In addition to microlensing to detect exoplanets, a coronagraph
will block out a large fraction of the light of target stars. With much of the glare of parent stars suppressed, the telescope will be able to directly image any planets orbiting that star. The goal is to produce as narrow an image of the space around the star as possible. This is referred to as the Inner Working Angle (IWA). The more that the IWA can be shrunk, the more inner planets can be imaged. It is possible that the enhanced WFIRST may be able to view planets as close as 1 astronomical unit (AU) to their parent star, depending on their distance from our solar system.
With the loss of another reaction wheel, he Kepler space telescope has lost the ability to maintain the stable orientation needed for observing stars to detect transits of exoplanets: Kepler Mission Manager Update – NASA.
The managers of the project, however, insist that the mission is not finished and they will still be able to do some interesting science with the spacecraft. There is also a lot of data left to analyze.
Nevertheless, for small planets with orbit periods like the earth or Mars, the longer the observation time the better. A earth sized planet only decreases the star’s light by about 0.01% when it transits across the face of the planet. So the more transits, the better. At least three transits are needed for confirmation of an exoplanet. Kepler began observations in 2009 so there would have been 3-4 transits at an earth size orbit but only 1-2 for a Mars orbit.
There was a NASA briefing this afternoon on the situation and some notes were posted at
Earlier this year participants in the Planet Hunters citizen science project
confirmed with 99.9 percent confidence the discovery of a Jupiter-sized planet called PH2b orbiting within the “habitable zone” of its star, the range where earth-like planets could have liquid water and possibly sustain life. The researchers also announced 42 new planet candidates, including 20 located in the habitable zone of their respective stars.
Participants in the project examine data from the Kepler space observatory, which monitors the light from over 100,000 stars simultaneously to look for dimming when a planet passes in front of the star as seen from earth.
Planets transiting across the face of a star will dim its light output.
While the Kepler group have software to find such dimming from the planet transits across the face of stars, there are significant advantages of humans examining the light data directly
Citizen scientists working on Planet Hunters, on the other hand, can consider transits on a case-by-case basis, and can visually detect planets which produce fewer dips in the light-curve; these are the planets with a wider orbit and a longer orbital period that Kepler algorithms often overlook. Nine of the recent planet candidates have orbital periods over 400 days, and most have periods longer than 100 days.
“I didn’t expect that volunteers would be able to find a significant number of planets that the Kepler computers couldn’t. Everything found by volunteers causes Kepler to improve their algorithms,” Professor Fischer added.
Examples of a Kepler data for a planetary transit: