What Time is it at (16) Psyche?

The Psyche Project is a mission to the asteroid (16) Psyche, featuring three science instruments, a gravity science investigation, and a Deep Space Optical Communication technology demonstration. (16) Psyche, located in the asteroid belt between Mars and Jupiter, will be the first potential metal world-instead of rock or ice─visited by the National Aeronautics and Space Administration (NASA). This Jet Propulsion Laboratory (JPL) managed mission will explore Psyche after a 2023 launch and a multi-year cruise. The mission uses a science instrument suite consisting of a pair of multispectral imagers, a gamma ray and neutron spectrometer, and a pair of magnetometers in a gradiometry arrangement. The Psyche timekeeping system is comprised of functions distributed throughout the Spacecraft, Payload, and Mission Systems. Readers will be introduced to the clocks and time systems used by the mission and the various correlation activities which transfer time knowledge between the Spacecraft Avionics and the ground and between the Spacecraft Avionics and the Payload instruments. This core of this paper provides a brief overview of the driving pointing control, pointing reconstruction, on-board ephemeris knowledge, and optical navigation requirements of the Psyche mission. Each of these requirements has a budget which suballocates the total allowable error to various sources, one of which is the timekeeping error. This paper will present a bottoms-up analysis of the timekeeping uncertainty for each driving pointing and navigation requirement for each phase of the mission. It will present the Project time budgets and walk through how each line item was calculated and the assumptions made in these calculations. The approaches and results of oscillator thermal stability, oscillator aging, flight system thermal performance, and avionics time correlation performance testing will be presented as supporting evidence of the time budget line items. The paper will provide readers an understanding of how to bound the uncertainty of reconstructed UTC measurement time, on-board ephemeris time knowledge, and predicted UTC command execution time for a deep space Spacecraft without an ultra-stable oscillator using the Psyche timekeeping architecture and mission plan as an example.