The Indian Space Research Organisation (ISRO) has announced the successful de-orbiting of Cartosat-2, the first of the second generation of high-resolution imaging satellites. Cartosat-2 was launched in January 2010 and served for 17 years, providing valuable data for various applications such as mapping, urban planning, land use, road network, water distribution and disaster management. In this article, we will look at the features, achievements and challenges of Cartosat-2 and its de-orbiting process.
Features of Cartosat-2:
Cartosat-2 was a polar, sun-synchronous satellite that performed 14.78 orbits around the Earth in a day. It had a panchromatic camera with a resolution of 0.8 metres and a multi-spectral camera with a resolution of 4 metres. It could capture images of an area of 9.6 km by 9.6 km in a single scene. It also had an onboard solid state recorder with a capacity of 64 GB to store the images. Cartosat-2 was designed to have a mission life of five years, but it exceeded its expectations and operated for more than three times its planned duration.
Achievements of Cartosat-2:
Cartosat-2 was one of the most advanced remote-sensing satellites of ISRO at the time of its launch. It provided high-quality images that were extensively used for various purposes such as:
- Mapping: Cartosat-2 generated large-scale maps of India and other countries, covering more than 90% of the Indian landmass. It also contributed to the National Map Policy and the National Spatial Data Infrastructure initiatives.
- Urban planning: Cartosat-2 helped in planning and monitoring urban development, infrastructure, housing, slums, traffic and transportation systems.
- Land use: Cartosat-2 enabled the assessment and management of land resources, such as agriculture, forestry, soil, water and minerals.
- Road network: Cartosat-2 supported the creation and updating of road network maps, including national highways, state highways and rural roads.
- Water distribution: Cartosat-2 assisted in the estimation and allocation of water resources, such as surface water, groundwater and irrigation systems.
- Disaster management: Cartosat-2 provided timely and accurate information for disaster response and recovery, such as floods, cyclones, landslides, earthquakes and forest fires.
Challenges of Cartosat-2:
Cartosat-2 faced several challenges during its operational life, such as:
- Space debris: Cartosat-2 was exposed to the risk of collision with space debris, which are fragments of defunct satellites and rockets that orbit the Earth. According to the European Space Agency (ESA), there are more than 34,000 pieces of space debris larger than 10 cm in size and millions of smaller ones.
- Obsolescence: Cartosat-2 became outdated with the launch of newer and better satellites by ISRO and other countries. For example, Cartosat-3, which was launched in November 2019, has a resolution of up to 0.25 metres and can cover an area of 16 km by 16 km in a single scene.
- Fuel depletion: Cartosat-2 had a limited amount of fuel to maintain its orbit and attitude. As the fuel level decreased over time, it became difficult to control the satellite’s position and orientation.
De-orbiting process
The natural de-orbiting phase of Cartosat-2 was estimated to be around 30 years. However, ISRO decided to lower its perigee from the original altitude of 635 km to 380 km in 2020 using the leftover fuel. This was done to reduce the collision risks and ensure safe end-of-life disposal of the satellite, in accordance with the international guidelines on space debris mitigation.
On February 14, 2024, ISRO further lowered the orbit of Cartosat-2 to 130 km before finally de-orbiting it, facilitating its re-entry over the eastern regions of the Indian Ocean. ISRO confirmed the re-entry of Cartosat-2 near the Indian Ocean using its System for Safe and Sustainable Space Operations in Bengaluru.
The de-orbiting of Cartosat-2 is a significant achievement for ISRO, as it demonstrates its commitment to responsible and sustainable use of space. It also paves the way for future launches of advanced remote-sensing satellites by ISRO, such as Cartosat-3A and Cartosat-3B, which are expected to have resolutions of up to 0.25 metres.
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