Would it make sense to design a standard stage for deep space missions?

Question

There are standard launchers and standard upper stages used for many different missions within cis-lunar space. Deep space missions are so rare maybe it makes no sense to try and come up with something like that for them. Then again, maybe if one existed there would be more deep space missions. Look at how many people have started using Cubesats.

Could a modular platform be created that could adapt to the all the kinds of payloads that exist, maybe by using small engines and solar cell units so sizing is very flexible? Would it help to save development and fabrications costs over many missions if there was a standard platform that could adequately shield instruments and integrate heaters and transmitters and such?

Answer 1

For deep space missions there's rarely any stage at all. It's usually a probe launched into cislunar space using standard cislunar stages, and then the probe uses its own propulsion system to reach its destination in deep space, no separate stage for that. But then, there could be a standarized system/platform for deep space propulsion, which isn't a stage, just a standarized probe module.

But...

While we got around to get a pretty consistent set of launchers, the development work for deep space propulsion is constantly ongoing. There are dozens of various ion engine designs, more or less standarized RCS propulsion systems, alternative propulsions like solar sail, and so on. It's all very much a work in progress - practically each new mission on top of the new mission goals is testing a new propulsion system.

So while creating a common, standard deep space propulsion system would come with some benefits, it would come with one critical disadvantage: depriving us of test platforms for new deep space propulsion systems. Any probe flying on the new standarized platform would be NOT testing a new, newly developed propulsion system.

Maybe once the development reaches some stalemate/cooldown situation where not much new can be designed and new designs will cease to sprout more frequently than new deep space missions occur that will make sense. If, similarly to current chemical engines, we reach a situation where there's quite hard to invent anything significantly better than existing designs, where developing a new platform around the new engine is less beneficial than going with "tried and true" (because the incremental advantages of the new engine aren't a significant improvement over the old), such platform - a standarized propulsion system for deep space - will become considerably advantageous. Currently there are simply too many good, new, untested systems and systems even better (and considerably so!) still in development to justify freezing the progress through adopting one standarized platform.

Answer 2

The problem is, all deep space missions have their own missions, which have different requirements. The masses change significantly, depending on the payload. Does it need to have fast acceleration, or slow? How much delta v? How long does the fuel need to be stored? All deep space missions have various amounts for all of these, making it difficult.

There is some modularity, however. There are common thrusters, tanks, lines, etc, all of which are relatively easy to get a hold of. These same parts can be used for satellites as well, reducing their cost. Overall, this is probably a better approach, to have standardized parts that can be fitted together, until we start sending a large number of nearly identical ships.