[Music throughout] A coronagraph is a way to see distant
planets hidden by the glare of the star they orbit.
The coronagraph reduces the light coming directly from the star to separate it from
the light reflected by the planet. The Nancy Grace Roman Space
Telescope's coronagraph doesn’t block the star’s light with an opaque disk
as a simple coronagraph might. Instead, it uses
a combination of disks with complex patterns and light-blocking stops
to create destructive interference with the star’s light,
effectively making it disappear, while allowing the light from planets to pass through.
A complicating factor is that the light picks up small
distortions as it reflects off the telescope’s series of mirrors, and
these distortions can reduce the effectiveness of the destructive interference.
Collecting more light increases the image signal, but the planets are still
hidden under blobs of leftover distorted starlight. To
remove these blobs, the coronagraph has special deformable mirrors that
can change shape by using hundreds of tiny pistons. This corrects
distortions in the light beam. As the mirrors deform, the
blobs of light slowly begin to disappear, revealing brighter planets.
Further adjustment brings fainter planets into view.
Advanced software processes this data, further improving the
contrast and clarity of the image. This processing makes
objects more than a billion times fainter than the star visible.
As a result, the Roman Space Telescope will provide the first look at
individual planets in star systems that might be similar to our own.
[Explore: Solar system & beyond]
[NASA]