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Home > Space & Science News > Space & Science News: May 2003

SARS from the stars? May 24, 2003
Where Mars life might be May 25, 2003
How alien can alien life be? May 2, 2003

SARS virus
SARS from the stars?
(May 24, 2003)

In a letter to the British medical journal The Lancet, Chandra Wickramasinghe of the Cardiff Centre for Astrobiology, and his colleagues, argue that the SARS virus is extraterrestrial in origin. Wickramasinghe is a leading advocate of the panspermia hypothesis and, in particular, that many global outbreaks of disease, including 'flu epidemics, are caused by organisms arriving from space, building up in the stratosphere, and then raining down on the Earth's surface. In their recent communication to The Lancet, Wickramasinghe et al. write: "With respect to the SARS outbreak, a prima facie case for a possible space incidence can already be made. First, the virus is unexpectedly novel, and appeared without warning in mainland China. A small amount of the culprit virus introduced into the stratosphere could make a first tentative fall out East of the great mountain range of the Himalayas, where the stratosphere is thinnest, followed by sporadic deposits in neighbouring areas. If the virus is only minimally infective, as it seems to be, the subsequent course of its global progress will depend on stratospheric transport and mixing, leading to a fall out continuing seasonally over a few years. Although all reasonable attempts to contain the infective spread of SARS should be continued, we should remain vigilant for the appearance of new foci (unconnected with infective contacts or with China) almost anywhere on the planet. New cases might continue to appear until the stratospheric supply of the causative agent becomes exhausted." Wickramasinghe's views remain highly controversial and his recent comments about the SARS virus have received short shrift from the medical research community.

Visit the Cardiff Centre for Astrobiology's website here and The Lancet here.

dune gullies of Russell Crater
Where Mars life might be
(May 24, 2003)

The best place to look for life near the surface of Mars today may be the mysterious Russell Crater in the Martian southern hemisphere at 54.5°S, 347.3°W. Two German researchers, Dennis Reiss and Ralf Jaumann, conclude (see reference below) that remarkable features in Russell Crater, shown in the photo here by Mars Global Surveyor, resemble terrestrial mudflows. (The image covers an area about 3 km across and shows one very large sand dune; the surface slopes from upper right toward lower left.) Observations of the region made during the local autumn and spring, when frost covers the dunes and then recedes, indicate liquid water may be present on the surface at certain times of the year. This water may be mixing with soil to create frequent mudflows which are possibly the youngest features on Mars, perhaps even forming from time to time during the present day. When winter arrives at Russell Crater, water vapour and carbon dioxide condense out of Mars' thin atmosphere and frost the dunes. Temperature and albedo (reflectivity) readings indicate that during the spring thaw, the frozen carbon dioxide sublimates – turns directly into a gas – leaving a thawed surface containing liquid water. In this place, for a few hours each day, just after noon in the summer, there could be liquid water on, or just below, the surface of Mars – an intriguing possibility for those in search of Martian life. Unfortunately, none of the spacecraft due to land on Mars in 2003-4 will go anywhere near Russell Crater: Beagle 2 will land on Issidis Planitia, about 10 degrees north of the equator, while the two Mars Exploration Rovers will touch down near the equator, halfway around the planet from each other.

Read the abstract of Reiss and Ralf's work, published in Geophysical Research Letters, here.

How alien can alien life be?
(May 2, 2003)

The alien from the "Alien" movies looks fantastically unfriendly and xenomorphic. But, in fact, it's probably hopelessly anthropomorphic in design: bipedal, hominoid torso, head with mouth and teeth, etc. Life "out there" might be more alien that we can possibly imagine. It could be wildly unfamiliar at the most basic level (Silicon instead of carbon? Ammonia instead of water? Energy instead of matter?) and/or remarkably unlike us at the gross level of appendages, sensory organs, brain structure, and so on. However, if we find extraterrestrial life that, like all Earth life, uses DNA for carrying its genetic code, then it may not have much leeway in deciding how that DNA is structured. Terrestrial life uses DNA with four bases – guanine, adenine, thymine, and cytosine. Scientists from New Zealand and Sweden have built a computer model to show that either 4 or 6 is the likeliest number of bases for life that uses DNA anywhere in the Universe. Paul Gardner and colleagues at Massey University, New Zealand, and Uppsala University, Sweden, simulated the progression from the hypothetical, primordial RNA World to the current DNA-dominated world. RNA is chemically similar to DNA but is much less stable and so less suitable for holding the blueprint information for building complex organisms. RNA World theorists think that RNA developed from simpler chemicals and only later evolved into DNA. Gardner and his colleagues programed a supercomputer to look at how RNA might have developed had it had 2, 6 or 8 bases, as well as the familiar 4. They found that 4- and 6-base RNA molecules were the most efficient at evolving into DNA. The 2- and 8-base RNAs got stuck somewhere along the evolution process. Four-base RNAs seemed best suited to overcoming RNA's greatest weakness: its susceptibility to making errors as it copies itself. However, if RNA-based lifeforms had developed the error-correcting techniques needed to repair the damage to their genetic code caused by mutation and degeneration, it's possible they might have developed into something with six-base DNA.


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