Questions tagged [time]

How passage of time impacts space exploration activities.

Filter by
Sorted by
Tagged with
26
votes
3answers
22k views

Determining orbital position at a future point in time

This might come of as a millionth-time award winner beginner question, but since I'm not familiar with either correct terms or designations, I'll put this question in my own language, since I'm not ...
32
votes
5answers
42k views

How does GPS receiver synchronize time with GPS satellites?

GPS satellites transmit time values regularly, but if we put in consideration the time delay between the satellite and the receiver, the time value received wouldn't be accurate insofar as I know GPS ...
9
votes
1answer
221 views

Problems as a result of clock drift that have occurred in space?

I was reading this question about the clock drift on the Apollo missions and am sure that a drift of 1 second / day on some of the longer missions would likely result in a mission failure due to the ...
9
votes
4answers
9k views

How to obtain UTC of the epoch time in a satellite TLE (two line element)?

I want to convert the epoch time of a TLE to UTC. At this moment I am less interested in explanations and history - I just want to know quantitatively, with certainty, how to convert. I'm confused ...
3
votes
2answers
222 views

Can the TLE epoch be listed as in the future? How?

Can the epoch time of a TLE be in the future? Context: ISS TLE from Heavens Above 1 25544U 98067A 18193.60071450 .00016717 00000-0 10270-3 0 9013 2 25544 51.6401 252.0472 0003848 304.4303 ...
27
votes
4answers
17k views

What time zone is used on ISS to define a day?

What time zone is used on ISS to define when a day starts? Is it the same as mission control? Do Russian cosmonauts use a different time zone respect to European and American astronauts?
13
votes
4answers
1k views

Day versus night launches

Most launches that I've seen have occurred during the day. But I've also seen a couple of missions that have been launched at night. Are there any specific advantages or disadvantages to a day launch ...
6
votes
0answers
347 views

Which astronaut has experienced the largest relativistic shift in time (relative to the surface)?

Following this answer and then this question (where I've linked to Cosmonaut Sergei Krikalev; the World's Most Prolific Time Traveller) I've noticed that currently Krikalev does not hold the precisely ...
7
votes
1answer
303 views

How far from earth have atomic clocks (or ultra-stable oscillators) been placed and monitored?

The various flavors of GPS satellite constellations use atomic clocks on each satellite. As far as I know, all of the constellations are "shells" of circular MEO orbits in 3 to 6 planes, 20,000 to 25,...
5
votes
2answers
2k views

Time, UTC, Julian Date, TLE epoch - how are they related quantitatively?

I am trying to understand the relationship (quantitatively) between JulianDate, UTC, and the epoch of Two Line Elements. It's a deep subject, especially if you include relativity, and a long subject - ...
5
votes
3answers
229 views

Has any other term been used for a solar day on a solar system body besides “sol” on Mars?

My interest was piqued by this question and answer. For several reasons NASA needed to refer frequently and extensively to a Martian solar day, and "sol" became the nom du jour. There have been ...
3
votes
3answers
352 views

How far can you travel until you can't get back to where you started?

I searched for this question but couldn't find it, so I'm asking. Lets just ignore turning into a liquid at high accelerations and the fact that an object with mass cannot travel at the speed of light ...
1
vote
2answers
79 views

What is the date for a Mars file?

When a robot on Mars does something like take a picture, how does it date that file? I imagine that the responsible laboratory is a possible referential, correct? Is it possible / does it make sense ...
41
votes
3answers
9k views

Have we attempted to experimentally confirm gravitational time dilation?

Mark Adler wrote in an answer to a different question that We would expect that Voyager 1's local time is faster than Earth time by about one part in one hundred million. I don't think that ...
8
votes
2answers
12k views

Would a Moon resident age differently than someone living on Earth?

Say there were a base on the Moon with people living/studying there. Would they age differently than those on earth due to a change in speed through space? Does the Moon move faster through space (...
11
votes
4answers
3k views

What decides if a launch has to be done instantaneously or during a window?

What determines if a launch has to be done instantaneously or has a launch window of minutes or hours? To what parts is it about celestial and ground issues? Just one example of alleged switching ...
9
votes
2answers
1k views

Which Earth time zone most closely matches the ISS astronauts' daily schedule? [duplicate]

The astronauts on the International Space Station have a daily schedule, particularly when they are asleep versus awake. Which Earth time zone is closest to their daily schedule? What time zone is ...
3
votes
1answer
260 views

Time dilation between Mars and Earth due to different mass

I am not sure I understand the Time dilation correctly but if mass has dirrect impact on time...than lets consider cosmological event - one orbit of planet Earth around Sun. This event will person on ...
1
vote
1answer
440 views

Do the Voyager probes experience time moving faster due to relativity?

Time goes faster the weaker the gravitational field you are in as long as your velocity is constant. The Voyager probes have moved a long way from the sun and its planets so I presume time must be ...
1
vote
4answers
1k views

Where can the term “Sol” used?

Alright, I know that "Sol" is used on Mars to count days. But is the sun called: "Sol"? And can you use that term on Earth as well? The reason for the question is that the term "sol" is used in two ...
7
votes
3answers
895 views

Is space mining and development as shown in the television show “The Expanse” realistic?

In the television show "The Expanse", we see the Solar System having been partially colonized and developed during the 23rd century. The spacecraft in the show appear to depend on conventional ...
6
votes
2answers
1k views

Is GPS time at least “really close” to TAI (International Atomic Time)?

@DavidHammen's answer got me thinking. GPS time "comes from" (US Naval Observatory) a whole bunch of atomic clocks, in space and on Earth. TAI or International Atomic Time also comes from a whole ...
3
votes
3answers
472 views

UTC timestamp format for launch vehicles

Has anyone ever seen UTC timestamps of the format xxx:HH:mm:ss.sss? What are the three x's at the front. For reference, this timestamp belongs to an upcoming launch in June of 2019.
2
votes
1answer
118 views

Please explain the time reference shown in shuttle launch engineering video

Many shuttle launch engineering videos show an apparent time reference to the right of the frame as red numbers counting up rapidly. For example, from the amazing video "Ascent". Assuming this is ...
-1
votes
3answers
180 views

Juno to Jupiter Budget

Would the Juno program be more cost effective if the spacecraft took a direct flight to Jupiter rather than using gravitational pull from planets, which took nearly 5 years instead of say, 2 years? ...