Do We Really Understand Gravity?

Scientists are set to study old data from the Pioneer 10 and 11 missions in order to resolve an old discrepancy. This article discusses the anomaly discovered during those missions which seem to not match what is currently understood about gravity. Once the spacecraft finished their missions and began moving out of the solar system, it was noted that they appear to be traveling slower away from the sun than gravity should predict. No one knows why this would happen. Some people think analyzing the data will yield a new understanding of gravity. Others think that we will find a conventional explanation. Either way, scientists are now set to go through the data after exhaustively recovering the old data off of archived magnetic tapes. Scientists are also interesting in tracking New Horizons once it finishes its mission around Pluto to see if they can see this same effect in a more modern spacecraft. This would prove that the anomaly is real rather than a result of bad data, which the truly skeptic scientists have proposed.