The purpose of the Telemetry System is to provide the capability to acquire, process, decode and distribute deep space probe and Earth orbiter telemetry data. Telemetry data consists of science and engineering information modulated on radio signals transmitted from the spacecraft. The Telemetry System performs three main functions: Telemetry data acquisition, telemetry data conditioning and transmission to projects and telemetry system validation.

The purpose of the Command System is to provide the means by which a Project controls the activities of its spacecraft. Control information (Command Data), provided by the Project, is modulated on the RF carrier and transmitted to a spacecraft by a DSN station. The Command System functions as a transfer medium between the Project Control Center and its spacecraft.

The purpose of the Tracking System is to provide two-way communication between Earth based equipment and spacecraft, to make measurements that will allow the state vector (position and velocity) of spacecraft to be determined.

The purpose of the Very Long Baseline Interferometry (VLBI) System is to provide the means of directly measuring plane-of-the-sky angular positions of radio sources (natural or spacecraft), DSN station locations, interstation time and frequency offsets, and Earth orientation parameters.

The field of Radio Science improves our knowledge of the solar system and the theory of general relativity through radio frequency experiments performed between spacecraft and the Deep Space Network's (DSN) Radio Science System. In the past, Radio Science has performed experiments which have allowed scientists to characterize planetary atmospheres and ionospheres, characterize planetary surfaces, characterize the planetary rings, characterize the Solar corona, confirm general relativity, characterize interplanetary plasma, search for gravitational waves, characterize planetary gravity , and determine the mass of the planets, moons, and asteroids.

The purpose of the Monitor and Control System is two-fold: to provide real time monitor data to projects which reflect the status of project support by DSN systems, and to provide monitor and control capabilities to operators of DSN systems' components.

In addition to serving as a communications instrument for deep space exploration, the DSN may be used as an advanced technological instrument for scientific research and development. The DSN makes its facilities available to any qualified scientist on a noninterference basis with spacecraft mission support. The DSN encourages the use of its facilities for those scientific observations that exploit its unique elements and capabilities. This includes collaboration with other NASA and non-NASA observatories.

The DSN anticipates and responds to user needs. The DSN maintains and upgrades its facilities to accommodate all of its users. This includes not only the implementation of enhancements to improve the scientific return from current experiments and observations, but also long-range research and development to meet the needs of future scientific endeavors.

Radio and Radar Astronomy. The acquisition and extraction of information from signals emitted or reflected by natural celestial sources; includes studies in the fields of astrophysics, Earth physics, planetary radar, gravitation and relativity.

Interferometry. The accurate measurement of radio source positions; includes astrometry, very long baseline interferometry, connected element interferometry, interferometry arrays and orbiting interferometry. Measurement of station locations and Earth orientation for studies of the Earth.

Earth Dynamics. The measurement of station locations and Earth orientation. The Global Positioning System (GPS) is a constellation of 24 satellites which is used for navigation and precise geodetic position measurements. The GPS, originally developed by the U.S. Department of Defense, has been applied recently to the study of earthquakes.

Sky Surveys. Identification and mapping of radio sources to create radio position reference frames; includes radiometry, polarimetry, spectroscopy and enhanced spectral analysis. The DSN has built a subnetwork of 11-meter antennas whose primary purpose is to support two orbiting VLBI Satellites. Both satellite missions are radio astronomy projects designed to provide high resolution maps of radio emissions from natural sources using the technique of Very Long Baseline Interferometry (VLBI).