When they are not communicating with spacecraft, the DSN antennas are used for radio astronomy.
For more than 30 years, the Deep Space Network has played a significant role in radio astronomy studies of our solar system, adding to our under standing of the magnetic fields and atmospheres of planets. For example, since 1972 radio astronomers have used the DSN to observe Jupiter, with its intense and dynamic magnetosphere. DSN astronomers use high-performance spectrometers to separate radio frequencies into millions of channels, allowing them to analyze the materials in comets, planetary atmospheres, and clouds of gas or dust in space. The DSN can also respond to observe unforeseen astronomical events such as the appearance of comets Hyakutake and Hale–Bopp.
The Deep Space Network’s large 70-meter antennas in California and Australia have been used to study how stars are born in clouds of gas and dust called nebulae.
The highly sensitive 70-meter DSN antennas have contributed to VLBI studies of extragalactic supernovae that are very distant, weak sources of radio emissions.
The high sensitivity, key locations, and special instrumentation of the radio telescopes of the Deep Space Net work make them priceless tools in our quest to understand the universe ...
The JPL DSN radio astronomy website is defunct, but the Internet Archive has a copy from 2013.
Here's a list of studies that used DSN observations. Cherry-picked a few
- 1967: First intercontinental very long baseline interferometry (VLBI)
- 1969 First jump in the period of the Vela pulsar detected
- 1986 First space-based VLBI with TDRSS antenna
- 1991 Measurement of the relativistic bending of radiation by Jupiter
- 1995 First image of infall onto a protostar
- 1997 First images from the HALCA Space VLBI mission
Arxiv has 21 papers that use DSN data, NTRS has more results. (some of these are false positives, there are papers on the use of DSN for communications too)