can we use a comet to propel a space probe

[MeteorWayne]

"When you land on the comet you are in the exact same orbit as the comet."<br /><br />Exactly. So what purpose does the comet serve other than a place to land on, and freeze your tail off out by Neptune <img src="/images/icons/smile.gif" /> <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[robnissen]

<font color="yellow">Yes, but you would gain that anyway if you did the same mission that far out from the sun and fell back toward the sun.</font><br /><br />Valid point. But there is an advantage of riding the comet, rather than matching the comet's orbit and that is that the comet can provide some protection from the sun (depending on the rotation of the comet). <br /><br /><font color="yellow">When you land on the comet you are in the exact same orbit as the comet. </font><br /><br />But you are NOT in the exact same orbit as the comet when you take off from the comet, UNLESS you take off in the exact direction of travel of the comet.

 

[derekmcd]

"<i>you have gained over 124,000 mph of velocity.</i>"<br /><br />You would gain that with or without the comet assuming you are in a state of freefall and starting out on the exact same trajectory.<br /><br />Without atmospheric drag, objects of differing mass will fall at the same rate. I think Galileo mentioned something about this <img src="/images/icons/wink.gif" /> <div class="Discussion_UserSignature"> <div> </div><br /><div><span style="color:#0000ff" class="Apple-style-span">"If something's hard to do, then it's not worth doing." - Homer Simpson</span></div> </div>

 

[MeteorWayne]

Actually, if you take off in the same direction as the comet is moving, you are no longer in the same orbit, since your orbital velocity will have increased, which would increase the semimajor axis, change the perihelion, aphelion....etc. <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[Mee_n_Mac]

<font color="yellow">Valid point. But there is an advantage of riding the comet, rather than matching the comet's orbit and that is that the comet can provide some protection from the sun (depending on the rotation of the comet). <br /></font><br /><br />Keying off an earlier thought ...<br /><br />Another potential advantage might be to mine the comet for fuel. Some comets might have enough hydrogen or hydrocarbons to make a useful fuel. If you knew this ahead of time and had sufficient technology, I guess you could get to the comet using 90% of your fuel. Ride the comet and refuel and then use this "free" energy to depart and match orbits with whatever body you were trying to get to. This would save you the mass of that fuel and the energy to lift it into orbit in the 1'st place. <br /><br /><br />Thinking a bit more ... if you had nuclear propulsion but didn't want to lift extra (above that needed to get to the comet) water into space to vaporize for reaction mass ... might a comet be a good place to land and mine for "fuel" ? <div class="Discussion_UserSignature"> <p>-----------------------------------------------------</p><p><font color="#ff0000">Ask not what your Forum Software can do do on you,</font></p><p><font color="#ff0000">Ask it to, please for the love of all that's Holy, <strong>STOP</strong> !</font></p> </div>

 

[MeteorWayne]

Mining for fuel might make some sense.<br />In that way you CAN gain energy from a comet. <img src="/images/icons/smile.gif" /> <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[wick07]

Or like someone mentioned earlier, used a giant net the "catch" the comet and accelarate the probe. Once the probe has been accelerated you could release it from the comet and then further accelerate. It sounds far fetched, but is at least plausable. <div class="Discussion_UserSignature"> <p><font color="#3366ff"><strong>_______________________________<em> </em></strong></font></p><p><font color="#0000ff"><em>"</em>If you are surrounded by those who constatly agree with you, then you're in an intellectual vacuum.  If you feel like trying to make a difference, you have to BE different.  How can you do that without interacting with those who are different from yourself?"</font></p><p><font color="#0000ff">-  a_lost_packet_</font></p> </div>

 

[Technicus]

<p>Using what I will refer to as the "standstill" scenario, where you *lasso* a comet to propel your craft, has 2 MAJOR issues. Lets say your net does get aligned in the perfect spot and the comet crashes right into it. What exactly is your craft (not to mention any human body) made of that it can withstand a 0 mph-1,000,000 mph near instantaneous acceleration? Not to mention the net itself? Any person without the use of an inertial shield would become liquified by such an acceleration. </p><p>No you would have a big hole where the net used to be or perhaps the net and some of your trail cables would be *stuck* on it, with the cables either being ripped from your craft or breaking somewhere along the lines.</p><p>&nbsp;If we had the technology for an inertial shield, we wouldn't need to *lasso* a comet for propulsion.</p><p>&nbsp;However landing on a comet and mining it for fuel would be ideal.</p>

 

[MeteorWayne]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Using what I will refer to as the "standstill" scenario, where you *lasso* a comet to propel your craft, has 2 MAJOR issues. Lets say your net does get aligned in the perfect spot and the comet crashes right into it. What exactly is your craft (not to mention any human body) made of that it can withstand a 0 mph-1,000,000 mph near instantaneous acceleration? </DIV></p><p>It's only 0 to 100,000 mph </p> <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>