Space-Time Reference with an Optical Link

TL;DR

This paper proposes a high-precision space-time reference system using a stable atomic clock in orbit synchronized via two-way laser communication with ground clocks, enabling picosecond timing and millimeter orbit accuracy worldwide.

Contribution

It introduces a novel method for creating a space-time reference by combining orbiting atomic clocks with ground-based standards through laser communication.

Findings

Achieves picosecond-level global timing accuracy.

Enables millimeter-level orbit determination.

Provides a high-accuracy, globally accessible time reference.

Abstract

We describe a method for realizing a high-performance Space-Time Reference (STR) using a stable atomic clock in a precisely defined orbit and synchronizing the orbiting clock to high-accuracy atomic clocks on the ground. The synchronization would be accomplished using a two-way lasercom link between ground and space. The basic concept is to take advantage of the highest-performance cold-atom atomic clocks at national standards laboratories on the ground and to transfer that performance to an orbiting clock that has good stability and that serves as a "frequency-flywheel" over time-scales of a few hours. The two-way lasercom link would also provide precise range information and thus precise orbit determination (POD). With a well-defined orbit and a synchronized clock, the satellite cold serve as a high-accuracy Space-Time Reference, providing precise time worldwide, a valuable reference frame for geodesy, and independent high-accuracy measurements of GNSS clocks. With reasonable assumptions, a practical system would be able to deliver picosecond timing worldwide and millimeter orbit determination.