Escape velocity to Mars

[spacester]

Oh man, that's uncalled for! I wasn't wrong! You just can't understand the math required to get a quantitative result. If you would slow down and read what I wrote . . . I was able to learn from you what the stupid term 'slingshot' is supposed to mean but you're so g-damd superior to the rest of us . . . tell me how the slingshot analogy allows anyone to actually *calculate* a patched conic solution, wise boy!<br /><br />You don't know how many times you've been wrong and I let it go . . . . because I know your fragile ego can't handle it . . . <br /><br />So much for trying to be a nice guy, I just get stabbed in the back . . . <br /><br />Grrrrrrrr <div class="Discussion_UserSignature"> </div>

 

[mcs_seattle]

So apparantly, if we keep doing gravity assists around the trailing edge we could eventually cause a planet to slow down or stop it orbit around the sun because the space craft speeds up and the planet slows down!

 

[spacester]

The angular momentum is taken from the rotation of the planet about its own axis, not the orbit of the planet around the sun.<br /><br />Of course, I don't work for NASA or one of its contractors, and I don't fall into lockstep with official policies, so what the hell do I know?<br /><br /><img src="/images/icons/wink.gif" /> <div class="Discussion_UserSignature"> </div>

 

[mcs_seattle]

"It's amazing what you can do with a calculator "<br />==============<br />Sadly, the "you" is not me.

 

[henryhallam]

<font color="yellow">The angular momentum is taken from the rotation of the planet about its own axis, not the orbit of the planet around the sun.</font><br /><br />This is NOT true! (not a NASA contractor but you don't need to be to know that)

 

[spacester]

Ah crap, I think you are right. That's always been my understanding but as soon as I posted that I got this bad feeling . . . I was going off of non-mathematical statements I've seen on the web and should have known better.<br /><br />This place is getting to me, I think I need to take a break or something . . . . I try to make a contribution but all everyone seems to be interested in is who's right and who's wrong. Aren't there any larger purposes here? <div class="Discussion_UserSignature"> </div>

 

[najab]

><i>I try to make a contribution but all everyone seems to be interested in is who's right and who's wrong.</i><p>Sorry spacester, but you're wrong there - let me tell you what's right. <img src="/images/icons/wink.gif" /> Your contributions are well appreciated, but you should appreciate as much as anyone that correcting mistakes and misunderstandings is important if we want this site to serve as a reference resource.</p>

 

[mcs_seattle]

I was making a factitious comment that each mission that does a flyby of Jupiter on the way to Saturn, cause a tiny slowing of Jupiter's orbit around the sun. Due to the mass difference between the spacecraft and Jupiter, the change in speed of Mars is tiny, but virtually zero.<br /><br />This quote is from: http://www2.jpl.nasa.gov/basics/grav/primer.html<br /><br />"The spacecraft is a physical mass, so it has its own gravitation. That's how the spacecraft can tug on Jupiter and actually decrease the planet's orbital momentum by a tiny amount. In the exchange, the spacecraft acquires momentum from Jupiter — a significant amount, compared to the momentum the spacecraft already had"

 

[spacester]

Ah jeez Dave, you're not reading everything in context. I amended my comment about the orbital velocity not having anything to do with it. That doesn't count I guess, you're going to cherrry-pick to serve your own agenda, you just want to have a pissing contest.<br /><br />If I thought you could handle the math I'd get into it some more with you but it's just not worth it. You obviously can't comprehend it or you wouldn't be acting like such a jerk.<br /><br />Bottom line: you have accused me of being wrong and I wasn't. I have ignored your inaccuracies in the past. You type without thinking all the time and everyone gives you a free pass. I've been nice and civil and you try to trash my contribution. So much for the Mr. Nice Guy approach with you, if accuracy is so dam important to you that you need to ignore my disclaimers and attack me, the gloves are off pal!<br /><br />There is no bad information in my posts on this thread, just poor reading comprehension on your part. You still give no indication that you get the whole plenetary frame of reference thing, which was the foundation of my so-called erroneous statement. Within the context of the hyperbolic trajectory *RELATIVE TO THE PLANET!!!!* my statement is accurate. I didn't want to argue, so I backed off and said something nice. Yet you want to argue so you attack me. Fine, you'll get your argument, pal, just remember that you started it.<br /><br />Grrrr . . . <div class="Discussion_UserSignature"> </div>

 

[mcs_seattle]

So, your plan is to argue rocket science with a rocket scientist?

 

[n_kitson]

Since we're nitpicking...<br /><br />- It's not "dam", the word you seek has an "n" on the end<br />- Don't think there is a word like "plenetary"<br /><br /><img src="/images/icons/smile.gif" /> *disclaimer for the anal retentive types, the above is humor*<br /><br />A lot of people nitpick on this site. Sometimes I get upset about it, now I just ignore it. Anyone that uses this site as a reference source is in any case rather lazy, so just ignore the nitpicking. I've noticed from your posts you generally apologize when you've been wrong, which makes you a bigger person than most on this site.<br /><br />Have fun, this is entertainment.

 

[spacester]

He's an Engineer, I'm an Engineer. There is precious little Science in Rocketry, it's almost all Engineering.<br /><br />I've done my homework in Orbital Mechanics. As a Professional Engineer, I know better than to opine on subjects in which I am not qualified. <br /><br />My plan is not to argue. My plan has <b>never</b> been to argue. My plan has <b>always</b> been to educate and I've given it a pretty honest effort. If a poor listener of whatever qualifications attacks me, I will defend myself. <br /><br />If my past efforts do not earn me the tiniest little bit of slack when I write posts in the middle of a busy day, then I am <b>no longer</b> going to extend that same courtesy to my attacker, as I <b>have done</b> for about 4 years now. His exalted place in the world of space flight does not earn him the right to be above correction, yet he has been shown that courtesy anyway. BTW, this is not a new subject between he and I.<br /><br />If the <b>only</b> thing that matters around here is <b>accuracy,</b> then no one should object to me shifting my approach towards greater accuracy on the part of <b>everyone.</b> <div class="Discussion_UserSignature"> </div>

 

[rfoshaug]

I have read the book "Mission Jupiter" about the Galileo probe that used gravity slingshot to get to Jupiter. It's a while ago, but I remember it discussed gravity assist.<br /><br />The probe passed Earth and Venus (I think it passed Earth twice, if memory serves), and they (ESA?) explained that the probe actually "steals" a bit of orbital (not rotation around its own axis) energy from Earth. The energy that Galileo gained was actually lost from Earth's orbital velocity.<br /><br />Needless to say, the amount of energy "stolen" was extremely small compared to the total velocity energy of our planet, so it only slowed the Earth down enough so that in a million (or was it a billion?) years, it will be some fraction of a second behind the place it would have been if not for the Galileo probe.<br /><br /> <div class="Discussion_UserSignature"> <p><font color="#ff9900">----------------------------------</font></p><p><font color="#ff9900">My minds have many opinions</font></p> </div>

 

[nexium]

High spacester: If the speed difference is 0.1c, can a probe/asteroid go even faster following the near miss of a small planet? Does the rotation of the planet change how much boost is possible? Can the smaller body give energy to the larger by approching from outside the orbit, or does the energy transfer only occur from more mass to less mass? No energy transfer is possible if they are equal mass? Neil

 

[nexium]

I think www.space.com is an excellent information source. Typically the half truths here can be identified more easily than at a site without interaction. Even the most learned and prestigous know some things that ain't so. Neil