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Questions tagged [time]

How passage of time impacts space exploration activities.

8
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1answer
124 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 ...
2
votes
0answers
46 views

What happened to time in 1962? (JPL Horizons changes displayed time from UT1 to UTC for dates starting in 1962)

I was viewing some observer output from JPL Horizons while writing this answer and I saw this annotation. "Prior to 1962, times are UT1. Dates thereafter are UTC". Presumably users of JPL's Horizons ...
4
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0answers
147 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 ...
5
votes
1answer
80 views

Synchronizing spacecraft communication

When NASA is giving commands to a distant spacecraft like Juno, how is that done in terms of timing and protocol? For example do they: give a command to burn for 15 seconds upon receiving the ...
0
votes
2answers
69 views

Time when traveling around the speed of light [closed]

I heard that if you travel at the speed of light or faster (say, to the Kelper systems ) and come back, thousands of years may have passed but you haven't experienced more than a few. How is this ...
2
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2answers
102 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 ...
4
votes
1answer
101 views

Martian Names for the Year and Month Time Units

A Martian day unit is called a Sol. A week is supposedly still 7 days/sols. Have there been any (real or fictional) suggestions for new names for other time units like the Martian year? How about ...
-3
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1answer
102 views

2 Hubble telescopes looking at each other in time [closed]

Hubble A (or a huge mirror) is 30 light minutes away looking at Earth and Hubble B. Hubble B is near Earth looking at Hubble A. A laser projector(similar to a movie projector) on Hubble A sends a live ...
7
votes
1answer
311 views

How long would it take to travel to Proxima b?

Proxima b is an Earth-like (i.e. rocky) planet, in orbit around the star Proxima Centauri, approximately 4.243 light years from Sol, our home star. If I had a space vehicle capable of accelerating ...
2
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1answer
137 views

Tesla Near Mars Orbit

When will the Tesla Roadster come into a near Mars orbit as shown in the SpaceX simulation shown in Elon Musk's tweet? Is it 10 years, 20 years or when?
10
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2answers
15k views

How long will it take for Starman to get to Mars?

How long will it take for the Starman to get to Mars? I'm following the incredible launch of the Heavy Falcon and Starman, and would like to know. Thanks!
2
votes
2answers
280 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
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0answers
80 views

Which one is older light or stars? [closed]

I kind of feel that light is older than stars. But is there any scientific theory or hypothesis on it?
28
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3answers
3k views

What does NASA mean when they use the term 'PDT (ERT)'

In a graphic describing Cassini's final approach to Saturn NASA lists the timestamps as 4:55 am PDT (ERT). What does this mean? I am assuming that PDT mean pacific time, but I can't find out what ERT ...
7
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2answers
611 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 ...
9
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1answer
2k views

How much light is there on the way from Earth to Proxima Centauri?

I want to know how much light is there for a spacecraft that flies from earth to Proxima Centauri. I know there's the sun but what happens after the spacecraft leaves the solar system? Are there stars ...
17
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7answers
3k views

How can we transmit a date to another species?

I thought about this the other day. We often send messages to outer space hoping that someone picks them up. How could you explain to aliens that we sent this satellite about 13.8 billion years after ...
3
votes
1answer
173 views

A laser can propel a spacecraft to 20% of light speed, time shorter on spacecraft?

So I recently learned about a project about using lasers on Earth to propel a spacecraft to 20% of light speed for interstellar traveling. So this brings an interesting question, how much shorter ...
38
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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 ...
0
votes
1answer
239 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 ...
4
votes
1answer
224 views

How would people measure time on Venus?

On earth we can divide our day into 24 hours, and 365 days in the year. I am trying to imagine how people living on airships above the cloud-tops would think about time on Venus given that a single ...
-1
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3answers
155 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? ...
8
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1answer
966 views

How is gravitational time dilation experienced by spacecraft near Jupiter such as Juno

I understand (I think) that a vehicle on or near a planet with greater mass - such as the Juno probe entering Jupiter's orbit soon- will experience time slightly slower relative to us on Earth. ...
3
votes
1answer
153 views

How did NASA refer to dates and times of a mission in the 1970s?

Back in the 1970s, how did NASA describe when an event happened during a mission? For example, when Mariner 10 did its fly-by of Venus, how did the Mariner team refer to that moment in time? Did ...
0
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1answer
206 views

Local Time Calculation

How To Calculate Local Time Of A Sun Synchronous Orbit With A Given Altitude ( Say 600 km ) , Inclination ( 98 degrees ) ?
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1answer
136 views

Can we displace earth? [closed]

From the gravitation equation it is clear the earth gets pulled but we fall due to negligible mass. But, if each and every person on the earth takes a jet-pack and jumps to a height equivalent to 20 ...
6
votes
1answer
213 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,...
4
votes
1answer
195 views

Why did the Zond 5 tortoises lose body mass so quickly?

For reference: https://en.wikipedia.org/wiki/Zond_5 It is now clear that when we are in space for a long time, our body loses some mass. The question I want to ask is, how much time is needed for a ...
0
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1answer
1k views

How long does it take for a satellite to reach MEO? [closed]

I'm just wondering how long it takes satellites from launch to orbiting in MEO.
15
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2answers
3k views

How are GPS satellite clocks synchronized with each other in the earth's frame of reference?

I have been looking at different threads. It seems like the receiver clock on Earth doesn't have to be synchronized with the satellite clocks. But I believe the satellite clocks need to be ...
15
votes
1answer
1k views

Scott Kelly age vs Twin's

Scott Kelly just returned from nearly a year of orbiting the Earth in the space station. How much younger is he than his twin, now that he has spent a significant amount of time, traveling at high ...
1
vote
1answer
155 views

Time dilation between Earth and a similar planet revolving around a supermassive Black hole [closed]

I was thrilled watching 'Interstellar'. It was only much later that I came to realize certain anomalies in the movie (like the scene in which McConaughey approaches the Gorgantua — his body ...
9
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4answers
6k 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 ...
4
votes
2answers
1k 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 - ...
6
votes
3answers
162 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 ...
0
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4answers
841 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 ...
5
votes
3answers
717 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 ...
11
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4answers
2k 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 ...
3
votes
2answers
667 views

How to calculate Coordinated Mars Time (MTC)?

I'm trying to figure out how to calculate Coordinated Mars Time (MTC). Can it be calculated directly from Earths current time/date, or calculated from the current Mars Sol Date (MSD)? From this wiki ...
0
votes
1answer
131 views

What would happen to perceived time in this scenario?

This is difficult for me to explain, but hopefully I can get my question across... Let's say there is a planet called Planet X one million light years from Earth (there probably is). Let's also say ...
11
votes
3answers
3k views

How much faster (or slower) would it be for a new probe to reach Pluto?

New Horizions just reached Pluto after almost a decade in space. That means it was launched with technology that is well over a decade old (when you factor in planning and construction time). If we ...
20
votes
2answers
13k 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 ...
0
votes
1answer
429 views

Considering the relativity of time, how is time experienced in deep space? [closed]

To be more specific, if the relativity of time is governed by the mass and gravity of objects (I.E the satellites orbiting earth experience minor time dilation compared to us on the ground), how is it ...
9
votes
2answers
993 views

If the Alcubierre Warp Drive was used to travel to Alpha Centauri, how much time would pass on Earth?

If the Alcubierre Warp Drive was used to travel to Alpha Centauri, how much time would pass on Earth? Per this article, it would take merely days to travel there. Say a ship travels there, spends a ...
14
votes
1answer
362k views

The true meaning of Sol regarding time on Mars

I'm writing a story about Mars and I'm really confused as to how one should use the word 'Sol when talking about the passage of time there. For example, Would one say to a colleague: "Today is Sol 345,...
0
votes
1answer
188 views

Theoretically, could gravitational time dilation ever be an issue when visiting an alien planet?

If humanity ever got to the point of being able to explore new planets (assuming we could land there), are there any known entities in the universe that are so massive that gravitational time dilation ...
8
votes
1answer
10k 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 (...
6
votes
1answer
164 views

What time of events is given for probes a long way away from Earth?

Philae is to land on 67P/Churyumov-Gerasimenko today at 17:02 CET. The comet is currently 3.409AU away from Earth. That means signals from the lander take a little over 28 minutes to reach Earth. Does ...
11
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4answers
2k views

Has an interplanetary date/time system been established yet?

Obviously, with no humans living permanently off-planet yet, Earth-style dates and times are the most common system is use, and reasonably so. And it helps that Mars's day is almost the same length ...
32
votes
5answers
35k 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 ...