Blasting out Earth’s location with the hope of reaching aliens is a controversial idea – two teams of scientists are doing it anyway

If a person is lost in the wilderness, they have two options. They can search for civilization, or they could make themselves easy to spot by building a fire or writing HELP in big letters. For scientists interested in the question of whether intelligent aliens exist, the options are much the same.

The 116 photos NASA picked to explain our world to aliens

If any intelligent life in our galaxy intercepts the Voyager spacecraft, if they evolved the sense of vision, and if they can decode the instructions provided, these 116 images are all they will know about our species and our planet, which by then could be long gone:

Interstellar Seeds Could Create Oases of Life

We only have one example of a planet with life: Earth. But within the next generation, it should become possible to detect signs of life on planets orbiting distant stars. If we find alien life, new questions will arise. For example, did that life arise spontaneously? Or could it have spread from elsewhere? If life crossed the vast gulf of interstellar space long ago, how would we tell?

Researchers Find “Frozen” Recipe for Extraterrestrial Vitamin

Vitamin B3 could have been made on icy dust grains in space, and later delivered to Earth by meteorites and comets, according to new laboratory experiments by a team of NASA-funded researchers. Vitamin B3, also known as niacin or nicotinic acid, is used to build NAD (nicotinamide adenine dinucleotide), which is essential to metabolism and probably ancient in origin. The result supports a theory that the origin of life may have been assisted by a supply of biologically important molecules produced in space and brought to Earth by comet and meteor impacts.

This is an artist’s concept of a protoplanetry disk surrounding a forming star that is ejecting jets of material (yellow beams). Such disks contain countless tiny dust grains, many of which become incorporated into asteroids, comets, and planets. Source: NASA

Signboards in Space

The Search for Extraterrestrial Intelligence (SETI) is expanding. Dominated for decades by the search for radio transmissions from aliens, SETI has recently included optical searches for laser beams. A third SETI option, the search for extraterrestrial artefacts, is also gathering pace.

New Method Finds Best Candidates for Telescope Time

If life exists on planets beyond our Solar System, its presence could be obscured by the haze and clouds in the planet’s atmosphere.

If starlight passing through a planetary atmosphere is blocked by clouds or haze, the resulting spectrum is flat and featureless, and no molecules or potential biomarkers are visible.

One hundred thousand billion free-floating planets in the Milky Way?

An international group of scientists led by the University of Buckingham in UK has claimed that life-bearing planets may exist in vast numbers in the space between stars in the Milky Way.

An artist's concept shows a planet floating freely through the Milky Way galaxy. Credit: NASA/JPL

Astronomers, curb your enthusiasm

All known examples of life belong to the same biology, but there is increasing enthusiasm among astronomers, astrobiologists, and synthetic biologists that other forms of life may soon be discovered or synthesized. This enthusiasm should be tempered by the fact that the probability for life to originate is not known. As a guiding principle in parsing potential examples of alternative life, one should ask: How many heritable “bits” of information are involved, and where did they come from? A genetic system that contains more bits than the number that were required to initiate its operation might reasonably be considered a new form of life.

Potential pathways to life on Earth, beginning with a habitable planet and ending with DNA/protein-based life. The planet is an artist’s conception of the recently discovered ‘‘Earth-like’’ planet Kepler-22b (image courtesy of NASA/Ames/JPL-Caltech). Prebiotic chemistry is represented by the Miller-Urey spark-discharge apparatus (modification of photo by Ned Shaw, Indiana University). Two examples of hypothesized pre-RNA life are shown, based on either threose nucleic acid (TNA) or glycol nucleic acid (GNA)

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• Joyce GF (2012) Bit by Bit: The Darwinian Basis of Life. PLoS Biol 10(5): e1001323, May 8, 2012