Seeing Orange in the Kalahari

Sand dunes, ancient rocks, a solar power plant, and the Orange River stand out in this image of the southern Kalahari Desert taken by a camera system on the International Space Station.

The dark line of South Africa’s largest river, the Orange, winds across farm-covered floodplains toward the Atlantic Ocean. Populations are small in this desert region. The small farming town of Groblershoop is barely visible compared to the local main roads, which show up as white lines etched across the landscape.

The strong orange color in this image is mostly due to geologically young dunes (only a few million years old) in what is known locally as the Duineveld (dune country). Poking up through the sands are sinuous hills made up of very ancient, dark-toned rocks. These rocks were folded and faulted around one billion years ago by mountain-building forces similar to those currently raising the Himalayas. The ancient mountains were later planed off by erosion over millions of years to form the dune-covered plains and low hills we see today.

Alongside one of the main roads lies a small, bright rectangular shape: This is the Bokpoort solar power plant. It was constructed specifically to take advantage of the high number of sunny days in the Kalahari Desert. The plant includes nearly 240,000 mirrors covering 0.65 square kilometers (about 0.25 square miles). Unlike the photovoltaic solar panels at many traditional installations, this power plant uses mirrors to focus the Sun’s energy on a large salt-filled storage tank (too small to see in this image). The focused sunlight melts the salt, which has a high heat storage capacity. This heat in turn drives steam turbines that can generate power long after sunset. This renewable-energy plant came online in 2015.

EarthKAM photograph 313841 was acquired on November 15, 2020, with a Nikon D2X DSLR digital camera using a 180 millimeter lens. The photo has been enhanced to improve contrast. It is provided by the Sally Ride [email protected] Camp on the International Space Station. The caption is provided by the Earth Science and Remote Sensing Unit, NASA Johnson Space Center. EarthKAM (Earth Knowledge Acquired by Middle school students) is a NASA educational outreach program that enables students, teachers, and the public to learn about Earth from the unique perspective of space. During Sally Ride EarthKAM missions, middle school students around the world request images of specific locations on Earth. Caption by M. Justin Wilkinson, Texas State University, JETS Contract at NASA-JSC.