M2020

Background

The Mars 2020 rover is scheduled for launch in the summer of 2020 and arrival at Mars in February 2021. The current plan is to have an onboard scheduler help the rover independently adapt to execution variances on the surface of Mars, enabling the rover to operate more efficiently. Specifically, if activities finish earlier or later than expected, the onboard scheduler will allow the rover to extend or add activities to perform more science, or delay activities to be performed later.

Problem

Efficiently operating a rover on the surface of Mars is challenging. Two factors combine to make this job particularly difficult: 1) communication opportunities are limited, 2) certain aspects of rover performance are difficult to predict. With limited communications, the rover must be given instructions on what to do for one or more Martian days at a time. In addition, the duration of many rover activities can be hard to predict, which leads to unpredictable energy use. Traditionally, conservatism is used to keep the rover safe and healthy. This approach, however can lead to a measurable loss in rover productivity. To regain some of this productivity, the Mars 2020 mission is prototyping the use of onboard scheduling software. The primary objective of this software is to identify and utilize opportunities that arise when actual rover performance is more efficient than the original, conservative prediction.

Impact

An analysis of Mars Science Laboratory operations [Gaines et al. 2016] indicates that significant onboard resources are made available during execution that cannot be used due to current rovers inability to change the uploaded schedule. If an onboard scheduler can leverage such resources, it can significantly improve rover productivity.

Status

Status as of March 2024 is as follows.

1. Post landing, post checkout (Summer 2021): Copilot used in ground operations to automatically schedule wake/sleep and preheat activities with manually planned fixed time Master/Submaster (MSM) primary activities.

2. November 2021: Constraint-based planning (CBP) enabled in ground operations. CBP can automatically schedule (eg find times) for primary (science and engineering) activities. These activities are uplinked as fixed time MSM activities.

3. October 2023: Onboard automated scheduling goes live as the primary operations method of the Perseverance Rover. As of 25 March 2024, the Onboard scheduler had been used in 75 tactical operations cycles covering 138 sols on Mars.

Publications

Team

Dr. Daniel Gaines
Gregg Rabideau
Vincent Wong
Elyse Fosse
Stephen Kuhn
James Biehl
Eddie Benowitz
Dr. Steve Chien
Wayne Chi
Jagriti Agrawal
Shannon Towey
Sarah Bhaskaran