Space Travel

[Foreigner]

Ever wondered how spacecraft are able to travel vast distances over decades?

Informative article provides brief explanation of the science of space travel:

https://cosmosmagazine.com/technology/how-do-spacecraft-travel-further-then-their-fuel-allows

 

[kamchatsky]

That is also how Juno (a huge spacecraft) get out of Earth's gravity to get to Jupiter and get into Jupiter's orbit. It uses Earth for gravity assist. It is one of the most common techniques used by NASA.

Juno | NASA

https://www.missionjuno.swri.edu/earth-flyby/

New Horizons used Jupiter gravity assist to get to Pluto 4 YEARS earlier without gravity assist.

https://www.nasa.gov/mission_pages/newhorizons/main/

http://pluto.jhuapl.edu/Mission/The-Path-to-Pluto/Jupiter-Science.php

It is quite fascinating!

 

[Warks]

Now we've got somewhere to visit outside our solar system but "within reach" if we can last 70 000 years in hibernation.


Discovery of potentially Earth-like planet Proxima b raises hopes for life
https://www.theguardian.com/science...-nearest-star-raises-hopes-for-life-proxima-b

 

[medhead]

The other big thing will be asteroid mining, that will allow future spacecraft to avoid the deltaV cost of 10km/s to get off the earth. Build the spacecraft in earth orbit, from materials mined in space.

I have a colleague whose other PhD was on asteroid mining. Interesting developments it seems.

 

[kamchatsky]

Now we've got somewhere to visit outside our solar system but "within reach" if we can last 70 000 years in hibernation.


Discovery of potentially Earth-like planet Proxima b raises hopes for life
https://www.theguardian.com/science...-nearest-star-raises-hopes-for-life-proxima-b

Well within a couple of centuries we should be able to travel faster than speed of light. That would cut down our travelling time to 4 years or less. That is according to Star Trek anyway.

 

[medhead]

Well within a couple of centuries we should be able to travel faster than speed of light. That would cut down our travelling time to 4 years or less. That is according to Star Trek anyway.

We can't get to the Star Trek level until they develop the solution to time dilation. But at least time dilation will work in favour of those in on the 70000 year trip.

 

[Warks]

Isn't there a notice board somewhere near Alpha Centauri warning of the imminent demolition of Earth by the Vogons for a pan-galactic expressway?

 

[Renato1]

If you Google "Project Orion" or "Nuclear Propulsion" you'll be surprised to learn that back in the 1950s, the Americans came up with a way to fly big ships at a tenth to a third the speed of light. None of this mucking around with ultra-slow gravity assists - just blast one's way quickly to whichever outer planet one wished to visit. Though travel to the nearest star to the sun would take 40 years or less.
Regards,
Renato

 

[JohnK]

The obvious answer is wormholes. Or is it the obvious answer are wormholes?

 

[Deleted member]

The obvious answer is wormholes. Or is it the obvious answer are wormholes?

Answers are vs answer is.

 

[medhead]

The problem with wormholes is time dilation. Time on an object moving away from earth at speed slows down compared to time on earth. The time dilation is related to the speed of the object compared to the speed of light. This arises because the speed of light is constant - for example if you're travelling towards a light particle the speed of the light particle does not increase to be the sum of your speed and the particle's speed. For light to remain at a constant speed then your time needs to slow down.

At low multiples of c (the speed of light) time dilation isn't that large, upto say 5% @ 0.3x c. But at high fractions of c time dilation is massive, in theory if you can get to c then time stops. Wormholes are considered to have travel speeds almost at the speed of light 0.99c. At that speed time on earth is 7 times faster than time on the space ship.

 

[Denali]

The problem with wormholes is time dilation. Time on an object moving away from earth at speed slows down compared to time on earth. The time dilation is related to the speed of the object compared to the speed of light. This arises because the speed of light is constant - for example if you're travelling towards a light particle the speed of the light particle does not increase to be the sum of your speed and the particle's speed. For light to remain at a constant speed then your time needs to slow down.

At low multiples of c (the speed of light) time dilation isn't that large, upto say 5% @ 0.3x c. But at high fractions of c time dilation is massive, in theory if you can get to c then time stops. Wormholes are considered to have travel speeds almost at the speed of light 0.99c. At that speed time on earth is 7 times faster than time on the space ship.

Last week we visited Space Place in Wellington (got to use the big telescope!)

I left sadden by how little Stargate actually prepared me for discussions such as this.

 

[medhead]

Last week we visited Space Place in Wellington (got to use the big telescope!)

I left sadden by how little Stargate actually prepared me for discussions such as this.

I did avoid the paper that discusses using wormholes to time travel.
Well it's not really time travel, as the traveller is just moving along their own time line. But the whole thing about relativity (time dilation and such) is it's all about the difference between the frames of reference of observer (fixed frame of reference) and travellers (moving frame). All dependent on the wormhole being fixed as the earth end, and being internally short so that time remains synchronised in the wormhole. One end of a wormhole links back to an earlier time on earth because of the time dilation between either end of the wormhole. or something like that.

 

[Boca68]

Well within a couple of centuries we should be able to travel faster than speed of light. That would cut down our travelling time to 4 years or less. That is according to Star Trek anyway.

I thought the general consensus was that going faster than the speed of light was theoretically (and most likely technically) impossible? And wormholes were just a script writers invention? The concept of time dilation is understandable, if you set aside the implausability (sp.?) of moving faster than the speed of light.

Ok, back to Star Trek for more research data, I think!

 

[TheRealTMA]

I thought the general consensus was that going faster than the speed of light was theoretically (and most likely technically) impossible? And wormholes were just a script writers invention? The concept of time dilation is understandable, if you set aside the implausability (sp.?) of moving faster than the speed of light.

Ok, back to Star Trek for more research data, I think!

Different universes for different folks.

 

[trooper]

Read "The Forever War"....

And you thought 30 years in the Army was a long time??? :mrgreen::mrgreen:

 

[medhead]

I thought the general consensus was that going faster than the speed of light was theoretically (and most likely technically) impossible? And wormholes were just a script writers invention? The concept of time dilation is understandable, if you set aside the implausability (sp.?) of moving faster than the speed of light.

Ok, back to Star Trek for more research data, I think!

The physics says that time stops, for the traveller, at the speed of light. That's a physical limitation. Having said that the wormhole paper, that I referred to previously, from the 1980s is based on a wormhole that is internally short so that clocks just inside either entry are synchronised, and travel time from one end to the other is instantaneous - i.e. faster than light. But formation of the wormhole, that is movement of the other end from earth, is at the 0.99 of c. So for that nearest plant it would take 4 years to form a wormhole to get there.

 

[Skyring]

Now we've got somewhere to visit outside our solar system but "within reach" if we can last 70 000 years in hibernation.

And just think of the mileage runs!

 

[marki]

Answers are vs answer is.

I feel like a wormhole in an apple ..... Going nowhere fast