is illuminating the southern hemisphere and the rings' shadows are falling broadly across the northern hemisphere.

"They're no longer concentrated in one place and they're spread out over a large part of the planet," Kurth said.

Scientists' hunch is that during the Voyager era the very deep ring shadow being very close to the region where the sun shined most directly on the upper atmosphere caused extraordinary convection to drive the storms.

"Currently we don't have that situation," Kurth said. "The ring shadows are in the north and the direct sunlight is in the southern hemisphere so you don't have the potential for that temperature contrast that you might have had at Voyager."

The new radiation belt was discovered just above Saturn's cloud tops by a Cassini instrument, showing that the belts extend much closer to the planet than had been known.

Radiation belts are invisible, symmetrical, doughnut-shaped regions in space where high-energy ions and electrons are confined by a planet's magnetic field.

Over the long term, radiation belts have an important role in the evolution of a planet's atmosphere and any moons and orbiting gas and dust, said Donald G. Mitchell, a scientist for the magnetospheric imaging instrument, from Johns Hopkins University, in Laurel, Maryland.

Temperature and chemistry of a planet's upper atmosphere are also affected by radiation belts, he said.

Kevin Baines, a scientist on Cassini's visual and infrared mapping spectrometer, also released new observations of Saturn's planet-sized moon Titan, documenting the extreme thickness of its atmosphere, which is greater than Earth's.

Cassini will launch its Huygens probe toward Titan in December. The probe will plunge into the moon's atmosphere in January, transmitting back images and science data.

posted by: kyawoo at 20:17 | link | comments |
saturn, unmanned missions

Saturn from 3.6 million miles

Saturn, a frigid ball of gas in the blackness of space, appears cool and serene in this natural color image.

(Aug 6, 2004) Cassini took this image of Saturn as it traveled away from the Ringed Planet after its arrival in orbit. Separate images were taken with its red, blue and green filters on July 17, and then merged to create a natural colour view. Cassini was 5.8 million km (3.6 million miles) away at the time.

The spacecraft obtained this view as it sped outward from the planet on its initial orbit. At left, Saturn’s shadow stretches almost completely across the rings, while at right the planet’s illuminated face appears to gaze down at the far-off Sun.

Images taken through blue, green and red filters with the wide angle camera were combined to create this natural color view. The images were taken on July 17, 2004, from a distance of about 5.8 million kilometers (3.6 million miles) from Saturn.

posted by: kyawoo at 19:36 | link | comments |
saturn, unmanned missions

Saturn's South Pole

A dark spot marks Saturn's south pole in this new image from the Cassini spacecraft. It was taken July 13 and released yesterday.

Around the polar region, concentric rings of clouds can be seen. To the north, wavy patterns are evident, resulting from the atmosphere moving with different speeds at different latitudes. Other observations have revealed that Saturn's winds change dramatically over time, having slowed down by 40 percent over two decades.

Cassini was 3.1 million miles (5 million kilometers) from Saturn when it snapped this infrared view. Contrast has been enhanced slightly to aid visibility.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. It is run out of the Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena. The imaging team is based at the Space Science Institute, Boulder, Colorado.

posted by: kyawoo at 19:31 | link | comments (1) |
saturn, unmanned missions

Picture of Earth and Moon

This image, taken by ESA’s Rosetta comet-chaser spacecraft, shows the Earth-Moon system from a distance of 70 million kilometres. This is close to the maximum distance reached by the spacecraft so far this year.

However, this is a tiny distance compared to Rosetta’s epic journey when, in 10 years time, it will have travelled distances of over one thousand million kilometres from Earth, and about 800 million kilometres from the Sun, to meet Comet 67P/Churyumov-Gerasimenko.

This image was taken by the Navigation Camera System (NAVCAM) on board the Rosetta spacecraft, activated for the first time on 25 July 2004. This system, comprising two separate independent camera units (for back-up), will help to navigate the spacecraft near the comet nucleus. The cameras perform both as imaging cameras and star sensors, and switch functions by means of a refocusing system in front of the first lens. ESA's Rosetta spacecraft will be the first to undertake the long-term exploration of a comet at close quarters. It comprises a large orbiter, which is designed to operate for a decade at large distances from the Sun, and a small lander. Each of these carries a large complement of scientific experiments designed to complete the most detailed study of a comet ever attempted.

After entering orbit around Comet 67P/Churyumov-Gerasimenko in 2014, the spacecraft will release a small lander onto the icy nucleus, then spend the next two years orbiting the comet as it heads towards the Sun. On the way to Comet Churyumov-Gerasimenko, Rosetta will receive gravity assists from Earth and Mars, and fly past main belt asteroids. Rosetta was launched on 2 March 2004. Rosetta's journey takes it out to 5.25 AU (about 790 million kilometres from the Sun).

The journey to Comet 67P/Churyumov-Gerasimenko lasts 10 years.
Comet 67P/Churyumov-Gerasimenko has a nucleus about 4 kilometres wide. It orbits aroud the Sun every 6.6 years, between 186 million kilometres and 857 million kilometres from the Sun.


It was discovered in 1969 by K. Churyumov (University of Kiev, Ukraine) and S. Gerasimenko (Institute of Astrophysics Dushanbe, Tajikistan)

posted by: kyawoo at 20:01 | link | comments |
astronomy, unmanned missions