An atomic clock that could be a big help for deep-space missions is hitching a ride aboard SpaceX’s Falcon Heavy rocket tonight. It’s one of 24 payloads heading into space. While most of us will tune in for the side booster landings, SpaceX will be monitoring satellite deployment into Tuesday morning. It’ll be T+ 3 hours and 34 minutes before the final satellite detaches.
The weather forecast is looking pretty good tonight with an 80% chance of favorable conditions according to the weather folks at the U.S. Air Force 45th Space Wing. The four-hour launch window opens at 11:30 pm EDT.
NASA describes tonight’s launch as “among one of the most challenging in SpaceX’s history.” Besides the usual challenges of landing boosters (SpaceX plans to land three tonight), tonight’s launch will feature four separate upper-stage engine burns and three different orbits.
Those engine burns and different orbits will place satellites ranging from DoD satellites and weather satellites from NOAA to NASA missions and university satellites. But, let’s talk about this atomic clock NASA is sending up tonight.
The Deep Space Atomic Clock (DSAC) measures 11 inches x 10 inches x 9 inches and weighs in at 35 pounds. Mercury ions are used to create a clock that is up to 50 times more accurate than the atomic clocks inside GPS satellites. NASA says that the clock “is stable to better than one microsecond per decade.”
To understand why this atomic clock has the potential to be a big deal, let’s take a quick look at how clocks are used to navigate spacecraft like New Horizons or Juno.
Right now, teams on Earth send signals to a spacecraft which are then sent back to Earth. Because we know how fast the signal travels (the speed of light) we can determine the distance a spacecraft is from Earth using atomic clocks. Send a bunch of signals and track the measurements, and you can figure out a spacecraft’s trajectory.
GPS satellites use atomic clocks to help make sure the Starbucks is where the screen says it is. But even their accurate clocks are sent updates twice per day to correct for drift throughout the day according to NASA.
If the Deep Space Atomic Clock works as it should, it’ll require much less communication from Earth. That means freeing up more bandwidth typically reserved for navigation. That means more bandwidth for data downlinking, communication, etc.
NASA’s Deep Space Atomic Clock test is expected to last at least a year. If everything goes smoothly, then one small piece of the gigantic puzzle that is getting a crewed mission to Mars will have been solved.
Tonight’s SpaceX mission is expected to liftoff at 11:30 pm EDT. Another launch window opens at the same time tomorrow night if weather or some other issue prevents tonight’s launch from happening.