The a new era of earth observation started with the launch of Landsat – 1 (earlier named as Earth Resource Technology Satellite or ERTS) in 1972. According to the latest data available (updated on 9th April, 2007) from the Union of Concerned Scientists (UCS, a science-based nonprofit organisation working for a healthy environment and a safer world) at https:// www.ucsusa. org/global_security/space_weapons/s atellite_database.html, at present there are 847 active satellites in the space being used for different purposes (Fig- 1). As per the classification done by UCS, only 4% are being used for remote sensing purposes and 8% for the earth observation/earth sciences. Upon studying the purposes and the sensors being used in the satellites, there are 50 satellites (6%), exclusively being used in the geospatial domain.
For the satellites under the geospatial domain, further, it was found that there are only 9 satellites being operated by the private organisations while the rest were being operated by the government.
Fig. 1 Distribution of satellites as per their purpose.
The country wise distribution of the already launched remote sensing satellites (till Dec 2006) are given in Fig-2a. This was compared with the remote sensing satellites, proposed to be launched (data available at www.space-risks.com) in the years to come (Jan 2007 onwards), and is shown in Fig-2b. At present there are 19 countries who own remote sensing satellites while, Argentina, Brazil and Thailand are the three new countries, who will have their own satellites in the years to come.
Fig. 2a Country wise remote sensing satellites (1984 – 2006)
Fig. 2b Country wise remote sensing satellites (2007 – 2013)
The present users of the satellite data are mainly government (Fig-3) while the rest 50% are split between civil, military and commercial users. Among these 4% of the military data is also used by the commercial users whereas
Fig. 3 Users of the remote sensing satellite data
8% of the government data is also used for the commercial purposes. Since 1984, till 2006, the number of satellites launched every year increased which saw a steep rise after 1999 (Fig-4a). There is a significant increase in the proposed launches in 2007, which will reach to 14 and the subsequent years having significant launches planned (Fig-4b). This year, till June 2007, satellites proposed to be launched
Fig. 4 Number of Remote Sensing satellites launched (1984 – 2006).
Fig. 4b Proposed launches of Remote Sensing satellites
- COSMO -Skymed (4X): 8th June, 2007
- GeoEye-1: 30th June, 2007
- CARTOSAT-2: 10th Jan, 2007
- ORBVIEW-5: 1st Jan, 2007
- RADARSAT-2: 31st March, 2007
- RAPIDEYE (5X): 30th June, 2007
- TERRASAR-X: 15th June, 2007
- THEOS: 30th June, 2007
- WORLDVIEW-1: 30th June, 2007
However, only three of them (Cartosat-2, COSMOSkymed & TereaSAR-X) have been launched. The remote sensing satellite launches, in the coming years, with their other details are given in Table-1 and these satellites with their operating life are shown in Fig-5. In the 1 m better resolutio there will be 9 s the end of this Europe wi “ Number of Satellite Year.
With the advancement and development in the sensor technology, remote sensing has reached a resolution of 0.7m (PIC-2 sensor in the Israeli satellite EROSB1, launched in April, 2006). Although IKONOS was the first satellite with MSS and PAN sensor, to reach 1m resolution in PAN, more and more satellites are being launched and scheduled to be launched in the near future with better resolution. Worldview1 and 2 will have 0.45m and 0.46m as its spatial resolution, scheduled for launch in 2007 and 2008. Although more satellites will be launched in the coming years, but according to the published data, no satellite will have spatial resolution better than the Worldview satellites. There were only three satellites with RADAR capability, till 2005, which will increase to 9, by this decade. RADAR satellites are mainly being launched by European countries with Argentina and India also venturing.
Surprisingly, USA does not have any RADAR satellite, nor they have planned for any! In the high resolution category (1m or better), there will be 9 satellites by the end of this decade and except 2 from 1 meter or lution category e 9 satellites by his decade and e will lead. ” Year Number of Satellite USA, one from India and Israel each, all five are planned by Europe (Germany, France and Italy). The coming years will see a lot of public- private partnerships, where the commercial operators will build, launch and manage the satellites and the data, and the government will be the major buyer of the data. The launch of TERRASAR- X on 15th of June started this trend which will soon be followed by other countries.
Another trend of collaborations between countries to build and launch satellites might change in the years to come. As the sensor technologies, hardware and other necessary equipments have become easily available, countries have started assembling the satellites and soon there will be a proliferation of satellites and availability of data, which should result cheaper satellite data and value added services and products for the end-users.
Every country and organisation responsible for the launch of the satellites, archive their data, but still there is a lack of a global metadata, availability of which could help the users in locating the desired data and procuring them. The above observations might be achieved in some or the other form, in the years to come.
Table. 1 Credits: www.ucsusa. org and
Please Note: The graphs in the article have been prepared using the date from UCS and EOSS websites