PhD, Rice University, 1971
- Galactic and extragalactic astronomy and astrophysics
- High-resolution Airborne Wide-band Camera (HAWC+)
- Stratospheric Observatory for Infrared Astronomy (SOFIA)
Harper's research deals with problems of formation of galaxies, stars, and planetary systems, physics of the interstellar medium, and properties of interstellar dust. His experimental research group constructs and operates infrared instrumentation. He helped pioneer astronomical research on airborne telescopes, and at the South Pole.