you'd probably want a different protocol than IPFS for that application. managing a DHT with extremely high latency isn't going to work very well. something like named-data networking would probably work better since the transmitter can know

1. exactly what prefixes need to be buffered based on the received interest messages from deep space 2. exactly which data rate is possible at any given time 3. exactly how much data needs to be sent from the buffer in each transmission

optimizing for high latency really pushes your design choices around compared to our comparatively very low latency uses here on earth. its pretty interesting to think about.