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Comment by cstross | Hacker News Reader

Two points:

Firstly SOFIA is a modified Boeing 747SP. The SP first flew in 1975 and the final SP was delivered in 1987: Boeing never made many of this type (a short-arse extra-long-range 747 that was designed for certain long-haul routes, back before high bypass turbofans had the fuel economy -- hence range -- we expect of today's airliners) and this was one of the last ones still flying.

Secondly, it's an infrared telescope. JWST does the same job much, much better. If JWST had failed, then we'd presumably see a hasty program to build a next-generation SOFIA airborn telescope around now. But given JWST's success to date, it's simply no longer needed.

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I don't think the latter is completely true. JWST can capture a smaller range of infrared for starters, and is obviously impossible to change, whereas an airborne platform can carry additional instruments if needed. And for observations in the solar system, the ability to move can be helpful too. E.g. if an occlusion is visible anywhere on earth SOFIA can move there, JWST is either in the right spot by accident or is no.

Not just that, but Jwst 's time is at an absurd premium, while sofia' s less so, allowing less filtering of what it's time can be used for, indeed having more than one infrared telescope is better than just having one

> JWST does the same job much, much better.

Close: JWST is near-infrared. SOFIA was the last and remaining far-infrared telescope. There's debate though if far-infrared was worth it though.

Not sure what you call near IR but JWST has a range from 600nm to 28micrometers. Typicaly people start talking about mid-air from 2 micrometers. So I would say JWST definitely covers beyond near IR

> Not sure what you call near IR but JWST has a range from 600nm to 28micrometers. Typicaly people start talking about mid-air from 2 micrometers. So I would say JWST definitely covers beyond near IR.

JWST covers the mid-infrared too, as you implied. But @exabrial's point still stands, that SOFIA's coverage included much longer wavelengths than JWST does. SOFIA had instruments that could observe wavelengths as long as 1600 microns[0].

[0] https://www.sofia.usra.edu/about-sofia/sofia-overview

Interesting 1600microns is mm waves, so that must be a different instrument? I don't think you could use the same "telescope* for imaging optical and what is essentially rf waves. Unfortunately the website doesn't give enough details without diving into the abbreviated instruments.

> There's debate though if far-infrared was worth it though.

I don't think there's debate about whether the far-infrared is valuable. The far-infrared has unique diagnostic power for some astrophysical phenomena, and the 2020 Decadal Survey for Astronomy specifically called for the far-infrared to be considered for a $1B "probe-class" mission. What was debated was the specific role and cost of SOFIA.

The proportions on that plane are all sorts of funny: https://aeroin.net/wp-content/uploads/2021/02/sofia_take_off...

SOFIA also had pretty good PR value - they had a program to put teachers on each science flight. I know a few of my local teachers got to go and it seemed like a nice program. I suppose it might now make a nice museum piece along with the shuttle carrier planes.

The environmentally and fiscally conscious astronomy community abhors it. It’s scientific value compared to those operational and environmental costs is terrible

> The environmentally and fiscally conscious

Sending telescopes to space being famously cheap and environmentally friendly.

They might not want to look into how many other jets are in the air at any given time then. And I doubt many of them are providing any scientific value.

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