It's about time! NASA's orbital atomic clock a boon for deep space navigation – if they can get it working for long enough
- Reference: 1625147105
- News link: https://www.theregister.co.uk/2021/07/01/nasa_atomic_space_clock/
- Source link:
[1]Reported in Nature , the results of more than a year's experimentation have shown the ion optical clock has outperformed current space clocks by an order of magnitude. NASA engineers believe the level of performance shows the approach could be used to enable near-real-time navigation of deep space probes.
Currently, GPS satellites use atomic clocks as part of navigation systems, but there are limits to the approach. They rely on atoms confined by a gas cell to serve as a meter for the clock, but the long-term stability of gas-cell clocks can suffer when the atoms collide with the "walls" of the cell, causing drift. GPS systems get signals from earthbound atomic clocks to correct the instability. But that gets trickier the deeper you go into space. Light signals can sometimes take up to 20 minutes to journey from Earth to Mars [2]so navigators can't make last-minute changes to a spacecraft's path .
[3]
Trapped-ion atomic clocks, in which charged atoms are prevented from colliding with walls by an electromagnetic cage, have been around since the early 2000s and are more accurate than earlier approaches to atomic time-keeping, which have been around since the 1950s. NASA's Deep Space Atomic Clock loses [4]one second every 10 million years , as proven in controlled tests on Earth.
[5]NASA reaches for graph DB to find people, skills for Moon and Mars missions
[6]Former NASA astronaut and Shuttle boss weigh in on fixing Hubble Space Telescope
[7]Hubble telescope in another tight spot: Between astrophysicists sparring over a 'dark matter deficient' galaxy
[8]NASA's InSight lander expected to survive most of summer before choking to death on Martian dust
In 2019, [9]NASA launched the trapped-ion clock into orbit around Earth . It was one of 24 satellites on the SpaceX Falcon Heavy Rocket mission.
Eric Burt, a scientist at the California Institute of Technology and principal member of the technical staff at NASA's Jet Propulsion Lab, and colleagues have shown that a year into its operation, its short-term and long-term stability beat current space clock technology by 10 times.
[10]
The paper claims that variations in radiation, temperature, and magnetic fields did not seem to limit the performance of the clock, making it suitable for operation in the extreme environment of space. All this despite developing a fault shortly after testing began.
Tests in space confirmed a "drift" of around 10 -16 seconds per day, exceeding current space clock performance by up to an order of magnitude.
[11]
There is just one catch: time. That is, the current Deep Space Atomic Clock has a predicted lifespan of three to five years, well short of what might be needed for a mission to Mars and beyond.
While promising to extend the durability of the new clock to 10 years or beyond, the authors point out that the development of trapped-ion space clocks could open up applications in one-way navigation for deep space exploration, without the need to phone home. ®
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[1] https://www.nature.com/articles/s41586-021-03571-7
[2] https://www.jpl.nasa.gov/news/nasa-extends-deep-space-atomic-clock-mission
[3] https://pubads.g.doubleclick.net/gampad/jump?co=1&iu=/6978/reg_offbeat/science&sz=300x50%7C300x100%7C300x250%7C300x251%7C300x252%7C300x600%7C300x601&tile=2&c=2YN3gsNX1lI35ERHHODNtcAAAAJU&t=ct%3Dns%26unitnum%3D2%26raptor%3Dcondor%26pos%3Dtop%26test%3D0
[4] https://www.nasa.gov/mission_pages/tdm/clock/index.html
[5] https://www.theregister.com/2021/07/01/nasa_reaches_for_graph_db/
[6] https://www.theregister.com/2021/06/30/hubble_repair/
[7] https://www.theregister.com/2021/06/29/hubble_galaxy_distance_dark_matter/
[8] https://www.theregister.com/2021/06/28/insight_dust/
[9] https://www.nasa.gov/press-release/nasa-technology-missions-launch-on-spacex-falcon-heavy
[10] https://pubads.g.doubleclick.net/gampad/jump?co=1&iu=/6978/reg_offbeat/science&sz=300x50%7C300x100%7C300x250%7C300x251%7C300x252%7C300x600%7C300x601&tile=4&c=44YN3gsNX1lI35ERHHODNtcAAAAJU&t=ct%3Dns%26unitnum%3D4%26raptor%3Dfalcon%26pos%3Dmid%26test%3D0
[11] https://pubads.g.doubleclick.net/gampad/jump?co=1&iu=/6978/reg_offbeat/science&sz=300x50%7C300x100%7C300x250%7C300x251%7C300x252%7C300x600%7C300x601&tile=4&c=44YN3gsNX1lI35ERHHODNtcAAAAJU&t=ct%3Dns%26unitnum%3D4%26raptor%3Dfalcon%26pos%3Dmid%26test%3D0
[12] https://whitepapers.theregister.com/
Paging Mr. Einstein...
" The paper claims that variations in radiation, temperature, and magnetic fields did not seem to limit the performance of the clock, making it suitable for operation in the extreme environment of space. "
One presumes any effects of time dilation due to gravity or acceleration are not of concern here?
i.e. they only want an accurate time in the frame of reference of vessel it's on, rather than comparing it to earth's frame of reference?
Might have been interesting to at least mention a nod in that direction...
Re: Paging Mr. Einstein...
The clock will measure the proper time along its worldine, like any good clock does. That's what you want it to do. A clock, say, in orbit around Earth can't somehow magically know that and adjust itself so it tells the right time on the surface.
Re: Paging Mr. Einstein...
I would assume it is important to take gravity into account for deep space clocks. GPS satellites near Earth already need [1]special and general relativity corrections .
[1] https://en.wikipedia.org/wiki/Error_analysis_for_the_Global_Positioning_System#Special_and_general_relativity
The 17:42 Mars shuttle service which is about to prepare for orbital injection is running approximately 0.42 Years late. This is due to the wrong kind of trapped ions in the system. We would like to apologize to all passengers wishing to use this service for the delay . . . etc. etc.
"Light signals can sometimes take up to 20 minutes to journey from Earth to Mars "
Can anyone explain to me the "sometimes" in terms of physics please?
Cheers
Re: "Light signals can sometimes take up to 20 minutes to journey from Earth to Mars "
Mars does not maintain a constant distance from Earth.
Sloppy design, I know, but that's how it goes with these cut-rate solar systems.
Re: "Light signals can sometimes take up to 20 minutes to journey from Earth to Mars "
The distance between Earth and Mars varies quite a lot so they are only "sometimes" 20 light minutes apart.
Re: "Light signals can sometimes take up to 20 minutes to journey from Earth to Mars "
Perhaps it's referring to when Earth and Mars are at their furthest apart along their orbits vs their nearest. (or points in between)
"Mars does not maintain a constant distance from Earth."
I should've thought of that! Anyone know how much it varies?
"...the first trapped-ion space clock..."
Ahem. Let me fix that:
...the first trapped-ion clock IN SPAAAAAAAAACE.