UK SENDS CLOVER AND ROCKS INTO SPACE.
European and UK scientists are eagerly waiting to retrieve their experiments when the unmanned Russian Foton spacecraft parachutes onto the open steppes of Kazakhstan after 16 days in orbit. On board are 240 kg of experiments provided by the European Space Agency and its member states. They include two innovative and unusual experiments from UK institutes.
One of the experiments carried inside the spacecraft comes from a group of scientists in the School of Biological Sciences at Nottingham University. The experiment, named SYMBIO, is investigating the interaction between the soil bacterium, Rhizobium, and 28 clover seedlings.
Rhizobium normally induces and inhabits nodules on the roots of leguminous plants, such as peas, beans and clover, where the bacteria extract nitrogen from the air and convert or "fix" it. The plant can then utilise the nitrogen to produce important compounds, such as amino acids and proteins. In this way, Rhizobium and legumes rely on each other, forming what biologists call a symbiotic relationship - hence the name of the Nottingham experiment.
The seedlings used in the SYMBIO experiment have been placed in individual tubes placed inside two foam-packed containers about the size of shoe-boxes. Each tube contains a nutrient-rich gel known as agar. As the roots of the seedlings grow through this substrate, they come into contact with the Rhizobium, which initiates the nitrogen-fixing symbiotic association. Although the temperature of the plants is regulated so that it stays between 20C and 29C, no light source is provided for the short period in orbit.
When the SYMBIO experiment returns to Earth, Nottingham scientists will study the changes caused by microgravity in the structure of the seedlings and the way in which the bacteria have colonised their roots. Since fluids do not circulate in microgravity, it is possible that the bacteria are able to stay in contact longer with the roots, so aiding nodule development.
"Our experiment is investigating how the bacteria responsible for fixing nitrogen in plant roots react to the lack of gravity in orbit," said team leader Dr Greg Briarty. "This will help us to understand more about the way in which Rhizobium interacts with plant roots and enables leguminous plants to grow in poor, nitrogen-deficient soils."
In the longer term, the experiment may also assist humankind to travel for many years through deep space. "Such information is essential for the development of life-support systems for long-term space flight," said Dr Briarty, who has previously flown plant-based experiments on the IML-1 space shuttle mission in 1992, and as part of the NASA-5 Greenhouse Experiment on the Mir Space Station.
The second experiment with UK involvement, known as FLYING STONES, is located in a much more hostile environment outside the Foton capsule. The satellite's heat shield, which prevents it from burning up on atmospheric re-entry, has been modified to carry and expose three types of rock.
The experiment is part of an ongoing investigation at the Open University and other European research centres into the possibility of life on Mars. One of the most intriguing scenarios being studied is the transfer of rocks across millions of miles of space from Mars to Earth.
To date, only 14 Martian meteorites have been found on Earth, even though calculations indicate that at least 100 tons of Mars material should be landing on our planet every year. In an effort to improve identification of such important specimens, several types of rock which might be found on the planet Mars have been placed on the Foton spacecraft's exterior.
One is a fine-grained basalt (a type of lava) thought to be similar to "Barnacle Bill", a rock examined by the Sojourner rover on NASA's 1997 Mars Pathfinder mission. The others are a dolomite, a form of limestone found in northern Italy, and a simulated clod of Martian soil held together with gypsum.
When Foton-12 returns to Earth later this week, the samples will be exposed to extreme heating, just like incoming Martian meteorites. By studying the ways in which these rocks are modified by the scorching temperatures, scientists hope to gain valuable information which will aid identification and recovery of the all-important missing Martian meteorites from favoured collecting sites such as the Antarctic ice sheet.
Foton-12 carries an international cargo of experiments from many European countries, including the UK, Germany, France and Sweden. The Foton satellite is designed to carry out experiments under microgravity conditions and return them to Earth after about two weeks. At the end of the mission, the spherical capsule will re-enters the Earth's atmosphere, deploy a parachute, and eventually touch down in Kazakhstan.
From there, the European experiments will be delivered to Moscow, handed over to ESA representatives, and returned to the European Space Technology Centre (ESTEC) in The Netherlands for collection by individual research establishments.
FLYING STONES is a European Space Agency project involving collaboration between the Open University, CNRS in Orleans, Laboratory Rene Bernas in Orsay, and the Natural History Museum in Vienna.
Photos of the FLYING STONES experiment prior to launch are available directly from Professor Colin Pillinger. (see below) For further information on the ESA Foton programme, visit the Web site at: http://www.estec.esa.nl/spaceflight/foton/