Taking picture of stars from weather balloon

[Space_launch]

I'm a high school physics teacher and my students are building a science payload to launch on a weather balloon. You can look http://www.donorschoose.org/donors/proposal.html?id=458390&challengeid=39361" to see some project details and even donate a couple bucks to help make the project a reality.

So here is the question: How can we take pictures of stars during the day from an altitude of 15-20 miles? I figure that we will be above enough of the atmosphere to make it possible. I'm imagining a camera pointed up at an angle (so it isn't pointing at the balloon) shielded from sunlight. But the big challenge is keeping the camera still, or being able to take the picture with a fast enough exposure.

So are there any cheap cameras that can image stars with a fast exposure? And if not, is there a cheap and lightweight way to keep a camera stationary long enough to image stars?

I'd also love to hook a spectroscope to a camera...maybe take a picture of the sun with it to show the change in absorption at high altitudes. Any thoughts on how I can pull that off?

Thanks!

 

[DaleSwanson]

I think that should be high enough that you'll see the blackness of space fine. http://www.google.com/images?&q=100000+feet+altitude" are similar pics. Getting stars in a picture though, will be a problem at any height. If the Earth, Sun, or the balloon (illuminated by the Sun) are in the frame then it'll be overly saturated and you won't get stars. See for example this picture from the Moon, which obviously has zero atmosphere:
http://upload.wikimedia.org/wikipedia/commons/5/5c/Earth-moon.jpg"

Since the Earth will fill below, and the balloons and Sun will fill most of above I imagine it may be quite hard to position a camera so that it only sees space. Perhaps you can put one camera on top of the balloons. I don't know enough about photography, but it may be possible to get stars if you increase the exposure, at the expense of totally saturating any part of the image with something illuminated by the Sun in it. You could test this by just trying to get stars to show up in pictures taken at night with something very bright (like a light bulb) in the frame.

As far as keeping it stable for the longer exposure needed, that may be difficult. Perhaps you could rig up something so that it is floating is a small amount of fluid. I'm not sure what kind of winds will be present. However, I'd guess if there are any significant winds keeping the camera still for a long exposure will be nearly impossible.

 

[Ich]

Look at http://www.physorg.com/news/2010-10-father-son-iphone-hd-camera.html" . I don't think there's a chance for long exposure.