[a_d]

Imagine if one were to launch a swarm of cubesats with cameras on them looking away from Earth —- what would you imagine those cameras would see? (Let’s say cameras allow very long exposure shots?) Another way to ask my question is: can cubesat be used as “mini-Hubbles” to get closeups of planets/moon in the solar system or nearby stars?

Second question (somewhat related to first) — can a cubesat stream video to a server on earth? (Or does one need a ‘big Sat’ to do video streaming?

[Ephil012]

So we are actually adding imagery to our satellite so I think I can answer these pretty well.

For question 1, I do think you could use it for astrophotography. You could probably capture pictures of the stars if you have stabilization on the CubeSat. However, the photos would probably be similar to the photos taken of space from the ISS. What I mean by this is you might be able to take photos of the stars, but it wouldn't be able to see anywhere as far out as Hubble. I know a bunch of CubeSats use smartphone quality cameras so you would probably get a decent photo that might make a nice desktop wallpaper, but it wouldn't really compare to a bigger satellite. It would show an overview of the stars, but it wouldn't be significantly different from existing images imo except maybe it being from a different perspective. As far as zooming in, that would actually be kind of hard due to space constraints. CubeSats are small, like really small (10 cm x 10 cm x 10 cm in some cases). So it would be hard to fit any substantial zoom lens system in there. That might make getting ultra close ups hard. Maybe as camera tech improves in the future what you are suggesting would be possible though. Aiming it at a specific planet also might be a bit of a challenge. CubeSats mostly don't have propulsion (although we are adding an ion thruster in ours). They can use reaction wheels to rotate though. However, accurately rotating it towards a tiny planet in the sky could be hard. However, I will say you could go for a really big CubeSat design and fit a good camera system in that. Then if you solve the aiming issue you could get some really cool images that are zoomed in on planets / stars.

For question 2, we actually considered trying this. I had the idea to live stream the satellite on Twitch. We discovered that livestreaming it was hard. If you are sending data from the CubeSat to earth, the data transmission is very slow. That basically rules out livestreaming. Maybe you could transmit it to a big communications sat in orbit which then sends it to Earth. However, I suspect the data transmission speed might still be less than ideal. Plus, using a communications sat network (like Iridium) could be expensive. Let's say though communication tech gets better and you can transmit directly to Earth at a fast speed. There is still are two major issues. Regulations and getting ground stations. Every single ground station (basically an antenna on Earth that gets data from space) requires you list it on your FCC application. If it involves ground stations in other countries (especially countries the USA isn't friendly with) it can get very messy from a regulations perspective. Also, getting those partnerships to begin with can be messy as well. There are some networks like SatNogs that do allow for receiving data from volunteer ground stations in other countries. Although, I don't know if they would really be practical for livestreaming due to coverage. I know Amazon has some offerings where they let you access their ground station network that might allow for livestreaming one day. However, I haven't really explored too much into it. I also haven't heard of any teams using AWS Ground Station personally though. Honestly, you'd be forced into using Iridium regardless due to coverage being shoddy for ground stations. Overall though, I think the data speeds just aren't there yet to livestream, at least not with LoRa (which is the protocol a lot of teams use for transmission).

[bagels]

Direct communication with ground stations is usually impractical for continuous communication for a couple reasons: they're over subscribed, and there aren't any stations where your satellite spends a lot of time.

Best bet is if starlink, oneweb, etc. provide a service for satellites to relay your data back.

[Ephil012]

Yeah that is also true. The CubeSats don't spend too much time over each ground station. You can technically get around this by swapping between ground stations and enable semi continuous communication, but it would require a ton of them to work well. Also, it wouldn't work over the ocean. There isn't really a way to partner with enough ground stations to get the needed coverage while over land. I don't think there are any ground station networks out there with enough coverage for this type of thing to be constantly swapping for near constant connectivity over land. We didn't actually need amazing connectivity. We were fine with just livestreaming occasionally, but the other issues I mentioned around data speed prevented it. I think if data speeds were better you could get live video temporarily (like 15 mins).

Also, for the satellite transmission via Starlink, I don't think Starlink / OneWeb offers that yet for CubeSats (might be wrong though). I do know Iridium allows for it though. However, as I mentioned earlier in the prev comment, the data speeds might suck still (could be wrong here too) and it costs a lot of money. I do think some ground stations would have wanted money too. We didn't actually need to livestream as it was just some fun PR trick. We ended up deciding it wasn't worth it in terms of cash / effort.

As far as over subscription, it depends. If you are using a public ground station network then its an issue. If you are partnered with no public ones then it's not as big of an issue. We were thinking of private ones only because public ones would not allow this kind of thing. So over subscription just didn't even matter for us really.

[a_d]

wow! Thank you so much for a detailed response! I learned a lot from your comment.

If I may ask another question: do you think the CubeSat ‘form factor’ (10x10x10 cm-cube) can have enough propulsion (combined with some gravtiy-assist) to be able to get into an orbit around another planet or another moon in our solar system? Meaning, can a CubeSat be sent to .. say Titan, as a probe (say a ‘mini-Cassini’).

(Just curious to understand whether cheap ‘CubeSats’ can be used as tiny probes for the entire solar system)

Thank you!

[Ephil012]

Oh yeah, forgot but to clarify you might be able to get something better than a smartphone camera with the right sensors and clever space saving in a 1U cubesat. It's just most of the 1Us I have seen don't use anything beyond smartphone level cameras due to their internals (e.g. reaction wheels, computer system, etc) taking up too much space and the fact they don't need something more advanced. Though if you were very clever about laying out the space and removing as many components as possible you could fit a small zoom lens in there and get something better quality. I suspect though there are people who have done this. I just don't think it would be anything super different from existing images taken from the ISS or other things in orbit. If you went for something bigger then maybe you could get something more substantial and get cool images of planets in our solar system close up. A 24 U might be able to pack quite a camera system, but as far as I know the general max size is 12U and anything past that is rare/theoretical. I know though at even a 2U you can get some pretty high quality images of Earth, but I don't know if that would really translate to anything super amazing of space given the distance most planets/stars are. I think those images would still look like they were taken with a high quality smartphone or maybe a dslr camera just due to the fact they are far out (even though technically 2Us pack way better camera systems than most smart phones).

As a whole though these camera system are mostly used for Earth as it's an easier target. Space images are more like astrophotography grade and not Hubble grade.

If you want an example of a good cubesat camera here are some. https://dragonflyaerospace.com/products/ I should note though that these would not generally fit inside a 1U given their smallest one takes up 1U worth of space.

[Ephil012]

There are CubeSats with various propulsion systems like ion thrusters and pulsed plasma thrusters in development. It's relatively new though iirc. These thrusters can last for an insanely long time. So maybe in theory it could reach a planet one day, but it would take ages. So in practice probably not practical and it just makes more sense to launch one from a rocket that is going to that planet.