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The Cold Gas System on TDX - Accurate in-Orbit Evaluation

Schulze, Daniel and Kahle, Ralph and Herman, Jacobus and Dietrich, Arno (2014) The Cold Gas System on TDX - Accurate in-Orbit Evaluation. In: SpaceOps 2014 - 13th International Conference on Space Operations. SpaceOps 2014 - 13th International Conference on Space Operations, 2014-05-05 - 2014-05-09, Pasadena, California, USA. doi: 10.2514/6.2014-1928.

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The TanDEM-X mission comprises two nearly identical satellites – TSX and TDX – that fly at an altitude of ~515 km in a close formation at distances down to 120 m. The standard orbit corrections are made with hydrazine propulsion on both spacecraft, but the relative geometry is maintained by a dedicated cold gas system on TDX only, which initially comprised 36 kg of nitrogen. The routine formation-keeping requires at least one pair of cold gas maneuvers daily. Formation flight started in late 2010 and continued ever since in several configurations. This means that by now of the order of 2500 cold gas maneuvers have been performed and the remaining amount of fuel will allow for another 1500 to be made. Maneuvers were done mainly with the four 40 milli-Newton thrusters of branch-A, but about 25 % of the time branch-B was used. The construction of a digital elevation model of the Earth requires very precise orbit information, which is delivered by the flight dynamics department at GSOC. This also yields an accuracy of <0.1 mm/s in the a posteriori reconstruction of maneuvers. The large number of maneuvers and the extremely accurate orbit information allow a unique in-orbit evaluation of the cold gas system. Thruster performance is reconstructed from the precise orbit determination combined with 1Hz telemetry during the burn and a priori laboratory measurements. Among others comparisons are made between the two branches and between maneuvers in flight- and anti-flight direction. The influence of the maneuver duration and the tank pressure will also be presented.

Item URL in elib:https://elib.dlr.de/92116/
Document Type:Conference or Workshop Item (Speech)
Title:The Cold Gas System on TDX - Accurate in-Orbit Evaluation
AuthorsInstitution or Email of AuthorsAuthor's ORCID iDORCID Put Code
Date:5 May 2014
Journal or Publication Title:SpaceOps 2014 - 13th International Conference on Space Operations
Refereed publication:No
Open Access:Yes
Gold Open Access:No
In ISI Web of Science:No
Keywords:Kaltgas, cold gas, cold-gas, calibration
Event Title:SpaceOps 2014 - 13th International Conference on Space Operations
Event Location:Pasadena, California, USA
Event Type:international Conference
Event Start Date:5 May 2014
Event End Date:9 May 2014
Organizer:American Institute of Aeronautics and Astronautics (AIAA)
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Earth Observation
DLR - Research area:Raumfahrt
DLR - Program:R EO - Earth Observation
DLR - Research theme (Project):R - Projekt TanDEM-X (old)
Location: Oberpfaffenhofen
Institutes and Institutions:Space Operations and Astronaut Training > Mission Operations
Deposited By: Schulze, Daniel
Deposited On:19 Nov 2014 09:43
Last Modified:24 Apr 2024 19:57

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