I've mentioned a couple of times that NASA's next big telescope, the Nancy
Grace Roman Space Telescope is launching Sunday morning on a Falcon Heavy at 7:26AM EDT, but I suppose I was quietly assuming that everyone has an idea about what
that telescope is.
I've been covering the NGRST since I first heard of it in February of 2022, and
I thought maybe the good thing to do would be repost important parts of what
I've covered. Rather than just post links to older posts, I'll "cut and paste"
the important stuff.
From NASA's Next Big Space Telescope
I stumbled across a story today of an instrument that I should have known
about but that had undergone a name change. It was first referred to as
the WFIRST, Wide Field Infra Red Space Telescope, a long but descriptive name
for its mission. It was recently renamed the
Nancy Grace Roman Space Telescope
by NASA; the name pays tribute to the late NASA executive and first Chief
Astronomer who was one of the driving forces in getting the Hubble Space
Telescope program through its hurdles.
The telescope was named in a poll of astronomers as the next most important
space telescope behind the James Webb Space Telescope. Why? The
old name said wide field and that's the telescope's feature.
That graphic gives the impression that the NGRST can capture 2,000 square
degrees of sky in one shot, compared to 1.6 square degrees from the Hubble Space
Telescope. That's not quite right. The NGRST's field of 2,000
degrees divided by the 1.6 of the HST says NGRST is 1,250 times bigger.
The NGRST website's FAQ says it's field of view is 100 times larger:
It has a primary mirror that is 2.4 meters in diameter (7.9 feet), and is
the same size as the Hubble Space Telescope's primary mirror. The mirror has
the same sensitivity as Hubble’s primary mirror but will only be one fifth
the weight, showcasing an advancement in telescope technology. It will have
the sensitivity and resolution comparable to Hubble, but with a field of
view 100 times larger, combining excellent image quality with survey power.
Like the JWST, the NGRST will be sent to orbit around the L2 Lagrange point,
about 930,000 miles away from earth in the direction radially away from
Earth. The mission is focused on the search for dark matter, dark energy
and exoplanets, and will only carry two instruments:
The Roman Space Telescope will have two instruments, the Wide Field
Instrument (WFI) and the
Coronagraph
Instrument (CGI) technology demonstration. The WFI provides wide field
imaging and spectroscopy, with performance characteristics optimized for
cosmology and exoplanet surveys. The CGI provides high contrast imaging and
spectroscopy for observations of exoplanets and debris disks. The WFI is a
288-megapixel multi-band near-infrared camera, providing a sharpness of
images comparable to that achieved by the Hubble Space Telescope over a 0.28
square degree field of view, 100 times larger than that of Hubble. The
Coronagraphic Instrument is a high-contrast, small field of view camera and
spectrometer covering visible and near-infrared wavelengths using novel
starlight-suppression technology.
Rendering of NGRST, from NASA
Let me bounce back to the present to throw in that the one thing that stood
out to me in that first article was that it said, "target date for launch is
currently set for May of '27 and they claim to be on schedule" and, of course,
August of '26 is pretty far ahead of "on schedule" when they said it would be
ready to fly by May of '27. Fortuitously, they had to schedule the launch on
the Falcon Heavy because when they were getting bids, nothing else was
available. I've always thought that if you called Gwynne Shotwell, SpaceX CEO,
to arrange a launch like this, you'd give her all the details and she'd come
back with something like "gee, it's too big for a Falcon 9... how about next
month?" or something that knocked your socks off like that.
Moving up to a recent post from this April,
The Nancy Grace Roman Space Telescope is complete
Here's where it gets wild. The September launch for the NGRST is
eight months ahead of schedule, and under budget. When's the last time
you heard something like that? I'm not sure I ever have.
According to NASA, Roman's primary mirror measures about 7.9 feet (2.4
meters) wide, which is similar to Hubble's. However, Roman has the ability
to take images that capture a patch of the sky at least 100 times larger
than Hubble can.
"Its surveying capabilities are over 1,000 times faster than Hubble, and can
chart 200 times more sky in a single image," NASA administrator Jared
Isaacman said during the conference. "What would take Hubble 2,000 years to
process, Roman can do in a year — the images it captures will be so large
there is not a screen in existence large enough to show them."
To put that
into context, over its approximately 35 years of service so far, Hubble has gathered
about 400 terabytes of data; once fully operational at its workstation in
space, Roman should be able to create 500 terabytes of data
per year.
The collection of different space telescopes; the Hubble, James Webb, and
more, allow ground based astronomers to choose the right instrument for the
objects they want to study in the sky.
Compared to the JWST, Roman's images — taken with its aptly named Wide Field
Instrument (WFI) — will be 50 times wider but more shallow, because Roman
doesn't need to access the deep universe the way the JWST does. As we
discussed, it can't see infrared like the JWST can and therefore would be
wasted in looking too far back.
More specifically, WFI is composed of a 300-megapixel
visible-to-near-infrared imaging camera and slitless spectrometer (a
special tool that allows scientists to capture light dispersion of objects
in a field of view). But there is something uniquely special about that
shallow, panoramic view.
The wide and shallow field will be well suited to surveying space, not getting
too much information from things that it can't look closer at.
They can just survey and hope to find a cool lead to zoom in on. This offers
Roman the ability to catch events that transpire very quickly, such as fast
radio bursts, and increases the chances that scientists can witness
remarkable supernovas, colliding neutron stars and other easy-to-miss
phenomena right as they happen.
Well, as the kids used to say, whoomp there it is. I think that's more science
on the NGRST than you're going to get anywhere else.