NASA - James Webb Space Telescope - Discussion and Updates

[speedevil]

Just, for the record, does anyone know just all (or most) of the missions that were lost or postponed due to JWST's cost overruns? Is a great deal of it just butterfly effect, or is there a number of specific missions?

I can think of just a few missions that were affected by the one-two punch of JWST overruns and sequestration, but there could've been more:
Am I missing anything?

Would the lack of overlap between GRACE and GRACE-FO count?
Fortunately, it doesn't affect calibration, but only a data gap.

[jbenton]

Just, for the record, does anyone know just all (or most) of the missions that were lost or postponed due to JWST's cost overruns? Is a great deal of it just butterfly effect, or is there a number of specific missions?

I can think of just a few missions that were affected by the one-two punch of JWST overruns and sequestration, but there could've been more:
Am I missing anything?

Would the lack of overlap between GRACE and GRACE-FO count?
Fortunately, it doesn't affect calibration, but only a data gap.

I would count that, if JWST over-runs had anything to do with it. Kinda fits with what I was sayin' about the other Earth Science missions, though. (I wasn't thinking about it- I've been really out of the loop for the pass year: I just assumed they were going to be able to keep the OG GRACE probes alive until FO was launched)

IIRC, GRACE-FO was "Tier-III" so I assume the decision to launch those ASAP, delayed some other, high tier launch even further (unless I'm mistaken about the nature of the tiers: are the tiers for priority or for exspence?)

[Blackstar]

I can think of just a few missions that were affected by the one-two punch of JWST overruns and sequestration, but there could've been more:

 - NASA's contribution for ExoMars
 - NASA's contribution for LISA
 - The large gap between Discovery 11 (GRAIL) and Discovery 12 (InSight) - not including the 26 month delay caused by the vacuum seal breach for InSight.
 - Something like half the Decadal Survey requested Earth Science missions won't fly before the next Survey

Am I missing anything?

You cannot really attribute the "loss" of those missions to JWST. For instance, backing out of ExoMars was done because OMB didn't want to be involved in a long-term Mars commitment. It wasn't because of a lack of money. And the slowdown in the Discovery cadence can mostly be blamed on the cuts to the planetary budget, which went to Earth science instead. And although it's not my area, I think that the lack of Earth science missions is a lot more complex than simply not having the money.

[as58]

The gap between astrophysics flagship launches between Spitzer* and JWST will be almost 20 years, so the clearest effect of delays and cost growth of an astrophysics flagship mission is to astrophysics flagships. I think the direct effect to other programs (even within astrophysics) is smaller than many people think, though the rest of the astrophysics certainly took some kind of a hit from JWST problems.

* Or more than 20 years between Chandra and JWST, since Spitzer wasn't quite a full-sized flagship.

[Jim]

 - The large gap between Discovery 11 (GRAIL) and Discovery 12 (InSight) - not including the 26 month delay caused by the vacuum seal breach for InSight.
- Something like half the Decadal Survey requested Earth Science missions won't fly before the next Survey

That is the Obama gap and not caused by JWST.  Nothing but  Earth Science missions were funded by Obama.

[vjkane]

 - The large gap between Discovery 11 (GRAIL) and Discovery 12 (InSight) - not including the 26 month delay caused by the vacuum seal breach for InSight.
- Something like half the Decadal Survey requested Earth Science missions won't fly before the next Survey

That is the Obama gap and not caused by JWST.  Nothing but  Earth Science missions were funded by Obama.

That assertion is misleading.  The Obama administration shifted resources to Earth science missions, but the planetary, astrophysics, and heliophysics programs remained strong.  You might want to recall that during this period, the Mars 2020 and OSIRIS-REx missions were approved and a large cost overrun for the Curiosity rover had its impact within the planetary program.

I suggest that you might want to compare the budgets of anyone of these science programs during this period with the entire ESA science budget in the same years to get a sense that NASA has had a vigorous science program this past decade.

You may prefer that resources be shifted to other programs than Earth science, but implying that the Obama administration starved the other science programs is misleading.  I'm not a fan of the current administration's science priorities, but acknowledge that except for some silliness around trying to cancel some specific missions, their budgets for Earth science are not that bad. 

[vjkane]

And although it's not my area, I think that the lack of Earth science missions is a lot more complex than simply not having the money.

I don't follow the Earth science program as closely as the planetary (but should given my professional use of the data).  My memory is that the cost estimates for the previous Earth science Decadal Survey were way too low.  Once realistic estimates were factored in, only a fraction could be funded.  I remember being at a professional conference and seeing a presentation with the bad news and learning that a couple of missions that would have really helped my research were effectively cancelled from consideration.

[Blackstar]

And although it's not my area, I think that the lack of Earth science missions is a lot more complex than simply not having the money.

I don't follow the Earth science program as closely as the planetary (but should given my professional use of the data).  My memory is that the cost estimates for the previous Earth science Decadal Survey were way too low.  Once realistic estimates were factored in, only a fraction could be funded.  I remember being at a professional conference and seeing a presentation with the bad news and learning that a couple of missions that would have really helped my research were effectively cancelled from consideration.

I think it was a lot more complicated than that. If I remember correctly, part of the problem is that the missions that were proposed were not the missions that were ultimately approved. There were significant differences. I don't know why that was, but there were disconnects (maybe totally justified) and so it's not accurate to say "Earth Science mission X was estimated to cost $200 million and ultimately grew to become $400 million."

[Jim]

 - The large gap between Discovery 11 (GRAIL) and Discovery 12 (InSight) - not including the 26 month delay caused by the vacuum seal breach for InSight.
- Something like half the Decadal Survey requested Earth Science missions won't fly before the next Survey

That is the Obama gap and not caused by JWST.  Nothing but  Earth Science missions were funded by Obama.

That assertion is misleading.  The Obama administration shifted resources to Earth science missions, but the planetary, astrophysics, and heliophysics programs remained strong.

Not really.  There are no LSP launches next year.  The Obama gap is real.

[jbenton]

I feel like I should know this, but: what's "LSP"?

[zubenelgenubi]

LSP = Launch Services Program

[Don2]

The fundamental problem with JWST is that the science requirements are excessive. This lead to a very large and costly design which uses a number of breakthrough technologies like the deployable mirror and the large deployable sunshade for cryogenic operation. A very serious issue with the new technologies is that they have not been properly tested in prototype form.

Most technical progress is incremental. However the government tends to be fascinated by revolutionary/breakthrough/leapfrog technologies. These are sometimes a good idea, but what is usually ignored is that they first generation of any revolutionary technology usually has a lot of problems. The right way to do things is to build and test fly prototypes. The Mars helicopter drone, the Moxie experiment on Mars 2020 and the Mars Pathfinder mission of the 90s are examples of this. The wrong way to do things is to build the revolutionary new technology into a massive mega-project like JWST and throw money at it in the hope of getting it to work.

To make things worse you can cost cap the project, which then leads to short cuts in the testing. About 80% of the cost of a program is determined when the initial requirements are written and the time to save money is right at the beginning when the goals can easily be trimmed back. It is too late to save money on JWST. The mission needs a thorough test program which will hopefully discover most of the problems that come from building a massive project on unproven technology. Fixing the numerous problems that testing is likely to find is going to be time consuming and expensive. However, if it works when it gets to space, then it will do exciting and groundbreaking science.

There are a lot of missions that have been lost because of the cost of JWST. The Europeans are moving into the lead in researching dark energy and exoplanet atmospheres with the  PLATO  mission and the ARIEL mission. There has been no successful flight of x-ray microcalorimeter technology. There are no plans to replace the X-ray capabilities of Chandra or the UV-visible capabilities of Hubble. There has been no follow up to  the very successful SWIFT gamma ray burst research mission.

In future, astrophysics missions should be cost capped at $2 billion. As the Europeans have shown, and as NASA showed with Kepler, $600 million can buy a good mission and this would be a good mission size to focus on in future.

[gosnold]

Quote from astrophysicist David Spergel at today's Senate hearing on JWST:

JWST would have been better had it been a 4-meter telescope launched a decade ago.

[Nomadd]

Quote from astrophysicist David Spergel at today's Senate hearing on JWST:

JWST would have been better had it been a 4-meter telescope launched a decade ago.

Better than what? Comparing something a little more capable than Spitzer to the JWST doesn't really mean much.

[jbenton]

* Or more than 20 years between Chandra and JWST, since Spitzer wasn't quite a full-sized flagship.

There are a lot of missions that have been lost because of the cost of JWST. The Europeans are moving into the lead in researching dark energy and exoplanet atmospheres with the  PLATO  mission and the ARIEL mission. There has been no successful flight of x-ray microcalorimeter technology. There are no plans to replace the X-ray capabilities of Chandra or the UV-visible capabilities of Hubble. There has been no follow up to  the very successful SWIFT gamma ray burst research mission.

Speaking of Chandra, that thing has been up there for over 20 years, and it still works. Assuming that everything goes right with JWST, How long could it possibly last past it's 5-year primary mission? I mean to say how long before it runs out of propellant, or some other consumable? How long do large space observatories usually last on there with out servicing?

[JH]

Speaking of Chandra, that thing has been up there for over 20 years, and it still works. Assuming that everything goes right with JWST, How long could it possibly last past it's 5-year primary mission? I mean to say how long before it runs out of propellant, or some other consumable? How long do large space observatories usually last on there with out servicing?

Propellant is its only consumable (one of the technical breakthroughs on JWST is the closed-loop cryocooler). It was designed with enough propellant for 10.5 years of operation. Estimates of propellant usage for station keeping and pointing at a Lagrange point vs actual usage tend to be quite pessimistic, so it would not be surprising if the propellant allows for longer than that. I have heard that system failures are the more likely cause of EOM than propellant, however.

[Dizzy_RHESSI]

Quote from astrophysicist David Spergel at today's Senate hearing on JWST:

JWST would have been better had it been a 4-meter telescope launched a decade ago.

Better than what? Comparing something a little more capable than Spitzer to the JWST doesn't really mean much.

A 4 meter telescope using modern 2K detectors with a multi-object spectrograph is hardly just "a little more capable" than a 85 cm telescope with 256x256 InSb detectors. Note in the HST & Beyond white paper they actually baselined a 4 meter for NGST.

A 4m aperture would have a light-collecting area 25 times greater than that of SIRTF and will reach the same point source flux level almost a thousand times faster (section 2.5), and will resolve morphological features at cosmological distances which would not be discernible with the smaller apertures of ISO or SIRTF. Such a mission will truly be a major scientific advance.

Dressler and co-authors didn't think a 4 meter was incremental. The point Spergel is making is that astrophysics would be in a much better state with a less complex mission which didn't massively break the bank. NASA might not have pulled out of IXO and LISA. The past two astrophysics decadal surveys have stressed the desire to return to a diverse portfolio of missions of all scales.

[notsorandom]

Correct me if I'm wrong but it wasn't the large segmented mirror which has broken the budget.

[speedevil]

Correct me if I'm wrong but it wasn't the large segmented mirror which has broken the budget.

The large segmented mirror drove the margins on everything else down, and made everything else harder by
constraining the mass/volume/... envelope further.
For example, it may have had a role in reducing the margin on the sensors which failed due to inappropriate testing requring very expensive rework as they were welded into place, rather than other potentially higher mass solutions. (It may not).

It certainly had a role in making the design of the heatshiled more complex.

[TripleSeven]

the big question here is what happens if Webb turns out to be a Hubble...ie there is some flaw in it that makes it less "generational"

then what?