The Envelope of Life? Please

The editors of the Astrobiology Magazine are impressed with the depth of interest and knowledge in this growing field, so take a bow.

The editors have introduced a new ‘Just Ask’ feature which categorizes a number of interdisciplinary terms important to the new field of astrobiology. These can be found on the menu at bottom left.

To enhance this dialog, we also have appended the flow of news stories with this snapshot of not only what you – the readers – think, but also what the researchers don’t necessarily know yet or soon hope to find out.

What We Think is True

According to Astrobiology Magazine’s polls, readers think:

  • primitive microbes (47%) will be the most likely life forms to find on another world
  • finding some kind of alien machine intelligence (11%) is not likely
  • life on Earth first arose from some kind of biological soup or RNA world(40%), not from cometary debris (20%) nor from interplanetary exchange (7%)
  • nuclear reactors are by far (52%) the most surprising extreme environment where life is found, followed by volcanoes, rock interiors, ocean vents, Antarctic lakes and the upper atmosphere (10%)
  • liquid water (41%) is the key factor needed to make a planet habitable, followed by a combination of all the elements [nutrient, water, oxygen, ozone, photosynthetic sources like sunlight, and carbon dioxide].
  • similarly, the presence of water and fossils are the most likely signatures of life we would find on another planet.
  • the best candidates for life once existing in our solar system are Mars and Jupiter’s moon, Europa.

What We Don’t Necessarily Know Yet

A good scientist is a person in whom the childhood quality of perennial curiosity lingers on. Once he gets an answer, he has other questions. —Frederick Seitz, President, Rockefeller University

According to the inquiries from readers of Astrobiology, the most popular questions to be researched and answered are:

1) What is the largest one-cell organism? Is the limit mainly nutrient and waste diffusion?

2) What is the driest place on Earth?
3) How do astronomers tell a binary star from a planetary system?
4) What is the oldest place on Earth?
5) What are the unique Cambrian life forms?
6) What are the causes of the Cambrian explosion?
7) What kind of things would you find on Mars?
8) What is the quickest way to oxygenate Mars? Is any accelerated path from Earth’s microbial history possible?
9) How does the doppler shift method of planet discovery work?
10) Are salt-loving (halophilic) organisms likely on Mars?
11) What is the origin of ocean salinity?
12) Was the early Earth anaerobic? If so, what life forms likely thrived?
13) Do carbon building blocks exist on any of the outer planets like Neptune or Uranus?
14) What telescopically is required to image an extrasolar planet in visible light?
15) Does life exist at high pressures?
16) Could you describe the goals of the NASA Kepler mission?
17) What is the life cycle of E. coli?
18) What organisms are specialized for the Great Barrier Reef, Australia?
19) Is water necessary for all life?
20) What is the role of oxygen in bacterial evolution?
21) Prior to the Cambrian explosion, did ocean life evolve in a more salty ocean?
22) How many light-years to the nearest suspected solar system?
23) What is the biomass subterranean on Earth? Quantity and types?
24) Can complex life as we currently classify it exist on a planet without oxygen? If not, what key hurdle does anaerobic living pose to complexity?
25) Can bacteria survive using metals as a primary nutrient?
26) What are the most extreme temperature and pressures found for growing organisms? On land and in deep sea?
27) What lifeforms are found around black smokers?
28) Could you describe the role of symbiosis in evolution?
29) What are the latest Rover designs?
30) What is the best theory for how the Moon formed?
31) What happened to the ancient oceans on Mars?
32) What percentage of the earth’s mass is contributed by the total biomass?
33) How does the carbon cycle work to keep the Earth ‘living’ or habitable?
34) What is the newest solar system discovered by current search methods?
35) What evolutionary branch gave rise to the earliest mammals?
36) What evidence suggests that the moon arose from a Mars impactor striking the Earth?
37) How many planets predicted in the Milky Way?
38) What are the ecosystem breakdowns following ozone layer decay?
39) What evidence exists that liquid water might exist beyond Earth, particularly cometary?
40) What is the origin and approximate age of the Mars gullies (sand tracks)?
41) What are the main challenges to seeing planets around other stars?
42) Do Antarctic microbes grow in ice fields?
43) Which moon in our solar system has an atmosphere most like Earth’s?
44) What is the most classic illustration of a current species that has self-evidently undergone (presently is undergoing) evolution?
45) What boilerplate plans are available for colonizing Mars?
46) What life forms are expected in or near Lake Vostok, Antarctica?
47) How does the continental biomass compare to the ocean–quantity and forms?
48) Are solar flares associated with any biologically significant events terrestrially?
49) How would the most robust rover maneuver over terrain barriers equivalent to its wheel size?

50) Are any of Jupiter’s moons potentially colonizable by Earth microorganisms? If not, could genetically engineered variants of ice-dwelling organisms adapt to Europa in place, for instance?
51) What are the primary handling contaminants in studying meteorites when found on Earth? How are these typically controlled for in bio-analyses?
52) How does the bacteria pyrococcus adapt to boiling (sterilizing) conditions in situ?
53) Can you compare and contrast the survival architecture of photosynthesizing vs. fermenting microorganisms?
54) Before methanogens, what was the Earth’s dominant success stories for the tree of life?
55) Speculate on the most likely kind of survivor today on Europa?
56) Is there a simple schematic or recipe method for understanding the key biomolecules that arose on Earth? Is there a particular reaction like carbon-dioxide catalyzed to water that became essential early on?
57) How do bacteria cope with hot dry conditions and can these survival techniques be adapted to terraform Mars?
58) What are the most probable mass extinction events in future Earth scenarios?
59) What key factors go into computer simulations of planet formation? Gravity+cooling+collisions?
60) What besides nutrient, waste and reproduction defines a living vs. non-living entity?
61) How does mitochondrial DNA figure in tracing the tree of life?
62) What are the specifics of the best rover wheel design for all (predicted and unexpected) terrain hazards?
63) Is there evidence of bacteria growing in sandstone with minimal water but without sporulation?
64) Define habitable zones? Is this terminology now out of scientific fashion?
65) Is there a planet discovery method based on pulsar timing events?
66) What protein biomolecules evolved from enzymes and how do these differ from other peptides and proteins?
67) What prebiotic chemistry is available in Titan’s atmosphere?
68) How does carbon dating work for determining the age of dormant bacteria? Are there any classic examples of this being done successfully today?
69) Are there prebiotic chemistries that might not hydrolyze even amidst the sulfuric acid content of say Venus?
70) Do radiation levels on Mars today (UV) have a bearing on the conclusion that the surface is barren? What depth of soil will shield known extremophiles like Radiococcus?
71) What remote sensing signal is most indicative of active photosynthesis on Earth when viewed from space–and to what distances would this photosynthetic signal be discernable with current state-of-the-art sensors?
72) What is the evolutionary split between Archae and Bacteria?
73) What technique is used to discern the wobble of a star with a planet vs. one without?
74) What are the most promising prebiotic molecules ever found on a meteorite? Other than water and carbon, are there actual amino acids?
75) Are the oceans still considered the originating ecosystem for all life on Earth? What evidence, if any, is there for continental origins including wetlands or swamps?
76) Does the Hubble Deep Field offer any revisions on the classic Drake equation for the total number of stars?
77) What microbes are found in geothermal vents?
78) What is a Trilobite? And what is its significance in evolution?
79) Were local climatic events influenced by the largest meteor strike on Earth?
80) Are viruses currently considered living parts of the tree of life or some alternative like a pollen grain (semi-dormant or host-dependent)?
81) Explain what is meant by left-handed vs. right-handed biochemistry, particularly in analyzing meteor chemistry?
82) What electrical storm hazards exist on Mars?
83) What in your opinion is the weirdest extinct animal?

Stay tuned as the Astrobiology Magazine tries to gather the latest answers to these important questions.