Satellite in orbit earth blue

Satellites in Earth orbit monitor climate, forests, oceans, and communications, providing essential data for science and society.

About this subject

Artificial satellites in Earth orbit are key components of modern infrastructure. Since the launch of Sputnik in 1957, thousands of satellites have been placed at various altitudes and inclinations for specific purposes. Earth observation satellites, such as the U.S. Landsat program and Europe's Sentinel series, capture multispectral images that enable monitoring of deforestation, urban growth, crop health, and glaciers. Weather satellites like the GOES series provide real-time data for forecasting and natural disaster alerts. In telecommunications, constellations like Starlink aim to deliver broadband internet to remote areas.

In Brazil, the CBERS (China-Brazil Earth Resources Satellite) program, developed in partnership with China, has launched satellites that image the national territory, aiding in Amazon monitoring and precision agriculture. Scientific satellites such as SCD-1 (Data Collection Satellite), launched in 1993, pioneered environmental data collection in the Amazon region. Low Earth orbit (LEO, up to 2,000 km) is the most populated, hosting everything from small CubeSats to the International Space Station. Geostationary orbit (GEO, about 36,000 km) allows communication and weather satellites to remain fixed over one point on Earth.

Maintaining these devices is challenging: solar radiation, space debris, and atmospheric drag degrade components over time. Hence, modern satellites feature ion thrusters and redundant systems. Despite these challenges, space exploration continues to advance with smaller, cheaper satellites like CubeSats, which have democratized access to space for universities and startups. A documentary image of a satellite in orbit against the blue Earth serves as a reminder of human reach and our planet's fragility.

Frequently Asked Questions

How many satellites are currently in orbit?

It is estimated that over 8,000 artificial satellites are orbiting Earth, with about 5,000 still operational. Most are in low Earth orbit (LEO), including large constellations like Starlink.

What is the difference between low Earth orbit (LEO) and geostationary orbit (GEO)?

LEO satellites (up to 2,000 km altitude) orbit quickly, about every 90 minutes, and are used for observation and low-latency internet. GEO satellites (≈36,000 km) match Earth's rotation, remaining fixed over one point, ideal for communications and weather.

Does Brazil have its own operational satellites?

Yes, Brazil operates satellites such as the CBERS series (in partnership with China) for Earth imaging, SCD-2 for environmental data collection, and SGDC for government communications and broadband internet.