NASA's next-generation space telescope currently under development, the Wide Field Infrared
Survey Telescope (WFIRST), has been renamed in honor of Nancy Grace Roman, NASA's first
chief astronomer. She paved the way for space observatories focused on the broader universe.
The telescope has had a rough existence thus far, having been denied funding twice by the
Trump administration only to have its budget restored by the US Congress.
Nancy Grace Roman Space Telescope, or simply Roman Space Telescope, is scheduled to launch
in the mid-2020s. It will investigate long-standing astronomical
puzzles, such as the force driving the universe's expansion, dark energy, and seek for distant
planets beyond our solar system. The Roman Space Telescope has a primary mirror
that is 2.4 meters in diameter (7.9 feet), which is the same size as the Hubble Space
Telescope's primary mirror. It will have two instruments: the Wide Field
Instrument and the Coronagraph Instrument. The Wide Field Instrument will have a field
of view 100 times larger than Hubble's infrared instrument, allowing it to capture more of
the sky in less time. L. Hustak (STScI) Being the primary instrument, the Wide Field
Instrument will measure light from a billion galaxies throughout the telescope's lifetime.
It will conduct a microlensing study of the inner parts of the Milky Way with the hopes
of discovering around 2,600 exoplanets. The spacecraft is now in design Phase B, with
a launch to space scheduled for 2025. The Coronagraph Instrument will use high contrast
imaging and spectroscopy to study dozens of individual neighboring exoplanets.
The instrument will be the first high-performance coronagraph system in space capable of directly
imaging mature exoplanet systems (such as our own) in reflected starlight. This will
clear the path for a future NASA mission aiming to image and characterize faint Earth-like
planets. The spacecraft will likely acquire significantly
more data than any previous NASA astrophysics mission.
It will map stars, galaxies, and dark matter to explore the formation and evolution of large
cosmic structures, like clusters and superclusters of galaxies, and investigate dark energy,
which is thought to accelerate the expansion of the universe.
The mirror of the Roman Space Telescope is coated with an extremely thin layer of silver,
which is used because of its ability to reflect infrared light.
It has a thickness of fewer than 400 nanometers, which is 200 times thinner than a human hair.
It is thoroughly polished, as are all advanced telescope mirrors.
The average bump on the mirror's surface is only 1.2 nanometers in height, which NASA
claims is twice as smooth as required for space missions. The tallest bump in the mirror
would be only 1/4 inch tall if it were the size of the Earth.
Since the mirror is twice as smooth as the design called for, it should provide better
science outcomes than expected. In February 2020, the mission passed a major
programmatic and technical milestone, giving it the official go-ahead to commence hardware
development and testing. The Roman Space Telescope also passed its
critical design review in September 2021, indicating that all design and developmental
engineering work has been completed. The team in charge of the telescope is currently
constructing and testing the observatory to guarantee that it will withstand the harsh
conditions during launch and spaceflight. With this review complete, the team will go
on to the exciting phase of assembling and testing the Roman hardware they hope to fly.
When all the flying hardware is complete in 2024, they'll hold the system integration
review, and integrate the Roman observatory. Finally, they'll test the entire telescope
in conditions that simulate launch and the orbit to ensure Roman will work as designed.
The mission is scheduled to launch no later than May 2027.
The Nancy Grace Roman Space Telescope will be an indispensable tool in the future due
to its fine resolution and large images, which have never been seen before on a space-based
telescope. Scientists will use Roman's surveys to help
us better understand the universe and our place within it.