[Spaceships] Will this design be effective?

[Trachmyr]

In the next game for my Epsilon Eridani Campaign, the PC's will be "Comet Wranglers". The system always faces threats from Kupier Belt objects as
it is in the "Late Heavy Bombardment" phase of development.

The following ship design is a standard "Comet Wrangler", but I'm wondering if
it would actually be effective in it's job. Assume most comets are intercepted no later than a Earth-Year before impact
(usually 5+ years), and detection rates are Extremely High, but many are "Mass-Extinction" event bodies.

Oh, and yes I know the $ and thrust for Fusion Rockets & Power Plants are not RAW (and Computer Complexity is Higher),
but that is the Advanced part of TL10 (Advanced).

Thanks in advance for any comments or feedback!
- Trachmyr

Hermes OCIO Interceptor, TL10 (Advanced Fusion)
(OCIO: Orbit-Crossing Impact Object)

	This is a rugged 3,000-Ton craft designed for the 
quick interception of Icy OCIOs in the Epsilon Eridani system. 
The vessel secures itself to the comet and uses it's engines to 
alter its course to eject the body from the system or direct it into
star. Onboard refineries allow it to maintain a steady thrust to
acomplish its mission.		[$73 Million]

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Front Hull
[1-2] Steel Armor ($1.2M, 14dDR)
[3-4] Mining ($6M, 30 Tons/hr, -2PP)
[5] Medium Battery ($10M, [1] 32cm Fixed Launcher, [1] 30mj Rapid Fire UV Laser Turret, 50 Tons Cargo) 
[6] Control Room ($6M, Sensor 8, Comp C10, 6 Workstations)

Central Hull
[C] Habitat ($3.1M, 12 Cabins, 1 Automed, 1 MiniFac, 1 Briefing Room, 1 Gym, 15 Tons Steerage Cargo)
[1-2] Steel Armor ($1.2M, 14dDR)
[3-4] Mining ($6M, 30 Tons/hr, -2PP)
[5] Water Fuel Tank ($1M, 6 DV)
[6] External Clamp ($0.3M)

Rear Hull
[C] Engine Room ($1M, 2 WS)
[1-2] Steel Armor ($1.2M, 14dDR)
[3-4] Fusion Power Plant ($20M, +4PP)
[5] Water Fuel Tank ($1M, 6 DV)
[6] Ultra-High Thrust Water Fusion Rocket ($15M, 0.1G)

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NOTE: All fusion Tech is priced as Fission. Fusion Rockets have 2x Thrust, 
or 2x DV for listed fusion costs. Ultra-High Thrust is available only for 
Water burning Rockets, total modifier is 10x Thrust & 1/10th DV. 
Computer Complexity is also +1 to Complexity listed, to a maximum of 11.

[David Johnston2]

Honestly it would be more effective to just arm your comet wrangler with an energy weapon. That way you can use the vaporizing comet to provide the rest of it with enough delta-V to steer it around.

[Fred Brackin]

Originally Posted by Trachmyr

The following ship design is a standard "Comet Wrangler", but I'm wondering if
it would actually be effective in it's job.

I am dubious of the External Clamp part. I doubt comets are really solid enough to be "clampable".

Also, since you don't seem to be _using_ the comets for anything why aren't you doing something simple like blowing them up instead?

[Trachmyr]

Thanks for the Replies...

External Clamp: I have no issue making this a specialized component... such as a series of hydrolic firing Pitons, or screws that run the main length of the vessel. Thus allowing them to work on comets but not on other craft.. well you could ;)

Would an energy weapon be more effecive? How would vaporizing it with a few 300mj lasers provide more DV than a continously operating 300 Ton thrust rocket? I'm not aware of the physics involved.


As for blowing up the commets... I was under the impression that it was less effective than hollywood has made it out to be.

One concern with the explosive route is that many of the colonies that are being protected are in fact beehive asteroids in Eridani's interior belt. Threats of impact, destablizing due to gravity and cascade events must be delt with. And while I know that the main belt is in fact quite sparse, Eridani is in the Heavy Late Bombardment phase with a Kupier Belt more than 1000x denser than our own... Would blowing up a 10-mile wide commet be prudent?

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The calculations I'm working with are: 6 Trillion Tons for a 10-mile diameter Comet with a density of just under 1/2 Earth's.

With 300 Tons of thrust (0.00000000005G), it would take 1 year to add 0.00001 MPS to it's trajectory.This would be a bit over 150 miles in the first year, another 450 in year 2, another 750 in year 3, and so on.

This does seem a bit anemic, but this is assuming a massive comet. Velocity change would be 1000x greater for a 1-mile comet, etc.

[Fred Brackin]

Originally Posted by Trachmyr

As for blowing up the commets... I was under the impression that it was less effective than hollywood has made it out to be.


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The calculations I'm working with are: 6 Trillion Tons for a 10-mile diameter Comet with a density of just under 1/2 Earth's.

That's not a comet. Earth's density is around 5.5 gm/cc and half that is 2.75 which is right in the range for solid granite. That's an asteroid and a pretty solid one too.

A 10 mile wide chunk of solid granite you could clamp to though I would call the component in question more of a docking collar. Actually a set of landing legs on the opposite side of the thruster would do too.

If you actually want a comet the usual assumptions about composition run more toward "dirty snowball" than "solid granite". That would be a density even less than the .92 or so for solid ice.

http://www.nature.com/nature/journal.../370349a0.html

.....this link puts Shoemaker-Levy-9 at around .0.5 gm/cc.

I wouldn't expect dirty snowballs to be solid enough to clamp. Lasering them to provide thrust would also be affected by the solidity thing. You'd be imparting energy to one chunk which would probably break free and shoot off by itself.

Scientists don't like nukes but it's probably because they're crude more than they are not a cheap way to apply a lot of energy to something in a short time.

The thing they don't emphasize about non-nuke schemes for diverting asteroids that tney're afraid will hit Earth is that you need about 3 close approaches warning before the hit. Cal it 40-60 years at least

On the first you detect the threat and spend the time until the next close approach preparing whatever you're going to do.

On the second close approach you launch your asteroid-diverter and it has a whole orbit to work.

Then on the third close approach (which you were afraid was going to be the impact) you've changed things enough that it misses.

On the scale of 1-5 years you're working on (and for a big comet coming in from the outer system that's probably about right) subtle may not be a realistic option.

If you blow the fluffy thing up it probably will coalesce again and it might even be in a short period of time from an astronomical perspective but that will be much longer than a year.

It ought to be multiple orbits as it's the effect of solar tidal forces that herd the bits together again rather than the object's own gravity. You could stand on the surface and throw snowballs at more than the comet's escape velocity. The problem is that you'll be throwing them into very similar solar orbits.

For the scenario you've outlined I'm afraid it's BOOM! time.

[David Johnston2]

Originally Posted by Trachmyr

Thanks for the Replies...

External Clamp: I have no issue making this a specialized component... such as a series of hydrolic firing Pitons, or screws that run the main length of the vessel. Thus allowing them to work on comets but not on other craft.. well you could ;)

Would an energy weapon be more effecive? How would vaporizing it with a few 300mj lasers provide more DV than a continously operating 300 Ton thrust rocket? I'm not aware of the physics involved.

You only brought two tanks of reaction mass. You won't be continuously operating for all that long. The advantage of using the laser is that you can use the comet's own mass as reaction mass. You'll never run out. Trying to push with your engines, you'll run out in no time.

[lexington]

Originally Posted by David Johnston2

You only brought two tanks of reaction mass. You won't be continuously operating for all that long. The advantage of using the laser is that you can use the comet's own mass as reaction mass. You'll never run out. Trying to push with your engines, you'll run out in no time.

The mining facilities can pull 120 tons of ice per hour from the comet to supply the engines for as long as they need. Of course, if he meant to use an asteroid that won't work.

[Trachmyr]

Yeah, it's meant to intercept a comet (Meteor interceptors would use Mass Drivers). I guess I just calculated the Density too high! I used GURPS SPACE to work out the mass, and based the density on the median number given for ICY CORES.

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And it should be able to operate continiously... the engine uses about 55tons of reaction mass per hour, and the mining facilities produce 60 tons per hour. It does mean that the vessel has only 12 DV to make the Rendevous and return trip... a bit tight. I considered using a lower thrust rocket, thus reducing the number of mining & power plant components needed... filling the empty slots with fuel tanks & perhaps a better sensor array.