Two technologies that could be invaluable to the search for life
NASA and its partnersare in the process of developing two cutting-edge technologies withthe potential to significantly advance the hunt for extraterrestrial life on distant Earth-like planets. The ambitious designs currentlyunder development could allow astronomers to cut through the intensedisturbance caused by an exoplanet's parent star, allowing them toimage the remote worlds directly, and make detailed observations.
The discovery of newand exotic exoplanets has began to feel almost routine at this point,largely thanks to the efforts of NASA's Kepler Space Telescope, whichhas been responsible for the discovery of over 1,000 alien worlds.
However, thanks tomankind's legitimate obsession with the discovery of anextraterrestrial civilization, the news that astronomers havedetected a world orbiting in a star's habitable zone is still a causefor excitement. This habitable or "goldilocks" zone isessentially a region of space around a star in which an orbitingrocky planet is subjected to temperatures conducive to the presenceof liquid water, and therefore life.
The problem withdetecting and characterizing these worlds is that, in most instances,an exoplanet's star shines many billions of times brighter than thesatellite body, leaving astronomers incapable of directly imaging the planet. Even when the world can be observed, interference from thenearby star makes it difficult for delicateinstruments known as spectrographs to ascertain the properties of theplanet's atmosphere.
These instruments are capable of breaking down light into its componentwavelengths, and exposing the presence of life through the detectionof oxygen, ozone, water, and methane, which could serve as evidencefor forests and living creatures dwelling on the planet's surface.
NASA and its partnersare actively working on two distinct methods of starlightsuppression. The first and arguably more ambitious of the twoventures has been imaginatively designated as the starshade, seen in the following video.
Currently, Engineersand scientists working on the project at NASA's Jet Propulsion Laboratory envision a vast,130 ft (40 m)-wide sunflower-like light-shield boasting a solidcentre lined with petal-like protrusions.
"The shape of thepetals, when seen from far away, creates a softer edge that causesless bending of light waves," states JPL's lead engineer on thestarshade project Dr. Stuart Shaklan. "Less light bending meansthat the starshade shadow is very dark, so the telescope can takeimages of the planets without being overwhelmed by starlight."
In order tosuccessfully utilize the starshade, a number of potent technologicalchallenges must be overcome. Much like the highly-anticipated James Webb Space Telescope, the massive sunshade would be fartoo large to launch in its fully-deployed state.
Instead, the petaledlight-shield would lift off folded into a cylindrical shape, designedto fit snugly within the fairing of its launch vehicle. Theprotective shade could either be inserted into orbit on its own, orin conjunction with a space telescope. The beauty of the concept isthat the starshade could utilize onboard propulsion to reposition itself, allowing it to be compatible with any telescope in orbit atthe time.
In order to be viable,NASA engineers will have to devise a method of keeping thelight-shield precisely fixed in space between the target star and thetelescope making use of the platform.
The second technologyunder development are advanced coronagraphs.The application of this technique would not require the complextandem actions of two spacecraft working in perfect concert. Instead,the light from a distant star would be cancelled out by a mechanismhoused within a next-gen orbital telescope.
A basiccoronagraph places an obstruction known as a "mask"in the path of a beam of light collected by a telescope from adistant star. As the light passes through the telescope, the maskremoves some of the glare from the targeted stellar body, allowingany orbiting planets to make themselves known.
Thelight reflected by the planets is received by the telescope's sensorsat a slight angle, as they are not in the exact same position as thestar. These distortions, as well as others created by miniscule vibrations in the telescope, could theoretically be accounted for with theuse of a deformable mirror, which could alter its shape with the useof hundreds of tiny pistons layering its underside.
Anumber of coronagraphs are being designed for implementation infuture NASA endeavors. One such mission, known as the Wide-FieldInfrared Survey Telescope (WFIRST), will see two separatecoronagraphs, known as the "hybrid Lyot", and the "shapedpupil", installed aboard an orbital telescope in the OcculatingMask Coronagraph instrument.
Should either of theseambitious technologies become a reality, the ability to block out thelight from a parent star, while preserving that of the orbitingexoplanet, would undoubtedly lead to significant breakthroughs in thesearch for life outside of our solar system.