Tiny cube to tackle space debris

By Rizwan Ali

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The CubeSail mission would expect to operate for about a year

UK researchers have developed a device to drag space debris out of orbit.

They plan to launch a demonstration of their "CubeSail" next year. It is a small satellite cube that deploys a thin, 25-sq-m plastic sheet.

Residual air molecules still present in the spacecraft's low-Earth orbit will catch the sheet and pull the object out of the sky much faster than is normal.

The Surrey Space Centre team says the concept could be fitted to larger satellites and even rocket stages.

The group also envisages that a mature system would even be sent to rendezvous and dock with redundant spacecraft to clean them from orbit.

"Our system is simple and very low cost; but we need to demonstrate that it can be done," said Dr Vaios Lappas, lead researcher on the project and senior lecturer in space vehicle control.

"It would help make space a sustainable business. We want to be able to keep on launching satellites to provide new services; but unless we do something, the amount of junk up there is going to grow exponentially."

Simplicity of approach

It is thought more than 5,500 tonnes of junk now clutters the region of space just a few hundred km above our heads.

Last year, two satellites even collided, showering their orbit with tiny fragments that now pose additional risk to operational spacecraft.

The controlling spacecraft is a box that is 30cm in its longest dimension

International agencies have agreed that retired hardware - old satellites or spent rocket stages - should be removed from space within 25 years of the end of service.

Using large deployable surfaces to increase the drag on these objects so they fall to Earth rapidly is one possible solution to the space litter problem.

CubeSail, unveiled on Friday, is a 3kg (6.6lb), 10cm x 10cm x 30cm (4in x 4in x 12in) nanosatellite.

It incorporates within its tiny frame a polymer sheet that is folded for launch to be unfurled once in space.

The simple deployment mechanism features four metal strips that are wound under tension and will snap into a straight line when let go, pulling the sheet flat in the process.

The team hopes to launch its demonstrator at the end of next year, riding piggy-back on another mission or as part of a cluster of small research satellites that are sometimes lofted en mass atop a single rocket.

Force of sunlight

The nanosat will then circle the Earth, going from pole to pole at an altitude of about 700km (435 miles), testing its systems and assessing the drag principle.

If successful, CubeSail could become a regular add-on system to satellites and rocket stages, opening up a new space business akin to the daily refuse services here on Earth.

"We would be looking to put it on our own satellites and to put it on other people's spacecraft as well," said Sir Martin Sweeting, the chairman of SSTL, the world-leading small-satellite manufacturer, which is supporting the research.

A demo of how the stowed sail would deploy

"We want this to be a standard, essential bolt-on item for a spacecraft; and that's why it's very important to make it small, because if it's too big it will interfere with the rest of the spacecraft," he told BBC News.

The researchers hope to develop the project as a propulsion system as well. The pressure of sunlight falling on such a large structure would also move it. The force is tiny but continuous.

This "solar sailing" technique has long been touted as a means of moving spacecraft around the Solar System, or even just helping conventional satellites to maintain their orbits more efficiently.

Indeed, some of the large geostationary satellites, for example, already use solar-sail flaps to maintain their attitude without firing their thrusters. This saves valuable chemical propellant and extends mission lifetime.

Delicate control

CubeSail will endeavour to demonstrate this "propellantless propulsion" by trying to shift the path it takes across the surface of the Earth by just a few degrees over the course of a year.

To do this though, the nanosatellite will have to carefully control the angle of the sail with respect to the Sun, just as an ocean vessel has to play with its sails to catch the wind.

The sail will be made from an extremely fine polymer

"We're going to control our sail with a very novel geometric technique; we're not going to use any thrusters," explained Dr Lappas.

"We have developed a tilting mechanism that uses very tiny motors. It's able to move in two directions. This enables you to change the centre of mass of the sail. We're also going to be using small magnets to control the sail because they will interact with the Earth's magnetic field."

Once its mission is complete, CubeSail will be instructed to take itself out of orbit.

The project is a private venture within the Surrey Space Centre, which is based at the University of Surrey, Guildford.

It has been funded by Europe's largest space company, EADS Astrium, which is one of the world's biggest manufacturers of satellites. It also produces Europe's heavy-lift rocket, the Ariane 5, which launches about half of the world's commercial satellite platforms.

The entire cost of the project is expected to be no more than £1m ($1.5m).

Other groups around the world are expected to launch solar sail demonstrators soon. The US space agency has been working on a project with The Planetary Society, a long-time proponent of the technology.

The Japanese, too, have work in progress. And even Astrium is sponsoring other space junk mitigation strategies within its own

Bloodhound supersonic car's lift problem fixed

Post By: Rizwan Ali

The aero solution is a major milestone in Bloodhound's design

Engineers designing the world's fastest car believe they now have a solution to keep the vehicle flat on the ground.

Bloodhound SSC is being built to smash the world land speed record by topping 1,000mph (1,610km/h).

Initial iterations of the car's aerodynamic shape produced dangerous amounts of lift at the vehicle's rear.

But the latest modelling work indicates the team has finally found a stable configuration, allowing the project to push ahead with other design areas.

"At Mach 1.3, we've close to zero lift which is where we wanted to be," said John Piper, Bloodhound's technical director.

"Up until this point, we've had some big issues. We've had lift as high as 12 tonnes, and when you consider the car is six-and-a-half tonnes at its heaviest - that amount of lift is enough to make the car fly," he told BBC News.

"We're very close now to fixing the exterior aero surface, which really opens the floodgates to the rest of the design work to really get going."

Computing power

By playing with the position and shape of key elements of the car's rear end, the design team has now found the best way to manage the shockwave passing around and under the vehicle as it goes supersonic.

The solution is a major milestone in Bloodhound's design.

The effort has been assisted greatly by project sponsor Intel. It brought immense computing power to bear on the lift problem.

Before Intel's intervention, the design team had worked through 11 different "architectures" in 18 months. The latest modelling work run on Intel's network investigated 55 configurations in just eight weeks.

To claim the world land speed record, Bloodhound will have to better the mark of 763mph (1,228km/h) set by the Thrust SuperSonic Car in 1997.

It will be powered by a combination of a hybrid rocket and a jet engine from a Eurofighter-Typhoon.

Three who worked on Thrust are also engaged in the Bloodhound project, including driver Wing Cmdr Andy Green, project director Richard Noble and chief aerodynamicist Ron Ayres.

They plan to mount their assault on the record in late 2011, driving across a dried up lakebed known as Hakskeen Pan, in the Northern Cape of South Africa.

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The power of imagination: Bloodhound's race with a Eurofighter

Bloodhound's aero shape is not completely fixed. Further work is still required on the jet intake ducts, the winglets that control lift, the air brakes (deployable structures that slow the car), and the large rear fin. The team also needs to model the air flow into the car.

But settling on the principal exterior surface means the team can now push forward on the main chassis structure and interior packaging of all the components that go into the vehicle.

John Piper intends to produce a master model of the car in late August, early September.

This will be followed by about five to six months of detailed drawing to direct the manufacture of components.

The aim is to have the car built and ready to begin testing in the second half of 2011.

Work is progressing on the wheels which will have to endure tremendous forces as Bloodhound races across the pan.

The 900mm-diameter, 120mm-thick aluminium discs will rotate at 10,300 rpm. The radial acceleration will be equivalent to about 50,000 g at the rims. Under those conditions, the alloy actually begins to stretch.

Lockheed Martin is working on the design. It will shortly run an experiment in which earth from Hakskeen Pan is fired out of an air gun at a sample of aluminium that has been pre-stretched to simulate the loads that will be experienced by the real wheels.

"A piece of dirt at Mach 1.4 is faster than a bullet so we've got to make sure we're not overstretching the material," said John Piper.

Tiger decline is 'sign of world's failure

Governments need to crack down on illegal tiger trading if the big cats are to be saved, the UN has warned.

The Convention on International Trade in Endangered Species (CITES) meeting in Doha, Qatar heard that tiger numbers are continuing to fall.

Organised crime rings are playing an increasing part in illegal trading of tiger parts, CITES says, as they are with bears, rhinos and elephants.

Interpol is working with CITES to track and curb the international trade.

Last year, World Bank chief Robert Zoellick said the global black market in wildlife products was worth about $10bn per year, making wildlife the third most valuable illicit commodity after drugs and weapons.

Global medicine

Despite attempts to protect tigers, numbers have approximately halved over the last decade, with fewer than 3,200 remaining in the wild.

The decline is seen across sub-species and in most range states. Many populations are small, and are threatened by deforestation as well as poaching.

"If we use tiger numbers as a performance indicator, then we must admit that we have failed miserably and that we are continuing to fail," said CITES secretary-general Willem Wijnstekers.

Skinning the tiger

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"Although the tiger has been prized throughout history, and is a symbol of incredible importance in many cultures and religions, it is now literally on the verge of extinction."

CITES enforcement officials said government agencies including police and customs needed to step up efforts to combat the illegal trade.

Although China and other East Asian countries are the principal consumers of tiger parts, exports travel much further afield.

Earlier this month, Operation Tram, co-ordinated by Interpol and including enforcement authorities in 18 countries, netted medicines containing wildlife products worth an estimated $10m.

Tigers, bears and rhinos were among the animals used in making the medicines.

Traditional cures

Conservationists also point to China's tiger farms as a threat to the wild animals.

Although China does not officially permit the sale of goods from these farms, in practice several investigations have revealed tiger parts are being sold.

Campaigners warn this perpetuates a market into which wild tiger parts can be sold, often commanding a higher value as products made from wild animals are perceived to be more "potent."

Just before the CITES meeting opened, the World Federation of Chinese Medicine Societies (WFCMS) called on traditional medicine practitioners to abandon the use of tiger parts.

"We will ask our members not to use endangered wildlife in traditional Chinese medicine, and reduce the misunderstanding and bias of the international community," said WFCMS deputy secretary Huang Jianyin.

"The traditional Chinese medicine industry should look for substitutes and research on economical and effective substitutes for tiger products."

Swift nesting sites 'hit by home improvements'

The number of swifts visiting the UK is in decline

A UK-wide survey of nesting swifts has suggested the declining bird species is at risk from improvement work being undertaken on old houses.

The RSPB study of more than 3,400 swift nest sites found nearly 80% were on houses, more than half of which were homes built before 1919.

It is not known why the birds are in decline, but numbers have fallen by almost a third in the past decade.

The charity says building work should not be done while swifts are nesting.

The birds tend to return to the same nesting sites each year and the RSPB said it was concerned the birds were suffering as a result of demolition and improvement works.

More than half the sites located in the survey had been known nesting places for swifts for more than 10 years, and about one in six spots was under threat, the RSPB said.

Emma Teuten, the RSPB's data management officer, said: "These are birds that don't touch down for two years or more after they first leave the nest - we need to make sure they have a safe, secure nest site to settle in when they come down to breed themselves."

Sarah Niemann, RSPB species recovery officer, said: "The scream of the swift marks the start of summer for many people. To think that we are losing them at such a fast rate is devastating.

"It was imperative that we find out exactly where they nest, so that efforts to help them can be effectively targeted."

Swifts make their nests in holes in buildings from where they can launch themselves back onto the wing as they cannot take off from the ground.

Their nests are protected by law while they are in use, so work on homes with nesting swifts should be done before they arrive in mid-May or after they leave in mid-August, the RSPB said.

The charity is appealing to the public for help spotting nests and talking to local councils and developers about how to retain and replace nest sites.