<blockquote>
<p>So... why haven't we launched at least one large, dedicated mid-to-short wavelength UV Space Telescope?</p>
</blockquote>
<p>Why dedicated? And why large? Large space telescopes are <strong>expensive</strong> and compete with other space exploration programs for rather limited space exploration budgets.</p>
<p>That said, the Hubble Space Telescope (which definitely qualifies as a large space telescope) does have multiple instruments that observe in the near ultraviolet. The Hubble is of course not dedicated to UV, but it does observe in the UV.</p>
<p>In addition, the <a href="https://fuse.pha.jhu.edu" rel="noreferrer">Far Ultraviolet Spectroscopic Explorer (FUSE)</a> satellite was a space telescope that was dedicated to observing in the far ultraviolet. It had its original budget of \$250 million slashed by half, and as a result the frequencies it observed were reduced, but it did observe in the far UV for over eight years.</p>
<blockquote>
<p>Are we planning one?</p>
</blockquote>
<p>The <a href="https://www.luvoirtelescope.org" rel="noreferrer">Large Ultraviolet Optical Infrared Surveyor (LUVOIR)</a> is currently in the evaluation/competition stage. Note well: This proposed space telescope is not dedicated to UV. It has already been proposed and approved for that next step to evaluation and competition. It has not yet been approved for funding for development, construction, launch, and operation. If funded, it will be launched in the late 2030s. That's another problem with large space telescopes: It takes a long time (decades) to go from concept to launch.</p>

CC BY-SA 4.0
2024-11-23T07:23:20.127Z
There was also [GALEX](https://en.wikipedia.org/wiki/GALEX), which was a UV imaging telescope with a slightly larger mirror (50cm) than each of the 4 mirrors (35x39cm) used by FUSE's spectrographs.
Dan Is Fiddling By Firelight
CC BY-SA 4.0
2024-11-23T18:54:01.190Z
There is perhaps less motivation to observe UV than longer or shorter wavelengths. Beyond the Lyman limit, even a tiny bit of hydrogen in the path blocks the light, so many interesting objects can't be observed.
John Doty
CC BY-SA 4.0
2024-11-24T02:35:48.383Z
for those interested, there's also more available about LUVOIR in Space SE: https://space.stackexchange.com/search?q=LUVOIR
uhoh
CC BY-SA 4.0
2024-11-21T14:39:45.770Z
2024-11-21T14:45:02.933Z
2024-11-21T14:45:02.933Z
David Hammen
<p>Most short-wavelength ultraviolet radiation is blocked by our atmosphere, correct?</p>
<p>So... why haven't we launched at least one large, dedicated mid-to-short wavelength UV Space Telescope?</p>
<p>Are we planning one??</p>

CC BY-SA 4.0
2024-11-21T14:09:18.130Z
https://en.wikipedia.org/wiki/Ultraviolet_astronomy
Mithoron
CC BY-SA 4.0
2024-11-21T14:12:53.033Z
Large? You mean like Hubble, or Webb? Thing is, ordinary mirrors don't work for EUV.
Mithoron
CC BY-SA 4.0
2024-11-21T14:36:52.507Z
Large ? So not IUE, EUVE or Galex?
ProfRob
CC BY-SA 4.0
2024-11-21T14:47:09.607Z
@ProfRob Or FUSE, OAO, and several others that were not "large".
David Hammen
CC BY-SA 4.0
2024-11-25T10:51:51.407Z
https://en.wikipedia.org/wiki/Spektr-UV - a Russian project of big dedicated near-uv space telescope. But, as most of Roscosmos projects - don't be surprised if it will never be built because of low funding and lack of technical readiness.
Heopps
CC BY-SA 4.0
2024-12-05T12:09:39.217Z
One answer might be that infrared is where really interesting action is. Everything far away is IR.
Miss Understands
<observational-astronomy><astrophysics><space-telescope><stellar-astrophysics><electromagnetic-spectrum>
Why aren't there any large Ultraviolet (UV) space telescopes?
Kurt Hikes
# Why aren't there any large Ultraviolet (UV) space telescopes?

(Asked by: username_0 on 2024-11-21)

Most short-wavelength ultraviolet radiation is blocked by our atmosphere, correct?

So... why haven't we launched at least one large, dedicated mid-to-short wavelength UV Space Telescope?

Are we planning one??

**Tags:** observational-astronomy, astrophysics, space-telescope, stellar-astrophysics, electromagnetic-spectrum
> **Comments:**
> **username_1**: https://en.wikipedia.org/wiki/Ultraviolet_astronomy  
> **username_1**: Large? You mean like Hubble, or Webb? Thing is, ordinary mirrors don't work for EUV.  
> **username_2**: Large ? So not IUE, EUVE or Galex?  
> **username_3**: @ProfRob Or FUSE, OAO, and several others that were not "large".  
> **username_4**: https://en.wikipedia.org/wiki/Spektr-UV - a Russian project of big dedicated near-uv space telescope. But, as most of Roscosmos projects - don't be surprised if it will never be built because of low funding and lack of technical readiness.  
> **username_5**: One answer might be that infrared is where really interesting action is. Everything far away is IR.  

---

## 1 answers

### Answer by username_3 on 2024-11-21. Score: 20

> So... why haven't we launched at least one large, dedicated mid-to-short wavelength UV Space Telescope?

Why dedicated? And why large? Large space telescopes are **expensive** and compete with other space exploration programs for rather limited space exploration budgets.

That said, the Hubble Space Telescope (which definitely qualifies as a large space telescope) does have multiple instruments that observe in the near ultraviolet. The Hubble is of course not dedicated to UV, but it does observe in the UV.

In addition, the [Far Ultraviolet Spectroscopic Explorer (FUSE)](https://fuse.pha.jhu.edu) satellite was a space telescope that was dedicated to observing in the far ultraviolet. It had its original budget of \$250 million slashed by half, and as a result the frequencies it observed were reduced, but it did observe in the far UV for over eight years.

> Are we planning one?

The [Large Ultraviolet Optical Infrared Surveyor (LUVOIR)](https://www.luvoirtelescope.org) is currently in the evaluation/competition stage. Note well: This proposed space telescope is not dedicated to UV. It has already been proposed and approved for that next step to evaluation and competition. It has not yet been approved for funding for development, construction, launch, and operation. If funded, it will be launched in the late 2030s. That's another problem with large space telescopes: It takes a long time (decades) to go from concept to launch.

> **Comments:**
> **username_6**: There was also [GALEX](https://en.wikipedia.org/wiki/GALEX), which was a UV imaging telescope with a slightly larger mirror (50cm) than each of the 4 mirrors (35x39cm) used by FUSE's spectrographs.  
> **username_7**: There is perhaps less motivation to observe UV than longer or shorter wavelengths. Beyond the Lyman limit, even a tiny bit of hydrogen in the path blocks the light, so many interesting objects can't be observed.  
> **username_8**: for those interested, there's also more available about LUVOIR in Space SE: https://space.stackexchange.com/search?q=LUVOIR  

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