David John Southwood CBE (born 30 June 1945) is a British space scientist who holds the post of Senior Research Investigator at Imperial College London.

He was the President of the Royal Astronomical Society from 2012–2014, and Director of Science and Robotic Exploration at the European Space Agency from 2001–2011.

[3] He obtained a PhD in physics from Imperial College London[2][3] with a thesis on the theory and data analysis of low-frequency waves in the Earth's space environment.

[5] Southwood conducted post-doctoral research at the University of California, Los Angeles,[3] working on magnetometer data from the ATS-1 spacecraft.

[6][failed verification] He then returned to Imperial College in 1971,[2][3] where he produced a theory of field-line resonances in the Earth's magnetosphere which now underpins most work on geomagnetic pulsations.

[2] Over the following decades Southwood and this research group were involved in missions including Ulysses, Mars 96, Cluster, Cassini, Rosetta, BepiColombo, and Solar Orbiter.

[2] The magnetometer on the Cassini Saturn orbiter found the first signatures that led to the discovery of geysers on the moon Enceladus.

[3] There he developed the Earth Observation Envelope Programme (EOEP), resulting in the Cryosat, GOCE, SMOS, and EarthCARE missions.