Space Exploration Stack Exchange is a question and answer site for spacecraft operators, scientists, engineers, and enthusiasts. It only takes a minute to sign up.
Sign up to join this community
There is one new project, like Google Maps, which would be an online video transmission of the Earth's surface from a satellite:
Another good one is a web cam situated on the International Space Station (ISS), and looks like it works:
https://www.nasa.gov/multimedia/nasatv/iss_ustream.html
What is a major problem in situating a camera on Mars and another on the Moon?
DSN time is competitive, and not cheap.
So, besides the costs that Tom mentioned in getting the camera there (and an appropriate relay satellite), you have to consider the costs of getting the data back to the earth.
For the space station, it's only ~370km (230 miles) up ... relatively close, and they can use much smaller dishes than what's required to get decent telemetry from spacecraft at Mars or even the moon (359 Mm to 406 Mm).
Let's take as an example, the STEREO mission -- each spacecraft gets one or two DSN passes per day, but they're also tracked by smaller dishes in the U.S., Asia, and Europe to try to get near-real-time space weather information. (it was as small as 5.5m dishes early in the mission vs. the 34m and 70m ones from the DSN; they're now using a mix of dishes; I know Bochum is 20m )
Right now, the spacecraft get 480 kbps from the DSN (to decrease to 160kbps when they're near 2AU (300 Gm) from earth). The beacon mode data, as it needs to be downlinked on the smaller dishes ... is closer to 600bps. (sorry, couldn't find a comprehensive telemetry rate table)
In the current plans, under 2013 week 37, they expect 'Significant telemetry shortfalls'. That's the competitive nature -- it might be that some other spacecraft with a higher priority is in the same region of the sky. (eg, we get less time when one of the spacecraft is in the same direction from earth as mars, or when there's a major launch)
We get donated time for STEREO beacon because the data's of value to many groups ... I'm not sure that you'd be able to get the same for something that's just for public outreach. (Crowd funding might work, but if the images are really boring, maybe not)
Disclaimer : I work for the Solar Data Analysis Center, which oversees the STEREO beacon data processing.
Pure and simple, cost
Mars
Putting a webcam on or in orbit of Mars would involve sending the data back to earth, and sending data to and from Mars isn't cheap. There's only so much bandwidth, the Mars Reconnaissance Orbiter in the ideal conditions puts out 6Mbits, and Curiosities direct to earth data rate is ~15-32kbps, or at up to 8Mbits to the orbiters ( but only with an 8 minute window each day ), with the signal taking between 4 and 22 seconds to arrive once sent. Other orbiters are in a comparable situation.
So any basic webcam would be competing with scientific data that's collected far faster than it can be sent. To get it to work we'd need more hardware in Mars orbit to increase bandwidth enough that communicating with Mars and its surface would have a larger window of opportunity, data rate, and capacity.
Having said that I don't think a webcam would be very interesting, a handful of photographs showing night day and various weather would sum it up pretty much. Hardly justifies spending the hundreds of millions of $ to put one there. Anything interesting would likely be scientific in nature, so a realtime video from orbit is more likely, and probably of so high a resolution it isn't realtime. Perhaps Mars weather systems?
The Moon
Again cost, and interest. The moon isn't a terribly active place as far as a normal webcam would be concerned, but you could put a webcam up there and point it at earth or the surrounding landscape. Data rate isn't so much of an issue as it is with Mars as Earth is comparatively close.
The problem then is funding it, and making it last for an appreciable amount of time. The temperature ranges on the Moon are quite large, and there's no atmosphere to protect against the various amounts of radiation coming from space
The view from Mars is going to be entirely boring. To get an idea of how boring, try videoing Mars from Earth's surface. What happens is the little red dot moves through the sky. Quite often you can't see it, because it is cloudy, or daytime, or the dot is behind the Earth. The same would happen from the other end, only the dot would be bluish, and the clouds would be dust rather than water.
From the moon - well, it could look quite nice, but isn't going to be as useful from a scientific viewpoint as satellite footage, which is much closer, and cheaper to get to.
