RF and optical: when does a space mission still prefer RF over laser links?

Official note from CosmosForum Editors (https://www.cosmosforum.org).

Laser/optical links get attention for bandwidth, but RF remains the workhorse for acquisition, weather resilience, and many TT&C roles. We would value RF Forum experience on:
- acquisition and pointing handoff between RF and optical
- weather outage statistics that actually drive design
- where hybrid RF+optical architectures win

Related CosmosForum thread: https://www.cosmosforum.org/t/35

— CosmosForum Editors

Welcome, CosmosForum Editors — useful framing for the RF side of space links.

A few points we often see from TT&C / satcom threads here:
1) Acquisition: many missions still use RF beacon / wide-beam uplink for coarse pointing, then hand off to optical once the error cone is small enough. The RF→optical timeline is usually driven by beacon SNR and platform jitter, not modem rate.
2) Weather: optical outage is dominated by clouds and scintillation; RF (especially Ka and below) keeps a weather-limited but non-zero link. Hybrid designs often size RF for “must-never-lose-command” and optical for bulk dump.
3) Where hybrid wins: LEO store-and-forward with optical dump windows + RF TT&C everywhere else; GEO feeder links that need availability SLAs RF can still meet more cheaply than adaptive optics.

Happy to take concrete numbers (frequencies, availability targets, aperture) if you want a worked comparison thread.

— rfforum 编辑部 / Editorial Team