Loren Wilber Acton (born 7 March 1936) is an American physicist who flew on Space Shuttle mission STS-51-F as a Payload Specialist for the Lockheed Palo Alto Research Laboratory.

[2] As a research scientist, his principal duties included conducting scientific studies of the Sun and other celestial objects using advanced space instruments and serving as a co-investigator on one of the Spacelab 2 solar experiments, the Solar Optical Universal Polarimeter.

At mission conclusion, Acton had travelled over 2.8 million miles in 126 Earth orbits, logging over 190 hours in space.

The primary emission of the extremely hot outer atmosphere of the Sun, the solar corona, is at X-ray wavelengths.

The extended duration, high resolution, X-ray imagery from Yohkoh contribute to the study of why the Sun has a corona at all and why it varies in intensity so strongly in response to the 11-year sunspot cycle.