Grand Tour

[jsmoody]

I think I saw a proposal for something like this several years ago...I don't remember where, but I think it might be a good idea.<br /><br />The idea is to have a large spacecraft, manned or unmanned, that would stay in space all the time, going from one planetary system to another as orbital mechanics and fuel allow. It would use Jupiter and other planets for a "sling shot" boost on to it's next mission. It would periodically return to Earth for refueling and/or reprovisioning. <br /><br />At each stop it could launch probes, landers, balloons, aircraft, whatever would be appropriate for the particular site. It would be like a space station but instead of being in Earth orbit, it would cruise around the Solar System using gravity assist from various planets.<br /><br />A manned version would be extremely expensive so maybe the first one would be unmanned, cruising around dropping off probes here and there. At some later time, when the radiation problem is solved and the funding is available, refurbish it and refit it for human habitation. <br /><br />Any thoughts? Has anyone else heard this idea before? <div class="Discussion_UserSignature"> No amount of belief makes something a fact" - James Randi </div>

 

[MeteorWayne]

The only grand tour that too place was by Voyager 2. It was possible beacuse of a fortuitious alignment of the planets which won't repeat for thousands of years.<br /><br />The fule required (and the cost of launch since weight= launch coasts) prohibits any such mission in our lifetime. Sorry.<br /><br />If you want to visit Mars and come back, that is possible, in fact that is one plan for a Mars-Earth cycler. <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>

 

[jsmoody]

okay...let me clarify. I wasn't talking about a Voyager-type grand tour. Maybe a couple of planets or three, a few asteroids, comets, etc. Then back to Earth to resupply. Then on to the next planet or two. Just stay in space, returning to Earth occasionally. I remember reading about the idea several years ago. They thought it was feasable at the time but of course we didn't have the technology or the funding then. <br /><br />We're already doing something similar, spacecraft are visiting more than one body in their missions. What I'm talking about is just taking that concept a step further (or a giant leap).... <div class="Discussion_UserSignature"> No amount of belief makes something a fact" - James Randi </div>

 

[h2ouniverse]

I would rather favour a highly-recurrent small weight explorer with standardized payload, so that cost per spacecraft would be low.<br />Have each for a recurring cost of about 50 mln$(*), and a launch cost of 50 mln$ (or 100 for a pair in dual launch), and for 3 bln$ (the cost of a flagship mission) you get THIRTY spacecrafts!<br />And can explore 30 bodies...<br /><br />Best regards.<br /><br />(*) = the cost of a small-medium recurring telecom sat

 

[3488]

I would agree with that too Joel.<br /><br />Minisats / Probes of a standardised design, but sent out to many different <br />targets would be very scientifically useful & as you mentioned, not for a lot of $$.<br /><br />I do not know how effective in someways that would be, a probe to Mercury or <br />3200 Pheathon @ perihelion, could not be the same as one to Neptune, or Eris, etc.<br /><br />But say a cluster of these to the Asteroid Belt or to the Jupiter system (no bias there is there <img src="/images/icons/laugh.gif" />),<br />or the Uranus system, etc lets say, could use a copied design.<br /><br />Personally I would like to see some more New Horizons be built, some for encounters <br />like the current one, perhaps a variant that could host a retromotor & extra tanks as orbiters, but all use the same science payload, so because <br />equipment would be standardised, all would use the same software & any can be <br />operated by the same ground based mission teams.<br /><br />That would probably be too expensive. <img src="/images/icons/frown.gif" /><br /><br />Andrew Brown. <div class="Discussion_UserSignature"> <p><font color="#000080">"I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before".</font> <em><strong><font color="#000000">Linda Morabito </font></strong><font color="#800000">on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.</font></em></p><p><font size="1" color="#000080">http://www.launchphotography.com/</font><br /><br /><font size="1" color="#000080">http://anthmartian.googlepages.com/thisislandearth</font></p><p><font size="1" color="#000080">http://web.me.com/meridianijournal</font></p> </div>

 

[jsmoody]

Yes, I like that idea too. Lots of small, inexpensive (relatively) spacecraft. Maybe several missions each, or at least 2 or 3. Good return on investment. <div class="Discussion_UserSignature"> No amount of belief makes something a fact" - James Randi </div>

 

[h2ouniverse]

That does not have to be that mini btw...<br /><br />You have a 5-ton 12kW @ 1AU telecom platform (for a 700 kg to 1t of GEO payload) placed in GTO for about 60 mln$ (satellite minus payload) plus <80 mln$ (launcher) = less than 150 mln$<br />For an interplanetary mission the payload mass / launch mass ratio is much lower but you can get at least 2%, i.e. more than 100kg of instruments for orbiters. And more for by-flyers.<br /><br />Best regards. <br />

 

[willpittenger]

Actually, I did think something up like that back in the late 1980s and early 1990s. Sometime in the past year, I did mention here in M&L. My version was powered by a HUGE solar sail. It would have been 5-10 miles across. The size was enough that it would never go inside the lunar orbit. (To much risk of collisions with man-made debris.) Rather, other craft would bring the cargo to it. It would also avoid the asteroid belt by flying above or below the ecliptic. It would have no need of gravitational flybys because of the linear routes that solar sails could use.<br /><br />The concept required the solar sail to move it sails such that they deorbited the sail. As such, only the pressure from the Sun would keep it from falling towards the Sun. It would use that pressure to move out. By orienting the sail slightly, it could steer. It would also be able to avoid Jupiter's high radiation belts unless that was the destination. (Even then, the cargo craft might be stuck with making that portion of the trip on its own.) To enter orbit, it would reverse the method used to leave the Earth's orbit. It would then return by leaving that orbit and collapsing its sails. Gravity would then pull it sunward. Once it was close to the Earth's orbit, it would slow down by unfurling the sail and return to Earth. <div class="Discussion_UserSignature"> <hr style="margin-top:0.5em;margin-bottom:0.5em" />Will Pittenger<hr style="margin-top:0.5em;margin-bottom:0.5em" />Add this user box to your Wikipedia User Page to show your support for the SDC forums: <div style="margin-left:1em">{{User:Will Pittenger/User Boxes/Space.com Account}}</div> </div>

 

[Huntster]

The Voyager "grand tour" spacecraft have proven themselves to be extraordinarily reliable and long-lived, but the pricetag was quite high and the instruments simply aren't as capable as new things being developed today. I just don't see it as worthwhile to develop long-term "flagship" missions, such as the Voyagers, any longer due to its equipment rapidly becoming obsolete...we are seeing the same thing happening to Hubble. In many respects it would be cheaper to orbit a new telescope, but I suppose the PR gained from keeping it aloft outweights such considerations at this point in time.<br /><br />The future lies with multiple smaller probes; while they cannot do quite as much science as a single large spacecraft, they are still quite effective at their jobs. Not to mention that far more of them can be sent out for the same cost, as H2Ouniverse mentioned above.<br /><br />Along the same line as jsmoody is proposing is something I <i>would</i> like to see. There is significant interest in the Jovian and Saturnian moons, so why not develop a carrier spacecraft designed to drop off multiple landers or orbiters, similar to but hopefully more capable than the Huygens probe? The "mothership" would function solely in the capacity as carrier and data relay, and would carry perhaps ten to twelve children in a Christmas tree arrangement along its body. After eventually dropping off its entire payload amongst various target moons, the carrier would establish a more permanent orbit around the planet and simply relay information for as long as the children function. For maximum loiter time (and thus maximum mission return) each probe would likely have to utilize a nuclear source for power and heat, and I suppose that will require a significant reduction in reactor size than what we have available today. Still, I think it would be worth the research for the amount of data that could be gleaned, not to mention a more permanent presence on or around these bodies. <div class="Discussion_UserSignature"> </div>

 

[3488]

Very much like the Pioneer Venus MultiProbe, a hugely<br />successful Venus mission in 1978.<br /><br />There is no reason at all why this would not work for Titan & for Venus again at some point.<br /><br />docm mentioned Minisats acting as relays. Yes that too would be desirable. Place several of these<br />in orbit around Jupiter & Saturn, perhaps Jupiter in the orbit of Callisto, Saturn in the orbit of Iapetus,<br />like stings of Pearls, so any science missions in opertation from these moons inwards, would have 24/7 relay coverage.<br /><br />Would not have to be expensive either. Modern electronics are becoming far <br />more efficient & smaller, that these mini sats would be just that, minisats.<br /><br />Andrew Brown. <div class="Discussion_UserSignature"> <p><font color="#000080">"I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before".</font> <em><strong><font color="#000000">Linda Morabito </font></strong><font color="#800000">on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.</font></em></p><p><font size="1" color="#000080">http://www.launchphotography.com/</font><br /><br /><font size="1" color="#000080">http://anthmartian.googlepages.com/thisislandearth</font></p><p><font size="1" color="#000080">http://web.me.com/meridianijournal</font></p> </div>

 

[JonClarke]

Hi Andrew<br /><br />The problem for minisats in the outer solar system is that they will all need RTG power. This instantly makes then laerger and more complex and more costly than ones in Earth orbit. Plus they will need more power and larger antennae anyway, simply to communicate.<br /><br />cheers<br /><br />Jon <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>

 

[h2ouniverse]

True, but you can mitigate that by:<br />* developing Stirling generators (smaller, cheaper than RTG) or other type of nuclear batteries. <br />* considering data relay satellites for Jupiter and Saturn missions<br />* investing in a more powerful ground network (e.g. SKA)<br /><br />All those three actions are going on btw.<br /><br />Regards.

 

[Huntster]

In my mind at least, the idea of sending a dozen small orbiters/landers at once had the added benefit of mass production, rather than tailoring each unit to a unique specification. While in practice it might not make such a big difference, it does present the possibility of lower costs. Not to mention, the actual mothership would not necessarily have to be that complicated...just navigate, demate each probe in sequence, orbit and relay data. If additional scientific instrumentations are desired, then so be it, but they aren't necessarily *required*. <div class="Discussion_UserSignature"> </div>

 

[JonClarke]

Stirling conversion is more efficient that simple thermal electric, but you still need an expensive isotopic power source. And are they reliable over the decade or two of operation? <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>

 

[h2ouniverse]

in reply to "are they reliable over the decade or two of operation?"<br /><br />That's all the question! But no reason not to hope. <br />There are other technologies btw.<br />Best regards

 

[MeteorWayne]

"Other" technologies are not necessarily more reliable or longer lasting than the older ones <img src="/images/icons/wink.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>

 

[alokmohan]

Right.

 

[h2ouniverse]

But they can be far less expensive and without Plutonium...<br />The point with RTG is that they are really expensive, and depend on a significant quantity of Pu.<br />So yes, they are qualified in US & Russia, but imho (and in NASA's own opinion!) we need something else. Which means development (and so development risks!).