In the 1980s, NASA discovered that its Pioneer probes, sent out in the late 1970s, were running late. This might not seem like a problem, but to engineers anything unexpected is a problem.The probes’ lateness — they were slowed by about 300 miles a year — disturbed the NASA engineers because it could mean that something was incorrect about Einstein’s gravity calculations. The probes seemed to be travelling slower than they should be based on what we know about gravity.
Finding out what could be tugging on the probes and slowing them down isn’t as easy as you would expect. A New York Times article published today, July 23, tells the story of the “space archaeologist” who did it, and proved Einstein’s theories right.
Russian physicist and gravitational expert Salva Turyshev is his name, and his search tool him through NASA’s archives and ancient technology, the story says:
…The Pioneers spanned the history of the space age and also of the computer age, occasioning a major effort in what Dr. Turyshev calls “space archeology.”
He and his colleagues had to scour NASA labs for old punch cards and magnetic tapes and for vintage devices that could read the data stored on them — then reformat all that data to a single modern standard.
Among other things, that meant ascertaining the positions of every antenna in NASA’s Deep Space Network to an accuracy of one centimeter over all that time.
It took much longer than Dr. Turyshev had imagined…
In the end Turyshev discovered the truth. It was the probes themselves that were off kilter, radiating more heat in one direction than the other, pushing the probes off course. The findings were published in a June 2012 paper in Physical Review Letters.
Heat is a form of light, so not only does the finding prove Einstein’s gravity right, it also shows that light (and heat) can carry momentum — an important feature of electromagnetism. Read the whole story in The New York Times.
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