Author Topic: Wide Field Infrared Survey Telescope (WFIRST)  (Read 15308 times)

Offline jgoldader

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Re: Wide Field Infrared Survey Telescope (WFIRST)
« Reply #60 on: 01/10/2017 03:05 PM »
There's much in common between this discussion, and the decadal survey discussion, and the "what to replace SLS with if it's cancelled" discussion.

There's the old saying that you never want to see sausage being made, or political decisions being made.  These funding decisions are irreducibly political, since they have to be made by politicians.  So low-balling prices gets you in the door, sunk cost keeps you going, and then you end up on the plate with eggs and potatoes.  It's ugly, from a strictly "pure" perspective, but not much that happens in political situations (or between even well-meaning people) is pure.  There are almost always compromises and bending of rules.
Recovering astronomer

Offline Blackstar

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Re: Wide Field Infrared Survey Telescope (WFIRST)
« Reply #61 on: 01/10/2017 03:22 PM »
This is a fundamental problem with our funding approach - if you price something at what it's going to cost, it'll never get funded.  If you price it to get funded, you're going to get criticized - or cut - when it ends up costing what it actually costs.

Except your phrasing assumes that it is easy to know what something is going to cost. It's not. These are estimates based upon a lot of unknowns, with a lot of assumptions and large error bars.

Disavow yourself of the belief that everybody is lying and deceitful and just trying to get something approved so that they can blow the budget later. I realize that's the stereotype, but the real world is not so clear-cut. This is a complicated and iterative process, meaning that they estimate, they proceed, then they estimate again. There are ways to improve the accuracy of that process, but it's not possible to create an entirely accurate estimate of costs for many of these things. (Oh, and it is the same way in business too, they just don't air their dirty laundry.)

Also, cost is an important factor, but it is not the only factor, nor is it necessarily the most important factor. That's true in everyday life too. If it wasn't, then everybody would drive only inexpensive cars.


Offline Blackstar

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Re: Wide Field Infrared Survey Telescope (WFIRST)
« Reply #62 on: 01/10/2017 03:25 PM »
There's much in common between this discussion, and the decadal survey discussion, and the "what to replace SLS with if it's cancelled" discussion.

There's the old saying that you never want to see sausage being made, or political decisions being made.  These funding decisions are irreducibly political, since they have to be made by politicians.  So low-balling prices gets you in the door, sunk cost keeps you going, and then you end up on the plate with eggs and potatoes.  It's ugly, from a strictly "pure" perspective, but not much that happens in political situations (or between even well-meaning people) is pure.  There are almost always compromises and bending of rules.

I skipped that thread because I figure that it's a lot of the typical flailing of arms and opinions masquerading as facts (I bet "Falcon Heavy and Red Dragon will get us to Mars!" is a common theme).

But I'd point out that the sciences have operated by a different set of rules than the human spaceflight program. The decadal survey process makes science mission selection much less political. Much less. There are not as many people trying to mess around with it and remake everything. That's why the decadal survey process is envied by a lot of people who look at the human spaceflight program and wish that it would be more orderly and stable and less higgledy-piggledy.

Offline Kansan52

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Re: Wide Field Infrared Survey Telescope (WFIRST)
« Reply #63 on: 01/10/2017 04:14 PM »
"Never ascribe to malice..." comes to mind during this discussion.


Offline Blackstar

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Re: Wide Field Infrared Survey Telescope (WFIRST)
« Reply #64 on: 01/10/2017 04:21 PM »
"Never ascribe to malice..." comes to mind during this discussion.



And since I'm playing contrarian here, I'll counter that one too. There are good and smart people working on these programs trying to do a good job. They're not screwups and liars. Running a really complex and cutting edge program is not easy. It's not possible to get everything right the first time.

Offline Kansan52

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Re: Wide Field Infrared Survey Telescope (WFIRST)
« Reply #65 on: 01/10/2017 04:39 PM »
Sorry, I was trying to say just that with the ellipse. Should have said more.

Offline JH

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Re: Wide Field Infrared Survey Telescope (WFIRST)
« Reply #66 on: 01/10/2017 06:05 PM »
I skipped that thread because I figure that it's a lot of the typical flailing of arms and opinions masquerading as facts (I bet "Falcon Heavy and Red Dragon will get us to Mars!" is a common theme).

There have actually been a variety of proposals, but the consensus seems to be that the SLS was arbitrarily sized, given the elements used in DRM 5.0. From this they conclude that it's role could be filled by any or all of the upcoming generation of commercial heavy launchers and that the money should therefore be spent on payloads and research into on-orbit refueling and autonomous assembly. I don't recall seeing Red Dragon mentioned. My suspicions about the thread were similar to yours before I looked at it.

Anyway, back to WFIRST!

Offline jbenton

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Re: Wide Field Infrared Survey Telescope (WFIRST)
« Reply #67 on: 01/17/2017 08:45 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.


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.

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).


NASA funded the develpment sensor for NEOCam (which apparently is called "the NEOCam sensor") as part of the Discovery #12 selection. The sensor is supposed to perform infrared observations with a warmer mirror:

https://www.nasa.gov/mission_pages/asteroids/multimedia/pia16955.html
http://neocam.ipac.caltech.edu/news/tracking-sensor-passes-test
http://www.spacesafetymagazine.com/space-hazards/asteroid-hitting-earth/nasas-asteroid-tracking-sensor-green-test/
 
Could some kind of enlarged version help WFIRST-AFTA with Far Infrared observations?

Offline as58

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Re: Wide Field Infrared Survey Telescope (WFIRST)
« Reply #68 on: 01/17/2017 09:20 PM »
NASA funded the develpment sensor for NEOCam (which apparently is called "the NEOCam sensor") as part of the Discovery #12 selection. The sensor is supposed to perform infrared observations with a warmer mirror:

https://www.nasa.gov/mission_pages/asteroids/multimedia/pia16955.html
http://neocam.ipac.caltech.edu/news/tracking-sensor-passes-test
http://www.spacesafetymagazine.com/space-hazards/asteroid-hitting-earth/nasas-asteroid-tracking-sensor-green-test/
 
Could some kind of enlarged version help WFIRST-AFTA with Far Infrared observations?

AFAIK the main novelty of the NEOCam sensor is that the sensor itself doesn't need to be as cold as with current techniques, so less cooling (or even completely passive cooling) would be enough. With WFIRST the problem is that the whole telescope is so warm that its own emission drowns the signal from astrophysical objects.

Offline Blackstar

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Re: Wide Field Infrared Survey Telescope (WFIRST)
« Reply #69 on: 01/18/2017 12:13 AM »
AFAIK the main novelty of the NEOCam sensor is that the sensor itself doesn't need to be as cold as with current techniques, so less cooling (or even completely passive cooling) would be enough. With WFIRST the problem is that the whole telescope is so warm that its own emission drowns the signal from astrophysical objects.

Aren't they also looking at different wavelengths?

Offline as58

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Re: Wide Field Infrared Survey Telescope (WFIRST)
« Reply #70 on: 01/18/2017 08:14 AM »
AFAIK the main novelty of the NEOCam sensor is that the sensor itself doesn't need to be as cold as with current techniques, so less cooling (or even completely passive cooling) would be enough. With WFIRST the problem is that the whole telescope is so warm that its own emission drowns the signal from astrophysical objects.

Aren't they also looking at different wavelengths?

Yes, NEOCam sensor is for 6 to 10 um while WFIRST red cutoff is around 2 um. To observe at NEOCam wavelengths (or anything much beyond 2 um), the whole telescope optics need to be cool/cold.

Offline Vultur

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Re: Wide Field Infrared Survey Telescope (WFIRST)
« Reply #71 on: 01/19/2017 05:50 AM »
If everybody in Congress took into account "the sunk cost fallacy" and simply canceled stuff when it got expensive, then nothing would ever get built.

Why? I thought the whole point of the "sunk cost" was simply that money already spent is irrelevant to a rational decision.

If Mission X was budgeted for $100 million, and you've already spent (some amount) and it now looks like it's going to cost $500 million (more) to finish, then you decide based on whether that mission is worth spending $500 million for.

"Sunk cost" doesn't necessarily mean ignoring political considerations or public support - it just means that "we've already spent $X so we shouldn't give up now" is irrational.

I agree that it's inherently impossible to perfectly estimate costs for something that hasn't been done before, before the fact. That doesn't mean pulling the plug isn't reasonable when the still remaining unspent cost becomes multiple times greater than the estimate the project was originally approved assuming.

Offline russianhalo117

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Re: Wide Field Infrared Survey Telescope (WFIRST)
« Reply #72 on: 01/19/2017 03:31 PM »
Work Begins in Palo Alto on NASA's Dark Energy Hunter

PALO ALTO, Calif., Jan. 19, 2017 /PRNewswire/ -- Lockheed Martin (NYSE: LMT) is helping NASA begin the hunt for dark energy, a mysterious force powering the universe's accelerating expansion. An instrument assembly the company is developing, if selected by NASA for production, will be the core of the primary scientific instrument aboard the Wide Field Infrared Survey Telescope (WFIRST), whose mission aims to uncover hundreds of millions more galaxies and reveal the physics that shapes them.

Scientists and engineers recently began work developing the Wide-Field Optical-Mechanical Assembly (WOMA) for WFIRST, NASA's newest astrophysics telescope program. WOMA comprises the major portion of scientific components on one of two instruments on the telescope. NASA chose Lockheed Martin's Advanced Technology Center (ATC) in Palo Alto to advance from an earlier study into the formulation phase. WOMA uses similar approaches to the Near Infrared Camera (NIRCam), which the ATC built as the primary optical instrument for NASA's James Webb Space Telescope.

"Lockheed Martin scientists achieved groundbreaking results with NIRCam's precision and sensitivity," said Jeff Vanden Beukel, WOMA program manager at Lockheed Martin.  "There's no time to lose as we support a fast-paced schedule, and our experience with NIRCam's precision optics positions our WOMA design to be capable, producible and on budget."

Scientists and engineers are collaborating to design optical systems, mechanisms, structure, electronics and thermal control components. Similar to NIRCam, the Wide-Field Instrument on WFIRST will be a powerful optical payload. However, WFIRST will have a massive focal plane array, 200 times larger than NIRCam, to capture what some liken to panoramic images of the star field.

In addition to dark energy research, WOMA will also use microlensing to complete the census of known exoplanets. Microlensing takes advantage of brief distortions in space to reveal new planets around distant stars, and WFIRST's wide field of view will allow scientists to monitor 200 million stars every 15 minutes for more than a year. When NASA launches WFIRST, it will work in concert with other observatories to jointly research new places and forces in our universe.

NASA plans to select a winning design next year for production, and WFIRST is expected to launch in the mid-2020s.

About Lockheed Martin
Headquartered in Bethesda, Maryland, Lockheed Martin is a global security and aerospace company that employs approximately 98,000 people worldwide and is principally engaged in the research, design, development, manufacture, integration and sustainment of advanced technology systems, products and services.
 
SOURCE Lockheed Martin

Caption: Lockheed Martin's optical expertise could deliver breathtaking panoramas of the star field

Offline as58

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Re: Wide Field Infrared Survey Telescope (WFIRST)
« Reply #73 on: 02/07/2017 05:51 PM »
Sad news related to the mission: Neil Gehrels, WFIRST project scientist and the PI of Swift mission died yesterday.
« Last Edit: 02/07/2017 07:14 PM by as58 »

Offline russianhalo117

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Re: Wide Field Infrared Survey Telescope (WFIRST)
« Reply #74 on: 02/07/2017 06:29 PM »
Sad news related to the mission: Neil Gehrels, WIRST project scientist and the PI of Swift mission died yesterday.
They might name WFIRST after him

Offline Blackstar

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Re: Wide Field Infrared Survey Telescope (WFIRST)
« Reply #75 on: 02/07/2017 07:03 PM »
Sad news related to the mission: Neil Gehrels, WIRST project scientist and the PI of Swift mission died yesterday.
 

Neil was a really nice guy. He worked on my recent study on NASA mission extensions. Always pleasant and soft-spoken.

Offline Star One

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Re: Wide Field Infrared Survey Telescope (WFIRST)
« Reply #76 on: 04/20/2017 09:12 PM »
Article includes a picture of the primary mirror assembly, first time I think we've seen that.

With an eye on growing cost, NASA aims for 2025 launch of next ‘great observatory’

Quote
NASA is currently looking at ULA’s Delta 4-Heavy or SpaceX’s Falcon Heavy rocket to send WFIRST into space, according to Dominic Bedford, the mission’s program scientist at NASA Headquarters.

Quote
NASA officials want to keep WFIRST’s total cost around $3.2 billion — in current-year economic conditions — and Bedford said the space agency could “descope” the mission by removing the coronagraph instrument if it looks like it will bust the budget cap.

“The coronagraph is not required for mission success, so we can back off the coronagraph if necessary,” Bedford said in the April 13 meeting of the NASA science advisory committee.

Multiple internal and external cost assessments will be completed in the coming months to inform NASA decision-makers on whether WFIRST should remain intact.

An cost assessment by the Aerospace Corp. in 2015 put WFIRST’s project cost between $2 billion and $2.3 billion. A report issued by the National Academy of Sciences last year said the cost of WFIRST had increased by $550 million since the Aerospace Corp. study, and the review panel recommended NASA slash the observatory’s capabilities, such as removing the coronagraph, if costs continued to grow.

Quote
“Budget is a big concern,” Bedford said. “The concern I’m mostly recognizing now is the overall mission cost of $3.2 billion. We have to make sure that we make the right choices to keep the science capability while keeping under that cost.

“The problem with mission design is you tend to have a function of science vs. cost that is steep,” Bedford said. “You lose more science than you lose cost.”

https://spaceflightnow.com/2017/04/19/with-an-eye-on-growing-cost-nasa-aims-for-2025-launch-of-next-great-observatory/

Offline as58

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Re: Wide Field Infrared Survey Telescope (WFIRST)
« Reply #77 on: 04/21/2017 10:40 AM »
More photos of the mirror are available at https://wfirst.gsfc.nasa.gov/gallery-photos.html.

I wonder how the price tag has gone from $2.6B- $2.8B given in last year's decadal mid-term to $3.2B. It's not quite clear if both estimates include the same things, though. Slides from last week's NAC Science Committee meeting don't seem to be available yet.

Offline Star One

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Re: Wide Field Infrared Survey Telescope (WFIRST)
« Reply #78 on: 04/21/2017 11:22 AM »
More photos of the mirror are available at https://wfirst.gsfc.nasa.gov/gallery-photos.html.

I wonder how the price tag has gone from $2.6B- $2.8B given in last year's decadal mid-term to $3.2B. It's not quite clear if both estimates include the same things, though. Slides from last week's NAC Science Committee meeting don't seem to be available yet.

Isn't it the addition of the Coronagraph pushing the price tag up?

Offline as58

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Re: Wide Field Infrared Survey Telescope (WFIRST)
« Reply #79 on: 04/21/2017 12:24 PM »
More photos of the mirror are available at https://wfirst.gsfc.nasa.gov/gallery-photos.html.

I wonder how the price tag has gone from $2.6B- $2.8B given in last year's decadal mid-term to $3.2B. It's not quite clear if both estimates include the same things, though. Slides from last week's NAC Science Committee meeting don't seem to be available yet.

Isn't it the addition of the Coronagraph pushing the price tag up?

Yes, but I believe that was already included in the previous cost estimate.

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