Abstract
Having just one example of a celestial body endowed with living beings ready for our studies, studies on biology on different celestial bodies necessarily are extrapolations which (must) rely upon our knowledge on chemical evolution, with some of the intermediates like HCN, HC2CN or amino acids present in meteorites, comets or planetary atmospheres elsewhere. These might suggest how things might go on/had already proceeded into formation of extraterrestrial life-forms given the conditions outlined in the previous chapter, and on chemical knowledge on possible precursors thereof and appropriate energy-sources for advancing chemical evolution (UV and particle radiations, lightning bolts, volcanoes, etc.) being present besides an arrangement of atmosphere, liquidosphere and solid ground at some site. Planets or moons within the Solar System are accessible or will soon be so for direct investigation, including lander probes, to find out whether this advanced chemical evolution did actually happen. For obvious reasons there is an emphasis on results and projects dealing with Mars and certain satellites of Saturn and Jupiter. Outside the Solar system, distances are way too large to cover them within meaningful periods of time; yet spectroscopic investigation of exoplanets will soon reach the point where additional statements become possible. Inside the Solar System, life-forms elsewhere thus should be detectable within the forthcoming decades—if they exist. Philosophically speaking, present investigation of the Solar System is going to change our perspectives of the neighborhood and ourselves quite as much as discoveries of and in other continents did in the late fifteenth to seventeenth centuries.
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Notes
- 1.
In the turbopause at some 85–90 km height where heavier (N2, O2, Ar) and lighter (H2, H, He, Ne, O atoms) components of Earth’s atmosphere start to unmix by gravitation in favor of the latter, which is the very height where most of the mass of shooting stars is evaporated (thus causing the visible emissions and radio reflections), there are enrichments of three typical compounds: CH4, H2O and HCN which latter is obviously derived from pyrolysis of N-containing organics in shooting-star particles (CH4 will not make appreciable HCN in shock waves in an N2-dominated atmosphere by the meteoroid particles being slowed down from some 25 km/s up there).
- 2.
Later it turned out that the IR absorptions then attributed to chlorophyll were in fact due to “semi-heavy” water HDO, and even that was located in the terrestrial atmosphere rather than somewhere on Mars!
- 3.
Although Mars5M was meant to place a rather huge probe on Mars, sampling was to be taken by a wire-control system just some 25 m around the site of landing. The sample return should weigh in just 8.7 kg of which some 500 g were meant to be Martian matter, planned to undergo sterilization in Earth orbit before eventually being returned to Earth. It is not known whether biological tests were to be done before sterilization. The head of the program, Kryuchkov, was finally sacked in 1978 as he could not convince authorities that the multiple automated docking procedures in both Earth and Mars orbits had any reasonable chance to succeed.
Concerning our issue of early or extraterrestrial life to be studied for comparison, avoiding contamination risks is crucial.
- 4.
Now the turnover time of the entire water body of Lake Vostok—some 700 km (!) long and 800 m deep and up to 70 km wide (comparable to Lake Malawi, SE Africa)—is estimated to be some 10,000 years, rather than millions of years without exchange.
- 5.
We should be glad that Martian rovers Opportunity and Curiosity are meant to be operated (and funded) simply as long as they keep on moving on the Red Planet; both did work beyond their designed lifetimes already.
- 6.
This did not happen due to some technical failure: rather, the heatshield was completely closed covering the entire lower part of Huygens lander in order to make it float on (then only presumed, till then discovered) liquid hydrocarbon pools/lakes/oceans if it happened to land there rather than on solid ground (actually, it came down, within a river bed just recently flooded by some liquid).
- 7.
That connection was interrupted by horizon separating Huygens and the Cassini orbiter which acted as a telecommunications relay satellite and moved behind Titan. Broadcasting went on for several hours until lander batteries wore out but the data could not be read from terrestrial radiotelescopes directly (they just caught and tracked the non-coded signal).
- 8.
Before the Pioneer 11 mission first to pass Titan in 1979, there were models predicting an even more massive N2-dominated atmosphere of some 20–30 bar (rather than the actual 1.55 bar) surface pressure on this Saturnian moon which would permit for liquid water at some sites of the surface indeed (N2 cannot be directly spotted by spectroscopy)! This would have been such a situation right in our backyard.
Reference
Witze A (2014) NASA plans Mars sample-return rover. Agency to narrow down list of landing sites for 2020 mission. Nature 509:272
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Markert, B., Fränzle, S., Wünschmann, S. (2015). Present and Future Projects on Chemical Evolution by Means of Space Research. In: Chemical Evolution. Springer, Cham. https://doi.org/10.1007/978-3-319-14355-2_6
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