I've seen multiple sources repeat the information that the Deep Space Atomic Clock will 'at first' orbit Earth, before moving on out of Earth orbit.

The Deep Space Atomic Clock (DSAC) is a miniaturized, ultra-precise mercury-ion atomic clock for precise radio navigation in deep space. It is orders of magnitude more stable than existing navigation clocks, and has been refined to limit drift of no more than 1 nanosecond in 10 days.

Wikipedia: "Its development will include a test flight in low-Earth orbit"

JPL: "the instrument will be tested in Earth orbit for one year, with the goal of being ready for future missions to other worlds"

What would it then orbit? The Sun? Or some L point? Other planets? Or will multiple ones orbit all of the above?

Edit: for those wanting to close based on "not astronomy", have you considered astronomy does not have to be done from earth and indeed much of the data astronomers use often comes from probes and satellites in space. Therefore 'how/where will this space beacon be used?' has strong impact on future of astronomy.


closed as off-topic by James K, Glorfindel, Jan Doggen, Mick, Rory Alsop Jun 6 at 10:38


  • $\begingroup$ This should really be on "space exploration". I think there is a misunderstanding. The demonstration clock will stay in Earth orbit. If it works well, then similar clocks can be installed on other spacecraft. $\endgroup$ – James K Jun 5 at 20:05
  • $\begingroup$ @JamesK it seems I've just done such a thing; Where would one deploy deep space atomic clocks? $\endgroup$ – uhoh Jun 6 at 0:20
  • $\begingroup$ I'm voting to close this question as off-topic because it belongs on Space Exploration $\endgroup$ – Jan Doggen Jun 6 at 7:14
  • 1
    $\begingroup$ @JanDoggen While I think it matches the SpaceSE, first what should be checked, if it matches this site. The policy is that in the case of a topic overlap, the question remains where it is. In my opinion, this question is enough well about astronomy to remain here. $\endgroup$ – peterh says reinstate Monica Jun 6 at 21:22
  • $\begingroup$ @JanDoggen peterh is right. Our site's Help Page says "You may ask about [artificial satellites'] orbit, but not their purpose, usage and safety features. Questions about satellites with an astronomical purpose should be focused on astronomical usage and not broader questions such as the construction of the non-optical components." As this question is clearly about DSAC's orbit, and the 2 answers are both useful, I'm voting to reopen it as demonstrably on-topic. $\endgroup$ – Reinstate Monica Jun 7 at 5:20

"The instrument will be tested in Earth orbit for one year, ..."

What would it then orbit?

It will continue to orbit the Earth, at least for a while. It will eventually end up not orbiting the Earth because it will be placed in low Earth orbit, where orbits decay due to atmospheric drag.

The project is a technology demonstrator, which means a limited amount of funding.


The DSAC to be launched in June 2019 is a Technology Demonstration Mission, in which they only test whether it works as well in space as it does on the ground. If it passes the tests, similar devices could simplify navigation for future missions elsewhere in the solar system.

It is one of many payloads sharing space on an Orbital Test Bed satellite, which will probably remain in Earth orbit until its orbit decays. The OTB is itself one of several payloads on the same launch vehicle.

