Techniques Adopted To Sustain The Data Services From IRS-P4 Mission Under Power Crunch Scenario
- Paper number
IAC-07-C1.5.03
- Author
Mr. Ambarisha Babu M., Indian Space Research Organisation (ISRO), ISTRAC, India
- Coauthor
Mr. S.K. Shivakumar, Indian Space Research Organisation (ISRO), India
- Coauthor
Mr. P. Soma, Indian Space Research Organisation (ISRO), India
- Coauthor
Mr. SUBRAMANIAN J R, Indian Space Research Organisation (ISRO), ISTRAC, India
- Year
2007
- Abstract
IRS-P4, an earth pointing satellite meant for Ocean Applications was launched in May 1999 and carried two onboard payloads namely, Ocean Color Monitor (OCM) and Multi-frequency Scanning Microwave Radiometer (MSMR). The MSMR payload was functioning continuously from June 1999 to October 2001 and collected data on a global basis. OCM payload was switched ON for a maximum duration of 14 minutes per orbit over Indian and international ground stations. Onboard power generation by two sun-tracking solar panels amounted to 785 watts ensuring a comfortable power margin.
In October 2001, the anti sun side solar panel (ASS) completely lost capability for rotation and was stuck permanently. This resulted in reduction of power generation duration for ASS panel during sunlit from 65 minutes to 19 minutes/orbit. This condition called for meticulous load management because of loss of 40
During the period of time from October 2001 to December 2006, 8 out the total 18 strings of the solar array failed, further aggravating the power crisis. The power generation was just sufficient to meet the mainframe load requirements and adequate power was not available to carry out OCM payload operations. A strategy was then devised to over come this crippling power crisis and to extend the useful mission life by providing payload data to global user community. The strategy was to orient the spacecraft solar panels towards Sun by retaining the inertial attitude of the spacecraft at the end of sunlit region for the rest of the orbit. This strategy was executed during all non-imaging orbits. Whenever payload operations were to be carried out, the spacecraft was brought back to earth pointing mode. Thus, the spacecraft had two attitude orientations, one to satisfy payload requirements and the other one to satisfy power requirements. However, this strategy had some associated issues, like thermal management and attitude maintenance, because of gyro drift due to gyro temperature variations in two spacecraft orientations. Both these issues were taken care by judicious planning of spacecraft operations on daily basis.
This strategy was followed from 26 January 2006 onwards by which sufficient power generation during non-payload orbits was ensured. This allowed charging of the battery fully to cater for 5 - 6 payload operations/day. This approach has led to extending the useful life of India’s only oceanographic spacecraft.
- Abstract document
- Manuscript document
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