I was wondering if it is technologically possible to send a CubeSat/Nanosatellites or constellation of nanosatellites to explore the water vapor jets in the southern region of Enceladus in the Saturn planetary system.
The problem with sending a cubesat to Saturn is power. A cubesat isn't large enough to carry a nuclear thermal generator, and almost certainly not large enough to carry enough solar cells to power it in the outer solar system.
Consider the Juno probe to Jupiter. Its solar cells weigh 340kg, yet generate only 240W of power at Jupiter, which has only 4% of the solar flux that's avaioable in Earth orbit. Saturn has only 1/4 of the solar flux as Jupiter, so even Juno's 8.9ft by 29ft solar panels would only generate about 100W at Saturn.
Cassini's transmitter at Saturn had 20W output. Input power would have been more. So you would need solar panels maybe 1/3 the size of Juno's just to power the transmitter, let alone all the heaters, scientific instruments, navigation, etc. So that's a minimum of 10ft X 10 ft of solar panels just for transmission.
Juno was considered a small outer planet mission. It still had a dry mass of 1,353 kg, and a wet mass with fuel of 3625 kg.
Cubesats are much smaller than this. The largest proposed cubesat design I've seen is 27u (54 kg, 34 x 35 x 36 cm). This is simply not big enough or massive enough to hold the number of solar panels required at Saturn, let along carrying enough fuel for rocket engines or the mass of an engine. There would be nowhere near enough power to drive electric propulsion. You'd have no way to manoever in Saturn's system. But even just the solar cells required for minimalist operation would exceed the size and weight budget of an entire cubesat.
Solar panels 1/10 the weight of Juno's would still be more massive than the entire allowed cubesat mass, and would only generate 10 watts or so at Saturn if weight scales linearly with size. It almost certainly doesn't, but it's a good enough assumption for an approximation since we are still at least an order of magnitude away from a size large enough to work, and that's still ignoring all the other power sinks in a deep space probe.
Yes it is not easy, but not impossible. This answer addresses the communications issues mentioned in comments.
The MarCO cubesats actually served as communications links between a spacecraft landing on Mars and the Earth. It was a slow link, only 8 kb/s using 5 W of power, and at the time the distance was only about 0.7 AU, whereas Saturn will be 9 or 10 AU away. That means that either their antennas would have to be larger, their power much larger, or the frequency would have to be higher so that the same size aperture would produce a narrower beam.
Of course optical communication would be the way to go.
- For more on MarCO's antennas see How does the pattern on the MarCo cubesat's antenna boost data-transmission?
For more on optical communications and how it compares to radio:
- Quantitatively, why will optical communication be better than X-band for deep-space communications?
- How is long-distance optical communications coming along in space?
- Are there plans or a program for an optical relay pathfinder for deep space?
- What is the highest non-optical frequency used or tested for use in deep space communication?