EG1106 GI – A Primer. 3 rd December 2004 Interplanetary navigation and Extraterrestrial cartography. TOPICS. Types of spacecraft Spacecraft navigation The Deep Space Network (DSN) The mapping of the Moon Mapping Mars Practical today. Types of spacecraft. Satellites Polar orbiters
3rd December 2004
Interplanetary navigation and
Meteosat NOAA Polar Orbiter
Launched in 1977 - Voyager 1 is still operational
Launched in 1989
Launched in 1989
Launched in 1976
A VLBI observation of a spacecraft begins when two DSN stations on different continents track a single spacecraft simultaneously. High-rate recordings are made of the downlink's wave fronts by each station, together with precise timing data. After a few minutes, and while still recording, both DSN antennas slew directly to the position of a quasar, which is an extragalactic object whose position is known to a high precision.
Then they both slew back to the spacecraft, and end recording a few minutes later. Correlation and analysis of the recorded wavefronts yields a very precise triangulation from which both angular position and radial distance may be determined.
This process requires knowledge of each station's location with respect to the location of Earth's axis with very high precision. Currently, these locations are known to within 3 cm.
The NASA Deep Space Network - or DSN - is an international network of antennas that supports interplanetary spacecraft missions and radio and radar astronomy observations for the exploration of the solar system and the universe. The network also supports selected Earth-orbiting missions.
Each DSS comprises a high-gain, parabolic reflector antenna dish steerable in azimuth and elevation, and its associated front-end equipment such as low-noise amplifiers and transmitters.
Lunar dust: orange glass (0.03mm) over three thousand million years old.