NASA is Sending an Atomic Clock Into Deep Space (howstuffworks.com) 71
An anonymous reader shares a report: On Saturday, June 22, SpaceX plans to launch its Falcon Heavy Rocket out of the Kennedy Space Center in Cape Canaveral, Florida. The reusable craft is coming off two successful flights; its maiden launch in early 2018 and a satellite delivery trip in April 2019. For its third adventure, the Falcon Heavy will ferry a trove of precious cargo up into space. Around two dozen satellites are going along for the ride this time. But the rocket's most interesting passenger has to be the Orbital Test Bed satellite. Its main payload is an experimental, toaster-sized gizmo called the Deep Space Atomic Clock (DSAC). If the thing works properly, future missions to Mars, Jupiter and beyond could become a whole lot easier -- and less expensive.
I predict: (Score:2)
It will run fast...
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I suspect they do that with our politicians also.
Cheaper how? (Score:4, Interesting)
The "how" is answered in the article, so blame editor rather than the author. Think "space GPS" - getting reference signals with atomically accurate timestamps from more than one point in the solar system will let spacecraft constantly and accurately track their current position just like GPS does for Earth and low orbits. Rather than the current mechanism which is more like cooperative radar range-finding: an Earth-based station has to "ping" the spacecraft, which immediately replies, and the round-trip time is used to calculate the distance. Which ties up communication antennas so that it doesn't scale well as the number of spacecraft being tracked increases, and also means we can only ever tell where a spacecraft was many minutes or hours in the past.
"Space GPS " would make navigation much easier, and a bit cheaper.
As for the clock - that depends very much on what they mean by "deep space", but Ned is probably right. Assuming they mean a (circular) orbit further from the sun than Earth, then it will necessarily be moving slower than Earth, and hence run faster than clocks on Earth - at least when only considering speed-based time dilation.
There's also gravitational time dilation - the deeper you are in a gravity well, the slower your clock will run. The DSAC will be much further from Earth's gravity well, as well as probably further from the Sun's much, much deeper gravity well, which will both speed it up. The only way the DSAC would run consistently slower is if it were considerably closer to the sun than Earth, so that the combination of higher orbital speed and being deeper in the Sun's gravity well combined to exceed the dilation experienced on Earth's surface.
GPS satellites do not determine or pinpoint (Score:5, Informative)
"Built-in atomic clocks help GPS satellites determine the distance between themselves and your smartphone. With that info, they can pinpoint your whereabouts."
What a terrible way to describe the process
GPS satellites do not determine the distance between themselves and your smartphone. They do not pinpoint your whereabouts.
Your phone, working with information transmitted from the GPS satellites determines your distance from those satellites and hence pinpoints your whereabouts
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So in this context, a "terrible" description means "exactly and completely wrong in every detail".
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Also yes and no. While most modern cell phones have real dedicated GPS chips within, few actually use them as true GPS, but rather Assisted GPS or AGPS.
In 99.99% of the time, your location is calculated by bouncing a signal to nearby cell towers who have a KNOWN location (in the olden days of GPS they might be call base stations used for accuracy correction for real GPS). By measuring the time it takes for the signal to return from multiple known call tower locations your phone is able to pinpoint your loca
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That was also the promise of Ada. And, as another poster noted, Haskell.
Bad software can be written in any language. Some languages prevent some classes of error, at a cost in ease of use, expressiveness, or complexity. No language prevents all classes of error, or even most of them.
Good Explanation Video (Score:2)
Gizmodo has a nice video explaining time's role in navigation and GPS.
Watch it here [youtube.com]
Comment removed (Score:5, Informative)
Re:What the hell? (Score:5, Funny)
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Yep, so many people get it wrong.
The satellites are all just shouting something "at exactly the same time". Depending on which one you "hear" first, lets you work out which one is closest, second-closest, etc. and because they are far enough apart, you can work out where you must be.
In reality they aren't shouting, just telling you what *they* think the time is, but it's pretty much the same thing as having them shout in perfect synchronicity after you do a bit of maths.
You can literally just demonstrate t
So they truned this Falcon Heavy Booster (Score:5, Interesting)
"its maiden launch in early 2018 and a satellite delivery trip in April 2019"
"On Saturday, June 22, SpaceX plans to launch its Falcon Heavy Rocket"
Just my 2 cents
Small problem with that.... (Score:1)
If we are launching an atomic clock into space to maintain an orbit, then there is a problem thanks to Einstein.
As the speed of the clock increases toward the speed of light, time will slow. It will be a very tiny difference, but there will be a difference. I would imagine that over many, many years of maintaining a high velocity orbit, the time difference between this clock and ground based clocks might have to be dealt with.
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True. In fact, GPS satellites DO deal with it.
But the effect is very small. Orbital velocity, v, is about 7 km/sec. The speed of light, c, is 300,000 km/second. The time dilation factor is SQRT(1-v^2/c^2).
Exercise for the student: compute what the time dilation factor is for a clock on a spaceship moving at orbital velocity.
Extra credit: using an internet search to find gravitational redshift, (hint: use the "00" component of the metric g_mn) calculate the gravitational effect on the clock rate.
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The effect is *big* for the purpose! (Score:2, Interesting)
Yes, in human time scales, it is very small.
But for GPS to work, the time must be very precise and the error very small too!
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I, for one, want to see how the Global Positioning System works when you're off the globe.</sarcasm>
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They already deal with this in current GPS satellites, this is no different.
Besides velocity, the strength of the gravitational field also affects time.
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There is absolutely no such thing as a fixed universal time base, precisely because of the problems you state. People misunderstand this greatly that there's a "time" across the universe that you can all do something or set your clocks to. It just doesn't work like that.
Like velocity, time is relative. Going "60mph" doesn't mean anything in the grand scheme of things when the earth is rotating, orbiting the Sun, which is itself rotating and orbiting the galaxy, which is itself rotating and orbiting a bla
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Damn, somebody needs to tell NASA quick! I don't think they could possibly have figured that one out without your help, Anonymous Coward!
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Clickbait (Score:5, Informative)
Skip the clickbaity dumbed down article, go straight to the release:
https://www.nasa.gov/mission_p... [nasa.gov]
Navigation ... (Score:3)
It is to laugh (Score:2)
Soviets send sub-atomic clock into space, to land on the Moon and claim Mars from there!
Yes, komrade!
Clocks and non clocks (Score:2)
Okay, clocks are important, but if there's a "trove of precious cargo" maybe they could mention some of the other items being sent.
Going from Rb/Cs to Hg atomic clock? (Score:1)
The second generation GPS satellites have 2 Rubidium atomic clocks and 2 Caesium atomic clocks. Both of the elements are in the Alkali metals column of the periodic table and appear as elements #37 and #55. Other Rubidium oscillator providers claim to off by less than 2 ns per day. For NASA to claim their Mercury based atomic clock drifts by no more than 1 ns every 10 days is really impressive.
However, given Mercury is #80 on the periodic table, I suddenly recall a Marty McFly quote: "This is heavy" [youtube.com]
Conspiracy Theory (Score:1)
OTC (Score:1)