Scientific Background and Objectives
Members of the Cardiff group have made pioneering contributions in several areas of cometary science that have now become the focus of international projects. The organic nature of cometary dust first proposed by V. Vanysek and N.C. Wickramasinghe (ApSS, 33, L19, 1975) appears to have been substantially vindicated, and current efforts are directed in the main towards determining the detailed composition of such material. The long-held belief that comets were "dirty snowballs" as suggested by Fred Whipple has essentially been disproved.
The connection between comets and terrestrial life (Hoyle and Wickramasinghe in Comets and the Origin of Life (ed. C. Ponnamperuma - D.Reidel, 1977) is also been taken seriously at the present time, at least to the extent of comets being accepted as the source of prebiotic material to the Earth (e.g. C.F. Chyba et al, Science, 249, 366, 1990). The even stronger hypothesis that comets might carry microbial life is beginning to receive a hearing, particularly after the 1996 discussions of possible microfossils in a Martian rock.
A few months ago J. Kissel reported that 5 interstellar dust particles were so far sampled by Stardust as they smashed on to the detector at 15km/s. The surviving fragments were said to be comprised of "three dimensionally cross-linked heteroaromatic polymers" consistent with the break-up of bacterial type grains. More recently there have been claims to detect complex organic matter relevant to life in material associated with the Leonid meteor shower of November 1999.
It is interesting to note that Mars sample return missions that are currently been planned are taking the remarkable precaution of incorporating the highest levels of quarantine cordons for the possibility of extraterrestrial microbes being returned.
Another area of research intimately linked to our group relates to comet-Earth interactions. Cometary interactions could not only cause mass extinctions (F. Hoyle and N.C. Wickramasinghe, Astrophys.Space.Sci. 53, 523, 1978) but also lead to climate changes through fluctuation of stratospheric particle loading (S.V.M. Clube et al., Astrophys.Sp.Sci., 245, 43, 1996). Such efforts could lead to the termination of ice ages as well as to their sudden onset.
Research Programmes
The astrobiology programme covers five central themes:
1. The identification of biological processes in the stratosphere
and middle atmosphere and its clouds.
2. Evidence of biochemicals and/or intact cells in comets, cometary
fragments and in interstellar dust particles from remote sensing
data (optical spectroscopy, radio astronomy and mass spectrometry)
3. The transfer of life-bearing material in space, between solar
system bodies, and retention of viability under extreme conditions
of flash heating, impact pressures and irradiation.
4. The direct detection of bio-molecules and processes via spaceprobe
instruments, and in samples from planets, and other extraterrestrial
material obtained from space missions.
5. The effect of space conditions on bio-processes - in terrestrial
pro- and eu-karyotic cells including microorganisms, particularly
extremophiles and human cells in culture.
 Identifiying
biomaterial from stellar and cometary spectra
Diffuse bands in the spectra of the visible light from interstellar
matter, like the Horsehead Nebula (picture on left), have
long been a mystery. Laboratory studies of certain biological material
(e.g.porphyrins) can be matched to some of these bands. Fred Hoyle
and Chandra Wickramasinghe have long argued for identifying biomaterial
from spectra of interstellar and cometary dust (From Grains to
Bacteria, University College Cardiff Press, 1984). Their arguments
used data in the near infrared where complex hydrocarbon signatures
can be unequivocally identified. But the biological interpretation
of such signatures was not absolutely unique. New astronomical data
in the far infrared from ESA's Infrared Space Observatory is allowing
firmer identifications. Data obtained at other wavelengths - radio,
visual and ultraviolet - gives further evidence of biochemicals
in space. Laboratory experiments will be planned to investigate
the possible role of biological materials as carriers of the diffuse
interstellar bands.
 Comets
and life
The exploration of Halley's comet in 1986, particularly with the
European GIOTTO probe, led to a new paradigm in cometary science.
Comets are now no longer to be thought of as uniform snowballs with
an admixture of mineral dust (the "dirly snowball" model). Comet
Halley revealed a highly structured surface, with gas emerging jet-like
from localised regions (GIOTTO picture of Halley's comet on left).
The GIOTTO probe traversed Halley's comet at high speed and was
able to record mass spectra of impacting dust particles. The majority
of of the dust grains were found to be largely carbonaceous, justifying
the description "CHON" material from their elemental compositions.
This confirmed the organic nature of the dust that was already shown
spectroscopically from the AAT (Anglo-Australian Telescope) observations
of Dayal Wickramasinghe and David Allen.
Max Wallis was a member of the GIOTTO team whose instruments also
identified complex organic gases as degradation products of possible
biomaterial. This led immediately to the idea that the shower of
comets that bombarded the early Earth brought with them the carbon
compounds (amino acids etc) that were thought to be a prerequisite
for the emergence of life. But it also renewed interest in regarding
comets as the carriers of microbial life (Hoyle and Wickramasinghe,
Living Comets University College Cardiff Press, 1985).
Max Wallis and Chandra Wickramasinghe are Science Team members
of ESA's Rosetta mission to a
comet that was launched in March 2004.
Cometary bacteria in the stratosphere
Some of the fragments and organic particles thrown off into space
by comets are swept up by planets including the Earth over millions
of years. The Earth collects roughly 100 tonnes a day of such material
mixed with meteorite dust. From an altitude of 70-100km this dust
settles through the middle atmosphere and stratosphere. Uplifting
of material from the Earth's surface also occurs. In the mid-1960's
stratospheric detections of microorganisms were claimed from balloon
experiments conducted under the auspices of NASA. But these early
detections were not taken seriously, in part because of contamination
problems.
Scientific instruments have long been flown on high altitude balloons
from the Tata Institute Balloon Facility at Hyderabad. It is only
in the past few years that reliable contaminant-free techniques
for collection of biomaterial from the atmosphere have become available.
A group of scientists in India headed by Professor J.V. Narlikar
has devised specially sterilised collectors in a cryopumped system.
Samples of frozen air are then filtered in sterile laboratory conditions
(Narlikar, et al, SPIE, 3441, 301, 1998). One hitherto
unknown bacterial strain which is significantly different from terrestrial
strains has already been isolated in this way. Further work by the
Indian team is in progress, and samples from different heights in
the stratosphere and above are to be analysed in India and independently
at the Cardiff centre.
Life processes in material from space
Modern techniques using gene sequencing and genetic markers are
proving very powerful in indentifying new strains and unknown microorganisms.
The deployment of bioluminescent markers is a technique pioneered
by Professor Tony Campbell and will be useful in detecting life
processes in material collected from space. Techniques using fluorescent
dyes sensitive to membrane potential, as well as electron and optical
microscopy will be deployed by Professor David Lloyd. Such techniques
make possible for the detection of just one viable cell without
the need for culturing. These procedures of detection can be applied
not only to the samples from the Indian experiment but also to stratospheric
cosmic dust (Brownlee particles) and meteorites. However a considerable
problem is contamination from the Earth before analysis.
One goal of our programme is to develop robotic bioluminescent assays
for in situ analysis on the Martian surface or on the surfaces
of comets. The use of firefly luciferase to analyse ATP on the Martian
surface was proposed but dropped from the first Viking expedition.
Detection of chirality - left-handedness or right-handedness of
biomolecules - is also an important indicator of biomolecules. Modern
micro-instrumentation makes in situ experimentation very
feasible for future exporation of solar system bodies.
The effect of space conditions on living
systems
Bioluminescent markers of chemical reactions in living cells offer
unique potential for investigating the effects of weightlessness
on biological processes. Bioluminescence analysis is extremely sensitive,
being able to detect several molecular processes in defined parts
of living cells, including free Ca2+ , ATP, proteases, phosphorylation,
and cell end responses with relatively simple instrumentation. Fluorescent
probes need sophisticated lasers, which are cumbersome and expensive
for spacecraft.
The recent development in Professor Campbell's laboratory of the
Rainbow protein technology, targeted to orgenelles, allows a close
study of the effect of weightlessnes on cell signalling. One can
now genetically engineer cells with luminous markers, which can
be sent into space, or to the space station, where robotics will
enable luminous signals from sites within living cells to be transmitted
to Earth.
Staff
The initial staff will comprise:
Professor N.C. Wickramasinghe, Director and full-time Head of the Centre
Professor A.K. Campbell, Director
Professor Sir Fred Hoyle, Honorary Professor
Dr. Max K. Wallis, Honorary Research Fellow
Dr. Shirwan Al-Mufti, Honorary Research Fellow
Visiting Fellows
Honorary Research Associates
The following scientists have very kindly agreed to participate in the research programme of the centre and/or to serve as Honorary Associates:-
Dr. Milton Wainwright,
Professor R.B. Hoover, Professor J.V. Narlikar, Dr. W.M. Napier, Professor D.T. Wickramasinghe, Barrry E.di Gregorio and Professor Serguei M. Pershin
We are grateful for their help
Email address:
Prof. N.C. Wickramasinghe [wickramasinghe@cf.ac.uk]
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