Astronomers have made some very interesting discoveries in space recently, each potentially bringing them one step closer to finding habitable exo-planets with signs of extra-terrestrial life-forms.
A study appearing this week in the journal Nature revealed findings extracted from the combined offerings of three NASA space telescopes: Hubble, Spitzer, and Kepler. Data from the telescopes showed clear skies and steamy water vapor on a gaseous planet outside our solar system.
The planet, known HAT-P-11b, is about the size of Neptune, making it the smallest for which molecules of any kind have been detected. It is located 120 light-years away in the constellation Cygnu and orbits another star. Unlike our Neptune, this planet orbits closer to its star, making one lap roughly every five days. It is thought to be a warm world with a rocky core and gaseous atmosphere, though not much else is known about its composition.
"The discovery is a significant milepost on the road to eventually analyzing the atmospheric composition of smaller, rocky planets more like Earth," said John Grunsfeld, assistant administrator of NASA’s Science Mission Directorate in Washington. "Such achievements are only possible today with the combined capabilities of these unique and powerful observatories."
Clouds in the atmospheres of planets can block the view to underlying molecules that reveal information about the planets’ compositions and histories. Finding clear skies on a Neptune-size planet is a good sign that smaller planets might have similarly good visibility.
"When astronomers go observing at night with telescopes, they say ‘clear skies’ to mean good luck," said Jonathan Fraine of the University of Maryland, College Park, lead author of a new study appearing in Nature. "In this case, we found clear skies on a distant planet. That’s lucky for us because it means clouds didn’t block our view of water molecules."
Part of the challenge in analyzing the atmospheres of planets like this is their size. Larger, Jupiter-like planets are easier to see because of their impressive girth and relatively puffy atmospheres. In fact, researchers have already been able to detect water vapor in those planets. Smaller planets are more difficult to probe, and what’s more, the ones observed to date all appeared to be cloudy.
"We are working our way down the line, from hot Jupiters to exo-Neptunes," said Drake Deming, a co-author of the study also from University of Maryland, College Park. "We want to expand our knowledge to a diverse range of exoplanets."
The astronomers plan to examine more exo-Neptunes in the future, and hope to apply the same method to smaller super-Earths — the massive, rocky cousins to our home world with up to 10 times the mass. Our solar system doesn’t have a super-Earth, but NASA’s Kepler mission is finding them around other stars in droves. NASA’s James Webb Space Telescope, scheduled to launch in 2018, will search super-Earths for signs of water vapor and other molecules; however, finding signs of oceans and potentially habitable worlds is likely a ways off.
"The work we are doing now is important for future studies of super-Earths and even smaller planets, because we want to be able to pick out in advance the planets with clear atmospheres that will let us detect molecules," said Knutson.
An even more exciting discovery was revealed in the journal Science last week, as scientists explained that one of the chemical building blocks of life, Iso-propyl cyanide, has been detected in a star-forming gas cloud called Sagittarius B2. The cloud was located in an active region of ongoing star formation in the centre of the Milky Wa,y around 27,000 light-years from Earth.
Iso-propyl cyanide has a branched carbon structure that is closer to the complex organic molecules of life than anything previously found in interstellar space; the branched structure indicates that interstellar space could yield more complex branched molecules, such as amino acids, that are necessary for life on Earth, and suggests that the galaxy could be littered with similar chemical compounds.
The molecule emitted radiation that was detected as radio waves by twenty 12m telescopes at the Atacama Large Millimeter Array (Alma) in Chile, with each molecule producing a different "spectral fingerprint" of frequencies.
Dr Arnaud Belloche from the Max Planck Institute for Radio Astronomy and lead author of the research, explained his findings: "The game consists in matching these frequencies… to molecules that have been characterised in the laboratory. Our goal is to search for new complex organic molecules in the interstellar medium."
"Amino acids on Earth are the building blocks of proteins, and proteins are very important for life as we know it," he continued." The question in the background is: is there life somewhere else in the galaxy?"