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My mostly hard sci-fi campaign


tkdguy

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Re: My mostly hard sci-fi campaign

 

OK, you can get something useful at http://cfa-www.harvard.edu/iau/MPEph/MPEph.html

 

This can give you asteroid positions. Type the asteroid names of interest in the first box (Ceres, Vesta, Pallas). Looks like the format it wants for the start date is yyyy mm dd.ddd, so for you e.g. 2076 07 04 would work for you (that's July 4, 2076).

 

For output you want the "heliocentric position vector" or perhaps the "heliocentric position/velocity vector". That gives you X, Y, and Z numbers. The units are in AUs, and (0,0,0) is the solar system barycenter (the Sun, for our game purposes). The X-axis points out toward the vernal equinox of Earth's orbit, and the Y-Axis toward RA 6 hours. The Z-axis is toward the north ecliptic pole. There's some very sketchy description at http://www.cv.nrao.edu/~rfisher/Ephemerides/ephem_use.html and http://www.cv.nrao.edu/~rfisher/Ephemerides/ephem_descr.html and it looks like the "JPL ephemeris" those last two pages are discussing is on the Web at http://ssd.jpl.nasa.gov/horizons.cgi

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Re: My mostly hard sci-fi campaign

 

Okay, I'm redoing the travel time between planets. Taking Cancer's advice, I'll use the formula acceleration = thrust/mass. Should I use the formula time = [2*distance/acceleration]^1/2 to find the travel time?

 

Note: I've decided to go with gas core reactor core rockets, which have higher thrust and delta-v than the VASIMR drive.

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Re: My mostly hard sci-fi campaign

 

Here's a rough timeline of the campaign:

 

2010: ISS completed; Orion spacecraft replaces the Space Shuttle

2015: Project Orion enables US ships to return to the moon

2017: Joint Russian-Chinese venture to the moon

2020: Lunar outposts completed; first use of VASIMR drive; rail guns become practical

2023: First space stations on L4 and L5 begin construction

2025: First space tug becomes operational

2028: First manned mission to Mars

2032: Several national and international outposts founded on Mars

2037: Military coup in Russia returns the Communist Party to power

2041: Asteroid mining becomes practical

2042: Gas core reactor rockets become practical

2048: Preliminary mission to Jovian moons

2050: Space stations orbiting Mercury and Venus completed

2053: Preliminary mission to Titan

2064: Space elevator in the Pacific Ocean becomes operational

2067: Western and Eastern natiions begin colonizing the moons of Jupiter and Saturn without notifying one another

2068: Territorial dispute over the moons begins; all involved nations agree to share the territories for now

2070: Russia and China arm their colonies on L4

2072: USA begins building military spacecraft in L5

2074: Mining accident on Ceres; sabotage is suspected and fingers are pointed

2076: Unexplained destruction of a Chinese spacecraft and the American space station where it was docking. Chinese and US ships investigate independently; a skirmish ensues. War is declared on September 12

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Re: My mostly hard sci-fi campaign

 

Okay' date=' I'm redoing the travel time between planets. Taking Cancer's advice, I'll use the formula acceleration = thrust/mass. Should I use the formula time = [2*distance/acceleration']^1/2 to find the travel time?

 

Note: I've decided to go with gas core reactor core rockets, which have higher thrust and delta-v than the VASIMR drive.

 

That time estimate is as good as any other. You might stick in an irreducible floor value of half a day for things that are really close. Doing realistic orbital mechanics solutions for the travel time is More Work Than You Want . Letting the travel times vary as the planets move is probably all the realism you need.

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Re: My mostly hard sci-fi campaign

 

FWIW, the L2 point is technically unstable, but with an active spacecraft, you can stay there more or less indefinitely. It is becoming the location of choice for deep space science missions (see, e.g., here).

 

The problem with L4 & L5 is that because they are stable, there's a population of naturally-accumulating space junk around each. This is a hazard (because "around" is literal; stuff "orbits" through the point) not only is there enhanced collision danger, but that population of accumulated junk makes for a cloud of trash in which stealthy/disguised warheads etc. can "hide". You could make an active reminder of this a feature of your campaign, of course. :eg:

 

L2, being unstable, lacks that "Bermuda Triangle" sort of tendency to accumulate trash.

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Re: My mostly hard sci-fi campaign

 

Thanks for the link, Cancer. I heard L2 was going to be the location of WMAP; I'm thinking of making the observatory there its successor. It will have booster rockets that will be used when its orbit needs to be stabilized. This would also be the case for the L1 station and the ill-fated L3 colony.

 

How much space debris is there in the L4 and L5 locations? I'm looking at the Kordylewski clouds entry on Wikipedia; perhaps there is a crew that clears out the debris (something from Planetes?). And the debris may indeed be hiding some nukes or other defenses.

 

As for the search for life on Europa, Enceladus, etc. The search continues, and there will be teams of scientists involved in those places looking for clues. Maybe something will be found; for now it's out of the scope of my campaign. However, it's a great idea for the continuation/sequel of the campaign.

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Re: My mostly hard sci-fi campaign

 

For the sake of convenience, I decided spacecraft engines could provide a thrust equal to 1% of the spacecraft's total mass. gives me these times:

 

Earth to Mercury: 49.6 days

Earth to Venus: 33.3 days

Earth to Mars: 45.8 days

Earth to Ceres: 84.3 days

Earth to Jupiter: 129.8 days

Earth to Saturn: 185.2 days

 

Trips to the moon, L4 and L5 would require less thrust, but such a trip would take only 2-3 hours.

 

I'll post the other travel times between other planets later.

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Re: My mostly hard sci-fi campaign

 

Thanks for the link' date=' Cancer. I heard L2 was going to be the location of WMAP; I'm thinking of making the observatory there its successor. It will have booster rockets that will be used when its orbit needs to be stabilized. This would also be the case for the L1 station and the ill-fated L3 colony.

 

How much space debris is there in the L4 and L5 locations? I'm looking at the Kordylewski clouds entry on Wikipedia; perhaps there is a crew that clears out the debris (something from Planetes?). And the debris may indeed be hiding some nukes or other defenses.

 

As for the search for life on Europa, Enceladus, etc. The search continues, and there will be teams of scientists involved in those places looking for clues. Maybe something will be found; for now it's out of the scope of my campaign. However, it's a great idea for the continuation/sequel of the campaign.

 

I'll look into the question about how much debris is at L4/L5. I think that in Earth's case people have recognized that it's going to be out there, but I'm not aware of any identified objects. Now, given that stuff does accumulate there, you could use that part of space as the place where whatever billion-year-old extrasolar McGuffin Machine that you might feel like introducing into your campaign is likely to be found.

 

For Jupiter, there's a population of largish asteroids (the Trojans) at its L4 & L5. Those guys will be kilometers in size. More than that I don't know at this point.

 

EDIT: There's been something in Scientific American in the last couple years about spacecraft in L2 and other "unstable" orbits. I'll see if I can find that more precisely.

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Re: My mostly hard sci-fi campaign

 

Found one paper of a direct imaging survey of the area around L4 & L5. They didn't find anything. Their limits are such that this means nothing 175 meters in diameter or larger if it's S-type, that is, silicaceous rock-type stuff, or 350 meters or larger if it's C-type (carbonaceous, a type of primitive rock we don't have on earth any more). C-type is substantially darker, so the limit on brightness means more "room" for a dark thing to remain undetected.

 

Heh. Only marginally related, but this looks interesting; it's from a forecast of the next fifty years, made in 1986.

 

EDIT:

The total number of L4 Trojans with radii ≥1 km is of order 1.6 × 10^5, and their combined mass (dominated by the largest objects) is ∼10^-4 MEarth.
That's talking about Jupiter's Trojans, not Earth's. That's from a more powerful survey than the one I found mentioned above looking for Earth-Trojans.
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