Let’s talk about safe mode! Today we discovered @NASAPersevere in safe mode a few hours after launch. It’s an interesting name for what it is.

We try to design these missions to handle everything. Redundancies, contingencies, multiple layers of fail safes. But sometimes! The unexpected still happens.

So then what do you do? How do you plan for the unexpected? You create a ‘safe mode’.

Safe mode usually involves stopping standard operations, prioritizing communications and pointing systems, and, as ET would say, “phoning home”.

The MOST IMPORTANT THING is to be able to keep talking to a spacecraft if something has gone awry.

So safe mode usually involves concentrating on communication. Usually if a spacecraft has gone into safe mode, the next time you swing the Deep Space Network towards it to check in, it’s bleating at you quite frantically.

This has happened with every (?) NASA spacecraft I’ve worked on.

It can be for something quite innocuous, like today’s event with Percy was a temperature range getting out of nominal, but quickly returning. Or it can be for something substantial, like Kepler’s reaction wheel failures.

(Actually the reaction wheels might have been emergency mode, not safe mode? @dacmess can correct me if I’m wrong). Kepler certainly had some safe modes when it pointed a bit too close to the Sun though.

Anyway, the point is, it’s a neat recovery mode built into spacecraft so that we can get them to look at us and talk to us if there’s an issue.

You always remember your first safe mode.

https://twitter.com/aussiastronomer/status/976565488460316672?s=21 https://twitter.com/aussiastronomer/status/976565488460316672