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NASA says Webb’s excess fuel likely to extend its lifetime expectations

• jl6 5y ago
  Would a hypothetical refuelling mission risk contaminating the mirror/sensor with manoeuvring propellant, assuming it would need to adjust its position very finely in the close vicinity of the JWST?
• comrh 5y ago
  https://blogs.nasa.gov/webb/2021/12/29/nasa-says-webbs-excess-fuel-likely-to-extend-its-lifetime-expectations/ https://blogs.nasa.gov/webb/2021/12/29/nasa-says-webbs-exces...
  • dang 5y ago
    Changed to that from https://www.npr.org/live-updates/morning-edition-2022-01-11 https://www.npr.org/live-updates/morning-edition-2022-01-11. Thanks!
  • tedivm 5y ago
    Thank you! The link really should be changed to this, as it's the only working one here and it comes right from the source.
• theandrewbailey 5y ago
  The page has changed.
• a_paddy 5y ago
  https://www.npr.org/live-updates/morning-edition-2022-01-11#nasa-now-believes-the-james-webb-space-telescope-has-enough-fuel-to-last-for-20-years https://www.npr.org/live-updates/morning-edition-2022-01-11#...
  • jve 5y ago
    Unfortunately this is not a permalink, but only a hashtag that will work well today, ofcourse. Let's hope it will in 2 years.
    • Karawebnetwork 5y ago
      Is it? That's the URL for morning-edition-2022-01-11 which is also what their share buttons injecting into the share popups. Are they pruning those often?
      • meepmorp 5y ago
        '/live-updates/' at the beginning of the path doesn't suggest durability.
    • Forge36 5y ago
      This is already broken for me (on mobile)
• dekhn 5y ago
  It's definitely a great example of an engineering/science project run by grownups. Compared to what I see in the daily cloud software engineering world...
  • bdamm 5y ago
    Well, if money is no object...
    • lmilcin 5y ago
      And if moving schedule by a decade is not an object...
  • boringg 5y ago
  • jve 5y ago
    Your average budget and timeline in daily cloud software is certainly multiple orders of magnitude less.
  • stackedinserter 5y ago
    Different requirements, different engineering. Nobody needs space-mission-ready CRUD that takes $10 billion and 15 years of development.
    • JaimeThompson 5y ago
      I wonder how much has been spent on electronic medical records and related software in the United States?
      • ajmurmann 5y ago
        This is an interesting example as the domain is probably closer (albeit still far away) to the JWST than a photo sharing app is. There is a very high minimum bar to get anything into production because of high regulatory requirements. I bet iterating in this area is much slower and harder because of regulatory hurdles. Definitely an area that requires different processes than your typical SaaS web startup.
• gostsamo 5y ago
  Is it likely that in 20 years we will be able to send a resupply mission or it will be easier to send a new observatory with better instruments?
  • plazmatic 5y ago
  • JaimeThompson 5y ago
    Assuming that things like Starship work then launching larger scientific instruments will be much easier as will refueling them. A considerable portion of the cost and risk comes from getting the mass and physical size down so we can launch them.
    • gostsamo 5y ago
      I get that part. The interesting part is if building a new instrument will be marginally more useful than resupplying the current one. A few years back there was a demonstration of an orbital vehicle for refueling satellites. So, which is better: spending a few more billions for capturing a few more frequencies of infrared light or spending a few hundred millions for extending the life of the current mission.
      • JaimeThompson 5y ago
        By current mission do you mean Hubble?
        • gostsamo 5y ago
          No, James Webb.
  • fredoralive 5y ago
    It isn't designed to be serviceable, so replacement is presumably the way to go. https://webb.nasa.gov/content/about/faqs/faq.html#serviceable https://webb.nasa.gov/content/about/faqs/faq.html#serviceabl...
• dahfizz 5y ago
  I didn't realize the JWT will need to burn fuel in its steady state. Its pretty disappointing that this took 20 years to build and we will only get 20 years of use out of it.
  • Buttons840 5y ago
    Hopefully the time limit will serve as a kick in the pants to build an even better telescope.
    • Sharlin 5y ago
      LUVOIR: https://en.wikipedia.org/wiki/Large_Ultraviolet_Optical_Infrared_Surveyor https://en.wikipedia.org/wiki/Large_Ultraviolet_Optical_Infr... (basically a bigger JWST but for UV/optical/NIR observations à la Hubble).
  • JaimeThompson 5y ago
    Currently we can only lift so much mass into orbit which limits such things drastically.
  • CabSauce 5y ago
    Hopefully we'll have cooler stuff in place by then. I'm assuming it can also be serviced, like Hubble.
    • btmiller 5y ago
      Current plans are for it not to be serviced. Considering that it’s sitting way beyond the moon at L2, it’d have been out of each even for the shuttles when they were still in service.
      • Sharlin 5y ago
        However, hopefully it’s not out of reach of the hardware we’ll have in 20 years. Even though right now our capability is actually less than 20 years ago…
• mygoodaccount 5y ago
  Does anyone else have an inexplicable subconscious desire for the JWST to fail catastrophically? I've been a huge fan of the project for years, but after launch my mind was constantly plagued with these urges. I can't seem to explain or get rid of it. "Call of the void", maybe? Anyone else with this problem? I'd really like to stop thinking these horrible thoughts.
  • sho_hn 5y ago
    Is that you, Hubble main computer? You still have the visible spectrum!
  • mlindner 5y ago
    I legitimately thought it for several years as I wanted it to act as a restorative force in the US space industry against mismanagement. It 'deserved' to fail to 'punish' those responsible for it's mismanagement. That was my thinking for quite a few years. However now I think SpaceX is doing a better job of leading that charge by simply pushing the industry forward towards being a little less risk adverse and avoiding analysis paralysis. Carrot is always better than the stick, when it works.
  • StapleHorse 5y ago
    I think it's because our boring safe lifes makes us want a little bit of thrill. It's the same feeling when you want society to colapse because 'how cool would be to be a survivor in an apocaliptical wasteland'. Or when you vote for a bad candite saying "f..k it, let's see what happens"
  • ufo 5y ago
    Hopefully the upcoming Moonfall movie can scratch that itch, allowing us to keep the real world JWST un-exploded.
    • lapetitejort 5y ago
      Gravity safely scratches that itch. As much as I love Hubble and the ISS, I love to see them disintegrate.
• satronaut 5y ago
  this just in, NASA is trolling us and it's actually mercury years /s
• emptyfile 5y ago
  Thanks Arianespace! Great job.
• willis936 5y ago
  I assume it could still be operated for a few months out of the year when it runs out of fuel, assuming the thermal cycles don't trash the ability to align and calibrate everything.
  • dredmorbius 5y ago
    The problem is maintaining station at L2. Insufficient fuel means not remaining on station. There's probably an end-of-life contingency to push the telescope "over the top" as EOL is approached, such that it transitions to an independent heliocentric orbit rather than endangering other L2 missions or returning (eventually) to Earth along an uncontrolled trajectory.
• artimaeis 5y ago
  I'm just a space nerd, all the below is conjecture. Lots of talk about refueling even with the 20 year lifespan, from what I've gathered having watched a lot of the NASA conferences and livestreams this past year, with this amount of operational fuel capacity the problem in 20 years will be on operational lifetime of wear components, not just the fuel. The reaction wheels are _large_ moving parts on the JWST. The cryocooler for the MIRI is a very finely calibrated moving part. It's a closed system, but still relies on pumps and electronics. After 2 decades of operation it's very likely that these will be experiencing some issues. While in 2 decades it might be feasible to refuel the JWST, it seems very unlikely it'd be worth it given the operational wear of every other component. Had we used too much fuel to correct the course to get where we are the math may have been very different. Seems to me that we're fortunate that we can instead dedicate resources to the next-gen observatories!
  • samwillis 5y ago
    With SpaceX Starship the space industry is going to be very different in 20 years time. Launching new telescopes, even larger ones, will be much easer. Attempts to refuel will be completely unneeded. Edit: This seems to be a controversial opinion (based on down votes). To clarify, my expectation is that if launch costs have come down as much as people suggest, launching a new and improved (potentially significantly larger) space telescope would be a better use of funds than a complicated and risky refuelling mission. There will be many lessons learnt from JWST that by then there will be an appetite for something new. My hope also is that if the cost to launch has come down so would the development costs of any new satellites, leading to reduced costs for science missions.
    • ericbarrett 5y ago
      That's negating the cost of the telescope itself, though. JWST may be more expensive than something you could launch with e.g. Starship, due to the need to fit into an Ariane 5 payload, but it's still an insanely high-precision instrument that would surely have cost $billions even without the unfolding procedure. If you could refuel it for, say, $250 million, because Starship, why not do that instead of launching a new telescope for $5 billion?
• easton_s 5y ago
  JWST will not produce products, only data. In the 10-20 years it will operate, it will ingest enough data for tens of thousands of scientists over hundreds of years to analyze.
  • stjohnswarts 5y ago
    That seems like a drastic overestimate. Any basis for that?
    • easton_s 5y ago
      We are still analyzing data from 70 years ago. https://carnegiescience.edu/news/old-plates-new-data-mysteries-observatories%E2%80%99-basement https://carnegiescience.edu/news/old-plates-new-data-mysteri...
    • justin66 5y ago
      The data don't get stale, so scientists will be able to make inferences based on that data for as long as they'd like. A lot of it will never stop being useful. If a much better telescope comes along or an especially dynamic phenomenon is discovered there might be a temptation to take more pictures of something that has already been captured, but otherwise, why would you? This data is expensive and will probably remain so for quite some time, for the obvious reasons.
  • dr_orpheus 5y ago
    > over hundreds of years to analyze Seems like an aggressive estimate. For example the Kepler spacecraft produced a lot of data for its planet finding mission. The light curves that it sent back had some automated processing, but had multiple rounds of inspection for identifying the "objects of interest" and then confirming actual planet candidates. The backlog was on the order of a year to when data was taken. This had the additional complexity that to confirm a planet transit you really had to see it pass in front of the star twice to confirm the orbital period. JWST will also be delivering similar data over its lifetime, but I would assume that ground processing of that data will significantly improve over that timeframe.
• p1mrx 5y ago
  "Why doesn't JWST use ion thrusters?" https://space.stackexchange.com/questions/57255/why-doesnt-jwst-use-ion-thrusters https://space.stackexchange.com/questions/57255/why-doesnt-j...
  • ricardobeat 5y ago
    Yet again, the harsh reality that we are launching two-decades-old designs. Hopefully these timelines seem to be speeding up a bit in the past decade.
  • ericbarrett 5y ago
    I have a related question. Would it be feasible to launch a future JWST-style mission into a simple heliocentric orbit, which doesn't require any stationkeeping at all? It will then drift away from Earth over the years, eventually being as distant as L3, before getting closer again. And I appreciate it can be harder to communicate to something that distant. Yet, communications tech has come a long way in the last few years, arguably even farther than stuff like ion thrusters, and I wonder if it wouldn't make more sense to put effort into providing sufficient bandwidth at 2 AU rather than better stationkeeping. Especially if the mission isn't meant to be serviced anyway.
    • p1mrx 5y ago
      It's probably more difficult to design a spacecraft to point at 3 things (earth, sun, target) versus 2 (earth+sun, target).
    • necubi 5y ago
      The main constraint for JWST is that it needs to be able to block all IR radiation from the Sun/Earth/Moon in order to pick out the faint IR signal it's looking for (from red-shifted light from the very early universe). By orbiting L2, it keeps Sun/Earth/Moon all on one side of the spacecraft, which it's then able to block with its sunshield.
• londons_explore 5y ago
  Fuel for station keeping depends on how accurately we can measure its location and predict orbits. With future tech and more research, we will be able to use the fuel it has far more effectively. the theoretical fuel use is zero... The actual use is proportional to how our calculations of orbits and stuff differ from reality.
  • dredmorbius 5y ago
    Any background / literature you're aware of on this? At what point do uncertainty effects (limits to measurement precision) and risk (danger of rolling "over the top" of the L2 point, and requiring reverse thrust, which JWST cannot deliver) come in to play?
  • sailingparrot 5y ago
    > the theoretical fuel use is zero... L2 point is unstable, so theoretical fuel use cannot be zero I believe.
• nielsbot 5y ago
  I couldn’t find a permalink to the NPR article, but here’s the linked NASA blog post: https://blogs.nasa.gov/webb/2021/12/29/nasa-says-webbs-excess-fuel-likely-to-extend-its-lifetime-expectations/ https://blogs.nasa.gov/webb/2021/12/29/nasa-says-webbs-exces...
  • ilamont 5y ago
    Thanks for posting. Question for astronomers: Based on the linked article from that blog post about the five LaGrange points relative to the Earth and Sun (https://webb.nasa.gov/content/about/orbit.html https://webb.nasa.gov/content/about/orbit.html) are there similar points associated with the other planets? If so, how does the heavier gravity of the Sun (for a planet like Mercury) or the gas giants and their large moons impact the points?
    • gspr 5y ago
      Most certainly: https://en.wikipedia.org/wiki/Lagrange_point#Solar_System_values https://en.wikipedia.org/wiki/Lagrange_point#Solar_System_va... I don't think I understand your question about the sun. The Lagrange point used for JWST is an Earth-Sun one.
    • wthomp 5y ago
      For mercury, the L1 and L2 points would be closer to the planet.
    • mlindner 5y ago
      The lagrange points exist regardless of the masses of the bodies. However the perturbing forces acting to pull bodies away from those points may be stronger or weaker depending on the masses involved. For Jupiter for example there are several thousands of asteroids that sit at it's L4 and L5 points and make up a group of asteroids called the Trojans[1]. So it's points are especially stable because of it's large mass. The Earth-Moon Lagrange points for example aren't very strong. [1] https://en.wikipedia.org/wiki/Jupiter_trojan https://en.wikipedia.org/wiki/Jupiter_trojan
      • 5y ago
• oversocialized 5y ago
  >science >belief If only there was math they could do based on the consumption and stored fuel
• dredmorbius 5y ago
  In terms of life-extension vs. replacement of JWST, it's helpful to think through what opportunities might exist. There are a set of telescope plans which are presently in consideration, including WIRST, the wide-angle infrared telescope; HabEx, the Habitable Exoplanet Imaging Mission; Lynx, a next-generation X-ray telescope; and the Origins Space Telescope, an infra-red telescope even larger than Webb. https://www.universetoday.com/139461/what-comes-after-james-webb-and-wfirst-four-amazing-future-space-telescopes/ https://www.universetoday.com/139461/what-comes-after-james-... This links as well to a good YouTube video describing each of the proposals. For telescopes, among factors I'm aware of are: - The total number of devices. More 'scopes means more points of the sky which can be imaged at any one time. This permits detecting either rare or transient events. There are also possibilities afforded by multiple devices operating in concert, providing both greater positioning sensitivity (angular resolution) and increased surface area, though more the former than the latter. - Wavelength specificity. Infra-red, radio, visible light, UV, and X-Ray sensitivity all permit detection of different phenomena. Devices suited to one wavelength may not be suitable for others. Specific research goals may favour specific observational methods. - Other sensing modes. Spectroscopy (which provides information on chemistry of remote objects). Gravity, gamma ray, and particle sensors (e.g., neutrino sensors, cosmic-ray detectors) may afford other options. There are proposals for space-based gravity-wave detectors, for example. - Compound devices. The HabEx system in particular has two components, the telescope itself, and a sunshield used to block the light of an observed star, which would operate at a separation of 100s of thousands of km. - Collector size. Larger mirrors permit gathering of more light. This permits shorter collection periods for brighter events, and imaging of previously undetectable phenomena. The Hubble Deep Field views are an example of the latter, and pushed the boundaries of known and and observable phenomena tremendously. - Storage, processing, and communications capabilities. I don't know how much this contributes to observation capabilities, though I suspect it has an impact. - Developments in phsyics, materials, and sensing, generally. Looking through lists of physics and chemistry Nobel awards since the 1970s, a surprisingly large number have concerned capabilities rather than fundamental characteristics or properties of matter or the universe. Many of these afford new capabilities in sensing and detection. - Probes. Rather than a single instrument which views distant objects, probes get close to a specific object, or set of objects, and make close or direct observations of these. Various landers, impactors, flyby, orbiter, and similar missions, to date all to objects within the Solar System, would be examples of these. These compete with other missions (manned, long-distance sensing). - Earth observation. Probably the largest class and most productive set of space-based observation platforms has been looking at our own planet. It's also worth thinking through what has made JWST possible, including launch platforms, experience with complex deployments, manufacturing, sensing, and control capabilities. These will have impacts on future missions, and further development might also extend their capabilities. In situ fabrication or assmbly might offer the greatest opportunity The possibilities of constructing telescopes either in low-Earth orbit and transporting them to an observation orbit, or on remote bodies (the Moon, perhaps an asteroid) also exist. I'm thinking through scenarios in which larger launch craft (Starship, SLS), space-based assembly, and possibly even temporary construction structures --- effectively an inflated balloon in which engineers and technicians could work in shirtsleeve or close-to-it conditions --- might be used to assemble very large structures without relying on the complex deployment ballet used by JWST, or being constrained to the dimensional constraints of the Ariane V launch vehicle and fairing. An asteroid, de-spun, could provide both a shield against solar and Earth-based radiation and emissions, and structure and materials for at least some assembly. This presumes that the asteroid's own orbit would be sufficient for observations and that instruments would be sufficiently aimable from that point. Finally: most technological improvement tends to follow a sigmoidal curve: an early period of slow development, a period of rapid attainment, then a slower period of approaching theoretical maximum efficacy. New developments or combinations of technologies may restart that curve, but often 15 years doesn't deliver transformational development. Rather older technologies are refined, reliability improved, costs reduced, or flexibility increased. I suspect we'll see a mix of these factors --- some diminishing returns as existing modalities and mechanisms are perfected, and some new avenues as novel combinations do become possible.
• SeanLuke 5y ago
  I don't understand why the Telescope requires fuel at all, except to change its orbit position. Couldn't it just rotate counterweights via electric motors, powered by solar cells?
  • Nick87633 5y ago
    Yes it does exactly this. It uses reaction wheels (circular counterweights) for rotation generally, but when they can no longer spin faster it will have to use propellant to adjust its angular momentum back to zero. In addition, it uses propellant for orbit position keeping (station keeping) as you wrote.
  • micromacrofoot 5y ago
    The first reason is that it needs to reach its destination... IIRC the JWST needed to accelerate itself to avoid damage on its initial orbital insertion (rather than relying on the launch vehicle). It also needs to stop once it reaches its destination. Electric propulsion doesn't provide enough thrust for this particular mission. Electric is better suited for very slow acceleration buildups rather than quick corrections. It does actually have reaction wheels to control attitude without propellant, but it needs fuel to unload the momentum. It's possible the JWST could get into a situation where electricity wouldn't unload the momentum fast enough. https://en.wikipedia.org/wiki/Spacecraft_bus_(James_Webb_Space_Telescope)#Rocket_engines,_attitude_control https://en.wikipedia.org/wiki/Spacecraft_bus_(James_Webb_Spa... https://jwst-docs.stsci.edu/jwst-observatory-hardware/jwst-momentum-management https://jwst-docs.stsci.edu/jwst-observatory-hardware/jwst-m...
  • gspr 5y ago
    But its orbit isn't perfect or perfectly stable: Other forces than just the Sun-Earth system act on it, albeit very weakly. Some include photonic pressure (photons from the sun pushing on one side, not the other), the moon, a few scattered particles (space isn't perfectly empty), etc. And the fact that the JWST itself isn't a point mass means that it is tugged at by gravity slightly differently in different places. Then add to all of these the most important fact that L2 is an unstable equilibrium (a local potential maximum, like a hill), and the telescope is more like a dancer on its toes needing to right itself by throwing something every now and then. All these things necessitate expending some fuel for station keeping.
• slackfan 5y ago
  Headline question - do they believe, or do they know? If the former - I worry for any space agency that can't do basic math.
  • jffry 5y ago
    Article answer to your headline question: "It's around 20 years of propellant, roughly speaking,” though he added that it’s a preliminary estimate. There are likely many factors that influence propellant usage which are unknowable - for example, photon pressure from the sun, which can vary over time in an unpredictable way.
• jakelazaroff 5y ago
  Can we change this link to include the hash, or find another one? The top headline I saw was "Chicago schools reopen this week. But the fight reflects a nationwide struggle" and I was really confused. (The <title> of my tab bar also reflects that headline even if I use the link with the hash, annoyingly). I had to scroll past nine other articles to find the James Webb Space Telescope one. Full link, for reference: https://www.npr.org/live-updates/morning-edition-2022-01-11#nasa-now-believes-the-james-webb-space-telescope-has-enough-fuel-to-last-20-years https://www.npr.org/live-updates/morning-edition-2022-01-11#...
  • ab_testing 5y ago
    I think it is a test to find out how many users reply about James Webb without reading the article :)
  • dang 5y ago
    We've changed to the NASA post now.
    • jakelazaroff 5y ago
      Thanks!
• sanj 5y ago
  Rocket engine binning!
• mrfusion 5y ago
  Where does it go when it runs out of fuel?
  • digitalsushi 5y ago
    Well, if it's 2040, I might figure it's within the realm of possibility that multiple vendors can somewhat predictably service it in whatever orbit it still has. QED the Webb launch itself, I think people working on this stuff are starting to grow a proven track record. 20 more years of practice might yield a simple process to 'top off the gas tank'.
• jonathankoren 5y ago
  Link to the actual article https://www.npr.org/live-updates/morning-edition-2022-01-11#nasa-now-believes-the-james-webb-space-telescope-has-enough-fuel-to-last-20-years https://www.npr.org/live-updates/morning-edition-2022-01-11#...
  • dang 5y ago
    Doesn't seem to work. We've switched to the NASA post now.
• icey 5y ago
  Is the fuel supply only designed to keep it in orbit? What happens when it runs out of fuel and leaves L2? Can it continue to do science while "on the float"?
  • baq 5y ago
    for a short while - for as long as reaction wheels can keep it pointing away of the sun and the high gain antenna can point towards Earth (it doesn't have 360 degrees rotation freedom). i don't know the details, but it'd probably amount to a few months at most.
• dmead 5y ago
  yea yea nasa. we get it https://www.youtube.com/watch?v=8xRqXYsksFg https://www.youtube.com/watch?v=8xRqXYsksFg
• WalterSobchak 5y ago
  Previous discussion: https://news.ycombinator.com/item?id=29725799 https://news.ycombinator.com/item?id=29725799
• stjohnswarts 5y ago
  I'm guessing they gave themselves some wiggle room :) . They did not miscalculate fuel. They did the classic "overestimate by 2-4x" and you'll come out smelling clean either way with the bosses.
• frebord 5y ago
  When we gonna start building the telescopes in space?