The National Physical Laboratory (NPL) has helped determine that a femtosecond comb laser could be used to provide highly accurate measurement of absolute distance for missions in space that require formation flying. The NPL worked with the European Space Agency to determine that the lasers were suitable for the task.

Formation flying missions in space sound like science fiction, but missions using multiple spacecraft are already in the planning stages. These missions will involve multiple spacecraft flying anywhere from tens to hundreds of meters apart. The highly accurate distance measurements would allow a formation to monitor their distance and turn the formation into a single large sensor.

One proposed use for the new technology is the International X-ray Observer due to launch after 2020. The 25-meter spacecraft for the mission will have to have an absolute measurement between the front and back of the craft because the body of the spacecraft will be flexible. Without a highly accurate potion cue, the spacecraft would not be able to position and orient its mirror, thereby preventing the capture of an image.

NPL reports that this type of accuracy aboard a spacecraft is very challenging and requires instrumentation with high accuracy that is robust enough to survive liftoff. The technology could also be used in a mission called LISA planned to look for gravity waves. The spacecraft in this mission would not fly in close formation.

However, the accurate femtosecond lasers would allow the formation to know their relative position to each other by plotting positions relative to known stars and establish lateral positions by laser pointers. This would allow the craft to detect slight movements that would signal the discovery of a gravity wave.

The NPL reports that prototype systems will need to have uncertainty claims verified by national standards laboratories like NPL and meet other stringent requirements to become space ready.