Given the fact that satellites orbit amongst one another at thousands of miles per hour, it's vitally important to know exactly how fast they're going, in order to avoid collisions. A new device offers an improved way of doing so, and it's appropriately named the Spacecraft Speedometer.
Ordinarily, satellite speed is gauged either by ground-based tracking stations using technologies such as radar and field of view sensors, or by GPS modules onboard the spacecraft themselves.
Unfortunately, though, ground stations are only able to track satellites as they're passing overhead. As a result, the craft remain untracked for hours or even days at a time, depending on their orbit.
While GPS is a bit more reliable, older satellites lack the technology. Additionally, GPS readings can be hampered by space weather events like geomagnetic storms, which is ironically one of the times when satellite positioning information is needed most.
And of course, neither ground stations nor GPS would work for gauging the speed of spacecraft orbiting other planets. That's where the Spacecraft Speedometer comes in.
Developed by scientists at Los Alamos National Laboratory and the United States Air Force Academy, the small satellite-mounted device incorporates two identical laminated plasma spectrometers. One of them faces forward, in the direction of the spacecraft's trajectory, while the other faces backwards.
The device is technically considered a "dual-sensor laminated-head electrostatic analyzer."
As the satellite moves forward, a relatively large number of space-plasma ions floating in the atmosphere strike the front spectrometer at a high rate of speed. Some ions do also strike the rear spectrometer, but much fewer and at a lower speed.
Therefore, by comparing the number and impact energy of ion-strikes on the front spectrometer to those on the rear, it's possible to calculate the speed at which the satellite is currently traveling.
"[The Spacecraft Speedometer] has the potential to provide critical onboard and real-time spacecraft velocity measurements,” says Los Alamos' Carlos Maldonado, principal investigator of the project. "These measurements are necessary for improving our ability to accurately predict satellite locations so that we can perform maneuvers to avoid other active satellites and debris."
The Spacecraft Speedometer has already been successfully tested on the International Space Station. Commercial partners are now being sought to take the device into production.
Source: Los Alamos National Laboratory