Delta-DOR explained

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."^{[1] [2]}

ESA has the ESA Deep Space Network, China has the Chinese Deep Space Network and India has the Indian Deep Space Network.

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. The technique was also used in guiding the ExoMars Trace Gas Orbiter during its cruise phase in 2016.^{[3] [4] [5] [6] [7]}

CNSA is using Δ-DOR technique for Chang'e series lunar spacecraft tracking^{[8] [9]}

ISRO is using Δ-DOR for the Mars Orbiter Mission (MOM).^[10]

ESA is using Δ-DOR for the ExoMars Trace Gas Orbiter (TGO).^[11]

References

1. Web site: Delta Differential One-way Ranging . Golombek, M. P.. et al . 15 July 2004 . DSMS Telecommunications Link Design Handbook.
2. Web site: Delta Differential One-way Ranging Design Handbook . July 15, 2004 . . https://web.archive.org/web/20130218052305/http://deepspace.jpl.nasa.gov/dsndocs/810-005/210/210.pdf . February 18, 2013 . dead .
3. Web site: Delta DOR . 28 September 2007 . ESA.
4. Web site: Delta-DOR A New Technique for ESA's Deep Space Navigation . Maddè Roberto . Morley Trevor . Abelló Ricard. et al . November 2006 . ESA Bulletin 2006 .
5. Web site: The European ΔDOR System . Luciano Iess, Dipartimento di Ingegneria Meccanica e Aerospaziale Sapienza Universita’ di Roma, Italy.
6. Web site: Recommendation for Space Data System Practices. DELTA-DIFFERENTIAL ONE WAY RANGING (DELTA-DOR) OPERATIONSю RECOMMENDED PRACTICE. CCSDS 506.0-M-1. MAGENTA BOOK . April 2011 . Consultative Committee for Space Data Systems (CCSDS) . https://web.archive.org/web/20160304023615/http://public.ccsds.org/publications/archive/506x0m1.pdf . 2016-03-04 . dead .
7. Web site: ExoMars/TGO Operations . European Space Agency (ESA) .
8. Web site: The XF type correlator for Delta-DOR in deep space navigation . 1 September 2014 . Chinese Academy of Sciences . https://web.archive.org/web/20160303232820/http://ivs2014.csp.escience.cn/dct/attach/Y2xiOmNsYjpwZGY6Njc5MjE= . 3 March 2016 . dead .
9. Orbit determination of Chang'E-3 and positioning of the lander and the rover . Chinese Science Bulletin . 59 . 29–30 . 3858–3867 . 1 September 2014 . 10.1007/s11434-014-0542-9 . Huang. Yong. Chang . Shengqi . Li . Peijia . Hu . Xiaogong . Wang . Guangli . Liu . Qinghui . Zheng . Weimin . Fan . Min . 2014ChSBu..59.3858H .
10. Book: ISRO, Indian Space Research Organisation. From Fishing Hamlet to Red Planet: India's Space Journey. Harper Collins Publishers India. 2015. 9789351776895. Rao. P. V. Manoranjan. Noida, Uttar Pradesh, India. EPUB.
11. https://cosmosmagazine.com/space/quasar-to-guide-esa-s-mars-landing Quasar to guide ESA's Mars landing. July 2016

External links

• Deep Space Network (DSN)
• ESA Deep Space Network (Estrack)
• Indian Deep Space Network (IDSN)