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Riggswolfe

Space travel times

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Posted (edited)

I was thinking of running a short tangent in my campaign where the PCs are hired to guard a cargo going from the moon to one of the moons of Jupiter which houses a secret corporate lab. But I'm curious about travel times. Is there a mention somewhere that I've missed that covers this?

It looks like in real life it takes around 600 days or so. That seems like a long tangent for my game!

Edited by Riggswolfe

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2 hours ago, Terefang said:

since artificial gravity and ftl have not been invented yet, most people will spend their travel time in suspended animation chambers at best.

In which case it'll be handy if you want to advance some narratives without player interference. Not so useful if you want a short side quest.

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You might be surprised at how quickly we can travel to the planets without needing to use exotic materials or fake science by using 1g acceleration. The "top" of the ship pointing at your destination would be "up" in the ship, which at that acceleration, would feel like gravity on Earth. Half-way though, the ship turns around, pointing its engines at your destination and then fire at 1g, decelerating the ship. Once again, the nose of the ship (now pointing at Earth) is still up and the 1g of decelerating again creates the feeling of normal gravity. What is mind blowing is how fast we can then get to places. This type of technology should be absolutely feasible in a society that can build a space elevator.

Luna: Three hours and 20 minutes

Mars: Just under two days

Jupiter: Five days and 16 hours

Pluto: 15 days and 7 seven hours

Proxima Centauri (4.2 light years away): Only five years and a few months!!! (Not sure if this includes the deceleration part)

Here is the link to the site I used: https://space.stackexchange.com/questions/840/how-fast-will-1g-get-you-there

Also, the greater the distance (hence speed), the more the Theory of Relativity is noticeable. 

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Posted (edited)
1 hour ago, saint1012 said:

Luna: Three hours and 20 minutes

Mars: Just under two days

Jupiter: Five days and 16 hours

Pluto: 15 days and 7 seven hours

Proxima Centauri (4.2 light years away): Only five years and a few months!!! (Not sure if this includes the deceleration part)

Here is the link to the site I used: https://space.stackexchange.com/questions/840/how-fast-will-1g-get-you-there

Also, the greater the distance (hence speed), the more the Theory of Relativity is noticeable. 

although the physics are correct the reality check is not -- fuel cost/efficiency is a major prohibitive factor.

https://en.wikipedia.org/wiki/Space_travel_using_constant_acceleration#Feasibility

why would someone spend Mega-Credits on a 5 day trip, if the same trip could be done in 40 days (x8 the time) but at 1/1000 the cost -- especially if the ships mass had to be a payload/fuel ratio of 1:3.

a realistic travel calculator http://nathangeffen.webfactional.com/spacetravel/spacetravel.php with ship mass/payload/fuel output

 

eg "The Expanse" (which i consider a good hard science setting example, except the third season) simply cheats some this with its "Epstein Drive" which is simply a 100 times more efficient Ion-Drive and yet has not the travel times above.

https://expanse.fandom.com/wiki/Travel_Time gives theoretical 1g Earth-Saturn transits at "5.89 days" but actual as "several weeks" tho.

"The Mormons Diaspora" to Proxima was considered a 100 years trip. At 1g speed it would have had a payload to fuel ratio of 1:5000 !

 

i also like to introduce you to the fact that space is not empty:

Quote

At ... 5g or more for 10-11 hours .... micro debris the size of a grain of sand would impact with the energy of a 100g TNT detonation.

 

Star Trek cheats this with its Warp Drive Geometry and Main Deflector Shields.

 

happy traveling

Edited by Terefang

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13 minutes ago, Terefang said:

 

eg "The Expanse" (which i consider a good hard science setting example, except the third season) simply cheats some this with its "Epstein Drive" which is simply a 100 times more efficient Ion-Drive and yet has not the travel times above.

https://expanse.fandom.com/wiki/Travel_Time gives theoretical 1g Earth-Saturn transits at "5.89 days" but actual as "several weeks" tho.

"The Mormons Diaspora" to Proxima was considered a 100 years trip. At 1g speed it would have had a payload to fuel ratio of 1:5000 !

I was also going to mention the Expanse when I saw Saint's post but you beat me to it. His description is basically the Expanse but ignoring fuel factors. I may settle on something like 3 months each way for this trip to Jupiter I have in mind.  I want some time to pass because there are events kicking off that are fallout from a previous session and I'd like to let the world get some changes in without just starting a session and going "so 6 months have passed and..." I think it'll be more interesting if we have a few sessions and I go "You saw on news reports that blah happened back on Earth." and spread this out over 3-4 sessions. (If you're curious, they inadvertently helped steal data that will make it easy to assassinate the chairman of Jinntekki and make it look like a stroke or heart attack. This is part of my plan to gradually change Jintekki into a whole new company from another franchise. *coughs*Yutani*coughs*YoumightknowwhereImgoingwiththis*coughs*

Ironically, I was going to weave in a bit of the Expanse into my campaign anyway, with a sort of protomolecule analogue being studied by Weyland.

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Posted (edited)
27 minutes ago, Riggswolfe said:

I may settle on something like 3 months each way for this trip to Jupiter I have in mind.

hmm .... x20 of the 1g travel times .... a good technical assumption.

reality check: 6 months Earth-Mars with proposed current technology

*coughs* W-Y ? *coughs* isnt the protocule *coughs* distilled out of the thingy *coughs* used by the Pilots ? *spits blood*

Edited by Terefang

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Posted (edited)

So you don't believe that in this future we could have a fusion drive that would allow for this type of travel? I am actually surprised at the amount of pushback my answer received. You agree with a space elevator and He3 fusion, but not this? The technology is quite viable for the technological level of Android.

As for reasons to make it slower such as cost or just for the story, that is for you to decide as the GM. Heck, make the acceleration .5g if you find 1g so outrageous. I was just providing details about the subject.

Space is not empty, so of course you could hit something. However, it is also almost impossibly vast and we don't have a ton of current data with our space travel. So far, Voyager 1 and 2 along with the Pioneer and New Horizons spacecraft have yet to be destroyed by hitting something. Are they lucky? Can a collision be so rare as to be negligible? Heck, we take risks each time we fly or drive right now, so what is different?

Conversely, since you will be in space for such a short amount of time, you expose yourself to that collision risk (including the risk of radiation exposure) for a much shorter amount of time. Pretty much any collision in space is going to be devastating, so your speed is not going to matter much. Even if you are travelling at a slower, more conventional speed, what's to say that an object itself moving at extreme speed relative to you won't hit you during your three-month or 600-day journey? It's like running fast in a rainstorm - do you get wetter or stay drier? Does it not matter? I seem to recall Mythbusters having fun with that one.

Anyways, just trying to make conversation about a subject that fascinated me long before The Expanse was around, so I thought I'd share.

Edited to clarify a sentence.

Edited by saint1012

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1 hour ago, Terefang said:

although the physics are correct the reality check is not -- fuel cost/efficiency is a major prohibitive factor.

https://en.wikipedia.org/wiki/Space_travel_using_constant_acceleration#Feasibility

 

eg "The Expanse" (which i consider a good hard science setting example, except the third season) simply cheats some this with its "Epstein Drive" which is simply a 100 times more efficient Ion-Drive and yet has not the travel times above

 

happy traveling

Except that link mentions fusion engines make the fuel issue go away. Additionally, The Expanse tries to do the science, but I never considered it since their drive is still impossible as far as we currently understand physics.

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1 hour ago, saint1012 said:

So you don't believe that in this future we could have a fusion drive that would allow for this type of travel? I am actually surprised at the amount of pushback my answer received. You agree with a space elevator and He3 fusion, but not this? The technology is quite viable for the technological level of Android.

As for reasons to make it slower such as cost or just for the story, that is for you to decide as the GM. Heck, make the acceleration .5g if you find 1g so outrageous. I was just providing details about the subject.

Space is not empty, so of course you could hit something. However, it is also almost impossibly vast and we don't have a ton of current data with our space travel. So far, Voyager 1 and 2 along with the Pioneer and New Horizons spacecraft have yet to be destroyed by hitting something. Are they lucky? Can a collision be so rare as to be negligible? Heck, we take risks each time we fly or drive right now, so what is different?

Conversely, since you will be in space for such a short amount of time, you expose yourself to that collision risk (including the risk of radiation exposure) for a much shorter amount of time. Pretty much any collision in space is going to be devastating, so your speed is not going to matter much. Even if you are travelling at a slower, more conventional speed, what's to say that an object itself moving at extreme speed relative to you won't hit you during your three-month or 600-day journey? It's like running fast in a rainstorm - do you get wetter or stay drier? Does it not matter? I seem to recall Mythbusters having fun with that one.

Anyways, just trying to make conversation about a subject that fascinated me long before The Expanse was around, so I thought I'd share.

Edited to clarify a sentence.

I'm definitely trying to get a feel for things space-wise, hence my topic. I feel like Android is on the cusp of a technological breakthrough in space travel. My understanding is that is Jack Weyland's entire focus, trying to make interstellar travel possible. The 1g thing is basically how the Expanse does it, though in the books they rarely go that fast during trips, usually going at something more akin to 1/3rd of a g even with their Epstein drive if memory serves. 

I'm not concerned with collision risks simply because, it's a game, I don't want to get bogged down too much in those details unless it has a dramatic purpose.  

I do think I'll be using constant acceleration and if the players ask about fuel I'll handwave it by mentioning the He3 fusion. I do think, even with that, fuel would still be a limiting factor as far as these kinds of engines go. But I haven't run the numbers obviously.

 

 

1 hour ago, Terefang said:

 

*coughs* W-Y ? *coughs* isnt the protocule *coughs* distilled out of the thingy *coughs* used by the Pilots ? *spits blood*

You pretty much got where I was going with it. Heck, the Genesis core book has a "Xenomorph" in it already. And it's not a big leap to equate the Protomolecule with that goo from the Alien prequels. (Ironically, I don't care for Prometheus or Covenant as Alien prequels but do like the concept of the goo as its own science fiction thing.)

This is all inspired by one of my players owing Weyland a big favor from the start of the game and declaring he liked his contact I'd made. "Peter Snow" who looks just like Guy Pierce and keeps stepping in to help their problems go away. He even took a rogue Nissei clone off of their hands, assuring them he had the perfect job for her. Of course, hopefully this telepathic clone doesn't get exposed to some kind of ... goo. That'd be a shame.

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Posted (edited)
4 hours ago, saint1012 said:

So you don't believe that in this future we could have a fusion drive that would allow for this type of travel? I am actually surprised at the amount of pushback my answer received. You agree with a space elevator and He3 fusion, but not this? The technology is quite viable for the technological level of Android.

i should mention that i have an education as electrical engineer with power systems and mechanical engineering as a secondary.

 

Hmm .... if you ask about the availability of the drive, thats a different case.

Yes, i think that the drive/technology can be available at the TL of Android.

No, i think that fuel efficiency/storage/cost are a limiting factor, that probits sustained 1g travel

Unless you find a way to circumvent Newton or use handwaveium, our physics are bound by its limitation (see https://en.wikipedia.org/wiki/Reaction_engine)

Edited by Terefang

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Posted (edited)
3 hours ago, Riggswolfe said:

I do think I'll be using constant acceleration and if the players ask about fuel I'll handwave it by mentioning the He3 fusion. I do think, even with that, fuel would still be a limiting factor as far as these kinds of engines go. But I haven't run the numbers obviously.

if its a dedicated personal transport ship (payload/fuel ratio of 50:50) -- sustained 0.3g is possible with 12days to Jupiter !
(having run the numbers)

Edited by Terefang

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Below is some info from the books on space travel. Feel free to ignore anything that could get in the way of fun.

A ferry shuttle trip from the Challenger planetoid to the moon takes between one and three days depending on where it is located with respect to the planetoid. (Sof p. 206)

The only reference to space travel time I can find for mars is in Android: Rebel (The Identity Trilogy Book 3):

Quote

During the months I'd been en route aboard Khloe, several major riots had broken out […]

The protagonist in that book travelled from the moon to mars aboard the Khloe, a cargo freighter. I assume passenger freighters would be faster.

I haven't found anything for travel time to Jupiter.

Pages 144 and 145 of the Worlds of Android book describes starship technology. (Power sources, drives, life support)

Quote

Thrust gravity achieved during acceleration and deceleration is used to provide passengers a more comfortable journey, but additional gravity can be produced by centripetal acceleration through spinning hull sections or internal carousels. Due to the technical and size limitations of the spin carousels used for these systems, gravity generation through centripetal acceleration is really only effective on the massive, long-haul ships that run the route between Mars and Earth, or the proposed deep space exploration and survey ships.

A sidebar on page 117 of the Shadow of the Beanstalk book describes Burke heavy freighters having rotating crew rings providing artificial gravity for long voyages.

A heavy freighter (p. 116), primarily used to transport cargo and people between the Earth and Mars, is describing as carrying 12 months of consumables.

If you need faster travel speed, you could advance the timeline by a few years. Worlds of Androids p. 144 describes a new drive technology being developed:

Quote

As technology advances, new and exotic drive technologies continue to be developed. Among the most promising of these new technologies is the outlandish nanoparticle field extraction thruster, which produces thrust via charged particles composed of carbon nanotubes. Developing systems like the nanoparticle field extraction thruster will power the next generation of deep space exploration ships and will open up even the farthest reaches of the solar system to human exploration and habitation.

On travel costs (Worlds of Androids, page 165):

Quote

The spaceflights from Earth to Mars are exorbitantly expensive even for coffin-sized accommodations, so most newcomers sign on with a corporation to pay for their passage.

Speaking of secret corporate labs, here is something that could fit the bill (Worlds of Androids, page 163):

Quote

[…]outposts[…] like the Ganymede Project on the Moons of Jupiter, actively recruit from Luna’s populace, promising a life of adventure and exploration.

 

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20 minutes ago, Aazlain said:

new technologies is the outlandish nanoparticle field extraction thruster, which produces thrust via charged particles composed of carbon nanotubes.

probably Androids version of the Epstein drive, where superconduction nanotubes (very energy efficient) are used to accelerate ion nanoparticles -- LOL.

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33 minutes ago, Aazlain said:

I haven't found anything for travel time to Jupiter.

assuming general engineering principles (having a minimal payload/fuel ratio 10:1) 
AND using the calculator from http://nathangeffen.webfactional.com/spacetravel/spacetravel.php
Earth-Jupiter transit (~ 5AU) at 0,001g constant acceleration/deceleration would take 200 some days (or 6 some months)

5AU at 0,0005g constant acceleration/deceleration would take 286 some days (or 9 some months) having a payload/fuel ratio 20:1.

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if someone whats to read more about, i can recommend:

  • "Fire Fusion & Steel", although being a Traveller/New Era Supplement (and heavy on the STEM side) is still one of the best products on the subject from a RPG perspective.
  • "GURPS Space" a lighter read (STEM-wise) with sections dedicated to Would Building and Alien Life.

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Wow, this is all very useful. I had envisioned a stop over at Mars for resupply. That novel saying it took months to get to Mars does provide a bit of an issue. Mars is about 1.5 AU from the Sun Now, I could be nice and say it was nearly on the other side of the Sun from the Earth during the time of the novel which would put it at something like 2.5 AU from Earth, especially since the ship would have to swing wide around the sun. So, assuming months is, say...3 months. Then I do get a rough travel time to Jupiter ranging from 6 months to a year depending on relative positions in orbit. I'm sort of doing this off the top of my head so am probably missing something.

I can easily turn this into 2-4 sessions or more or a side tangent in the campaign which gives things on Earth time to naturally progress and also gives a change of pace to the game. One of my players is mechanically inclined, another can pilot almost anything and another is a Loony, so I think they might enjoy a trip in space anyway!

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Posted (edited)
32 minutes ago, Riggswolfe said:

Then I do get a rough travel time to Jupiter ranging from 6 months to a year depending on relative positions in orbit. I'm sort of doing this off the top of my head so am probably missing something.

but you got the concept.

 

in previous sessions (other rpgs) i have used the transit formula (wildly simplified orbital mechanics) for going out of the system: D=(Ds1+Ds2)*PI/2

so with Earth (Ds = 1AU), Mars (Ds ~ 1.5AU), Jovian System (Ds ~ 4.2AU):

Earth-Mars would be 3.9AU

Mars-Jupiter would be 8.95AU

 

going sunward we used: D<=(Ds1+Ds2)

Jupiter-Earth would be at most 5.2AU, since you could target a much better orbital position during flight time anyhow

Edited by Terefang

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Posted (edited)
1 hour ago, Riggswolfe said:

…That novel saying it took months to get to Mars does provide a bit of an issue.…

The protagonist was travelling on a private cargo freighter as part of the crew (no passengers aboard). A passenger ship or a corp owned transport could probably travel significantly faster when the main concern is not delivering cargo in a cost efficient manner.

 

7 hours ago, Riggswolfe said:

You pretty much got where I was going with it. Heck, the Genesis core book has a "Xenomorph" in it already. And it's not a big leap to equate the Protomolecule with that goo from the Alien prequels. (Ironically, I don't care for Prometheus or Covenant as Alien prequels but do like the concept of the goo as its own science fiction thing.)

You do know that you are now required to include a sociopathic bioroid with a hidden agenda as part of the ships's crew, don't you? Is Ash LV426 too obvious a name?

Edited by Aazlain

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1 hour ago, Riggswolfe said:

I had envisioned a stop over at Mars for resupply.

makes sense travel wise ... 

making Earth-Mars in a 1AU Window and waiting on Mars for a Mars-Jupiter 3AU Window

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3 hours ago, Aazlain said:

You do know that you are now required to include a sociopathic bioroid.

it need not be sociopathic, we just override its command structure so that it keeps information from the crew ...

... yes, dave. i can not do that ...

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5 hours ago, Terefang said:

if someone whats to read more about, i can recommend:

  • "Fire Fusion & Steel", although being a Traveller/New Era Supplement (and heavy on the STEM side) is still one of the best products on the subject from a RPG perspective.
  • "GURPS Space" a lighter read (STEM-wise) with sections dedicated to Would Building and Alien Life.

I still have mental trauma from trying to use FF&S back in high school (before I had a calculator or computer that could handle those formulae).

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Posted (edited)

I found a mention of travel times in the book.  The heavy freighter talks about the new engines it has and says it can make it to Heinlein in a matter of days. So if the newest engine on the market takes days to get to Luna, then I suspect our travel time is still pretty accurate.

Edited by Riggswolfe

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Posted (edited)
On 5/13/2019 at 2:38 AM, RustamShamshiri said:

figuring flight times with sustainable accelerations

the theoretical math is ok, but it does not include orbital mechanics (eg. https://en.wikipedia.org/wiki/Orbital_speed).

so if you starting to leave from the jovian system, you already have (the jovian system) speed vector of 13.07 km/s (47052 km/h) which you need to cope with.

on the other hand, earth has an orbital speed (but different vector) of 29.78 km/s (107208 km/h).

 

basically it boils down to the issue of playability vs realism, but what you need is simple consistency.

 

PS: in an other rpg universe where nobody wanted to do the math,
it was decided by handwavium that travel times were simple R1+R2 in AU in weeks
(Earth->Mars = 1+1.5 = 2.5 weeks, Mars->Jupiter = 1.5+4.2 = 5.7 weeks)

PPS: and in that rpg universe every ships engine had a drive multiplier you would multiply this time with
(ie. greater multipliers = longer travel times)

PPPS: that reminds me, we later added "realism" by changing the travel times from X.Y (weeks) to X d10 + Y (days),
(ie. Mars->Jupiter = 5d10+7 days times drive multiplier)

Edited by Terefang
corrected dice type from old notes

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