Demonstration of optical telecommunications from the Artemis programme

It is well known that an optical link presents several advantages if compared with the classical RF approach like the wider transmission bandwidth and the smaller space loss.
 
In particular, the far smaller space loss of narrow laser beams represents a valid response to the limitation in transmission power and antenna size of Deep Space radio links. In the last years deep space missions have often required the implementation of multi-frequency links: Rosetta and Mars Express make use of the S and X band frequencies. The Ka-band is available to future exploration missions requiring higher performances in terms of data rate capacity or radio science measurement accuracy.

Bepi Colombo will make use of three simultaneous links: X/X, X/Ka, Ka/Ka. The possible extension of these concepts up the optical frequencies (for instance considering multi-frequency link approach based on integrated RF-Optical systems) will become an important issue for future exploration missions to Mars.

Taking as a reference the Mars Sample Return (MSR) mission, this activity shall investigate the relative advantages of optical and radio communications. The trade-off shall consider the current state of the art technology and should focus on a high-speed telemetry downlink. The following tasks are foreseen:

• Overall system concept definition, in particular: on-board optical subsystem, optical ground station terminal and ground/space interface
• On-board TT&C subsystem design:
• Evaluations of optical link access statistics, mission coverage gaps, and link visibility taking into account:
  • Mission profile
  • Spacecraft attitude profile and possible attitude constraints
  • Spacecraft accommodation possibilities and constraints
  • On-board and on-ground coarse pointing capabilities
  • Possible weather outages and solar exclusion angles
• · Extended optical link budget analysis that includes information on achievable telemetry rates (min/average/max) with mission time, and takes into account considerations on link visibility (geometric as well as weather visibility), varying background noise and pointing accuracy issues.