Author Topic: Wide Field Infrared Survey Telescope (WFIRST)  (Read 22278 times)

Offline Star One

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Wide Field Infrared Survey Telescope (WFIRST)
« on: 01/06/2016 04:33 PM »
And so it officially begins as a project.

Quote
NASA’s next flagship astronomy mission after the James Webb Space Telescope will become a formal project in February thanks to increased funding and direction from Congress, even as the agency looks to make cuts elsewhere in its astrophysics program.

Paul Hertz, director of NASA’s astrophysics division, told astronomers attending the 227th Meeting of the American Astronomical Society here Jan. 4 that the Wide Field Infrared Survey Telescope (WFIRST) will enter its “formulation phase,” the beginning of NASA’s project management process, in February after the proposed space telescope passed a mission concept review in December.

That decision also comes after the passage of the fiscal year 2016 omnibus spending bill in December that provided $90 million for WFIRST, far above NASA’s request of $14 million. The report accompanying the bill adopted language approved by Senate appropriators in June directing NASA to move WFIRST into the formulation phase by early 2016.

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The baseline plan for the mission calls for the use of one of the 2.4-meter mirrors provided to NASA by the National Reconnaissance Office in 2012. The spacecraft will operate at the Earth-sun L-2 Lagrange point for a prime mission of at least six years.

http://spacenews.com/nasas-next-major-space-telescope-project-officially-starts-in-february/

By the way is this slated for Falcon Heavy, Delta Heavy or possibly Vulcan?
« Last Edit: 01/06/2016 05:07 PM by Star One »

Offline as58

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Re: Wide Field Infrared Survey Telescope (WFIRST)
« Reply #1 on: 01/06/2016 08:41 PM »
The baseline mission in SDT final report from Feb 2015 (available somewhere on the revamped WFIRST website http://wfirst.gsfc.nasa.gov/) has Delta IV Heavy as the launch vehicle, but that's probably not definite yet. In fact, the baseline mission had a 28.5 degree geosynchronous orbit but if spacenews.com reporting is accurate, this has changed to L2. The SDT report does mention that a more detailed assessment of the orbit trade would be done in 2015 and that Delta IV Heavy enables both geosynchronous and L2 missions with healthy margins.

Offline Star One

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Wide Field Infrared Survey Telescope (WFIRST)
« Reply #2 on: 01/06/2016 09:50 PM »
The baseline mission in SDT final report from Feb 2015 (available somewhere on the revamped WFIRST website http://wfirst.gsfc.nasa.gov/) has Delta IV Heavy as the launch vehicle, but that's probably not definite yet. In fact, the baseline mission had a 28.5 degree geosynchronous orbit but if spacenews.com reporting is accurate, this has changed to L2. The SDT report does mention that a more detailed assessment of the orbit trade would be done in 2015 and that Delta IV Heavy enables both geosynchronous and L2 missions with healthy margins.

Would the Delta IV Heavy still be in active production by launch time?
« Last Edit: 01/06/2016 09:50 PM by Star One »

Offline arachnitect

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Re: Wide Field Infrared Survey Telescope (WFIRST)
« Reply #3 on: 01/07/2016 01:43 AM »
The baseline mission in SDT final report from Feb 2015 (available somewhere on the revamped WFIRST website http://wfirst.gsfc.nasa.gov/) has Delta IV Heavy as the launch vehicle, but that's probably not definite yet. In fact, the baseline mission had a 28.5 degree geosynchronous orbit but if spacenews.com reporting is accurate, this has changed to L2. The SDT report does mention that a more detailed assessment of the orbit trade would be done in 2015 and that Delta IV Heavy enables both geosynchronous and L2 missions with healthy margins.

Would the Delta IV Heavy still be in active production by launch time?

ULA say they will support DIV-H until Vulcan-ACES is operational (around 2024).

Offline bolun

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Re: Wide Field Infrared Survey Telescope (WFIRST)
« Reply #4 on: 02/10/2016 11:29 AM »
ANNOUNCEMENT OF OPPORTUNITY FOR EUROPEAN SCIENTISTS TO JOIN THE NASA WFIRST FORMULATION SCIENCE WORKING GROUP

9 February 2016

The purpose of this Announcement of Opportunity (AO) is to solicit the participation of scientists affiliated with institutes located in the ESA Member States in the NASA WFIRST Formulation Science Working Group (FSWG).

http://www.cosmos.esa.int/web/wfirst

Offline catdlr

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Re: Wide Field Infrared Survey Telescope (WFIRST)
« Reply #5 on: 02/18/2016 09:50 PM »
WFIRST Spacecraft Animation

Published on Feb 18, 2016
WFIRST, shown here in an artist's rendering, will carry a Wide Field Instrument to provide astronomers with Hubble-quality images covering large swaths of the sky, enabling several studies of cosmic evolution. Its Coronagraph Instrument will directly image exoplanets similar to those in our own solar system and make detailed measurements of the chemical makeup of their atmospheres.

Credit: NASA's Goddard Space Flight Center/Conceptual Image Lab

Tony De La Rosa

Offline catdlr

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Re: Wide Field Infrared Survey Telescope (WFIRST)
« Reply #6 on: 02/18/2016 09:50 PM »
WFIRST: The Best of Both Worlds

Published on Feb 18, 2016
NASA officially is beginning work on an astrophysics mission designed to help unlock the secrets of the universe -- the Wide Field Infrared Survey Telescope (WFIRST).

Tony De La Rosa

Online matthewkantar

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Re: Wide Field Infrared Survey Telescope (WFIRST)
« Reply #7 on: 02/18/2016 10:58 PM »
Interesting to hear the mirrors from the NRO are deformable, I have been wondering about that for some time.

Matthew


Offline b0objunior

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Re: Wide Field Infrared Survey Telescope (WFIRST)
« Reply #8 on: 02/19/2016 01:54 AM »
Interesting to hear the mirrors from the NRO are deformable, I have been wondering about that for some time.

Matthew

That's because adaptive optics were researched, in it's beginning, for the army.

Offline Blackstar

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Re: Wide Field Infrared Survey Telescope (WFIRST)
« Reply #9 on: 02/19/2016 03:24 PM »
Have they made a final decision that they will use the NRO mirror for WFIRST? I heard a lot of grumbling that it's not really good for that mission (not qualified for very cold temperatures, for instance) and that may drive up the cost substantially.

Offline whitelancer64

Re: Wide Field Infrared Survey Telescope (WFIRST)
« Reply #10 on: 02/19/2016 03:41 PM »
Speaking of the cold, it doesn't look like there's a sun-shade on it. Active cooling? Or just some good insulation on it, like the Hubble.
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Online vjkane

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Re: Wide Field Infrared Survey Telescope (WFIRST)
« Reply #11 on: 02/19/2016 05:27 PM »
Have they made a final decision that they will use the NRO mirror for WFIRST? I heard a lot of grumbling that it's not really good for that mission (not qualified for very cold temperatures, for instance) and that may drive up the cost substantially.
Everything I've heard is that they plan to use the NRO mirror + structure.  The wide field and larger aperature substantially improves the measurements vs the Decadal concept.  The larger spacecraft probably does drive costs, but the science return is much large.  I think the coronograph is also driving cost.

Offline as58

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Re: Wide Field Infrared Survey Telescope (WFIRST)
« Reply #12 on: 02/19/2016 06:18 PM »
The plan is to use the NRO parts. WFIRST entered formulation (Phase B?) officially on Wednesday so I'm not sure if the decision is absolutely final, but it's hard to see them reversing it. Sensitivity at longer wavelengths is lost because the telescope is warmer than in non-NRO plans, but the larger mirror allows higher resolution and sensitivity at shorter wavelengths. FOV isn't really that different from the non-NRO design, I think it may actually be even a bit smaller.

Telescope will operate at a similar temperature as HST (because the mirror isn't designed for cold temperatures), so there's no need for anything like JWST-type sun-shade.
« Last Edit: 02/19/2016 06:22 PM by as58 »

Offline as58

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Re: Wide Field Infrared Survey Telescope (WFIRST)
« Reply #13 on: 02/19/2016 06:20 PM »
Interesting to hear the mirrors from the NRO are deformable, I have been wondering about that for some time.

Matthew

AFAIK the only deformable mirrors are in the coronagraph, not in NRO supplied parts of the telescope.

Offline Blackstar

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Re: Wide Field Infrared Survey Telescope (WFIRST)
« Reply #14 on: 02/19/2016 11:24 PM »
Talked to somebody knowledgeable.

Yeah, they are using the NRO optics (they were not given all the optics). They have to build a lot of stuff to get it up to spec, because it was not designed to astronomy spec.

Using the optics loses some of the farther IR stuff because the optics cannot get too cold. However, compared to the earlier WFIRST concept, this one can do much more exoplanets stuff. So they lose things but gain things and whether this is good or bad depends upon which bit of science you want to do. Some people are very unhappy, the exoplanets people are happy.

The tough issue is cost. This is going to cost a lot more than originally planned. I think that the original plan was to do it at around $1.8 billion in FY15 dollars. The actual price is going to be significantly more than that (although probably not twice as much). Those numbers may already be public, but if not, they soon will be. What I don't know is if the NRO optics actually saved any money. Maybe if they had started from scratch they could have kept the cost lower. We'll have to wait a decade or more for somebody to write a paper about that.

Offline chirata

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Re: Wide Field Infrared Survey Telescope (WFIRST)
« Reply #15 on: 02/20/2016 03:49 AM »
Hi all,

WFIRST has indeed entered formulation (i.e. now in Phase A). To answer some questions:

1. The baseline has changed from geosynchronous orbit to Sun-Earth L2. In the pre-phase A study we concluded both were possible; the geosynchronous orbit had a substantial advantage in terms of data downlink, but L2 is lower risk for the payload in many areas including radiation (one avoids the trapped electron belt), stray light from the Earth and Moon, and thermal stability. The payload is the hardest part of this mission and it’s prudent to take the lower-risk option.

2. The existing telescope does not have a deformable mirror -- the deformable mirrors will indeed be inside the coronagraph.

3. The telescope is warm (we’re looking at around 284 K), but remember that the infrared science program that was selected for WFIRST by the Decadal Survey goes out to a wavelength of 2 microns. Thermal emission is determined by the Wien part of a blackbody curve, multiplied by the net emissivity of the mirrors, and with margin tacked on; that depends very strongly on both wavelength and temperature, but basically it is less than the sky background from the zodiacal light at wavelengths up to ~1.76 microns (exact number depends on where you look) and rises rapidly thereafter. In the reddest wavelength filter used for imaging on WFIRST (still being discussed, but roughly 1.7-2.0 microns) it works out that the sensitivity of the warm 2.4 m telescope is about the same as a cold 1.5 m telescope (what was recommended in the Decadal Survey). If you went farther into the infrared, the colder, smaller telescope would be better, but for most of the planned science program the 2.4 m is a big win.

[3B. The coronagraph uses silicon detectors sensitive to ~1 micron and so the thermal emission isn’t an issue there. The wide-field near infrared camera is affected by the telescope emission, and the optical design actually re-images the primary mirror and has a mask to block the thermal emission from the baffles and secondary support struts, which are much more emissive than the silver coating on the telescope mirrors. This is a common procedure in astronomical IR instrumentation. Note that the 3-mirror optical design gives you a natural place in the instrument to do this.]

4. The telescope points into empty space and needs heaters to maintain it at the operating temperature. The detectors, on the other hand, really do need to be cold (in the range of 90-100 K) to suppress dark current. They will be actively cooled with a closed-loop (no consumables) mechanical cryocooler.

5. The launch vehicle has not been selected yet. WFIRST could fly on the Delta IV Heavy, and of US vehicles flying today that would be the only option that provides sufficient margin, but there may be other vehicles in this class by the time the launch services contract goes out.

6. Some modifications to the telescope are needed (discussed in the SDT report referenced earlier in this thread). To make a corrected wide-field reflecting telescope you need at least 3 powered mirrors, we are given 2 (these will have some modifications) and the 3rd is new (located in the wide-field instrument).

7. The mission is being given a cost cap but I don’t know if that number has been made public yet.

Offline dror

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Re: Wide Field Infrared Survey Telescope (WFIRST)
« Reply #16 on: 02/20/2016 08:17 PM »
I know it's early, but is there a target date (year) for launch?
"If we crave some cosmic purpose, then let us find ourselves a worthy goal. "
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Offline AnalogMan

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Re: Wide Field Infrared Survey Telescope (WFIRST)
« Reply #17 on: 02/20/2016 10:38 PM »
I know it's early, but is there a target date (year) for launch?

NASA Introduces New, Wider Set of Eyes on the Universe
Press Release 16-016 - Feb. 18, 2016

"WFIRST is slated to launch in the mid-2020s."

http://www.nasa.gov/press-release/nasa-introduces-new-wider-set-of-eyes-on-the-universe

Offline Star One

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Re: Wide Field Infrared Survey Telescope (WFIRST)
« Reply #18 on: 02/20/2016 11:10 PM »
I've seen the figure banded around of $2.5 billion for this mission, but I've no idea where that originates from.

Offline Blackstar

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Re: Wide Field Infrared Survey Telescope (WFIRST)
« Reply #19 on: 02/21/2016 10:24 AM »
I know it's early, but is there a target date (year) for launch?

2024 or 2025.

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