The Wide-Field Infrared Survey Telescope (WFIRST) had a tumultuous history so far. Mostly due to funding issues and then the competition with other space crafts that were considered a higher priority, such as the James Webb Space Telescope (JWSP). However, WFIRST will use gravitational microlensing to look for exoplanets.
NASA Administrator Jim Bridenstine was the one that had to make tough decisions such as cutting funds for WFIRST and pass the financial favors to JWSP for the fiscal years 2020 and 2021. Luckily that didn’t happen and WFRIST received money for implementation.
Although JWSP is the favorite, WFIRST has something that JWSP doesn’t. Apart from the Coronagraphic Instrument that will help find cosmic objects hidden in a star’s dazzling radiance, WFRIST will also be using gravitational microlensing.
WFIRST will search for exoplanets by using gravitational microlensing
This astronomic phenomenon will be used by WFRIST to do things that JWSP can’t even begin to dream about. JWSP will be using the common transit method to find exoplanets, it is following the Hubble Space Telescope’s steps with only higher precision.
But gravitational microlensing will give WFIRST the chance to accomplish far more inaccessible things. It will find way smaller and distant exoplanets. Planets that no other method could make visible. It will measure dark energy effects and the curvature of spacetime. It will, once again, test Einstein’s general relativity.
“Microlensing signals from small planets are rare and brief, but they’re stronger than the signals from other methods,” said David Bennett, the gravitational microlensing group’s leader at NASA’s Goddard Space Flight Center.
Gravitational microlensing is a rare phenomenon that describes the overlap of two cosmic bodies. A bright one, such as a star or a quasar, and a less-brighter one that otherwise couldn’t be observed.
When the less-brighter object sufficiently aligned to the background luminous star, the star’s light is bending and that makes the foreground object become a lens-object. “Since it’s a one-in-a-million event, the key to WFIRST finding low-mass planets is to search hundreds of millions of stars,” said David Bennett.