Stardust - a surprise package?

by Dr. Michael Martin-Smith


February 7 saw the successful start of a seven years' space odyssey, in the shape of a small but sophisticated spacecraft called Stardust, whose mission is a new "first" in space exploration - the first return of material from a celestial body other than the Moon. Unlike the Apollo and Soviet lunar missions, the returns are to be only a few grams of dust and fine particles, rather than many kilograms of solid lunar rocks, but the potential scientific interest is far-reaching.

The target, Comet Wild 2, is a recent arrival in our inner solar system. For countless eons, it existed in the outer reaches of the solar system, left over as a relic from the earliest beginnings, 4.6 billion years ago, until it became a long period comet,. skirting the outer reaches of our planetary system, in a long period orbit, thousands of years ago. In 1974, however, the massive gravitational field of the planet Jupiter intervened, and altered its orbit so that it approaches to within 242 million miles from the Sun, in 2004 AD - at which time, it will, for the first time receive a visitor from Earth - the Stardust spacecraft.

Since Comet Wild 2 has only made a few such comparatively close passes by the Sun, very little of its surface ices or dust particles have been blasted off into the spectacular clouds of dirty steam we usually see as tails, and so the material to be encountered by Stardust will be unaltered, essentially, from the solar system's earliest days, and may even, perhaps, precede its birth.

Vital clues to the connections between the birth of our solar system and local conditions in interstellar space could result, and , since comets are now widely believed to be a major source of Earth's oceans, and earliest biochemistry, the origins of life should be illuminated. However, there are even more radical possibilities; for over 20 years two distinguished astronomers, Professors sir Fred Hoyle, and Chandra Wickramasinghe, have proposed, in numerous papers, conventions, and books, that life itself , in the shape of bacteria and viruses, originated in Space, and has reservoirs located in watery mini-oceans located in the cores of the comets. These are, they say, heated, as is the Earth's core, by radioactive elements left over from the initial formation of the solar system. These radio-active elements are the remnants of a supernova, whose eruption caused the shock wave which initiated the contraction of an earlier interstellar dust cloud in the process which led to the formation of the sun and its family of planets, asteroids, and comets, 4.6 billion years ago. Recycling is not confined to earthly conservationists!

Furthermore, Hoyle and Wickramasinghe go on to propose that biological Evolution is driven in fits and starts, by the addition of new genetic material in the shape of virus particles from space, as meteoroid or comet dust particles. They cite the fact that viruses are proven to be capable of attaching themselves silently to a host cell's genes, rather than being solely destructive.

They also have ascribed certain epidemiological mysteries in virology to the influx of virus particles from Space - the emergence for instance of new strains of disease, and the fact that people appear to catch infectious diseases in the absence of other people, in some cases - for example on islands, or remote rural areas.

It is fair to say that this body of ideas is not entirely accepted in orthodox medicine, virology or astronomy, but the discovery, from the European Space Agency's Giotto probe visit to Halley's Comet in 1986 that the nucleus or central core was much darker and richer in organic (carbon based) matter than expected gave some food for thought. At the very least, the idea that cometary cores contain complex chemistry relevant to the origins of Life , and also contributions to our early oceans, is increasingly respectable, if not universally accepted.

Stardust 's mission is to reach Comet Wild 2 , after two orbits around the Sun, in the year 2004, and approach to with 93 miles of the nucleus, at a speed of 13,600 miles per hour. During this incredibly rapid passage, it will unfurl a tennis racket sized scoop made of a very light weight foam material, called Aerogel, which will capture several grams of ice and dust particles as they stream off the surface of the comet's nucleus, at 242 million miles from Earth. Aerogel is a porous sticky material which can slow down and capture these particles without inflicting damage upon them. These will then be packaged up, and returned to a parachute landing in the Utah Salt Flats in January 2006, where a grain by grain analysis, using fine analytical techniques undreamed of at the time of the lunar missions, will begin.

Stardust, the fourth of NASA's Discovery class "faster, cheaper, better" missions, was launched by a Boeing Delta 2 rocket, at a total mission cost of $200 millions, and which took a mere three years from conception to lift-off.

Chicago University has also contributed a dust particle detector which is riding shotgun on the spacecraft's bumper shield. Also on board is a camera to record fine resolution images of the comet's surface, and two acoustic microphones, from England's Kent University, to record impacting dust particles, at 13,600 miles per hour - a "pinger with the mostest". On a more populist note, there is also a chip with one million names recorded on board, including all 25,000 members of the National Space Society, including this author's.

There is thus an exciting mission underway which should yield new insights into interstellar space, solar system formation, the earliest phases of ocean and life development on Earth, with perhaps a true wild card - evidence of life beyond the Earth, and a new mechanism for epidemics and evolution. A real surprise package could be in the making!

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