Delta-Differential One-Way Ranging (or Delta-DOR, Δ-DOR for short) is an interplanetary radio-tracking and navigation technique.

How it is done

Radio signals from the spacecraft are received by two widely separated deep-space ground stations on Earth and the difference in the times of signal arrival is precisely measured (and used to calculate a bearing). This is corrected using information about the current delays due to Earth's atmosphere, obtained by simultaneously tracking (from each ground location) radio signals from a quasar (within 10 degrees of the same direction).

NASA The National Aeronautics and Space Administration (NASA ) is an independent agencies of the United States government, independent agency of the federal government of the United States, US federal government responsible for the United States ...

uses its

Deep Space Network The NASA Deep Space Network (DSN) is a worldwide Telecommunications network, network of spacecraft communication ground segment facilities, located in the United States (California), Spain (Madrid), and Australia (Canberra), that supports NASA' ...

to pick up signals from the spacecraft that tell navigators where the spacecraft are located. This navigation service is called "tracking coverage" and it includes Doppler, ranging and delta differential one-way ranging, or "Delta DOR." ESA has the

ESA Deep Space Network The European Space Tracking (ESTRACK) network consists of a number of ground-based space-tracking stations belonging to the European Space Agency (ESA), and operated by the European Space Operations Centre (ESOC) in Darmstadt, Germany. The stat ...

, China has the

Chinese Deep Space Network The Chinese Deep Space Network (CDSN) is a network of large antennas and communication facilities that are used for radio astronomy, radar observations, and spacecraft missions of China. The CDSN is managed by the China Satellite Launch and Trac ...

and India has the

Indian Deep Space Network Indian Deep Space Network (IDSN) is a network of large antennas and communication facilities operated by the Indian Space Research Organisation (ISRO) to support the interplanetary spacecraft missions of India. Its hub is located at Byalalu, ...

Missions that used it

Δ-DOR navigation has been used by number of NASA planetary missions. Other space agencies have also used the technique, on missions such as:

ESA The European Space Agency (ESA) is a 23-member international organization devoted to space exploration. With its headquarters in Paris and a staff of around 2,547 people globally as of 2023, ESA was founded in 1975 in the context of European ...

used a Δ-DOR system for Venus Express' orbit insertion in April 2006 and to Rosetta's Mars swingby in February 2007. The technique was also used in guiding the ExoMars Trace Gas Orbiter during its cruise phase in 2016.

CNSA The China National Space Administration (CNSA) is a government agency of the People's Republic of China headquartered in Haidian, Beijing, responsible for civil space administration and international space cooperation. These responsibilities ...

is using Δ-DOR technique for

Chang'e Chang'e ( ; ), originally known as Heng'e (), is the goddess of the Moon and wife of Hou Yi, the great archer. Renowned for her beauty, Chang'e is also known for her ascending to the Moon with her pet Yu Tu, the Moon Rabbit and living in the Mo ...

series lunar spacecraft tracking

ISRO The Indian Space Research Organisation (ISRO ) is India's national space agency, headquartered in Bengaluru, Karnataka. It serves as the principal research and development arm of the Department of Space (DoS), overseen by the Prime Minister o ...

is using Δ-DOR for the Mars Orbiter Mission (MOM). ESA is using Δ-DOR for the

ExoMars Trace Gas Orbiter The ExoMars Trace Gas Orbiter (TGO or ExoMars Orbiter) is a collaborative project between the European Space Agency (ESA) and the Russian Roscosmos agency that sent an atmospheric research orbiter and the ''Schiaparelli'' demonstration lande ...

(TGO).Quasar to guide ESA's Mars landing. July 2016
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References

External links

Deep Space Network (DSN)

ESA Deep Space Network (Estrack)

Indian Deep Space Network (IDSN)
Spaceflight technology {{radio-comm-stub