Viewing a single comment thread. View all comments

Astrokiwi t1_jb995xe wrote

Maybe just barely!

The maximum possible resolution you can physically get depends on the size of the telescope. The next generation of ground-based optical telescopes will have mirrors around 30m in size. At the distance of the Moon, these could have a resolution of about 5 or 10 metres, if they have perfect optics. So you might be able to make out the lander as a fuzzy blob at the limit of resolution, but won't be able to see any astronauts, and definitely not any footprints. You'd really want something like a 200m telescope if you wanted down to 1 metre resolution.

Interferometry isn't the best thing to help here. While you can combine light from multiple telescopes separated by some distance to increase their resolution, this is really tricky to do with visible wavelengths, and you're limited to a small number of telescopes on the same site. What you end up with isn't quite an image as you don't have enough combinations of baselines between telescopes to get the full visual information. At lower wavelengths (e.g. radio) it becomes easier to do interferometry affordably with a large number of telescopes (possibly even spread over the world!), but longer wavelengths also inherently have a lower resolution, and you're often dealing with a much dimmer image - the Sun emits a lot of visible light, so most things in the solar system are brightest in the visible ranges.

Overall, to photograph the Moon (and many other solar system objects) you get much better resolution by sending a small telescope to orbit the Moon than building a big one on Earth.


mdw t1_jb9p080 wrote

You don't mention that there will be issues with atmospheric seeing. To realize the potential of the telescope you'll need adaptive optics and I am not sure if the usual wavefront sensors will work well with a target like Moon.


Astrokiwi t1_jb9pbou wrote

Yeah, this is assuming totally ideal circumstances with perfect optics.


mfb- t1_jb9yclg wrote

Starship HLS is pretty white while the surface of the Moon is pretty dark. Landing near the pole will also mean it's at a nice angle relative to our line of sight. So maybe it's an elongated blob.


ChrisGnam t1_jbd8sc9 wrote

> get much better resolution by sending a small telescope to orbit the Moon ...

Just to comment on this part, we already have such a probe! We at NASA Goddard operate tbe Lunar Reconnaissance Orbiter (LRO) which has two a Narrow Angle Camera's (LROC NAC-L and NAC-R), each have a focal length of ~700mm and so are effectively mini telescopes.

Infact, with these camera's we've been able to photograph the old Apollo landing sites

If anyone is interested in diving further, all the imagery taken by the LRO is available to the public and can be explored using the LROC QuickMaps tool. If you zoom in you'll see the actual mosaic of NAC images. You may be wondering why each segment of the image looks really long, and this is because NAC is a push-broom sensor rather than a framing one. A framing sensor (like in most camera's today) is a rectangular grid of pixels where each pixel on the sensor is sampled once and corresponds to one pixel in the final image. A push-broom sensor is a single line of pixels, which each pixel represents a column of the final image. It is sampled at a regular interval, and each time it's sampled, that forms a new row of the image. So as you fly over a surface, you construct the image one row at a time. It maps the surface kinda like you're pushing a broom over the surface, hence the name.


draenogie t1_jba6qfk wrote

What about image stacking with many photos? I see that technique getting amazing resolution of galaxies.


Astrokiwi t1_jba953w wrote

That is useful for reducing the noise and increasing the exposure time, but doesn't actually increase the resolution.


mfb- t1_jbce8if wrote

Lucky imaging should still be useful if the adaptive optics doesn't work perfectly.


bkinstle t1_jbaapys wrote

Would it be better with a space telescope like Hubble?


mfb- t1_jbcdq2r wrote

No. It doesn't have the atmosphere to worry about, but the mirror size is too small (2.4 m vs. 30 m for upcoming telescopes) and resolution scales inversely with that size. At best it could detect a brighter featureless blob.


IllstudyYOU t1_jbal69m wrote

What if they write " Hi Mom " On the moon dust with their foot prints in big letters?


zekromNLR t1_jbj740f wrote

There is also the problem of atmospheric seeing, which uncorrected limits the resolution to about 1 km at the distance of the Moon with excellent seeing conditions.