How small nations think big…
|Once in space, the BIOPAN (above) lid flips open, like the top of a waffle iron, exposing experiments inside to the cold vacuum of space, and, when BIOPAN is in the sun, to ultraviolet and other radiation with no intervening atmosphere. |
Long before Astrobiology was even a real word, scientists in Europe had started using space research to try and find answers to deep-rooted questions about life. From simple beginnings, the experiments became more complex and more ambitious. Looking at the effects of space on living systems, exploring new worlds for life or the building blocks of it, searching for habitable planets outside our Solar System; step by step Europe has developed a strong and diverse programme of space research for astrobiology.
Blasting life into orbit
From as early as 1975, French scientists had started blasting biological and organic samples into space to see what would happen to them. The first experiments took place using the KNA exposure facility. Hitching a ride into space on the Russian BION spacecraft, biological samples were exposed to the space environment for 11-13 days, enabling scientists to look at the effects of space radiation on living organisms during actual space flight. The European Space Agency (ESA) later joined this initiative, and flew experiments on three consecutive BION missions between 1987 and 1992.
Next came BIOPAN, ESA’s technologically superior successor to the KNA, with in-built temperature, UV, radiometer, and pressure sensors. This pan-shaped exposure facility has enabled researchers from many European nations to test the effects of solar and space radiation, the space vacuum, and weightlessness, on organic molecules, and biological samples including plant seeds, yeast cells, and shrimp embryos. It has been so successful that it is still in use today. Four two-week flights aboard the Russian FOTON spacecraft have incorporated 25 different experiments, and collected lots of valuable data (1994, 1997, 1999, and 2005). The next BIOPAN experiment is due to be launched in 2007. Results have indicated that even in just two weeks, space radiation can have detectable effects on biological systems.
The new EXPOSE facility, to be mounted on an external platform of the International Space Station in 2007, will hold nine experiments prepared by scientists from various European institutes. It will allow exposure of biological and organic samples whilst recording data on temperature and radiation spectra. EXPOSE will help to determine whether meteorites can offer enough protection to support life after long periods of time in space. Together, BIOPAN and EXPOSE constitute Europe’s two ongoing facilities for astrobiology experiments in Earth orbit.
In 1999, STONE became the world’s first artificial meteorite experiment. Attached to the heat shield of BIOPAN, its aim was to test whether sedimentary Martian meteorites could cross the atmosphere (since none of the known Martian meteorites discovered on Earth is composed of sedimentary rock). STONE 5 consisted of a sedimentary rock loaded with micro-organisms, and was designed to find out whether simple life forms in a meteorite could survive a trip through the Earth’s atmosphere. Analysis of the returned samples is still in progress.
Looking for answers further afield
Mars, Titan, and comets. Long cited as the most likely abodes for life, or clues to it, in our Solar System, Europe has sent spacecraft to investigate all three. The Huygens probe was launched in 1997 as part of the joint NASA/ESA Cassini-Huygens spacecraft. Its target, reached in 2005, was Saturn’s largest moon Titan. With its thick atmosphere, scientists have long been fascinated by Titan and its promise of astrobiological triumphs beyond the fog. The probe descended by parachute towards the surface of Titan, analysing the atmosphere and the surface of this mysterious moon. As scientists continue to analyse Huygens data, they hope to understand how the Earth’s atmosphere might have evolved. They have also found complex organic chemistry involving molecules that may have been the building blocks of life on Earth.
|With its thick, distended atmosphere, Titan’s orange globe shines softly, encircled by a thin halo of purple light-scattering haze. |
Credit: NASA/JPL/Space Science Institute
ESA’s Mars Express mission, so called because it was built more quickly than any other comparable planetary spacecraft, was Europe’s first spacecraft to Mars. Its main objectives were the search for water and life. Launched in 2003, it continues to be a resounding success, delivering stunning high-resolution images from its position in orbit around Mars, detecting water at the poles, and providing information about the deep sub-surface of the planet using a ground-penetrating radar. Its passenger, the Beagle 2 lander, designed by a UK-led team, unfortunately didn’t fare so well. Designed to look for signatures of life on the red planet, contact was never made with the lander after its deployment from the Mars Express probe.
The third mission of the trio, Rosetta was launched in 2004, although it will not reach its destination, Comet Churyumov-Gerasimenko, until 2014. When it does so, Rosetta will go into orbit around the comet, mapping its surface before descending to land and explore its interior. It will stay on the cometary nucleus for a year and a half, and monitor how this changes as the comet is warmed on its approach to the Sun. By looking at the composition of the cometary nucleus, this mission should help determine whether comets provide the building blocks of life. In particular it will be looking for ‘left-handed’ amino acids, which are the components that make up all proteins on Earth. Organic material transported by comets may have played an important role in starting life on Earth.
Telescopes peer even further
Space telescopes, operating from various orbits around the Earth, are an important component of Europe’s investigations into the questions of astrobiology, both now and in the future. ESA’s Infrared Space Observatory (ISO) was operated from 1995-98, and involved the participation of ISAS (the Japanese Aerospace Exploration Agency) and NASA. This telescope performed nearly 30,000 observations, and made several great contributions to astrobiology research. It discovered over 100 complex organic molecules in space, and also detected large amounts of water. ‘ ISO found water basically everywhere. It was in our Solar System, including the atmospheres of the giant planets and Saturn’s moon Titan, in the areas around stars, in the cold interstellar medium, and in other galaxies’, said Alberto Salama (ISO Project Scientist). These results suggested that space is full of the building blocks of life. The Herschel Space Observatory, previously known as FIRST, will succeed ISO in the search for complex molecules in space. This new infrared telescope is due for launch in 2007. Herschel, in which NASA is a partner, is one of the four cornerstone missions of ESA’s Science programme. As part of a three year programme of observations, it will study discs where planets may form, and look at cometary atmospheres full of complex organic molecules.
A new French-led space telescope, called Corot, is scheduled for launch in October 2006. One of its aims is to search for extrasolar planets around nearby stars by studying stellar oscillations. Until now, only Earth-based telescopes have searched for extrasolar planets, and Corot will have the advantage of being high above the distorting effects of Earth’s atmosphere. By measuring changes in the brightness of stars, caused by planets passing in front of them, scientists hope to find several Earth-like rocky planets.
A related mission, Darwin, is one of the cornerstones of ESA’s Cosmic Vision space science programme, and has an estimated launch date of 2015. Darwin is a mission to look for the signatures of life on Earth-like planets around Sun-type stars, has been under development by ESA since 1997. It will consist of three large space telescopes, and will use the technique of interferometry in infrared wavelengths to detect and study terrestrial exo-plantets. A ‘target list’ of 1000 stars to be investigated is currently being put together. It may sound like a familiar concept – NASA’s Terrestrial Planet Finder (TPF) mission has similar goals. Malcolm Fridlund, Project Scientist on the Darwin Mission, said, ‘Darwin and TPF have identical objectives. From the beginning, TPF and Darwin have collaborated, first informally…then it evolved into an official collaboration covered by a Letter-Of-Agreement. This specifies the joint members on science and technical teams, the collaboration in developing, at least theoretically, methods and aiming towards the selection of a joint mission concept for eventual joint implementation.’
|A perspective view obtained by the HRSC on board ESA’s Mars Express, showing an unusual ‘rock glacier’ in the eastern Hellas region. Ice-rich material seems to have flowed from a small, 9 km wide crater into a larger 16 km wide crater below. The ice may have precipitated from the atmosphere a few millions years ago. |
Credits: ESA/DLR/FU Berlin (G. Neukum)
Bold visions for the future
Aurora is ESA’s new long term programme of planetary exploration. Endorsed in 2001, the primary planetary target is Mars, and the two missions in the near-term plan are Exo-Mars, and Mars Sample Return. ‘Understanding the distribution and fate of life in the Universe are among the goals and objectives of the Aurora Programme. Aurora should help to answer some key scientific questions, and also help prepare for future exploration of the Solar System, in particular human missions to Mars’, said Piero Messina, of the Exploration Programme at ESA. The programme will involve a step-by-step development of capabilities. As yet the only planned and funded mission of the programme, Exo-Mars will build on the knowledge gained through Mars Express. Due for launch in 2011, it will consist of an orbiter and a Mars rover that will look for signs of past and present life on the red planet. A Mars Sample Return mission should follow shortly afterwards.
Greater than the sum of its parts .
The European Space Agency is a unique framework for a multi-national space exploration programme in Europe, and strong collaborations are the key to success. By combining ideas and expertise from many nations, Europe has made great progress in finding answers to some of the astrobiological questions that have been asked for centuries. In addition to the space missions, progress in the field is being made through a diversity of ground-based research across Europe. The European Astrobiology Network Association (EANA) was set up in 2001 to coordinate national research centres. It now plays a central role in bringing together European scientists from the diverse array of fields encompassed by Astrobiology, and inspiring new space missions relevant to the field. Astrobiology research in Europe is flourishing, and by building on what has gone before, plans for the future look set to deliver even more exciting results.