# Tag Info

23

The official time zone is GMT, or UTC. As for the number of times they could celebrate, well, that's a bit tricky. The station goes towards the east, which is actually backward in time. There are a total of 38 time zones (Yikes!), spread from UTC +14 to UTC -12. Of course, the ISS would have to be in that particular time zone. The max is likely around 16-...

15

I was interested in the bonus question and decided to do an ad-hoc survey using ISS Tracker in historical mode. I entered the appropriate 2020-01-01 00:00:00 for each apparently relevant time zone (-11 through +13 and the likely half-hour time zones I could find--less than all 38). My analysis shows that the ISS astronauts could have celebrated one and a ...

7

This is the n-th day of the year, going from 1 to 365 (or 366). So 006 would be January 6.

5

To confirm other answers that the leading three-digit number is day number for the year starting with 1 being 01-Jan: Note the counter in the lower-left of the video [ISS] Launch of Antares Rocket with Cygnus CRS-2 Spacecraft to ISS is 194 16:52:14.xxx at launch, corresponding to a 13 July 2014, 16:52:14 launch time, with 13-July-2014 being the 194th day of ...

5

@JCRM figured it out. After about 04:45 in the video: The time code that you’ll see in the LED display on the right hand side is actually positioned between the two sprockets on the 16 mm frame, and the time code is UTC time code, it’s in IRIG-B format, and you’ll see it’s 21 hours, being UTC it’s 5:02 PM local time, 2 minutes, 11 seconds, and the three ...

5

For some reason, I saw, or read this question as simply asking "How fast can you get to Mars if fuel is no expense". So this answers that question. I don't mind deleting it if that is considered appropriate. Anyway, it depends what you mean by "if fuel is no expense". If you are assuming something more or less along the lines of current rockets, but are ...

5

STEREO A and B, 2006-047A and B, (29510 and 29511) were launched together from "Cape Canaveral Air Force Station in Florida on a Delta II 7925-10L launcher into highly elliptical geocentric orbits". The elliptical orbits intercepted the Moon's trajectory, and because of a small but carefully design difference in their two positions, one was thrown "...

4

days:hours:minutes:seconds.fractions_of_seconds

4

Here's a quick visual analogy. Imagine you want to "hop a train"; jump onto a flatcar as it is rolling along the tracks. The traditional approach is to run in the same direction the train is going, and then when you get beside the car make sure your speed matches, grab it, and jump on. It's dangerous, but very doable. Your suggested approach is to run in ...

3

Faster travel is generally better: less time for random or wear-down mechanical failures, less exposure to cosmic rays, lower probability of collisions. Direction and relative velocity of collisions with meteoroids is highly variable and essentially random. Going faster might make the average impact energy of collisions infinitesimally higher, but not ...

3

Despite two answers that say "irrelevant" there can be some other second-order effects beyond the ones nicely described in @JayDawn's answer: If you are launching into a dawn-dusk Sun-synchronous orbit you would obviously be launching around dawn or dusk, and not mid-day or mid-night. If there are operations that are important to be recorded visually with ...

3

To reach one body in space from another, you need to consider their speeds, not just their positions. To leave Earth going the other direction, you need to cancel out Earth's orbital velocity around the sun (about 30km/s), and then when you reach Mars you need to turn around and match Mars's velocity. This is much more expensive in fuel than more direct ...

2

This answer is highly suspect and should be independently verified. Also, it only talks about the timers and the Master Timing Unit: The computers themselves: The IBM System/4_PI architecture was used as the system architecture for the AP101 source The timer feature on this system was a full word (so, presumably 32 bits) Source, but not a primary source ...

2

Velocity is calculated usually to minimise fuel needed, or sometimes to minimise time - but the time piece is generally about resources/mass, not minimising risk of collisions. "Safe speed" is pretty much irrelevant until you get up to significant percentages of the speed of light, so your question doesn't really work.

2

See the FAQ of the JPL's website: Coordinate time is the time used in the development of ephemerides for solar system objects. Under General Relativity, the rate at which actual clocks tick is called proper time. The rate of proper time depends on the location and motion of the clock, so there is no single proper time for the solar system as a ...

1

Does the change in gravity result in time dilation in this case? It sure does! The change in speed is still not even close to the speed of light - and so I don't imagine it has much of an effect. It turns out that both relativistic effects have similar magnitudes; in the first equation below both terms have a $1/c^2$. In order to stay in space for long ...

1

Would I be correct in thinking that UT1 => JD(UT1) requires no accounting for leap seconds in contrast to UTC which does? Yes, that's correct. However, UT1 is neither predictable nor uniform either. It depends on polar motion, nutation, and precession of the Earth. UTC is a close approximation to UT1, and the IERS ensures that UTC stays within 0.9 seconds ...

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