<story><title>Greg Robinson fixed NASA’s James Webb Space Telescope, reluctantly</title><url>https://www.nytimes.com/2022/07/11/science/greg-robinson-webb-telescope-nasa.html</url></story><parent_chain><item><author>saalweachter</author><text>The obvious number to make is 5; currently we only have one at L2.  What about L1, L3, L4 and L5?</text></item><item><author>dylan604</author><text>I can&amp;#x27;t wait for JWST 2.0, but we&amp;#x27;re only talking about JWST #2. We&amp;#x27;re not talking about upgrades, just another copy. I mean, it should be easy, right? It&amp;#x27;s in the cloud so to speak, so just spin up another instance and push to a different region. No problemo.</text></item><item><author>jmyeet</author><text>I&amp;#x27;m not sure you&amp;#x27;re correct.&lt;p&gt;Consider fabbing chips. Fabs spend an awful lot of time verifying the produced chips. I&amp;#x27;ve seen estimates that verification cost exceeds fabrication cost.&lt;p&gt;How much of the development cost of JWST 2.0 would be spent on verification? I honestly don&amp;#x27;t know but I would guess it&amp;#x27;s high.&lt;p&gt;Another factor: part of making a production process is predicated on how many you&amp;#x27;d build. We had a process for making Saturn-V rockets based on the number of Apollo missions we planned for. If you then up and decide you need 500 Saturn-Vs you might have to go through a whole new process for something that will scale that high.&lt;p&gt;Yet another factor: the launch vehicle. If you decide to do JWST 2.0 in 10 years, what launch vehicle will you use? The same one might not exist so the new mission will have to be designed for what is available.&lt;p&gt;And another: materials science changes. We don&amp;#x27;t make the same materials that we did 50+ years ago for good reasons but those materials are a key part of the design of something like Saturn-V.&lt;p&gt;So I imagine JWST 2.0 would be cheaper but 90% cheaper? I&amp;#x27;m not convinced.</text></item><item><author>WalterBright</author><text>A while back I raised a bit of a furor here saying that a duplicate could be made and launched at a tenth of the cost. A lot of people said I don&amp;#x27;t know what I&amp;#x27;m talking about, that little money would be saved.&lt;p&gt;But it seems patently obvious. After all, 10 technologies don&amp;#x27;t have to be reinvented. No research would need to be redone. No test rigs would need to be redesigned and duplicated. And on and on.&lt;p&gt;The most bizarre argument against building a duplicate was there wouldn&amp;#x27;t be anything extra worth looking at. Yet I watched the NOVA episode on the scope last night, and everywhere they look where we thought there was &amp;quot;nothing&amp;quot; turns out to be crammed with 10,000 galaxies and stars.</text></item><item><author>jmyeet</author><text>The cost of launch is relatively low, meaning several hundred million out of a a $15-20B budget.&lt;p&gt;But a given launch system is deeply intertwined with designing the mission. The size, the weight and the mass distribution.&lt;p&gt;Moving parts are a nightmare for reliability. Every moving part is something that can cease up and go wrong. It&amp;#x27;s a motor that can fail and gears that can get jammed.&lt;p&gt;JWST has two key components that involve a lot of moving parts:&lt;p&gt;1. The mirror. Hubble was smaller enough to be deployed fully constructed in the Space Shuttle so didn&amp;#x27;t have to deploy in space. JWST&amp;#x27;s mirror is 3-4x larger an there&amp;#x27;s no current launch vehicle that could launch it fully assembled. That&amp;#x27;s why you have all the beryllium hex mirrors that had to deploy the mirror once in orbit. These motors, actuators, assemblies, etc need to be &lt;i&gt;incredibly&lt;/i&gt; precise and reliable; and&lt;p&gt;2. The heat shield. JWST has to be incredibly cold to operate (5K IIRC). The only way to get rid of heat in space is to radiate it away. The heat shield separates JWST from the Sun, the Earth and Moon (each of which reflect enough light to interfere with operations). The shield is several layers and it&amp;#x27;s large, like tennis-court sized. Obviously this too had to be deployed in space.&lt;p&gt;There were like 10 technologies for JWST that had to be invented to make the mission possible. That&amp;#x27;s less than ideal.  It adds to the cost, the complexity and the timelines.&lt;p&gt;In hindsight it probably would&amp;#x27;ve been worth having a stepping stone between Hubble and JWST that proved some of these technologies in a cheaper and less risky way, probably with a smaller mirror. But here we are.</text></item><item><author>derekp7</author><text>Question -- Is the cost of projects such as Webb so high because of high launch costs, which in turn has a cascade effect on limiting the the projects that get launched to space, and therefore requiring that they be built to higher specifications because you only get one shot at it?  If so, then will the lower cost of space access from future vehicle development (such as Star Ship, and others that may follow) make projects such as future James Webb scopes and deep space probes much cheaper, if they know they can easily launch replacements and iterate the designs?  Or is this just fantasy at this moment?  I haven&amp;#x27;t really found much other than speculation comments (such as mine), but would like to see a professional&amp;#x27;s opinion.</text></item></parent_chain><comment><author>jmyeet</author><text>The other 4 Earth Lagrange points are unsuitable for various reasons:&lt;p&gt;L1: between the Sun and the Earth. The Sun reflecting off the Earth would interfere with instruments.&lt;p&gt;L3: This is suitable for positioning but impractical because of distance from a communication and perspective.&lt;p&gt;L4 &amp;amp; L5: these are unsuitable because they&amp;#x27;re &lt;i&gt;stable&lt;/i&gt;. Distance is an issue too. Why are stable Lagrange points unsuitable? Because things tend to collect there. Over the eons a whole bunch of crap has built up there and will continue to do so. That&amp;#x27;s not what you want when dealing with sensitive instuments.&lt;p&gt;Now you could say that you could orbit L4 or L5 like JWST orbits L2 and that&amp;#x27;s true but you still expend energy for stationkeeping. At L2 you spend energy to stay around the L2 point. At L4 and L5 you spend energy to avoid falling into the Lagrange point.&lt;p&gt;According to [1][2] it&amp;#x27;s more expensive (in delta-V terms) to get to L4&amp;#x2F;L5 than L2 but not hugely so.&lt;p&gt;[1]: &lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;space.stackexchange.com&amp;#x2F;questions&amp;#x2F;27010&amp;#x2F;how-does-the-delta-v-to-reach-and-orbit-l4-and-l5-compare-to-entering-orbit-arou&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;space.stackexchange.com&amp;#x2F;questions&amp;#x2F;27010&amp;#x2F;how-does-the...&lt;/a&gt;&lt;p&gt;[2]: &lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;space.stackexchange.com&amp;#x2F;questions&amp;#x2F;57463&amp;#x2F;what-is-the-delta-v-required-for-insertion-to-sun-earth-l2&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;space.stackexchange.com&amp;#x2F;questions&amp;#x2F;57463&amp;#x2F;what-is-the-...&lt;/a&gt;</text></comment>
<story><title>Greg Robinson fixed NASA’s James Webb Space Telescope, reluctantly</title><url>https://www.nytimes.com/2022/07/11/science/greg-robinson-webb-telescope-nasa.html</url></story><parent_chain><item><author>saalweachter</author><text>The obvious number to make is 5; currently we only have one at L2.  What about L1, L3, L4 and L5?</text></item><item><author>dylan604</author><text>I can&amp;#x27;t wait for JWST 2.0, but we&amp;#x27;re only talking about JWST #2. We&amp;#x27;re not talking about upgrades, just another copy. I mean, it should be easy, right? It&amp;#x27;s in the cloud so to speak, so just spin up another instance and push to a different region. No problemo.</text></item><item><author>jmyeet</author><text>I&amp;#x27;m not sure you&amp;#x27;re correct.&lt;p&gt;Consider fabbing chips. Fabs spend an awful lot of time verifying the produced chips. I&amp;#x27;ve seen estimates that verification cost exceeds fabrication cost.&lt;p&gt;How much of the development cost of JWST 2.0 would be spent on verification? I honestly don&amp;#x27;t know but I would guess it&amp;#x27;s high.&lt;p&gt;Another factor: part of making a production process is predicated on how many you&amp;#x27;d build. We had a process for making Saturn-V rockets based on the number of Apollo missions we planned for. If you then up and decide you need 500 Saturn-Vs you might have to go through a whole new process for something that will scale that high.&lt;p&gt;Yet another factor: the launch vehicle. If you decide to do JWST 2.0 in 10 years, what launch vehicle will you use? The same one might not exist so the new mission will have to be designed for what is available.&lt;p&gt;And another: materials science changes. We don&amp;#x27;t make the same materials that we did 50+ years ago for good reasons but those materials are a key part of the design of something like Saturn-V.&lt;p&gt;So I imagine JWST 2.0 would be cheaper but 90% cheaper? I&amp;#x27;m not convinced.</text></item><item><author>WalterBright</author><text>A while back I raised a bit of a furor here saying that a duplicate could be made and launched at a tenth of the cost. A lot of people said I don&amp;#x27;t know what I&amp;#x27;m talking about, that little money would be saved.&lt;p&gt;But it seems patently obvious. After all, 10 technologies don&amp;#x27;t have to be reinvented. No research would need to be redone. No test rigs would need to be redesigned and duplicated. And on and on.&lt;p&gt;The most bizarre argument against building a duplicate was there wouldn&amp;#x27;t be anything extra worth looking at. Yet I watched the NOVA episode on the scope last night, and everywhere they look where we thought there was &amp;quot;nothing&amp;quot; turns out to be crammed with 10,000 galaxies and stars.</text></item><item><author>jmyeet</author><text>The cost of launch is relatively low, meaning several hundred million out of a a $15-20B budget.&lt;p&gt;But a given launch system is deeply intertwined with designing the mission. The size, the weight and the mass distribution.&lt;p&gt;Moving parts are a nightmare for reliability. Every moving part is something that can cease up and go wrong. It&amp;#x27;s a motor that can fail and gears that can get jammed.&lt;p&gt;JWST has two key components that involve a lot of moving parts:&lt;p&gt;1. The mirror. Hubble was smaller enough to be deployed fully constructed in the Space Shuttle so didn&amp;#x27;t have to deploy in space. JWST&amp;#x27;s mirror is 3-4x larger an there&amp;#x27;s no current launch vehicle that could launch it fully assembled. That&amp;#x27;s why you have all the beryllium hex mirrors that had to deploy the mirror once in orbit. These motors, actuators, assemblies, etc need to be &lt;i&gt;incredibly&lt;/i&gt; precise and reliable; and&lt;p&gt;2. The heat shield. JWST has to be incredibly cold to operate (5K IIRC). The only way to get rid of heat in space is to radiate it away. The heat shield separates JWST from the Sun, the Earth and Moon (each of which reflect enough light to interfere with operations). The shield is several layers and it&amp;#x27;s large, like tennis-court sized. Obviously this too had to be deployed in space.&lt;p&gt;There were like 10 technologies for JWST that had to be invented to make the mission possible. That&amp;#x27;s less than ideal.  It adds to the cost, the complexity and the timelines.&lt;p&gt;In hindsight it probably would&amp;#x27;ve been worth having a stepping stone between Hubble and JWST that proved some of these technologies in a cheaper and less risky way, probably with a smaller mirror. But here we are.</text></item><item><author>derekp7</author><text>Question -- Is the cost of projects such as Webb so high because of high launch costs, which in turn has a cascade effect on limiting the the projects that get launched to space, and therefore requiring that they be built to higher specifications because you only get one shot at it?  If so, then will the lower cost of space access from future vehicle development (such as Star Ship, and others that may follow) make projects such as future James Webb scopes and deep space probes much cheaper, if they know they can easily launch replacements and iterate the designs?  Or is this just fantasy at this moment?  I haven&amp;#x27;t really found much other than speculation comments (such as mine), but would like to see a professional&amp;#x27;s opinion.</text></item></parent_chain><comment><author>amluto</author><text>L3 may have some challenges with its Earth uplink, and we wouldn’t be able to see a satellite there very easily. L3, L4, and L5 might need separate shielding from the Earth and the sun.</text></comment>