Remote Sensing Cooperation Between Brazil and China
Remote sensing is a continuously evolving process. Technology has made the satellite images available to everyone, not only to specialized people. Thus, we are beginning a real transformation of remote sensing all over the world. Many new applications and uses of satellite images are expected to appear as remote sensing becomes more and more popular.
In the beginning, satellite availability was restricted to a few countries. The capabilities and characteristics of the payloads were not very large. Currently, spatial resolutions are very diverse, from a few centimeters to hundreds or thousands of meters; swaths are as narrow as a few kilometers to as wide as two thousand kilometers. There are missions with only one instrument, and missions with various instruments.
|Jose Carlos N. Epiphano|
Coordinator of the CBERS Application Program, Sr. Researcher at INPE (National Institute for Space Research)
São José dos Campos, Brazil
This diversity of resolutions is important for users, as they can choose the best combination of sensors, satellites, and data policies to fit their needs. At the same time, more and more countries are becoming part of the club of satellite owners.
Brazil was one of the first countries to build and operate a ground station to receive Landsat-1 data back in 1973. Since then, remote sensing has become strong there, counting on the support of educational programs at various levels, including graduate courses at masters and doctoral levels. Based on these foundations, a number of remote sensing research and application programs were developed.
As Brazil is large geographically—more than 8.5 million km2—and has high biodiversity, special ecosystems such as the Amazonian and Pantanal regions, an ever-growing agriculture, a fast-changing land use and land cover, and a long coastline, it is especially suited for space-based remote sensing developments. Thus, it was natural that Brazil would envisage its own remote sensing satellite development.
CBERS: China-Brazil Earth Resources Satellite
At the end of the 1980’s, Brazil began the development of a civilian remote sensing satellite program with China. This cooperation is now 20 years old and has launched three satellites successfully. It was one of the first programs in the world involving two countries under development striving to build and launch a satellite – an effort that brings difficult technological challenges. To be successful, the cooperative effort had to overcome many obstacles. The first one was the language; since the two countries have languages that are very different, a third one had to be chosen to work as a common language. The cultures are very different also, and adaptations from both sides had to be done so that both teams could work together. Many other obstacles had to be overcome as the project evolved.
The initial signed agreement was for the development and launch of two remote sensing satellites. In October 1999, the first satellite, CBERS-1, was launched from Xi’An (a Chinese launching base), and was carried by Long March-IV launch vehicle. The second CBERS was launched four years later, in October 2003. In 2002, before the launching of CBERS-2, a new agreement was signed for the continuity of the CBERS mission, which included two new remote sensing satellites, with new characteristics and payloads. However, as CBERS-3 would be launched only around a 2010 time frame, after the de-commissioning of CBERS-2, both countries decided to sign a third agreement in 2004, for the development of CBERS2B, very similar to CBERS-1 and -2, using as much as possible engineering parts from the first two satellites. CBERS-2B was successfully launched in a very short time, in September 2007.
The cooperation between Brazil and China for development of remote sensing satellites has been so successful and useful for both countries that a new CBERS family is under way, with CBERS-5 and -6. The continuity of the CBERS Program is viewed as strategic for the environmental monitoring of both countries.
Figure 2 - Field campaign for CCD/CBERS calibration.
The orbit of CBERS satellites is a sun-synchronous, quasi-polar, 26 days phased and circular orbit, at 744-km altitude, and 10:30 Equator crossing time. The main payload of the first three CBERS satellites is a CCD camera with 20-m GIFOV (ground instantaneous field of view), five bands (blue, green, red, NIR, pan), 8 bits, 113-km swath, and ±32° across-track viewing capability. The second important payload present in these three satellites is a Wide Field Imager (WFI), with two bands (red and NIR), 260-m GIFOV at nadir, 890-km swath. As part of CBERS-1 and -2, there was an Infrared Scanner (IRMS) with four bands (pan, TIR, and two in SWIR), 80-m (160-m TIR) spatial resolution, 120-km swath. For CBERS-2B, this scanner was replaced with a High Resolution Camera (panchromatic, 2.7-m spatial resolution, 27-km swath). Figure 1 depicts an HRC image. CBERS-2 is still operational, but only the CCD camera is working; CBERS-2B is fully operational. All CBERS satellites have onboard recording capability. Figure 2 shows a field campaign to calibrate CCD/CBERS-2.
The CBERS second generation is composed of two new satellites: CBERS-3 and -4. The orbital characteristics are the same as for CBERS-1, -2 and -2B. The multi-payload is composed of a Multispectral Camera similar to the CCD from previous CBERS. A second camera is a Panchromatic-Multispectral Camera (10-m XS-ñ blue, green, red, NIR, 5-m Pan), with 60-km swath and across-track viewing capability. The WFI was improved: four bands (blue, green, red, NIR), 70-m spatial resolution at nadir, 860-km swath. The scanner was also improved: four bands (pan, two SWIR, one TIR), with 40-m (80-m TIR) spatial resolution. The on-board recording capability is 15 minutes for all instruments altogether.
Data Policy and Applications
One of the main aspects of the CBERS Program is the data policy adopted after the CBERS-2 launch. Brazil adopted the free-of-charge CBERS data distribution policy when data are requested in electronic format. Initially adopted for Brazilian users, it was extended for neighboring countries, and then to the world. Currently, all CBERS data gathered at Cuiaba, the Brazilian ground station, is distributed free of charge to everyone(www.dgi.inpe.br/CDSR).
Each year, more than 100,000 CCD scenes have been distributed inside the country to thousand of users and institutions. The processing system is very fast and it takes only a few minutes for the user to have his request for a full-resolution scene fulfilled. This kind of data policy and easy distribution system promoted a strong increase in the number of users and applications.
Today, there is no organization related to agriculture, environment, geology, or hydrology in the country that is not a CBERS user. Hundreds of businesses in remote sensing were opened after the adoption of the current data policy. The environmental control by the society was also increased. Figure 3 shows the CCD/CBERS images requested in just one month. Almost all of Brazil and parts of other countries covered by the Cuiaba ground receiving station have requested data at least one time in that particular month.
Figure 3 - Number of CCD/CBERS-2 images requested in just one month. Each star indicates one path/row requested at least one time.
Figure 4 - CCD/CBERS stereoscopic data for feature extraction.
In general, governmental institutions have difficulty in acquiring up-to-date remote sensing data. This problem is worse in developing countries. For instance, the deforestation in the Amazon region is a main environmental issue in Brazil. Actions from the governmental environmental protection agency depend on monitoring, based on remote sensing COMdata. The fast and free access to CBERS data allows the agency to use up-to-date satellite data to map and measure deforested areas. The map and figures of deforested areas in the Amazon region on an annual basis used to be based on Landsat data, and now the map has the help of CCD/CBERS data (www.obt.inpe.br/prodes/index.html).
Another important activity in Amazonia is the project called DETER (Detection of Deforestation in Near Real Time; www.obt.inpe.br/deter/metodologia.pdf), which is aimed at detecting early signs of deforestation and at alerting the environmental agency in time to take action. This is a permanent monitoring system based on MODIS and WFI/CBERS data.
Brazilian legislation requires that each farmer identify and notify the environmental agency about areas to be protected on each farm. This procedure is called environmental licensing and has been adopted in many states around the country. Currently, most of this procedure is done based on CBERS images and has opened hundreds of small businesses specializing in this kind of service. As CCD/CBERS has stereo-viewing capability, its data can be used for feature extraction (Figure 4).
An interesting application of CBERS images is in tax enforcement (Figure 5). Some states use CBERS to help them to monitor farms to assure that all declarations made by farmers are in accordance with the tax law. More examples of applications of CBERS data in Brazil can be found at www.dsr.inpe.br/seminariocbers/.
Figure 5 - CCD/CBERS image helps Brazilian fiscal agency to apply tax enforcement law.
As part of the objective of making the CBERS Program as useful as possible to mankind, Brazil and China decided to launch the project CBERS for Africa, which will distribute CBERS images for African countries to help them control deforestation and protect the environment. This project is part of the contribution of both countries to the GEO (Group on Earth Observation). At least two ground receiving stations in Africa will be able to have direct downlink of CBERS remote sensing data beginning later this year.
The CBERS Program, developed under a Chinese and Brazilian cooperation, is an important and very useful data provider to both countries and their neighbors – and now to Africa. The data policy that assures free access to CBERS images brought new remote sensing users, applications and business. Applications related to environmental protection were improved with CBERS data availability and free access.
Editor's Note: See Fall 2007 Policy Watch column for related article about CBERS and China's emerging Earch observations program.