Myth Dispelled: HST can observe the moon

[statickid]

On some other thread a while back, someone mentioned that the HST can't look at the moon because it is too bright. I read that and just thought "hmm... yes that makes sense." Just ran across this and thought I'd post it not only for the cool pictures, but also just to spread the word that HST can in fact observe the moon, it just chooses not to. :tiphat:

http://www.slate.com/blogs/bad_astronomy/2013/03/10/hubble_photo_of_the_moon_the_crater_tycho_up_close_and_personal.html?wpisrc=most_viral

 

[Urwumpe]

I thought the myth was, that Hubble should be seeing the moon and prove that nobody landed there, but the evil US gov is not allowing that.

 

[Eccentrus]

well it can, but it is more economical and utilizes its potential to a more full capacity when it's observing stars, well things like the HST have a limited lifetime and so every second counts, that's why it only looks at the earth or moon only for calibrating, observation that is useful for its life cycle, and can sometimes be beautiful as well. Either way, the less of a photographer probes that we send there actually send much more meaningful data since they also elicit the topography and surface gravity of the object of study itself, and hence the relative disinterest of the moon by the HST team.

 

[Izack]

I had thought that it was because Hubble can't track objects with apparent motion as large as the Moon's. I guess the nature of the myth is another myth.

 

[MattBaker]

Thought the same like Izack, too since the HST is travelling with 7500 m/s around the Earth. I'm not sure if you can make a stable image with that, but since we're on the internet here's the obligatory xkcd. (With that link to this photo stating that the exposure time was just half a second.)

 

[Astronut25]

http://what-if.xkcd.com/32/

the HST can take a look at the Moon, the gyroscopes can barely keep up, and since the HST is designed to look at distant objects, it is very farsighted. Any image of the Moon would not be of great quality, and the Earth would be just a blur.

:ninja:'d, why didn't my web browser show the last post? I guess thats what I get for using IE. :firefox:

 

[Urwumpe]

What happened to the former spy satellites? They will have Earth observation gyroscopes and are just not permitted to look at Earth... but could observe to moon easily.

 

[N_Molson]

Who can the most can usually do the less.

 

[MattBaker]

What happened to the former spy satellites? They will have Earth observation gyroscopes and are just not permitted to look at Earth... but could observe to moon easily.

You mean the ones "donated" by the NRO last year? [ame="http://en.wikipedia.org/wiki/2012_National_Reconnaissance_Office_space_telescope_donation_to_NASA"]Wikipedia[/ame] has an article on that stating they could be used as a Wide Field Infrared Survey Telescope (WFIRST) to search for exoplanets and dark energy. But due to the JWST it's currently NET late 2010's (so 2026).

 

[garyw]

I had thought that it was because Hubble can't track objects with apparent motion as large as the Moon's. I guess the nature of the myth is another myth.

No myth. It's true. They have to point hubble 'ahead' of where the moon will be then take the image as the moon dashes past.

The Moon is not too bright for Hubble. Funny though, it is hard to observe by HST, but that’s actually because it’s moving too fast in the sky. Hubble isn’t designed to track that quickly, so what they do to observe it is put it in “ambush mode”: Aim Hubble in the sky where the Moon will soon be, then wait. When the Moon moves in, Hubble grabs the snapshot. This has been done many times, actually (like in 1999 and 2005).

Source: http://www.slate.com/blogs/bad_astr...n_the_crater_tycho_up_close_and_personal.html

 

[RisingFury]

HST can observe the Moon... ish.

The "too bright" thing is nonsense. All you need to do to counter that is to shorten the exposure time. What makes it difficult for Hubble to observe the Moon is that the Moon is in orbit around Earth and moves around at a certain velocity. To compensate for that, you need to rotate Hubble as it takes its image and that's where the problem lies: Hubble can't actually spin very fast. It's been designed to stare at the same spot for weeks. That means to keep it stable, it needs to make very small adjustments. It's incapable of making quick ones and keep control of itself...

 

[statickid]

I thought the myth was, that Hubble should be seeing the moon and prove that nobody landed there, but the evil US gov is not allowing that.

Yeah I've heard that one too, :lol: I just though I'd post this since I did see someone saying specifically it was too bright some time ago (don't remember what discussion). I didn't know any different, never bothered to research it or anything. Figured I'd stash this article in our forum search archive for future generations.