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 uses its Deep Space Network 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, China has the Chinese Deep Space Network 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 to support the interplanetary spacecraft missions of India. Its hub is located at Byalalu, Ramanaga ...

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 used a Δ-DOR system for Venus Express' orbit insertion in April 2006 and to Rosetta's Mars swingby in February 2007. CNSA is using Δ-DOR technique for

Chang'e Chang'e ( ; , alternatively rendered as Chang-Er or Ch‘ang-o), originally known as Heng'e, is the Chinese goddess of the Moon. She is the subject of several legends in Chinese mythology, most of which incorporate several of the following elem ...

series lunar spacecraft tracking

ISRO The Indian Space Research Organisation (ISRO; ) is the national space agency of India, headquartered in Bengaluru. It operates under the Department of Space (DOS) which is directly overseen by the Prime Minister of India, while the Chairman ...

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