HardSF craft design questions

[kelvinzero]

Hi, Im trying to come up with a plausible craft for travelling within the solar system, set say 100-150 years from now. In doing so, I have come up with a series of questions:<li> With Zubrin's Mars Direct design, with centrifugal gravity via a tether, where do they place the dish to maintain radio contact with earth? How do they keep it aligned?<li> Again with Zubrin's design, for escaping solar flares they retreat to a special area that appears to be shielded on all sides.. wouldnt it be better to align the axis of spin with the sun so that it only needed to be shielded in one direction?<li> How plausible would it be to have a fusion or fission powerplant but use it to power an ion drive instead of directly for thrust? (my current rough concept has a heavy powerplant as counterweight to the habitable section, with an electric engine at the center of gravity)<li> Also do you have any good links to designs I should consider?<br /><br />Second part:<br />Consider these three types of trip<li> Shuttling between moons of saturn (but not landing)<li> Travelling between earth and mars<li> Travelling between Saturn and earth<br />Is it plausible for a single craft design to be sensible for all of these trips? Im assuming we have perfected indefinite lifesupport given power. I cant think of a necessary difference except carrying some extra tanks.<br /><br /></li></li></li></li></li></li></li>

 

[Aetius]

My best guess is that the high and low gain antennae would be mounted on top of the hab module, to enable repair by astronauts/cosmonauts/yuhangyuan.<br /><br />I'd imagine that it would be important to have a side of the hab module facing the Sun whenever possible, as both it and the spent upper stage revolve on opposite ends of a tether. The solar panels mounted on the sides of the hab should have constant sunlight.<br /><br />I could easily be wrong (hey, I'm a factory worker...not a rocket scientist), but I've always assumed that Zubrin's tuna can habitat module was to be solar-powered...at least in the beginning. Nukes will obviously be necessary for surface activities (as solar would impose laughable mass requirements), but using solar during interplanetary cruise would save lots of money and lessen shielding requirements.<br /><br />I've read that while the use of nuclear thermal rocket engines may greatly increase the amount of Earth-to-Mars payload for a given super heavy-lift launcher, they will not appreciably reduce transit times...courtesy of Isaac Newton.

 

[Aetius]

Unless it's a demonstrably cheaper way to get to Mars (over the lifetime of the vehicle), why pay for a reusable spacecraft? That's where the science-fictiony aspect of things meets hard realities.<br /><br />I hope to see suspended animation techniques developed to the point where space travellers in stasis can be warehoused inside large Mars-bound freighters, and awakened upon arrival on their new homeworld. A reusable spacecraft might then be quite profitable, if it can haul dozens or hundreds of people at a time...with minimal life support and consumable requirements.<br /><br />It's not romantic, but you know what they say...No bucks, no Buck Rogers. <br /><br />P.S. Edited for word choice.

 

[Aetius]

Speaking of a ship design where the nuke and hab modules are mounted at opposite ends of a large truss, and revolve around an ion drive in the center, NASA has some wicked cool animation of a spacecraft just like that.<br /><br />I'd check out their websites. I'm sure you'll be able to find it easily.

 

[Aetius]

One more thing: If you haven't already purchased Zubrin's book, <i>Entering Space: Creating A Spacefaring Civilization</i>, <b>do it</b>. If I remember correctly, most of your questions are addressed therein.<br /><br />It's a fascinating read, and quite accessible to laypeople like me or you. Worth every penny.

 

[a_lost_packet_]

A bunch of cool ideas from the guys that are trying to get us there: <br /><br />http://ehw.jpl.nasa.gov/events/nasaeh04/presentations/presentation_pdf/Millis_Phys.PDF<br /><br />http://www.grc.nasa.gov/WWW/bpp/ (The old BPP page is finally down I think.)<br /><br /><br />How about a water-ice shielded and fueled "fusion pulse" propulsion craft? Put a weak plasma field on it maintained by outgassing of the water-ice ball. Then, it's off to the stars! Err.. I mean planets. It wouldn't be a starship but would be suitable for interplanetary missions. Grab the water from oh.. I dunno.. make it up as you go. Just don't get it from the Moon or anything that has a steep gravity well. If we could lift that much water, we probably wouldn't need it. <br /><br />Note: Some of those in the pdf are suitable for interstellar travel.. if they turned out to be workable that is. <div class="Discussion_UserSignature"> <font size="1">I put on my robe and wizard hat...</font> </div>

 

[kelvinzero]

<blockquote><font class="small">In reply to:</font><hr /><p>A bunch of cool ideas from the guys that are trying to get us there: <p><hr /></p></p></blockquote><br /><br />That is a good PDF.. Ive added it to my collection. For this project though I want to avoid any breakthrough feel. Im not even sure I want fusion power. Interstellar travel will probably still feel like science fiction to them. However, life support is well developed. If a trip to mars has to take 6 months, then thats what it takes.. though I would prefer to think that they had sufficient power to accelerate to surplus speed and then decellerate at the target. Im undecided.

 

[kelvinzero]

<blockquote><font class="small">In reply to:</font><hr /><p>Speaking of a ship design where the nuke and hab modules are mounted at opposite ends of a large truss, and revolve around an ion drive in the center, NASA has some wicked cool animation of a spacecraft just like that. <br /><br />I'd check out their websites. I'm sure you'll be able to find it easily. <br /><p><hr /></p></p></blockquote><br /><br />Rats.. couldnt find it.<br /><br />I liked the idea of an entire ship spinning to avoid any complicated joins, but i couldnt decide what it should point its axis at.<br /><br />Pointing the axis of spin in the direction of thrust seems best if you have electric thrust for a large proportion of the journey. On the other hand you could point the axis so a dish can have uninterupted communication, or you could point it at the sun to simplify shielding and perhaps solar panels<br /><br />Ill probably align the axis to the thrust but this still leaves me unsure where the dish would be placed. <br /><br />Im going for a reusable craft because I want the technology to feel everyday, post colonisation.

 

[Aetius]

I'd originally seen the NASA animation of a spinning, nuclear-electric vehicle with an inflatable hab on NASA TV. It was shown doing a hypothetical mission to Mars, with the rotational axis pointing toward the thrust vector (did I say that correctly? <img src="/images/icons/wink.gif" />).<br /><br />Now I can't find the animation, either. Maybe it was never on the Internet, or it was and got taken down.

 

[qso1]

KelvinZero:<br />Hi, Im trying to come up with a plausible craft for travelling within the solar system, set say 100-150 years from now.<br /><br />Me:<br />If there is going to be a long period of technological stagnation starting in the next decade or so...a plausible craft for travelling the solar system is not practical, maybe not even possible.<br /><br />The question I would ask before I can proceed to give you some kind of answer is...what is the purpose of the design? That is, are you wanting a plausible design for a book your writing, or are you actually doing some kind of proposal for a real craft? <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>

 

[a_lost_packet_]

In a hundred and fifty years, a six month trip to Mars is what I would expect an automated service freighter would do. Big, slow, automated resource/trade freighters or something. Think "Nostromo" size but without all the life support. There may not be a huge number of them, but a few in transit at any one time with enough cargo room could easily keep a couple of research stations supplied and pickup any interesting raw/finished goods along the way.<br /><br />I'd say plan on something that's like a 20 to 60 day trip depending on when you leave. Actually, you could have cruise-excursion ships that took the long 60+ day route just so passengers could enjoy the high-life and catch some extra sites if you're planning on making it a heavily populated system.<br /><br />We may not be colonizing Mars in 150 years. But, I think engine technology will be advanced enough by then to get us around the solar system in pretty good time. An engine is just an engine. All the parts, cogs, soda machines and toilet roll dispensers involved in a space-colony is a different matter entirely. I think engine tech will far outpace efforts at colonization. We'll have the propulsion long before we really need it, IOW. So, if it were me. I'd build on a ship-centric view, not very many manned colonies anywhere, alot of research stations and several industrial concerns trying to get semi-automated startups going on their own. That kinda thing. Fast ships, all dressed up, not alot of places to go. <div class="Discussion_UserSignature"> <font size="1">I put on my robe and wizard hat...</font> </div>

 

[kelvinzero]

Im just considering some hardSF 3D modelling projects that would all belong to a consistent universe. At some point it might spark plot ideas.<br /><br />My design philosopy is to be as optimistic as possible with as little speculative science as possible. Huge scale space industry, multiple space colonies, no antimatter, possibly no fusion. Probably no true AI, to keep the universe about people.<br /><br />I already have a rough design I like for asthetic reasons and am trying to decide if I can justify it.<br /><br />hmmm.. it also occurs to me that if I go the fission way, I havent put much thought into the availiblity of fissionable materials in the solar system, outside of earth.

 

[qso1]

Your scenario is probably closer to being possible in just under a century but then, nobody really knows. I was faced with a similar problem when writing my graphic novels. The need for as realistic tech and astronomy as possible while focusing on the people side of the story.<br /><br />I solved the problem for my own purposes but I do not know if it would play well with readers since my stuff is not likely to ever reach a market of significant size. <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>

 

[kelvinzero]

Im not worried about readers or anything like that. Where is your graphic novel anyway?

 

[nyrath]

I've got a few notes on realistic spacecraft on my website:<br />http://www.projectrho.com/rocket/index.html

 

[nyrath]

Electric thrust = <b>Ion Drive</b>

 

[kelvinzero]

Thats a great looking site! It has lots of things I have been looking for eg Discovery deck plans.<br /><br />I have been proceeding with my own design slowly. It is still hard SF but I have been taking lots of artistic liberties. Im trying to throw in a slight wwII lancaster and also galleon feel, so it is a weird looking beastie. Its tempting to put portholes all over it but there really isnt much point on a spinning hab section. The only reason I can think of is to survey your own ship for damage in the event of a bang and a shimmy and all the video cameras going out.

 

[kelvinzero]

I also saw that nice collection of spacesuit designs on your site.<br /><br />Here is one I came up with a while ago. It is meant to be a futuristic suit that you could live in for days.<li> Rather than becoming more formfitting, it is more spacious so you can pull your arms back inside and scratch your nose, have lunch or repair punctures from the inside.<li> Rather than a mansized airlock, you can move directly between the suit and a habitat via the port at the back, so there is little tramping of material back and forth.<li> Rather than gloves I have postulated some sort of animatronic hands with pads on the fingertips that convey sensation mechanically, eg arrays of needles that rise and fall to duplicate texture.</li></li></li>

 

[kelvinzero]

2nd attempt:

 

[qso1]

KelvinZero:<br />Im not worried about readers or anything like that. Where is your graphic novel anyway?<br /><br />Me:<br />Sorry it took so long to answer your question. My GN is still in production. I have finished ones but haven't final reviewed them yet and still need a website to market them on. <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>