Beaming scientists last week showed off the first images from NASA's Terra satellite. The flagship of the $11 billion Earth Observing System, Terra is dedicated to long-term monitoring of the home planet's surface, ocean, ice and atmosphere.

All five of Terra's instruments have checked out “in great shape” since the satellite's December launch, says NASA's head of Earth science, Ghassem Asrar. Although it is likely to take months for Terra to produce significant scientific results, the instruments are already showing their great sensitivity.

For example, the Japanese ASTER (advanced spaceborne thermal emission and reflection) instrument caught the aftermath of Mount Usu's volcanic eruption on 31 March (see top left). The three dark streaks in this visible–infrared image are ash deposits.

The US-built moderate-resolution imaging spectroradiometer (MODIS), aside from tracking vegetation changes on the land, is unique among satellite sensors in its ability to monitor the health of plankton in the ocean by measuring fluorescence (see top centre). This MODIS view over the Arabian Sea shows the highest amounts of photosynthetic activity in blue and lower ones in red.

The Canadian MOPITT (measurements of pollution in the troposphere) sensor maps atmospheric carbon monoxide at levels of one part in ten million (see top right). The red and violet areas over western Africa in this image show high carbon monoxide levels caused by seasonal fires.