Zero-G flying is just like throwing a football through the air, explains test pilot Captain Gilles Le Barzic as he briefs an audience about to leave gravity behind: "Except instead of a ball we have an aircraft."
Le Barzic is one of three expert pilots on ESA's A-300 'Zero-G' Airbus, billed by its operator Novespace as 'the plane that removes gravity'. The aircraft has been specially strengthened to fly parabolic arcs enabling researchers to carry out experiments in weightlessness without going into space.
Last week saw the start of ESA's 35th Parabolic Flight Campaign. Twelve teams from seven European countries and Canada and Russia gathered at Bordeaux-Mérignac Airport, in France, to prepare and fit their experiments inside the modified white-padded Airbus fuselage. On 14 October 2003, the A-300 lifts off for the first of three consecutive flight days.
Flying 31 parabolas each two-and-a-half-hour flight provides experimenters with about 10 minutes of weightlessness per day. Rockets and space flights provide much longer and continuous weightlessness, but only on parabolic flights can experimenters ride alongside their experiments.
The experiments on board are very diverse. They range from assessing how bubbles form in artificial blood and testing an exercise machine designed for astronauts to studying the behaviour of so-called 'complex plasmas' found in cometary tails and judging the effectiveness of weightlessness surgery. The one common factor in the experiments is their need for weightlessness.
Bubbles in blood
How do bubbles form in simulated human blood? A Belgian group from the University of Brussels is linking up with investigators from the Universities of Thessaloniki and Thessaly in Greece to find out. "We use a tiny quarter-millimetre heater to produce the bubbles in the liquid," explains Professor Thodoris Karapantsios of the University of Thessaloniki. "It's the same thing when bubbles form in the blood of divers experiencing the 'bends', or a spacewalking astronaut suffers an explosive decompression. Gravity and convection currents do not distort these bubbles. They stay spherical and keep stable which makes them easier to study."
Two unusual passengers on this week's flights are a pair of rats named Ariane and Apollo. However, they will not be aware of their free-fall. A medical team from the University of Bordeaux will perform some simple surgery on the anaesthetised rats. In this way, the team intends to investigate the feasibility of carrying out operations in space. This is something that astronauts may one day need to know how to do for long-term manned missions.
Testing for space
Several experiments are testing hardware destined for the International Space Station (ISS). One will test the concept of the flywheel-based Resistive Exercise Device. Developed by ESA with the Karolinska Institute, from Stockholm, Sweden, this invention has been specially designed to improve existing astronaut fitness machines. Astronauts rely on fitness machines to stave off the wasting effects of long-term weightlessness.
There are also two experiments flown by the Max Planck Institute for Extraterrestrial Physics – the latter in collaboration with the Moscow Institute for High Energy Density. These experiments evaluate experimental apparatus for the study for complex plasmas on ISS, entitled PK-3 and PK-4. An earlier, more basic version of the equipment is already on board the ISS and yielding results.
Complex plasmas are electrically charged gases together with dust particles that exhibit unusual behaviour. For example, during weightlessness, lattice-works of statically charged particles form, called 'plasma crystals'. Complex plasmas occur in interstellar dust clouds, proto-planetary clouds, comet tails, and planetary rings. Understanding them better might help reduce costly dust contamination in the manufacture of plasma-etched silicon circuits, here on Earth.
Results on show
Visitors to Belgium's Euro Space Centre in Redu will soon be able to see some results from this parabolic flight for themselves. Students from the Centre's Space Camp are performing a variety of experiments designed to clearly show the effects of weightlessness on everyday objects.
"We're recording the results on ESA 3D cameras," says Centre teacher Pierre-Emmanuel Paulis. "We will put them on display at the Centre as soon as possible, and use them to teach young children about space." ESA also organises parabolic flight campaigns for students. Do you have a promising idea for a weightlessness experiment? It could be your ticket to ride, so send your application for next year's 7th Student Parabolic Flight Campaign before 12 January 2004.