On a calm November evening in 1988, the 300 foot radio telescope at Green Bank Observatory collapsed. While the collapse was a huge blow to radio astronomy, it is somewhat surprising that it lasted as long as it did. The radio telescope was proposed in 1960 as a way to fill the observational gap between earlier radio telescopes and telescope arrays such as the VLA, and was intended to operate for about five years. In a way it was meant to nurture success out of failure.
The 140 foot telescope at Green Bank. Credit: NRAO/AUI/NSF
At the time, the major radio telescope under construction was Green Bank’s 140 foot telescope. This telescope was polar-aligned, and had a tracking mechanism that could follow objects as they moved across the sky. This would allow for high-precision observations of radio objects such as pulsars. Unfortunately the gearing necessary to move such a large telescope was plagued with flaws, and the construction of the telescope faced increasing delays and costs. While the 300-foot telescope was larger, it was also lighter and had limited mobility, making it cheaper and easier to build. It depended upon the rotation of the Earth to bring objects into its view for about 40 seconds before drifting out of range, but that was enough to make good observations of things like pulsar remnants. It was also able to make a survey of the radio sky at a higher precision than ever before. When the 140 foot telescope was finally completed in 1965, it was able to further these discoveries, and even made radio observations of complex molecules in space, opening the door to astrochemistry.
The Robert C. Byrd Green Bank Radio Telescope. Credit: NRAO/AUI
If the 140 foot telescope hadn’t faced delays, the 300 foot telescope would likely not have been constructed. What began as a stop-gap solution became a powerful telescope in its own right. Because it lasted much longer than its original design, astronomers came to depend upon it, upgrading the telescope over the years. That’s why its collapse was such a blow. But the radio telescope had more than proven its value, so in the years following its demise a new telescope was proposed. This would be only slightly larger than the 300 foot telescope, but would be fully steerable and capable of tracking objects through the sky. Basically it would combine the best features of the 3oo foot and 140 foot telescopes. It was completed in 2001, and came to be known as the Robert C. Byrd Green Bank Telescope. To this day it is the largest movable land structure on the planet. Of course it wouldn’t have been built if the 300 foot telescope hadn’t collapsed.
So one of the most powerful radio telescopes we have was built because of the structural failure of a telescope that was built because of the design problems of another telescope. It’s a classic example of how sometimes failure can lead to greater things, which is often what science is all about. Science is about pushing past boundaries, and often that means using a failure to move forward.
