Another Grand Tour?

[lensman]

Voyager 2 was able to survey the outer planets because of their alignment in the 1980s. What kind of Grand Tour would be possible for another Voyager-type probe, given the alignment of the outer planets over the next 20 years or so? Would at least a Jupiter-Saturn mission be feasible?<br /><br />Lensman

 

[mattblack]

No, don't think so. And good luck getting funding! Also, flyby missions except to Pluto are now passe'. Future missions will be dedicated orbiters and landers to most planets. <div class="Discussion_UserSignature"> <p> </p><p>One Percent of Federal Funding For Space: America <strong><em><u>CAN</u></em></strong> Afford it!!  LEO is a <strong><em>Prison</em></strong> -- It's time for a <em><strong>JAILBREAK</strong></em>!!</p> </div>

 

[najab]

><i>Would at least a Jupiter-Saturn mission be feasible?</i><p>Jupiter-other planet is always doable, its a multi-planet mission that's hard. You could do a Grand Tour now, but it would be expensive in either time, propellant or both.</p>

 

[hansolo0]

In a related story , I think I read that cassini may as an extended mission fly on to Uranus or Neptune..?

 

[mikejz]

The Saturn via Jup window is only once every 20 years

 

[mattblack]

>>In a related story , I think I read that cassini may as an extended mission fly on to Uranus or Neptune..?<<<br /><br />Cassini doesn't have enough fuel to leave Saturn's orbit. <div class="Discussion_UserSignature"> <p> </p><p>One Percent of Federal Funding For Space: America <strong><em><u>CAN</u></em></strong> Afford it!!  LEO is a <strong><em>Prison</em></strong> -- It's time for a <em><strong>JAILBREAK</strong></em>!!</p> </div>

 

[alokmohan]

Grand voyager type is not possible because we dont have similar alignment soon.

 

[radarredux]

> <i><font color="yellow">And good luck getting funding! Also, flyby missions except to Pluto are now passe</font>/i><br /><br />I could see a technology demonstration craft or small effort like Clementine or Lunar Prospector. Maybe a solar sail or ION drive system (solar or nuclear) that will accelerate slowly but for a long period of time.<br /><br />Maybe some philanthropist will launch "Project Beacon", a Nuclear Electric Propulsion spacecraft designed to (1) hold a library of human history (including DNA code for humans and many other organisms), (2) emit a high-energy beacon at regular intervals (e.g., once every six months), and (3) orbit a distant star. Other intelligent life, or maybe or own descendants, could find it a few million years in the future.<br /><br />Assuming the NEP-drive is matured by NASA or others, and the payload being relatively small (library of information + beacon/transmitter), I wonder what such a spacecraft would cost?</i>

 

[holmec]

If we do a next one, it will be powered.<br /><br />Ion drives, solar sails, navigational tricks (sling shot around the sun??) and so on. <div class="Discussion_UserSignature"> <p> </p><p><font color="#0000ff"><em>"SCE to AUX" - John Aaron, curiosity pays off</em></font></p> </div>

 

[henryhallam]

<font color="yellow"><br />sling shot around the sun<br /></font><br />Just for general interest:<br />"Slingshot" around the sun is very different to the usual type of gravitational assist carried out with planets.<br /><br />The way a normal planetary grav. assist works:<br />Eject from Earth orbit into an elliptical solar orbit with periapsis at Earth's orbital radius (since that is where you came from and it would take pointless extra dV to change the periapsis) and apoapsis at Jupiter's orbital radius. You arrange the phasing such that you arrive at apoapsis just before Jupiter reaches the same point. At apoapsis you have an absolute minimum velocity (zero outward velocity by definition, and very little "forward"/tangential velocity because the orbit is so elliptical). Imagine throwing a ball in the air, it's essentially stationary at the high point. Then along comes Jupiter at 13 km/s and suddenly you are in Jupiter's "sphere of influence" which essentially means you are now in a Jovian orbit. But since you entered with such a high velocity, you are in a hyperbolic orbit which means you do a sort of U turn around the planet and come out again with the same velocity w.r.t. the planet that you entered with. You can think of it like bouncing a perfectly elastic ball off a bat.<br />So you leave Jupiter's sphere of influence in the opposite direction to which you entered, i.e. you bounce back out the way you came, but you come out at 13km/s relative to Jupiter, going the same direction as Jupiter. So you now have 26km/s velocity relative to the sun! This means your apoapsis is way higher than Jupiter, and in fact you can escape the solar system entirely with that velocity starting from Jupiter.<br /><br />The clever part is in arranging the hyperbolic Jovian orbit such that you exit in a certain direction (you don't have to bounce perfectly back the way you came, in fact you can exit in more or less any direction). In this way you can target your final o