The Lunar Exploration Ground Sites, or LEGS, are several NASA space communication complexes created to support lunar exploration. They are in addition to the existing NASA Deep Space Network and the Near Earth Network. The LEGS mission is to provide direct-to earth communication and navigation services for missions operating from 36,000 kilometers (km) in the GEO to cis-Lunar and other orbits out to 2 million km. To fully support distant orbits there will be three LEGS sites roughly equally spaced around the Earth. [1] [2]
The existing NASA DSN is already heavily utilized, and an audit in 2023 [3] revealed limitations of the current DSN, in particular its support of crewed and uncrewed lunar missions:
LEGS will help this situation by providing additional resources explicitly for the lunar program.
The 2 million km figure arises from the International Telecommunication Union specifications, which sets aside various frequency bands for deep space and near Earth use. This standard defines "deep space" to start at a distance of 2 million km (1.2 million mi) from the Earth's surface, [4] whereas "near space" is anything closer. Therefore LEGS will operate in the near space bands. Since the distances are considerably less than those supported by the DSN, LEGS will use 18 meter antennas, as opposed to the 34 and 70 meter antennas of the DSN.
The three stations will be White Sands Missile Range, Matjiesfontein in South Africa, and a third location in Australia at a site yet to be determined. [5] [2]
The NASA Deep Space Network (DSN) is a worldwide network of spacecraft communication ground segment facilities, located in the United States (California), Spain (Madrid), and Australia (Canberra), that supports NASA's interplanetary spacecraft missions. It also performs radio and radar astronomy observations for the exploration of the Solar System and the universe, and supports selected Earth-orbiting missions. DSN is part of the NASA Jet Propulsion Laboratory (JPL).
The Goldstone Deep Space Communications Complex (GDSCC), commonly called the Goldstone Observatory, is a satellite ground station located in Fort Irwin in the U.S. state of California. Operated by NASA's Jet Propulsion Laboratory (JPL), its main purpose is to track and communicate with interplanetary space missions. It is named after Goldstone, California, a nearby gold-mining ghost town.
The X band is the designation for a band of frequencies in the microwave radio region of the electromagnetic spectrum. In some cases, such as in communication engineering, the frequency range of the X band is rather indefinitely set at approximately 7.0–11.2 GHz. In radar engineering, the frequency range is specified by the Institute of Electrical and Electronics Engineers (IEEE) as 8.0–12.0 GHz. The X band is used for radar, satellite communication, and wireless computer networks.
The Canberra Deep Space Communication Complex (CDSCC) is a satellite communication station, part of the Deep Space Network of NASA's Jet Propulsion Laboratory (JPL), located at Tidbinbilla in the Australian Capital Territory. Opened in 1965, the complex was used for tracking the Apollo Lunar Module, and along with its two sister stations at Goldstone, California and Madrid, Spain is now used for tracking and communicating with NASA's spacecraft, particularly interplanetary missions. Its DSS-43 antenna is the only antenna on Earth that can send commands to Voyager 2. It is managed in Australia by the Commonwealth Scientific and Industrial Research Organisation (CSIRO) for NASA’s Space Communications and Navigation program (SCaN) at NASA Headquarters in Washington, D.C.
Time History of Events and Macroscale Interactions during Substorms (THEMIS) mission began in February 2007 as a constellation of five NASA satellites to study energy releases from Earth's magnetosphere known as substorms, magnetic phenomena that intensify auroras near Earth's poles. The name of the mission is an acronym alluding to the Titan Themis.
The Manned Space Flight Network was a set of tracking stations built to support the American Mercury, Gemini, Apollo, and Skylab space programs.
The Near Earth Network provides orbital communications support for near-Earth orbiting customer platforms via various ground stations, operated by NASA and other space agencies. It uses a number of different dishes scattered around the globe. The antennas must be able to move fast for tracking of objects in low Earth orbit (LEO). The NEN and Space Network (SN) combined were previously referred to as the Spaceflight Tracking and Data Network (STDN).
The forerunner of the Deep Space Network was established in January 1958, when JPL, then under contract to the U.S. Army, deployed portable radio tracking stations in Nigeria, Singapore, and California to receive telemetry and plot the orbit of the Army-launched Explorer 1, the first successful U.S. satellite.
Mars Cube One was a Mars flyby mission launched on 5 May 2018 alongside NASA's InSight Mars lander. It consisted of two nanospacecraft, MarCO-A and MarCO-B, that provided real-time communications to Earth for InSight during its entry, descent, and landing (EDL) on 26 November 2018 - when InSight was out of line of sight from the Earth. Both spacecraft were 6U CubeSats designed to test miniaturized communications and navigation technologies. These were the first CubeSats to operate beyond Earth orbit, and aside from telecommunications they also tested CubeSats' endurance in deep space. On 5 February 2019, NASA reported that both the CubeSats had gone silent by 5 January 2019, and are unlikely to be heard from again. In August 2019, the CubeSats were honored for their role in the successful landing of the InSight lander on Mars.
LunIR is a nanosatellite spacecraft launched to the Moon collecting surface spectroscopy and thermography. It was launched as a secondary payload on the Artemis 1 mission on 16 November 2022.
The Deep Space Atomic Clock (DSAC) was a miniaturized, ultra-precise mercury-ion atomic clock for precise radio navigation in deep space. DSAC was designed to be orders of magnitude more stable than existing navigation clocks, with a drift of no more than 1 nanosecond in 10 days. It is expected that a DSAC would incur no more than 1 microsecond of error in 10 years of operations. Data from DSAC is expected to improve the precision of deep space navigation, and enable more efficient use of tracking networks. The project was managed by NASA's Jet Propulsion Laboratory and it was deployed as part of the U.S. Air Force's Space Test Program 2 (STP-2) mission aboard a SpaceX Falcon Heavy rocket on 25 June 2019.
Lunar Polar Hydrogen Mapper, or LunaH-Map, was one of the 10 CubeSats launched with Artemis 1 on 16 November 2022. Along with Lunar IceCube and LunIR, LunaH-Map will help investigate the possible presence of water-ice on the Moon. Arizona State University began development of LunaH-Map after being awarded a contract by NASA in early 2015. The development team consisted of about 20 professionals and students led by Craig Hardgrove, the principal investigator. The mission is a part of NASA's SIMPLEx program.
The Lunar Gateway, or simply Gateway, is a space station which is planned to be assembled in orbit around the Moon. The Gateway is intended to serve as a communication hub, science laboratory, and habitation module for astronauts as part of the Artemis program. It is a multinational collaborative project: participants include NASA, the European Space Agency (ESA), the Japan Aerospace Exploration Agency (JAXA), the Canadian Space Agency (CSA), and the Mohammed Bin Rashid Space Centre (MBRSC). The Gateway is planned to be the first space station beyond low Earth orbit.
Earth Escape Explorer (CU-E3) is a nanosatellite of the 6U CubeSat format that will demonstrate long-distance communications while in heliocentric orbit.
EQUULEUS is a nanosatellite of the 6U CubeSat format that will measure the distribution of plasma that surrounds the Earth (plasmasphere) to help scientists understand the radiation environment in that region. It will also demonstrate low-thrust trajectory control techniques, such as multiple lunar flybys, within the Earth-Moon region using water steam as propellant. The spacecraft was designed and developed jointly by the Japan Aerospace Exploration Agency (JAXA) and the University of Tokyo.
In orbital mechanics a near-rectilinear halo orbit (NRHO) is a halo orbit that passes close to the smaller of two bodies and has nearly stable behavior. The CAPSTONE mission, launched in 2022, is the first spacecraft to use such orbit in cislunar space, and this Moon-centric orbit is planned as a staging area for future lunar missions. In contrast with low lunar orbit which NASA characterizes as being deep in the lunar gravity well, NRHO is described as being "balanced on the edge" of the gravity well.
CAPSTONE is a lunar orbiter that is testing and verifying the calculated orbital stability planned for the Lunar Gateway space station. The spacecraft is a 12-unit CubeSat that is also testing a navigation system that is measuring its position relative to NASA's Lunar Reconnaissance Orbiter (LRO) without relying on ground stations. It was launched on 28 June 2022, arrived in lunar orbit on 15 November 2022, and was scheduled to orbit for six months. On 18 May 2023, it completed its primary mission to orbit in the near-rectilinear halo orbit for six months, but will stay on this orbit, continuing to perform experiments during an enhanced mission phase.
The International Mars Ice Mapper Mission (I-MIM) is a proposed Mars orbiter being developed by NASA, Japan Aerospace Exploration Agency (JAXA), the Canadian Space Agency (CSA), and the Italian Space Agency (ASI). As the mission concept evolves, there may be opportunities for other space agency and commercial partners to join the mission. The goal of the orbiter is the quantification of extent and volume of water ice in non-polar regions of Mars. The results are intended to support future Mars missions, especially with respect to the search for habitable environments and accessible In situ resource utilization (ISRU) resources. The International-Mars Ice Mapper is an "exploration precursor mission", comparing it to the Lunar Reconnaissance Orbiter (LRO) mission. The mission was envisioned to be launched as early as 2026. However, in March 2022, it was revealed in its fiscal year 2023 budget proposal that the US government would terminate NASA financial support for the Mars Ice Mapper, casting the project's future into uncertainty.
Queqiao relay satellite (Chinese: 鹊桥号中继卫星; pinyin: Quèqiáo hào zhōngjì wèixīng; lit. 'Magpie Bridge relay satellite'), is the first of the pair of communications relay and radio astronomy satellites for the Chinese Lunar Exploration Program. The China National Space Administration (CNSA) launched the Queqiao relay satellite on 20 May 2018 to a halo orbit around the Earth–Moon L2 Lagrangian point Queqiao is the first communication relay and radio astronomy satellite at this location.