indianspacestation.com

ISRO's Trend towards Micro and Nano-satellites

ISRO’s Trend towards Micro and Nano-satellites

ISRO has been launching multi-purpose satellite for a long time to reduce the cost of the satellite launch. In addition, the size/weight of the satellite built during early days used to heavy. Also, the technology was not matured enough during those early days to reduce the payload size considerably. The problem with this flow is that a payload ready for a particular mission has to wait for other payloads (different mission objectives) to complete. When the remaining payloads do get ready, the integration becomes complex and that delays the satellite launch further again...  However, after a decade long research in the various fields the launch cost has been reduced considerable. Also there is a significant development in the technology required to miniaturize the payload size. ISRO is all set to change their design methodology to take benefit of the various matured technologies.

micro

ISRO is planning to launch many small satellites intended for specific applications. It is getting away with multi-purpose satellite approach to reduce the complexity and also the time-to-launch. It is planning to launch a series of small satellites making use of the advanced miniaturization technologies. Broadly, they have two types of miniaturize satellite categories, micro and nano/mini-satellites. Here are the characteristics of those categories.

Parameter                           Micro                              Nano/mini      
Total Satellite Weight           100 kg                            < 450 kg      
Payload weight capacity      < 30 kg                           < 200 kg      
Power generated                  200 W                             573 W      
Payload power                     30 W                               200 W      
Pointing accuracy                 0.1                                 0.2      
Drift rate                               5 x 10-4                          1.0 x 10-4 / s      
Data transmission              10 Mbps in S-band              20 Mbps in X-band     

The performance of the micro/mini satellites may not match the performance IRS class satellites for sometime. To get the same performance, the ISRO will have to do a lot of optimization in the design of the various sub-systems (decade long design methodology has to change). However, as the technology improves the performance gap will reduce significantly.


List of micro/mini satellites planned/launched:
TWSAT
Third world satellite (TWSAT) is the first micro-satellite that was launched by ISRO. It has been renamed to IMS-1. The mission objective was to provide data for the academic organizations and research organization in developing countries free of cost. TWSAT carries a 4-band multi-spectral camera with a spatial resolution of 36m.  The data provided by TWSAT can be used for application like resourced management in agriculture, forestry, and land use and in disaster management. Here is the list of the sub-systems in TWSAT in the increasing order of the total weights,
·    Actuators
·    Power
·    Structure
·    Sensors
·    Payload
·    Integration
·    Thermal/BMU/Mechanism

Details:
Orbit                                                                        Polar sun synchronous      
Altitude                                                                    635km      
Mission life                                                               2 years      
Mass                                                                       83 kg      
Data storage                                                            16 Gb solid state recorder      
Telemetry,tracking, command and data handling         S-band      
Launch date                                                             24/04/2008     




Launch of IMS-1 on PSLV-C9

YouthSat:
Youth Satellite is the second in the series of micro-satellite category by ISRO. The satellite is being developed jointly between Russian universities and Indian universities. It is expected launched somewhere during late-2009.

The mission objectives are,
·    To study the solar activity
·    To study the effect of solar activity on ionosphere.

The scientific instruments are being developed by students in both the countries to give them a hands-on experience in space experiments and data processing.

SARAL:
Satellite with Argos and ALtika is the first mini/nano-satellite being developed /to be launched by ISRO.  It is a satellite with 2 payloads (Argos nd ALtika) from French space agency, CNES. The satellite is planned to be  placed in sun-synchronous orbit of 800 km. CNES is providing the payload module consisting of the AltiKa altimeter, DORIS, LRA, and Argos-3 DCS (Data Collection System), and the payload data reception and processing functions, while ISRO is responsible for the platform, launch, and operations of the spacecraft. The satellite is expected to be launched during late-2010.

The mission objectives of SARLA are,
·    To realize precise, repetitive global measurements of sea surface height, significant wave heights and wind speed for
·    The development of operational oceanography (study of mesoscale ocean viability, coastal region observations, inland waters, marine ecosystems, etc.)
·    Understanding of climate and developing forecasting capabilities
·    Operational meteorology.


Add comment


Security code
Refresh