How does JUICE navigate autonomously

Question

Introduction

To kick things off, I'd like to introduce myself as a 23-year-old novice learner when it comes to space exploration but I've been listening to astronomy-specific podcasts since 2022 and I've been trying to learn as much as I can about the subject since then despite this being kind of irrelevant to my field of study at university (CS).

Overview

Overall, there is basically a series of mathematical and computational processes involved with which the spacecraft is directed to its destination. I'm going to make some assumptions for the rest of the overview. For instance, I know just a little about the Hohmann transfer orbit which is a way for spacecraft to gradually align their path with the orbit of their target object. This, however, is calculated fairly accurately by a computer that is either on the spacecraft itself so that it can be somewhat autonomous as it approaches the target(but I'm not quite sure if that's how missions like Voyagers or Pioneers were done) or operators manually or in an automated fashion, send the individual instructions required to direct the spacecraft to the right path, to the spacecraft using earth-based radio transmitters.

The Crux

What methods have been used for guiding JUICE and how technologies such as AI, CNN-based Image Processing, and optical navigation have been used to increase efficiency?

Answer 1

It would appear 'Autonomous Navigation' may be generous in terms of what JUICE is doing. This Airbus document limits itself to describing edge detection to fine tune instrument pointing on the fly, and smart upset recovery. This is useful for maximising science collection and reducing risk but does not make the craft able to self direct around Jupiter on long time scales.

All space probes including JUICE are severely power and mass constrained, and JUICE in particular has to operate in a highly hostile radiation environment meaning that it cannot fly serious computer power. In the case of Juice the solar panels have a designed power output of 850 watts (enough for a gaming laptop but not server farm).

Navigation in terms of current position and velocity is a complex question. Orientation can be determined with star trackers since the early ballistic missiles of the 50s, and most space craft since the voyagers have been able to autonomously work out which way they are facing and then find earth should communications fail. However getting position/velocity in absence of GPS type beacons is much harder and is normally done by measuring Doppler in the downlink to earth. JUICE does have a low power radar that may be aiding flybys by confirming distances are as expected though this is not explicitly stated.

This means that the bulk of the trajectory determination and future planning will still be happening on earth, with the 'Autonomous' allowing minor errors in sensor pointing or software to not result in a missed opportunity to collect data or loss of vehicle.

True AI has little place in space exploration since by definition it will behave unexpectedly, which is hard to justify on billion dollar missions. Less bleeding edge systems such as image processing algorithms to support navigation and identify boulders during touch down certainly are used. While not AI the posited cause of Chandrayaan 2's failure is an example both where some degree of autonomy might have saved the mission (having 'plan has failed, just land somewhere' code), but also a situation that would trap a poorly designed AI (ending up inverted).

True autonomy will probably not show up in deep space missions until there are enough duplicate missions in operation that failures can be allowed for and accepted while the system learns.