Citation
Abstract
A positioning and timing (PNT) solution is essential for conducting operations on the surface of a planetary body. The Joint Doppler and Ranging (JDR) scheme was introduced in prior papers to provide real-time 3D position determination for a user on the lunar surface. This paper proposes and analyzes an in-situ relay architecture that uses relative JDR to obtain real-time position estimates of a user on the surface of Mars. JDR with the Law of Cosines (LOC) utilizes a novel Doppler based approach in addition to range measurements for relative navigation. Although the LOC method requires a reference station, it facilitates the use of Doppler-derived pseudorange equations, which allow for positioning with only Doppler measurements. This Doppler-only method is then modified to include range measurements, which enable precise real-time positioning with only a few navigational nodes (as few as a single orbiter). In this analysis, the user and a reference station were simulated on the surface of Mars with a maximum of two orbiters in view. Orbiter ephemeris, velocity, and measurement errors were modeled as Gaussian variables in a Monte Carlo analysis. The simulated measurements were processed by a JDR-based Kalman Filter to calculate a real-time estimate of the user’s position. The resulting 3D root mean squared error for position estimates ranged from under 40 meters for the nominal error cases to under 5 meters for the optimistic error cases. Ultimately, this analysis describes a viable implementation of an in situ relay PNT solution on the surface of Mars. JDR enables real-time PNT knowledge for surface users with a minimal required infrastructure.
Details
- Volume
- 42-224
- Published
- February 15, 2021
- Pages
- 1–14
- File Size
- 4.8 MB