Space Thread

[Jez 0]

Extreme DIY: http://news.bbc.co.uk/1/hi/world/7953792.stm

Gotta love it! What a feeling that would be to be involved!

[Jez 0]

Astronauts fail to budge stuck cargo carrier

File imageby Staff Writers

Washington (AFP) March 23, 2009

The Discovery astronauts were unable to dislodge a stuck cargo carrier system during their third and final space walk Monday, and carried on with their busy to-do list on the orbiting space station, NASA said.

Richard Arnold and Joseph Acaba, two former science teachers turned astronauts, emerged from the decompression chamber at 1537 GMT, some six minutes earlier than planned.

One of their tasks during a six-and-a-half hour walk in space was to unblock the external cargo carrier after Acaba and fellow astronaut Steven Swanson inadvertently inserted a restraining pin upside down on Saturday.

Their attempts to fully deploy the system, however, were unsuccessful and mission control told them to stop trying and secure the system with "long-duration tethers," which will protect the hardware until another attempt can be made in the future.

"Because the problem is not yet understood, Mission Control cancelled Acaba and Arnold's installation of a similar payload attachment system on the starboard side" of the ISS, NASA said.

Discovery and the International Space Station (ISS) maneuvered into lower orbit Sunday to avoid a piece of floating debris that could have passed close by during Monday's spacewalk.

Discovery's steering jets turned the shuttle and space station 180 degrees for three hours to increase drag, which altered the vessel's trajectory, lowering it by two miles (3.3 kilometers) to avoid the debris, explained NASA spokesman Bill Jeffs.

The object, which measures a little over 10 centimeters (four inches), came from a Chinese rocket launched in 1999 that broke up in March 2000.

The most important task during the third spacewalk is to reposition an equipment cart from one side to another of the Mobile Transporter, the ISS's rail line.

The cart is used in the maintenance of the station's Canadian-built robot arm and the Dextre service robot. The robot arm will move the cart to another worksite at the station for tasks to be performed in upcoming space shuttle missions.

Elsewhere on the ISS, experts were working on a water-recycling unit that processes astronauts' urine and sweat into drinking water. A replacement part was brought by the Discovery and testing began Sunday. The samples will be taken back to Earth for analysis.

The machine, which was delivered to the ISS in November -- and has not yet functioned properly -- is key to sustaining a bigger crew on the orbiting station and for long-term space expeditions, such as moon landings or missions to Mars.

Carrying large amounts of water aboard the shuttle or other space vessels is expensive and takes up room needed for other equipment.

The two astronauts will also grease the hand joints of the ISS's robot arm and will install a thermal blanket on the Dextre robot. Dextre can be attached to the robot arm to manipulate small objects for tasks usually completed by an astronaut.

One of the Discovery mission's biggest tasks was to deliver the last set of solar arrays, which were successfully unfurled Friday.

The ISS now has four solar panels, two per wing, containing 32,800 cells that convert sunlight into electricity.

They will boost the outpost's full power generation from 90 to 120 kilowatts, providing the power the space station needs to carry out scientific experiments aboard Kibo and the European Columbus laboratory.

The additions also make it possible to double the space station's crew from three to six, beginning in May.

Discovery's latest mission, which blasted off last Sunday from Florida with a crew of seven astronauts, is one of the last major efforts in a decade-long push by 16 countries to build the 100-billion-dollar outpost in space.

NASA has scheduled nine shuttle flights through 2010 to finish building the space station. Upcoming shuttle flights also include the last mission to service the orbiting Hubble telescope in May.

Discovery is due to land back on Earth on March 28 at 1742 GMT, two days after a Russian Soyuz mission takes off for the ISS carrying a crew of three, including US billionaire businessman Charles Simonyi, who has shelled out 35 million dollars for his second trip as a space tourist.

On Discovery, crew member Koichi Wakata became the first Japanese astronaut to join the ISS for a long stay. He is scheduled to remain on the orbiting station until June. The Discovery mission, delayed five times, is the first by a US space shuttle in 2009.

[Jez 0]

That lucky b#####d!!

Space tourist blasts off to ISS

The Soyuz launch went entirely according to plan

A Russian Soyuz rocket has blasted off from Kazakhstan's Baikonur cosmodrome to ferry a three-member crew to the International Space Station (ISS). Among them is US billionaire Charles Simonyi, aged 60, who is the first space tourist to make the trip twice.

The software tycoon, who has paid $35m (

[Jez 0]

Gravity satellite feels the force

By Jonathan Amos

Science reporter, BBC News

Europe's innovative Goce satellite has switched on the super-sensitive instrument that will make ultra-fine measurements of Earth's gravity. The sophisticated gradiometer will feel the subtle variations in Earth's tug as it sweeps around the globe.

The spacecraft has also fired up the British-built engine that will help maintain its orbit.

Goce needs tiny but continuous levels of thrust to keep it stable and prevent it from falling out of the sky.

European Space Agency (Esa) mission manager Rune Floberghagen said all systems on the spacecraft had now been activated following the launch from Russia last month.

Goce is being overseen from Esa's "mission control" in Germany"The big news today is that the gradiometer is fully working; all its accelerometers have survived the launch and they are producing meaningful data," he told BBC News.

"Now we must learn to drive our super-satellite."

To acquire its data, Goce carries a set of six state-of-the-art high-sensitivity accelerometers. These have been arranged in pairs and sit across the three axes of the spacecraft.

As Goce "bumps" through Earth's gravity field, the accelerometers will sense fantastically small disturbances - as small as one part in 10,000,000,000,000 of the gravity experienced at the Earth's surface.

This exquisite measurement capability meant some very fragile mechanisms had to be built into the gradiometer, and developing these delicate technologies so they could also survive the intense shaking experienced at launch proved to be one of the major design challenges of the mission.

Monday's switch-on will be seen as vindication of the extraordinary engineering work on the gradiometer and its accelerometers, led by the Thales Alenia Space and Onera companies (France).

Gravity data can tell scientists about the nature of the Earth's interior"This was a pivotal moment in the mission, for sure," said Dr Floberghagen.

"What's very important in this first phase is that we see some consistency between the measurements from the six sensors onboard; and we do see that, which is all very exciting. But still, we need to characterise each one of these very precise sensors, and that process is not over."

The other major milestone in the commissioning of Goce has been the successful start-up of its electric propulsion system.

Built by UK technology firm Qinetiq, the T5 ion engine is a critical part of the mission. The satellite flies so low in order to get a good gravity signal that it actually brushes through the top of the atmosphere.

Without the constant force applied from the T5 unit, the drag on Goce would rapidly pull it out of orbit. But the engine's presence is also integral to the acquisition of the gravity data itself.

The buffeting from air molecules would ordinarily upset Goce's gradiometer instrument, so the British engine is designed to throttle up and down to counteract this disturbance and leave a clean signal.

ELECTRIC PROPULSION ON GOCE Satellite carries two engines; one is back-up in case of failureT5 unit draws power from solar panels on side of spacecraftElectrons are stripped off xenon atoms to give them chargeAn electric field then hurls the xenon ions through rear nozzleXenon exits at speeds in excess of 40,000m/s to provide thrustAmount of thrust is moderated by gradiometer information

'Cruise control' for spacecraft Gravity satellite leads new wave The levels and range of thrust needed, however, are tiny - a continuously variable force of anywhere between one and 20 millinewtons during the science phase of the mission.

This is similar to the force a postcard will exert when laid down on a surface.

Put another way, you would need to strap together 650 million Goce spacecraft to achieve the same amount of thrust as Europe's mighty Ariane rocket at launch.

Commissioning last week saw both T5 "chains" (there are two engines; one is a back-up) perform precisely to specification.

The levels of thrust delivered were shown to be within 10 micronewtons of what was being demanded at any one time. The drive is also very straight, with the spacecraft deviating offline by only 0.6 of a degree.

"You work on these things for so many years that you should be cold and confident that it will all work, but there's always a risk that it won't," Neil Wallace, who leads the Qinetiq electric propulsion team, told BBC News.

"One of the tests we did was to demand a thrust ramp, from one to 20 millinewtons, as quickly as possible. This is one of the most critical requirements and the most difficult to achieve, and both chains did it perfectly."

The T5 was then switched off to allow controllers to concentrate on the gradiometer's behaviour.

"The other reason was to let the spacecraft's orbit decay. All the time we are thrusting, Goce is going up. We did one orbit at 8.3mN and we went up by 150m."

Neil Wallace reveals the inner workings of Goce's ion engineGoce was placed initially by its Rockot launcher in an orbit some 283km above the Earth. Spacecraft operators are allowing it to fall by between 150m to 200m a day.

It is now just above 275km and will continue to drop to its target science altitude of 263km.

By then, the satellite will have been put in a "closed loop" mode whereby the gradiometer and the engine will be working in tandem to fly a stable path and gather the gravity data.

Scientists will use Goce to help them construct high-resolution maps of the geoid, which, simply put, is an idealised globe with a surface of constant gravity.

Geoid information has many applications but perhaps the biggest knowledge gains will come in the study of ocean behaviour.

Understanding better how gravity pulls water - and therefore heat - around the globe will improve computer models that try to forecast climate change.

GRAVITY FIELD AND STEADY-STATE OCEAN CIRCULATION EXPLORER 1. Goce senses tiny variations in the pull of gravity over Earth 2. The data is used to construct an idealised surface, or geoid3. It traces gravity of equal 'potential'; balls won't roll on its 'slopes'4. It is the shape the oceans would take without winds and currents5. So, comparing sea level and geoid data reveals ocean behaviour6. Gravity changes can betray magma movements under volcanoes7. A precise geoid underpins a universal height system for the world

[Medilloni 6]

Great stuff Jez,

Love the bit about "...need to strap together 650 million Goce spacecraft to achieve the same amount of thrust as Europe's mighty Ariane rocket at launch", and especially, "similar to the force a postcard will exert when laid down on a surface.".

See? Brit's still building the best injuns

Just a thought, why aren't NASA and other bods using this technology for powering spacecraft once they're away from the effect of gravity? An example would be manouvering for docking to the space station - surely the weight of conventional fuel saved during lift-off would be important....

[Max Mosley 2]

Dr Floberghagen says 'und next ve vill take over ze world!'.

Oh and are those T5s ion engines? I thought they were being considered for some space missions as a main source of propulsion. The thrust is small but there's no resistance in space. Wonder how long they can fire for and what the final speed could be. Perhaps the idea was to use hydrogen instead but there surely isn't enough of the stuff in space?

Another idea was solar sails, and they generate very small accelerations too but of course the acceleration is continuous so eventually large speeds would be obtained.

[Rainmaster 7]

^I love it when Murray talks dirty.

[Max Mosley 2]

[AutoRacer5 0]

Stephen Colbert won the vote to have a node on the ISS named after him, but NASA still has the final say.