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  [Discuss] WFIRST infrared space telescope

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Author Topic:   [Discuss] WFIRST infrared space telescope

Posts: 3544
From: Sierra Vista, Arizona
Registered: Nov 1999

posted 06-04-2012 03:40 PM     Click Here to See the Profile for SpaceAholic   Click Here to Email SpaceAholic     Edit/Delete Message   Reply w/Quote
The Washington Post reports that the National Reconnaissance Office (NRO) has decided to give NASA two telescopes as big as, and even more powerful than, the Hubble Space Telescope.
Designed for surveillance, the telescopes from the National Reconnaissance Office were no longer needed for spy missions and can now be used to study the heavens.

They have 2.4-meter (7.9 feet) mirrors, just like the Hubble. They also have an additional feature that the civilian space telescopes lack: A maneuverable secondary mirror that makes it possible to obtain more focused images. These telescopes will have 100 times the field of view of the Hubble, according to David Spergel, a Princeton astrophysicist and co-chair of the National Academies advisory panel on astronomy and astrophysics.

The surprise announcement Monday is a reminder that NASA isn’t the only space enterprise in the government — and isn’t even the best funded. NASA official Michael Moore gave some hint of what a Hubble-class space telescope might do if used for national security:

“With a Hubble here you could see a dime sitting on top of the Washington Monument.”

NASA officials stressed that they do not have a program to launch even one telescope at the moment, and that at the very earliest, under reasonable budgets, it would be 2020 before one of the two gifted telescopes could be in order. Asked whether anyone at NASA was popping champagne, the agency’s head of science, John Grunsfeld, answered, “We never pop champagne here; our budgets are too tight.”

But this is definitely a game-changer for NASA’s space science program...


Posts: 821
From: Honolulu, HI, USA
Registered: Sep 2010

posted 06-05-2012 01:20 AM     Click Here to See the Profile for mode1charlie   Click Here to Email mode1charlie     Edit/Delete Message   Reply w/Quote
Very cool indeed. The NYT also has some good reportage on this story.

Some excerpts:

The telescope’s short length means its camera could have the wide field of view necessary to inspect large areas of the sky for supernovae.

Even bigger advantages come, astronomers say, from the fact that the telescope’s diameter, 94 inches, is twice as big as that contemplated for Wfirst, giving it four times the light-gathering power, from which a whole host of savings cascade.

Instead of requiring an expensive launch to a solar orbit, the telescope can operate in geosynchronous Earth orbit, complete its survey of the sky four times faster, and download data to the Earth faster.

Equipped with a coronagraph, which blocks light from the sun’s disk to look for exoplanets, another of Wfirst’s goals, the former spy telescope could see planets down to the size of Jupiter around other stars.

If it sounds almost too good to be true, it might be, cautioned Adam Riess, one of the three dark energy Nobelists, who noted that a thorough estimate of the new mission’s costs had not been done yet.

But still, he said, “When someone hands you a hand-me-down like that, you have to be excited,” Dr Riess said. “They’re not sitting around at Walmart.”


Posts: 3544
From: Sierra Vista, Arizona
Registered: Nov 1999

posted 06-05-2012 05:48 AM     Click Here to See the Profile for SpaceAholic   Click Here to Email SpaceAholic     Edit/Delete Message   Reply w/Quote
Additional background at Ars Technica.
In the meantime, the agency has to work within some limits imposed by the telescopes' history. It won't be able, for example, to release any pictures until after the lenses are covered by all that additional hardware. USA Today's Dan Vergano was given an image of the telescope that was used at a recent meeting of the National Research Council. The level of redaction indicates that there will be some significant limits on any NASA design teams.

There are a couple of things that really need to be emphasized: NASA did not get a complete system and still has a lot of work to do. It could save them money, but those savings will mostly go toward taking a project in development and making it more likely to fly in an era when NASA is strapped for funds. And despite the similarities in mirror sizes, this is not a replacement for when Hubble inevitably starts to fail, since the hardware is quite different. But that's not a bad thing, given that it will answer questions we can't currently address.

As for the fact that NASA was given two pieces of hardware? Michael Moore of the Astrophysics group said, "We don't anticipate ever being rich enough to use both of them, but it sure is fun to think about, isn't it?"


Posts: 2470
From: Belfast, United Kingdom
Registered: Feb 2002

posted 06-05-2012 09:15 PM     Click Here to See the Profile for Blackarrow     Edit/Delete Message   Reply w/Quote
What rocket would be needed to launch this? Would Delta IV Heavy or Atlas V be up to the job, or would it require the new super-booster?

I'm assuming it was designed as a shuttle military payload.

Jay Chladek

Posts: 2270
From: Bellevue, NE, USA
Registered: Aug 2007

posted 06-06-2012 01:04 AM     Click Here to See the Profile for Jay Chladek   Click Here to Email Jay Chladek     Edit/Delete Message   Reply w/Quote
If these are KH-11s like I believe they are, Titan III and IV boosters were used to fly those (and I believe likely at least one shuttle mission as hints have been dropped on that).

A Delta IV Heavy could likely loft one of these, but if they are talking about sticking one in Geosynch orbit, it is going to take a pretty massive trans stage to get it up that high. The KH-11s to my knowledge were placed in LEO orbits since they were intended to look down at targets on the Earth and pass over large swatches of terrain.

Saying these are "more powerful than" Hubble might be a bit misleading. Sure, they could be as large as Hubble, if not larger. But the mirrors were ground to a different spec as this thing was looking for different targets. Plus, Hubble is designed to focus on some very distant targets and take some rather long exposures compared to a recon satellite designed to shoot on the fly over a fast moving target on the ground (due to the speed of the orbit). It is going to take a bit of work to convert these for sky watching in the same class as Hubble.

Jim Behling

Posts: 923
From: Cape Canaveral, FL
Registered: Mar 2010

posted 06-06-2012 08:35 AM     Click Here to See the Profile for Jim Behling   Click Here to Email Jim Behling     Edit/Delete Message   Reply w/Quote
Originally posted by Jay Chladek:
A Delta IV Heavy could likely loft one of these, but if they are talking about sticking one in Geosynch orbit, it is going to take a pretty massive trans stage to get it up that high.
Not really, prop requirements are much different in GSO than LEO. Reconsats carried thousands of pounds of propellant for orbital adjustments and drag makeup.

Delta IV Heavy can put more than 15klb into GSO directly. HST weighed around 24klb but had more instruments and was man and EVA rated. These are only mirrors and a spacecraft can be built around them within Delta and Atlas capabilities.

Plus, Hubble is designed to focus on some very distant targets and take some rather long exposures compared to a recon satellite designed to shoot on the fly over a fast moving target on the ground...
Those are spacecraft/instruments characteristics and not applicable to mirrors/telescopes.

Robert Pearlman

Posts: 34053
From: Houston, TX
Registered: Nov 1999

posted 03-18-2014 11:19 AM     Click Here to See the Profile for Robert Pearlman   Click Here to Email Robert Pearlman     Edit/Delete Message   Reply w/Quote
National Academy of Sciences release
Redesign of Planned Space Telescope Would Add Scientific Capabilities, Costs to Original Mission

The opportunity to increase the aperture and resolution on NASA's planned Wide-Field Infrared Survey Telescope (WFIRST) would significantly expand the scientific capabilities of the mission, but the risk of cost growth is significantly higher than for NASA's original design, says a new report from the National Research Council.

WFIRST was ranked the top-priority large space mission in the National Research Council's 2010 decadal survey of astronomy and astrophysics research. WFIRST would probe the nature of dark energy – the as yet unexplained driver behind the accelerating expansion of the universe; study the architecture of other solar systems; and advance understanding of how galaxies, stars, and black holes evolve. This science program, together with the mission's moderate cost, low technical risk, and mature design were key factors in its top ranking among large space missions.

NASA initially considered a design of WFIRST with a 1.3-meter aperture. In 2012, the National Reconnaissance Office gave NASA hardware for two 2.4-meter telescopes -- the same size as the currently operating Hubble Space Telescope. NASA dubbed these the Astrophysics Focused Telescope Assets (AFTA) and began to study an alternative to the original telescope design. After the NRO telescopes were acquired, NASA also began to consider the addition of a coronagraph, an instrument that would advance goals in the study of exoplanets.

The new Research Council report compares the WFIRST/AFTA design both with and without a coronagraph to the original mission concept, on the basis of their science objectives, technical complexity, and programmatic rationale, including projected cost. The report does not recommend which design NASA should adopt.

The committee that wrote the report found that the larger aperture provided by the 2.4-meter design "will significantly enhance the scientific power of the mission" for cosmology, exoplanet surveys, and general infrared survey science, such that the mission is consistent with the scientific goals described in the decadal survey. This new design also makes inclusion of a coronagraph attractive.

However, the inherited hardware was designed for another purpose, and the degree to which changes to the hardware must be made to accommodate a different launch vehicle and scientific requirements is uncertain at this time. This uncertainty contributes to higher technical risk and a greater likelihood that costs will increase beyond current estimates, the report says. The WFIRST/AFTA without the coronagraph was estimated to cost $2.1 billion, up from an estimate of $1.8 billion for an earlier design which was more similar to the mission recommended in the 2010 survey report.

A coronagraph was not envisioned by the 2010 Research Council report as being a part of WFIRST, but it has the potential to advance objectives aimed at the eventual realization of a future Earth-like planet imaging mission. However, the coronagraph design is immature, and there has been limited study of accommodating the instrument on the mission, the report says. Recognizing the scientific importance and public excitement surrounding exoplanet science, the committee recommended that NASA move aggressively to mature the coronagraph design and develop a credible cost, schedule, performance, and observing program so that the coronograph's impact on the WFIRST mission can be determined.

Subsequently, an independent cost and technical evaluation of WFIRST/AFTA with a coronagraph should be conducted to determine whether the instrument's impact on the mission and the NASA astrophysics program is acceptable or if the coronagraph should be removed from the mission. The report says that if pursuing the WFIRST/AFTA with the coronagraph compromises the overall balance of the NASA astrophysics program, then it is inconsistent with the 2010 survey's guidance.

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