Heidi Hammel improvements to the adaptive optics systems of the Keck telescope, astronomers became able to capture "unbelievably crisp images" and view many details that could not be seen before. Hammel's planetary research with Hubble and Keck has demonstrated that both Uranus and Neptune are dynamic worlds. Hammel primarily studies the outer planets and their satellites, focusing on observational techniques. She was a member of the Imaging Science Team for the Voyager 2 encounter with the planet Neptune in 1989. In 1994, Hammel led the team that investigated Jupiter's visible wavelength response to the impact of comet Shoemaker-Levy 9 using the Hubble
Comet Shoemaker–Levy 9 largest impacts. The waves were thought to be travelling within a stable layer acting as a waveguide, and some scientists thought the stable layer must lie within the hypothesised tropospheric water cloud. However, other evidence seemed to indicate that the cometary fragments had not reached the water layer, and the waves were instead propagating within the stratosphere. Radio observations revealed a sharp increase in continuum emission at a wavelength of after the largest impacts, which peaked at 120% of the normal emission from the planet. This was thought to be due to synchrotron radiation, caused by the injection of relativistic