Mars in a month, my ideas

[grooble]

http://www.space.com/businesstechnology/technology/technovel_sail_050211.html<br /><br />Wouldn't it be better to build the microwave beam on the moon? Use lunar solar power. <br /><br />No atmosphere and close promiximity to the sail may reduce the power requirements, or increase the speed perhaps.<br /><br />Oh yea, and no public health and safety issues of using a 60MW microwave beam!<br /><br />

 

[pet8]

I solve This problem much better way - the trip could take 5 days to one week. Without beamer or other to big and unrealistic thing like space gun, space elevator etc... solution still exist - how long time You will wait. Way to LEO and beyond could by widely open during one or two year. I'm able build functional prototype ship in scale 1:20 during half a year and small amount of money we talking about 117 thousands $. If I don't find relevant investor in states i sell this invent to other country.

 

[vogon13]

You do seem rather anxious to get $117000.<br /><br />Rather a precise figure for such a significant engineering project which should be fraught with unknowns. <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>

 

[nacnud]

I wonder in what currency $117k is a nice round number?

 

[vogon13]

Had not thought of it that way. Good point.<br /><br /><br /><br />Still waters run deep, and there won't always be somebody there<br /><br />to pull you out<br /><br />Lynn Anderson <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>

 

[mott]

could the microwave not be mounted on the craft itself.. for long trips seems a better idea than needing line of sight..

 

[centsworth_II]

<i>"...could the microwave not be mounted on the craft itself[?]"</i><br /><br />The photons shooting out of the microwave generator would push the craft backward, then hit the sail, pushing it forward... result: standstill. <br /><br /> <div class="Discussion_UserSignature"> </div>

 

[mott]

i thought the power came from the gas stored in the paint?? the microwave energy is just the heater

 

[centsworth_II]

<i>"i thought the power came from the gas stored in the paint??"</i><br /><br />Right! Some of the power anyway. The gas expelled from the paint ADDED to the force of the microwave photons hitting the sail give the total thrust. Using a craft-mounted microwave generator would cancel the force of the photons hitting the sail, leaving only the force of the gas expeled from the sail, which may be less than half of the original combination. Also, there would be the added weight of the microwave generator to accelerate. <div class="Discussion_UserSignature"> </div>

 

[centsworth_II]

But it is an interesting idea. And who knows, eventually a material may be found that gives a great enough thrust to work even with the energy generator mounted on the craft. But if the generator were carried on the craft, I wonder at the need to use a sail shape for the material. No thrust from photons from an attached generator, but maybe to double as a sail for solar photons or moon, Earth, or satelite-emitted photons. <br /><br />If the attached energy generator is the only source of thrust, the system would resemble an ion drive. If a system where an energy beam is used to create a gas which provides thrust can be more efficient than simply turning the energy beam around and using it to provide the thrust itself, I don't know. <div class="Discussion_UserSignature"> </div>

 

[rpmath]

<font color="yellow">could the microwave not be mounted on the craft itself.. for long trips seems a better idea than needing line of sight.. <br /></font><br />The problem is how to get the power plant for the 60 MW microwave generator on board.<br /><br />If you use a chemical energy source, it would need a huge amount of fuel to get that power, and much less efficient than just throwing away the produced gases like current rockets do.<br /><br />A nuclear power plant?<br />The Prometheus reactor with only 100 kW is still hard to develop... now a 60 MW?<br /><br />Solar power?<br />To get 60MW you need 44 000 m² at the Earth orbit light intensity, and everything 100% efficient, (I think solar cells have near 20% efficiency, and I don’t know the number for microwave generation, perhaps 50%?). It will need a circle with a radius of more than 100m, that grows to some hundreds when you take account of efficiencies. <br />Then the needed size will get even bigger as you move away from the sun.<br /><br />It would be most efficient just to reflect the sun light from a big sail to a smaller one where paint can be blown by light, but the first one must still be huge, and you must align both in such a way blown matter doesn’t hit the big sail producing thrust in the wrong direction.

 

[tap_sa]

<font color="yellow">" Using a craft-mounted microwave generator would cancel the force of the photons hitting the sail, leaving only the force of the gas expeled from the sail, which may be less than half of the original combination."</font><br /><br />This concept was discussed in Science & Astronomy too. The New Scientists reported force to be several times stronger than expected.

 

[centsworth_II]

<i>"...reported force to be several times stronger than expected."</i><br /><br />If the the sail component is a minor part of the total force (and would be no component if the microwave generator were mounted on the craft), why bother with the sail? Like I said, if you mount the microwave generator on the craft, it is similar to an ion drive. The hydorgen source could be a compact block, rather than spread out on a sail. The energy beam (originating near the fuel block) would heat the end of the block. Energized hydrogen would stream out a nozzle. It would require a <b>much</b> less powerful beam to heat a concentrated hydrogen source from a short distance.<br /><br />The only purpose for a sail would be if it were being used as a sail, not just a support to hold the reactive paint. If the microwave beam were coming from a location off the craft, the sail could capture its momentum as well as the paint providing extra thrust. If the beam originates on the craft, the sail is of no use. <br /><br />Its a matter of two different concepts: An enhanced sail vs. something similar to an ion drive. My initial point was that the sail concept does not work with the energy beam mounted on the craft. <br /> <div class="Discussion_UserSignature"> </div>

 

[mott]

thank you cents that makes sense.. but what of either cold fusion, or antimatter?? i know they are still working on the problem but who knows in 20 or 30 years...

 

[centsworth_II]

Re: cold fusion, or antimatter<br /><br /><i>"...i know they are still working on the problem..."</i><br /><br />To say the least! <img src="/images/icons/laugh.gif" /><br /><br /> <div class="Discussion_UserSignature"> </div>

 

[mott]

well i have a feeling they will get there.....someday...

 

[yevaud]

It wouldn't work anyways, because the theoretical velocity you can get from a light-sail - at least over planetary distances - is very, very low. <br /><br />This is the problem with any planned mission to Mars.<br /><br />As things stand now, the best we can do is about 1/100th of a G, sustained. That's (on average, ballpark) 459 days to Mars.<br /><br />Now if there were some way to develop a drive system with a sustained boost of 1 G, here's what could occur:<br /><br />Sustained boost to midway point, flip, deaccelerate the other half of the journey. Total trip time: 4.59 days.<br /><br />Pretty nifty. <div class="Discussion_UserSignature"> <p><em>Differential Diagnosis:  </em>"<strong><em>I am both amused and annoyed that you think I should be less stubborn than you are</em></strong>."<br /> </p> </div>

 

[quasar2]

i read somewhere once about an idea for a solar sail made of a nuclear fuel. <div class="Discussion_UserSignature"> </div>

 

[yevaud]

There wouldn't be any benefit of doing this, and quite a few drawbacks also.<br /><br />A light sail would have to be of a very thin, very tough material, and have a large surface area for maximum light pressure. <div class="Discussion_UserSignature"> <p><em>Differential Diagnosis:  </em>"<strong><em>I am both amused and annoyed that you think I should be less stubborn than you are</em></strong>."<br /> </p> </div>

 

[scottb50]

Any chance of using nuclear/electric engines or light sails is equally ridiculous, they could be of use going to Jupiter and beyond, but between Mars and Mercury chemical engines are the practical choice. <div class="Discussion_UserSignature"> </div>

 

[Peter the Dane]

if you were to use the paint as fuel and are to generate trust to go to mars. you will need a very thick layer.<br /><br />building the power plant on the moon, you have to use one of the poles if you are to have sun ligth all the time. building it at a lagrange point will give the option of 24/7 power management.<br /><br />would it be possibel to simply mirror the sunligth? you would need some serius lense work....<br />but it should be fairly easy to put up a square mile of foil.<br /><br />

 

[nexium]

Using a mirror to make a tight beam of sunlight is practical to perhaps 100 kilometers range. For longer range the mirror surface accuracy requirements become very difficult to keep the beam from spreading. Neil

 

[cyrostir]

is it possible there will be objects (tiny) in the way that might punch a hole in the solar sail if say it was heading to mars...?

 

[tempel1]

Dear friends <br />Go here please:<br />http://saturn.jpl.nasa.gov/news/press-release-details.cfm?newsID=117 <br />” The spacecraft's VELOCITY RELATIVE TO THE SUN is at about 26 kilometers per second (about 59,250 miles per hour). Cassini is now more than 9 million kilometers (almost 6 million miles) from Earth”. <br /><br />Since our probe is launched from the earth, it has already a velocity of 65,000 miles per hour (earth's velocity). <br /><br />Why have NASA engineers steered Cassini on this trajectory? <br /> http://www.space.com/php/multimedia/imagedisplay/img_display.php?pic=h_cassini_trajectory_02.gif&cap=The <br /><br />Instead of increasing Cassini's velocity they have slowed down it at 59,250 miles per hour. <br /><br />NASA engineers think the earth is the center of our solar system and don't consider earth's velocity. <br /><br />In this wrong way Cassini has travelled for 2 200 000 000 miles to meet Saturn. <br /><br />Cassini would have been able to fly along a straight line travelling for less than 1 000 000 000 miles. <br /><br />65,000 miles per hour (earth velocity) + 36,000 miles per hour (spacecraft's velocity) = 101,000 miles per hour <br /><br />1 000 000 000 miles : 365 days : 24 hours : 101,000 miles per hour = 1.13 years <br /><br />If NASA engineers considered the earth's velocity, Cassini could meet Saturn in one year! <br />

 

[craig42]

<blockquote><font class="small">In reply to:</font><hr /><p>building the power plant on the moon, you have to use one of the poles if you are to have sun ligth all the time. building it at a lagrange point will give the option of 24/7 power management. <p><hr /></p></p></blockquote><br /><br />Build the power plant at a Sun-Mercury Lagrange point. That way your solar collectors can be smaller that needed at Earth normal sunlight levels.