ESA: Green’ satellite fuel designed to make space safer

On the day running up to launch when a spacecraft is fuelled, ground personnel look more like astronauts than engineers, putting on spacesuit-like protective gear.

This is an essential precaution when dealing with the current hydrazine fuel, but a new development could make satellite fuelling no more dangerous than filling up a car.

First used in rocket engines by the German Luftwaffe during World War Two, hydrazine remains the main propellant of choice for a satellite’s onboard thrusters, used for orbit correction or stationkeeping during its working life.

It is a high-performing storable propellant that is also ‘hypergolic’ – meaning it ignites spontaneously on contact with oxidiser or by itself with a catalyst, which makes a spacecraft designer’s job a lot easier.

Unfortunately hydrazine is also highly corrosive and extremely toxic. When leaked into the environment, it degrades in a few days but has the potential to harm plants and marine life, while exposure is considered harmful to people at just 50 parts per million.

Seeking an alternative, ESA has been working with a Swedish company called ECAPS, part of the Swedish Space Corporation Group, to build and test a thruster that runs on a safer, more environmentally friendly fuel.

ECAPS informs us that the development of High Performance Green Propulsion (HPGP) was initiated with the goal of meeting the requirements for future satellite missions. After more than 10 years of R&D, the HPGP technology is emerging as an enabling technology for improved performance, enhanced volumetric efficiency, reduction of propellant handling hazards and safer launch operations.

The HPGP technology developed by ECAPS, includes a storable monopropellant blend based on Ammonium DiNitramide (ADN) and thrusters with high-temperature resistant thrust chamber and catalyst.

For more information you can download ECAPS HPGP brochure here

NASA: Shuttle Replacement takes shape, the X-37

It's been a long wait—in some ways, more than 50 years—but in April 2010, the U.S. Air Force is scheduled to launch an Atlas V booster from Cape Canaveral, Florida, carrying the newest U.S. spacecraft, the unmanned X-37, to orbit.


The X-37 embodies the Air Force's desire for an operational spaceplane, a wish that dates to the 1950s, the era of the rocket-powered X-15 and X-20.


In other ways, though, the X-37 will be picking up where another U.S. spaceplane, NASA's space shuttle, leaves off.

With a wingspan of 15 feet and a length of 27.5 feet, the X-37 looks like a tiny space shuttle. It has a blunt (though windowless) nose, and one rocket engine bell instead of the shuttle's three.

Two cargo doors open just as the shuttle's do, revealing a four- by seven-foot bay. Like the shuttle, the X-37 was designed for low Earth orbits—in the latter's case, altitudes of 125 to 575 miles. And the craft will fly like a shuttle, reentering the atmosphere with the orbiter's 40-degree nose-high attitude.

After reentry, it will change to a 20-degree nose-down glide and, flying at up to 220 mph, land at Vandenberg Air Force Base in California, with Edwards Air Force Base as an alternate.

But as for the period between launch and landing, no one, save for a select few in the Department of Defense, knows exactly what the little Boeing-built spaceplane will do, or for how long.

The Air Force Rapid Capabilities Office, which is running the program, says only that the orbital test version, the X-37B, will take a suite of next-generation technologies to orbit and will break new ground in the realm of launch, recovery, and reuse, all with an unmanned twist that the shuttle never offered.

At a 2008 Space Foundation breakfast in Washington, D.C., Gary Payton, deputy under secretary of the Air Force for space programs, recalled the X-37's origins. Payton started the program while at NASA.

"Then, the X-37 was intended to be a testbed for new technologies that could retrofit into the shuttle: predominantly guidance, navigation, and control, and [thermal protection system] technologies," he said. In that era, planners imagined the shuttle carrying the X-37 to space in its cargo bay and releasing it.

Now, with the shuttle's retirement looming, it appears the X-37 will have an independent, post-shuttle life. Payton envisioned such a role for the X-37, saying: "It would be really advantageous in my mind if we had a system you could launch, recover, change out the payload bay quickly, and put into a different orbit, and do all that measured in weeks instead of decades."

David Hamilton, director of the Rapid Capabilities Office, says in an e-mail: "Eventually, I see the unique possibility to operate X-37B more like an aircraft and explore the needs of responsive, reusable spacecraft."

Unlike a satellite, he points out, the spaceplane returns, enabling "detailed inspection and significantly better learning than can be achieved with [a satellite's] remote telemetry alone. Experiments can be modified and reflown, with the objective of shortening the technology maturation timeline."

"The space shuttle was designed to be a very heavy payload lifter, and it has performed that job extremely well," says Mark Lewis, a University of Maryland hypersonics expert who recently completed a four-year appointment as chief scientist for the Air Force. "But you don't need to send a Mack truck into space when a Toyota Celica will do."

The question is: Will do what? Lewis, whose enthusiastic speech barely keeps pace with his mind, is happy to talk about the skin-deep similarities between the shuttle and the X-37. ("A lot of the basic reentry physics is treated the same way," he says. "Blunt configurations. The shuttle has very blunt leading edges.") But when he's asked about anything more than the X-37's aerodynamics, he clams up.

So does everyone else. "While some aspects of the…program have been designated as unclassified and been released to the public; information regarding specific technical and performance capabilities will not be released at this time," writes David Hamilton.

"Hide it in plain view," says one observer of the Air Force's practice of letting out just a little about the X-37, enough to make it seem like it will never be more than a research tool. Read More....

This prosthetic arm designed by Hans Alexander Huseklepp

Immaculate arm

This prosthetic arm was designed by Hans Alexander Huseklepp, a designer in Norway.

It is designed to be connected to the wearer's nervous system, like the most advanced, but less aesthetically designed, prosthetics currently are.

Because each of its joints is a globe joint it is capable of a larger freedom of movement than a normal human arm.

The exterior parts of the arm are made from the plastic Corian, the inner layer is textile.

This image is a model built to demonstrate the concept.

Out of uncanny valley

Huseklepp says that he wanted to get away from traditional designs, which hide their technological skeletons under silicone rubber.

"They imitate the look of a natural arm perfectly but as soon as someone touches it they realise it’s a prosthetic," he says.

This can make things awkward due to an effect dubbed "Uncanny Valley", a term used to describe how close mimics of human appearance seem more creepy than more stylised attempts.

(Image: Hans Alexander Huseklepp)