Citation
Abstract
Positioning, navigation, and timing (PNT) services at the Moon are needed to support the Artemis program, which will begin launching the first of dozens of landed and orbiting assets to the Moon in the 2020s. These PNT services and standards are currently defined in the LunaNet Interoperability Specification (LNIS), but several details remain to be determined [1]. NASA’s Moon-to-Mars program aims to create PNT capabilities to support an initial human Mars exploration campaign and may be able to use some aspects of the lunar PNT architecture. This article describes architectures and technologies needed for providing PNT services at the Moon and Mars and recommends technology investments that will both help enable the envisioned lunar PNT capability as well as successfully extend it to Mars. Architecturally, an initial lunar deployment of relay satellites in elliptical frozen orbits would maximize coverage over the lunar South Pole, a focus of the Artemis program. We recommend these assets and future surface assets, to establish a free-running autonomous timescale (which we call “LTC”) with differences to UTC continually monitored. This is preferable to deploying UTC itself at the Moon, which would involve overcoming unnecessary challenges in handling leap seconds and in closed-loop tracking of significant time-varying relativistic effects. The lunar service providers should establish their orbits and time through a variety of technologies, including existing CCSDS ranging standards, DSN tracking, weak-signal GPS reception, and high-quality atomic clocks. These assets in turn would provide LNIS-standard PNT services to lunar users. Investments needed to enable a fully capable Lunar PNT system include the development of high-performance space atomic clocks; high-performance software-defined radios such as UST-lite and Iris that are capable of advanced communications and navigations techniques with multiple frequencies; navigation autonomy; ground stations; and a terrestrial beacon service. In critical aspects, technologies that work at the Moon will not work at Mars. System engineering studies and architecture trades to identify the differences between the lunar and Mars operational scenarios should begin immediately. The outcome of these studies will inform appropriate technology investments to make and test (to the extent possible at the Moon and with precursor missions to Mars) so that they are ready for Mars exploration beginning in the 2030s.
Details
- Volume
- 42-237
- Published
- May 15, 2024
- Pages
- 1–60
- File Size
- 5.3 MB