Developing long range space travel

[ngc4303]

I did read up on Matter-Antimatter propulsion and it sounds like one of the best ideas yet! The only reason that I haven't taken further interest is that I didn't get any statistics on speeds in the research I did. Could you give me a link to research that estimates the speed?<br /><br />Wormholes are interesting because they eliminate the need for centuries of interstellar travel. Research is in fact being done to make them a reality. We might very well see them within our lifetimes, provided that you are not already an old fogie <img src="/images/icons/smile.gif" />

 

[quantump7]

The most recent (I think) way of harnessing it is an antimatter trap. Here's an (kinda old) article about antimatter propulsion. It's a pdf document:<br /><br />http://www.engr.psu.edu/antimatter/Papers/web_LiH_final.pdf<br /><br />It's a link to research done by Penn State. They used to have an antimatter propulsion research lab, but I don't think they do anymore. I know that one of the scientists responsible for the antimatter propulsion research there is now working for Positronics. <br /><br />I do know that companies like Positronics are still carrying on this research. <br /><br /><br />Edit: they are still researching wormholes? Could you provide some links to the companies/universities conducting the research?

 

[mrmorris]

<font color="yellow">"It's a link to research done by Penn State. "</font><br /><br />That's more interesting than what I expected. Most M/AM propulsion suggestions are subclasses of the Orion model. However, reading the article, the method produces a (mathematically optimal) thrust of 35mN at an iSP of 5800. By contrast, Deep Space 1, which was essentially a testbed produced a thrust of 90mN at an iSP of 3100s.<br /><br />Given the problems and expense of creating and storing antimatter -- unless the thrust and iSP go up <b>considerably</b> -- M/AM propulsion of that style doesn't have enough advantage over ion propulsion to be worth the additional engineering and inherent danger.

 

[ngc4303]

There are so many sites that I have seen that talk about scientific projects associated with the wormhole theory. Just google serch it and your sure to find lots of sites.

 

[Boris_Badenov]

<font color="yellow"> Orion Nuclear Impulse Propulsion <br /> </font><br /><br /> Behold; Orion <img src="/images/icons/cool.gif" /><br /> <div class="Discussion_UserSignature"> <font color="#993300"><span class="body"><font size="2" color="#3366ff"><div align="center">. </div><div align="center">Never roll in the mud with a pig. You'll both get dirty & the pig likes it.</div></font></span></font> </div>

 

[ngc4303]

mrmorris,<br /><br />I've heard things about deep space 1 and ion propulsion. The major problem that I see is that it accelerates so slowly! When it finally reaches top speed it is capable of an increrdible rate of travel, but it could take several generations of explorers to even reach that top speed.<br /><br />P.S. Are they doing any more research on ion propulsion?

 

[ngc4303]

Orion was shut down by the govornment because it produced radiation, but there's a very easy way to deal with that: build the craft in orbit and then send it on it's way! I just wish I could get that message across to the govornment.<br />Unfortunately I'm pretty certain that they wouldn't listen even if I did send a letter or something. NASA is like that. <img src="/images/icons/frown.gif" /><br /><br />Orion is a great idea though and I think that it would work.

 

[quantump7]

Yeah, I'm really hoping that they find some way to greatly increase the acceleration potential of the ion thrusters. <br /><br />I agree with what the person above me said about the isp and thrust needing to go way up for M/AM propulsion models. We would also need to find a (MUCH) cheaper way of producing antimatter. <br /><br />I just wanted to say, also, that many universities are researching ion propulsion (I've looked because I want to go into an engineering program to study aerospace propulsion), so hopefully they'll come up with something very viable in the near future. <img src="/images/icons/smile.gif" />

 

[vogon13]

Earth orbit turned out to be too close to earth for nukes. The original Telstar satellite was zorched by one.<br /><br /> <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>

 

[mrmorris]

<font color="yellow">"The major problem that I see is that it accelerates so slowly!"</font><br /><br />Yes. Understand that I wasn't promting ion drives so much as I was noting that the M/AM propulsion scheme didn't provide enough of an advantage <b>over</b> ion drives to be worth the additional expense, dangers, and engineering challenges.<br /><br /><font color="yellow">"Are they doing any more research on ion propulsion? "</font><br /><br />Quite a bit, yes. The Dawn spacecraft to the asteroids will use an ion drive.

 

[mrmorris]

<font color="yellow">" I'm really hoping that they find some way to greatly increase the acceleration potential of the ion thrusters."</font><br /><br />That's easy. Provide more power. <b>Lots</b> more power.<br /><br />Increasing the velocity of a spacecraft is all about adding kinetic energy to it. Essentially to make a spacecraft go faster, you must convert non-kinetic of one form or another <b>into</b> kinetic energy to generate acceleration.<br /><br />Chemical propulsion has energy stored in the form of one or more chemical compounds that produce a highly exothermic reaction (i.e. the reaction generates heat). It's unfortunate that the more exothermic the reaction is, the more volatile (and dangerous) these chemicals are to have in close proximity. Put another way -- the more efficient a chemical rocket it -- the closer it is to a big bomb. Also -- the best of chemical reactions simply don't contain *much* energy when compared to the kinetic energies required for rapid space travel.<br /><br />Ion drives work by taking a propellant that *has* no inherent energy potential, then using electrical power to strip away electrons (giving it a charge and therefore making it subject to manipulation by magnetic fields), then using an electromagnet to accelerate it to extremely high velocities. Because the velocities of the propellant are **much** higher than that generated by chemical propulsion, ion drives make more efficient use of the propellant mass. This is the upside.<br /><br />The downside is that the energy *still* has to come from somewhere. So far, ion drives have used large solar panels to generate the wattage to ionize and accelerate the propellant. The power provided by the panels limits the amount of propellant that can be accelerated. I haven't done exhaustive investigation, but I expect that there is also a tradeoff on velocity. Given this, you'd be better off hoping for advancements in solar cell efficiency than in ion drives. If you had

 

[mrmorris]

Now this is <b>very</b> interesting. If this ion drive is even half as good as they claim, it has a ridiculously high iSP. The M/Am thruster spoken of above has an iSP of 5800. Deep Space 1 had an iSP of 3100s and SMART-1 had an iSP around 2500s. Given the exhaust velocities they're claiming for this drive (210,000 m/s), by my calcs it has an iSP of 21,428s. Supposedly their four-grid design also reduces pitting. Pitting happens when an accelerated ion hits the rear grid. This not only degrades the hardware, but also each hit must provide retro-thrust, as the velocity at impact will push 'back'. Reduced pitting means increased efficiency.<br /><br />Now if you stick one of *those* on the back of an S8G-powered spacecraft... there's a real potential for some thrust. <img src="/images/icons/smile.gif" />

 

[spacefire]

I'd like to see an 'external' ion thruster. Or as I like to call it, a space prop. basically a series of blades spin around the core of the spacecraft, scooping atoms which are centrifugally accelerated towards the tips. There the principles of an ion thruster can be applied to charge the atoms into ions and expel them backwards.<br />Say you have multiple flexible blades miles long, they might be able to scoop some particles (protons in the solar wind are already charged, you get a bonus there! <img src="/images/icons/smile.gif" />) and this spacecraft could run long after a regular ion thruster is exhausted.<br />Of course, reach high enough speeds and it might suffer erosion from particles hitting the blades, also it might, like a Bussard ramjet, end up producing more drag than thrust.<br /> <div class="Discussion_UserSignature"> <p>http://asteroid-invasion.blogspot.com</p><p>http://www.solvengineer.com/asteroid-invasion.html </p><p> </p> </div>

 

[owenander]

hah I remember reading an article in something about the DS4G, at the time it had just been approved for this testing, I thought it was extremely interesting and then completely forgot about it.<br /><br />Both the VASIMR and the DS4G look to have similar capabilities. Does anybody know the weight of a S8G reactor, I searched, but couldn't find the numbers?

 

[docm]

The weight of a USN reactor is probably classified.<br /><br />As for using a sub reactor; why? A safer & much simpler desigh is the PBR (pebble bed reactor). Gas cooled (helium, CO2, nitrogen etc.), no need for a pressure vessel (MUCH lighter), meltdown is virtually impossible, can directly drive turbines and easily refueled if re-use is desirable. <br /><br />They mainly use standard reactor grade uranium, but thorium, plutonium and naturally enriched uranium are other options. There is also work being done on using MOX fuels in PBR's. <br /><br />MOX IS a non-explosive blend of plutonium and natural uranium, reprocessed uranium, or depleted uranium. Nice way to use up weapons grade plutonium without blowing anything/one up. <br /><br />On the generation end there are very compact MW class units coming. Long Electromagnetics makes a 5MW unit that is 4x2x2 meters and that includes a gas turbine engine, power conditioner and cooling system; 2,700 kg. The trick: high temperature superconducting windings.<br /><br />NASA and the USAF are working with them on 2 projects, one a 5MW unit similar to thae one above and one "not disclosed".<br /> <div class="Discussion_UserSignature"> </div>

 

[nexium]

I agree ion engines can in theory eject mass at 0.9999c which would be extreme ISP. Is there any chance we can use ion engine technology to to accellerate the output of a nuclear engine? Neil

 

[docm]

The logical method is to generate electric power with the reactor then use that to drive a high output ion (DS4G or PIT) or plasma drive (MPD or VASIMR). <br /><br />PIT ion thrusters are advantageous in that there are no electrodes to wear out unlike gridded thrusters like DS4G, but the latter seems to be the ion-drive de jour.<br /><br />Between MPD and VASIMR there has been a lot of dev time measured in decades. Dunno VASIMR's progress since it went private earlier this year, but MPD has the advantage of simplicity and light weight. <br /><br />If raw power were always best regardless of the powerplants mass then 500cid Cadillac Eldorado's would still be around <img src="/images/icons/wink.gif" /><br /><br /> <div class="Discussion_UserSignature"> </div>

 

[Boris_Badenov]

OMG, NASA has built a VASMIR Engine test bed <div class="Discussion_UserSignature"> <font color="#993300"><span class="body"><font size="2" color="#3366ff"><div align="center">. </div><div align="center">Never roll in the mud with a pig. You'll both get dirty & the pig likes it.</div></font></span></font> </div>

 

[spacefire]

if a life-extension teratment is developed, along with effective ways to counter space radiation, journeys involving slow but efficient solar sails or ion engines do not sound so far fetched. It's all a matter of persepctive, for us getting to Mars in 3-4 years sounds like a waste of lifetime, but for somebody living 200+ years it would be an acceptable trip duration. <div class="Discussion_UserSignature"> <p>http://asteroid-invasion.blogspot.com</p><p>http://www.solvengineer.com/asteroid-invasion.html </p><p> </p> </div>

 

[owenander]

Umm, as stated by somebody earlier, with current ion engine technology it would take roughly 20 days to reach Mars because the acceleration is constant. Now think if you put multiple ion engines on board, to me the bigger issue is power. That 5 Mw reactor given earlier sounds great for the needs.

 

[owenander]

So if you put a 48 MW nuclear reactor on an ion engine which has an iSP of roughly 21,000 (with 5k of power), what kind of iSP would you be looking at?

 

[spacefire]

should be the same? I don't think the voltage changes, but the amout of ions you can accelerate is greater (i.e. you can make a bigger engine) <div class="Discussion_UserSignature"> <p>http://asteroid-invasion.blogspot.com</p><p>http://www.solvengineer.com/asteroid-invasion.html </p><p> </p> </div>

 

[owenander]

The higher the voltage difference the faster the ions are accelerated and thus more thrust and more efficiency.

 

[docm]

<blockquote><font class="small">In reply to:</font><hr /><p>Boris1961 said;<br /><br />OMG, NASA has built a VASMIR Engine test bed<p><hr /></p></p></blockquote><br />That PDF is 5-6 years old. Franklin Chang-Diaz and VASIMR have been commercial since last January;<br /><br />http://www.spaceref.com/news/viewpr.html?pid=18828<br /><br />Ad Astra Rocket Co: http://www.adastrarocket.com/home.html<br /><br />We can only hope he has as much luck as Bigelow. <div class="Discussion_UserSignature"> </div>

 

[j05h]

<i>> Way more work needs to be done, but solar sails are never going to be practical for bulk hauling of mass in space to any major degree. It just takes too long.</i><br /><br />You've obviously decided to make it so. If a project was delivering long-lead time items (like water or parts) in a continuous chain, then solar sails can make sense. One-shot flights to deliver a probe? Maybe. People delivered by light-pressure? Probably not. Saying "never" often puts you on the wrong side of history.<br /><br />Josh <div class="Discussion_UserSignature"> <div align="center"><em>We need a first generation of pioneers.</em><br /></div> </div>