Using the ISS/Shuttle to go to both the Moon/Mars

[qso1]

So basically we could change a vehicles orbit from 51 degrees to a near equatorial lunar orbit with little energy requirement. <br /><br />Was I right by any chance on the need for boosters for ISS? <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>

 

[qso1]

I'd like to be able to answer you but my knowledge base isn't worth spit. I bombed big time on my answer about plane changes. I usually try to back up what I say but sometimes cannot find the links to do that. But someone else did and found a good link to a lunar orbit simulator that apparently shows the plane changes to be a lot easier than I thought.<br /><br />I'm waiting now for a reply on whether ISS would need a booster to reach the moon. <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>

 

[drwayne]

One bit of semi-related trivia.<br /><br />The Apollo flights to the moon were basically on an Earth orbital trajectory, with an apogee near the moon, and perigee in a low Earth orbit.<br /><br />SG's answer is related to a lower enegy method of orbital plane transfer, in which the original orbit is changed to one with a high apogee, low perigee, and therefore low velocity at apogee. This low velocity at apogee means that the rotation itself is essentially free.<br /><br />Wayne <div class="Discussion_UserSignature"> <p>"1) Give no quarter; 2) Take no prisoners; 3) Sink everything."  Admiral Jackie Fisher</p> </div>

 

[scottb50]

There's also a trick with elongated orbits where little energy is needed to make pretty dramatic inclination changes. A much smaller circle to move in, a degree in inclination is a fraction of what it is in LEO. Move around the tip of a cone instead of the base.<br /><br />The only reason for the ISS orbit is Russian access and the Shuttle pays a penalty in performance. The main thing is an Equitorial orbit is still the best place to start out and a Polar Orbit the next best. Equitorial to get to most places we would want to get to and Polar to cover as much of the surface as possible. <br /><br />Then it just becomes a matter of how much propellant and how many engines to get from point a to b. <br /><br /> <div class="Discussion_UserSignature"> </div>

 

[qso1]

I appreciate the feedback guys.<br /><br />I gotta figure out someway to be able to continue participation in discussions without constantly screwing up so give me a little time. My knowledge base has never been adequate but then, I have never been able to work in the space field or even been a decent hobbyist.<br /><br />I do try to maintain a good disclaimer base LOL. <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>

 

[drwayne]

Note that the plane change is essentially free in the scenario I talked about, but you do have to pay for getting into and out of your elliptical orbit that you use to change plane.<br /><br />Wayne <div class="Discussion_UserSignature"> <p>"1) Give no quarter; 2) Take no prisoners; 3) Sink everything."  Admiral Jackie Fisher</p> </div>

 

[willpittenger]

Tom specically asked about <b>historical</b> plans rather than current ones. He also asked about pre-Challenger plans. <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>

 

[qso1]

Thanks shuttle_guy.<br /><br />I wasn't sure what "G" force ISS could take but its fairly obvious even to a layman such as me that the mass and layout of the various appendages would pose a problem in accellerating fairly rapidly. <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>

 

[qso1]

shuttle_guy:<br />Shuttle -C was too expensive then also.<br /><br />Me:<br />We always see ideas on this board about resurrecting Saturn-V which would require much reworking at complex 39 at the very least. Then theres utilizing Sea Dragon which would require a clean sheet start across the board from facilities to boosters and where to manufacture, launch, etc. And yet, shuttle "C" which should be the minimal cost impact path to an HLLV, the infrastructure and LV are already in place. You have said shuttle "C" was too expensive and I've heard that before, years ago from equally reliable sources. What I haven't quite pinned down was why? What made it so expensive? <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>

 

[marcel_leonard]

Like the good doctor said the original Apollo mission was nothing more than a large elliptical shaped orbit towards the moon. There is nothing stopping us from using the orbital momentum of the space station in a trajectory towards a lunar orbit. All this talk about how much stress the ISS can take is nothing more than pure speculation. <div class="Discussion_UserSignature"> "A mind is a terrible thing to waste..." </div>

 

[pathfinder_01]

Like the good doctor said the original Apollo mission was nothing more than a large elliptical shaped orbit towards the moon. There is nothing stopping us from using the orbital momentum of the space station in a trajectory towards a lunar orbit. All this talk about how much stress the ISS can take is nothing more than pure speculation.”<br /><br />You know, It possible to turn lead into gold, but the cost of turning lead into gold would far exceed the value of gold. <br /><br />As for the ISS being unable to take the stress that is more than just pure speculation. The ISS was not built to leave earth orbit. Depending on how you apply the thrust (fast or slow) it might not be able to take the forces put on. <br /><br />Then there is the problem of building the rocket to provide the delta V to get there. The ISS is massive, it will take an unimaginable amount of fuel just to push it to the moon. <br /><br />After all is said and done it would be much better and cheaper to build a new space station in lunar orbit than try to move the ISS there. Remember the ISS was built for low earth orbit. A station built as a lunar outpost would likely have slightly different requirements.<br />

 

[scottb50]

I would think the only reason to change orbit to a specific inclination would be mission driven. For the most part most operations would be to a Station in an advantagous orbit and most Tug missions would be to orbits in that plane, just at different altitudes. <br /><br />Spy stuff would be the only reason I could see much need for major plane changes anyway. Eventually you can see everything from polar orbit, if your in that much of a hurry propellant is a minor consideration anyway. <div class="Discussion_UserSignature"> </div>

 

[qso1]

marcel_leonard:<br />Like the good doctor said the original Apollo...<br /><br />Me:<br />Actually, I think shuttle_guy could tell you that stress would be a factor. Though objects are weightless in space, the still have mass. Accellerating massive objects that were designed to remain in orbit may have detrimental effects. But assuming I'm wrong, which I may be since I suck at this. Why not just go ahead and design craft for the purpose of lunar exploration? ISS is somewhere depending on various estimates, between $40-100 billion dollars.<br /><br />You still need boosters to get it to the moon which will require more launch vehicle flights from the ground, but thats just my speculation. <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>

 

[qso1]

Shuttle_guy and others pointed out what they said was mistakes on my part on transferring from highly inclined orbits to equatorial lunar orbits and because of their expertise in all things space. I figure they are right.<br /><br />I'm not very bright anyway but something still nags at me and I'll put up some graphics in the hopes the experts can help clear this up for me.<br /><br />The graphic here shows orbits for spacecraft in equatorial orbit around the Earth and Moon as indicated by the red lines. Number 1 showing the orbits edge on while number 2 shows the graphic tilted a bit.<br /><br />The north pole on both Earth and Moon is at the top of each body in the image. <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>

 

[qso1]

In this graphic, the yellow arrow above Earth points to the direction of travel both Earth and Moon follow around the Sun. The green arrow is the Moons orbit around Earth. The Sun would be located about where the word "Earth" is and we would actually be looking at the side of the Earth and Moon not illuminated by the Sun. But for simplicities sake, no lighting effects.<br /><br />The purple line indicates a spacecraft such as Apollo coming out of Earths orbit and heading into lunar orbit. Also for simplicities sake, the motion of the Moon is not shown. The orbits around Earth and Moon because they are equatorial, line up. There could be a few degrees difference and there is a few degrees difference between the moons orbital inclination relative to Earth (Not shown here) but not enough to be outside Apollos capability to enter lunar orbit. Basically, the Moon is in a roughly equatorial orbit around the Earth.<br /><br />BTW, the purple part of the orbit is half of the elliptical orbit referenced by "pathfinder_01" in his post.<br />Where he stated "Like the good doctor said the original Apollo mission was nothing more than a large elliptical shaped orbit..." <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>

 

[qso1]

At number 1 in this graphic, a spacecraft orbits Earth at 51 degree inclination. The craft may raise or increase the altitude of its orbit as shown in the green circle. With the engine pointed along the velocity vector, the orbit will simply become a larger orbit with the same inclination. If fired long enough to achieve escape velocity, as shown in yellow, the craft will simply speed away from Earth along the direction of travel it was on while in orbit.<br /><br />Number 2 is a slightly canted view to show the approximate size and direction of travel for spacecraft orbiting Earth. <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>

 

[qso1]

Now we want to go from a 51 degree Earth orbit to a roughly equatorial lunar orbit. To do this, we must fire the engine at the point shown in Earth orbit. The difference is in the direction the engine is pointed. For this change, the spacecraft ACS is used to point it so that the engine is pointed roughly equatorially, or when it fires the ACS or main engine gimballing effects the required plane change.<br /><br />This is where I see the problem. And that problem is...overcoming the 17,500 mph forward momentum of the original 51 degree orbital velocity vector. Put another way, if one is in this 51 degree orbit, and throws a bag of trash out. The trash bags orbit will increase in size according to the bags momentum and per the previous graphics description of making a larger 51 degree orbit. However not much of an increase in orbital size as the bags relative velocity is that of the persons pitching arm velocity so to speak. And the inclination remains virtually the same. If one were to throw the same bag of trash out and try to aim it at the lunar equatorial orbit, they will have to overcome the forward momentum with far more energy than just throwing the trash out as previously described.<br /><br />The curving in the green line is a graphical indication of the directional change required which in turn must require some additional energy to overcome the 17,500 mph forward momentum and transfer that not only to 17,500 mph redirected momentum but increase the velocity to 24,500 mph to escape Earths gravity as Apollo had to do.<br /><br />And so this brings me to my question, what am I missing here? I know for a fact that the shuttle cannot go from equatorial to polar orbit because of that being an issue with Hubble servicing mission crew inability to go to ISS in the event of an emergency.<br /><br />What did I miss? <br /><br />BTW, someone posted a link to what looks like a good simulation program but I was unable to download it.<br /><br />Number 2 is just the tilted version <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>

 

[willpittenger]

At that maximum acceleration, how long would it take to reach the moon? Assume that thrust and fuel supplies are non-issues. <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>

 

[willpittenger]

So was the shuttle completely written out of the 80's era Mars plans? <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>

 

[krrr]

On the LTOC homepage, there is a 3-D illustration of an Earth-Moon trajectory where a roughly equatorial Earth orbit results in a polar lunar orbit. Now if you rotate that picture by 90 degrees, you get a trajectory from polar LEO to equatorial LLO. Of course, the plane of that trajectory is then roughly perpendicular to the equatorial plane. Surely, similar trajectories exist for 51.5 degrees LEO to equatorial LLO.<br /><br />It's indeed difficult to comprehend the mechanics which cause that plane change. My explanation goes like this:<br /><br />One deliberately misaligns the trajectory (your magenta ellipse) somewhat. That is, one aims for an apogee point slightly below/above and/or "left"/"right" and/or in front/behind the Moon. Then apparently the geometry can be such that near the Moon, lunar gravity bends the spacecraft's path into a different inclination, essentially for free.

 

[henryhallam]

You have the right idea, krrr. Qso, why don't you get a copy of the excellent free and pretty accurate "Orbiter" space flight simulator. There are some addons for it called TransX and IMFD which allow you to plan and execute this kind of trajectory. You can adjust all the variables and see the result in real time both graphically and numerically, then fly it and see where you end up.

 

[lampblack]

Would it be fair to say that the main problem with launching lunar missions from a 51-degree low earth orbit isn't whether it's possible or not -- but rather how frequently it could happen?<br /><br />Lunar vessels assembled at the space station would line up just right only once every other blue moon or so, I seem to recall reading. <div class="Discussion_UserSignature"> <font color="#0000ff"><strong>Just tell the truth and let the chips fall...</strong></font> </div>

 

[henryhallam]

I haven't tried any simulations of it in a while but my hunch is that you get two windows per month. If it's the latter then there may be problems since not all of those will end with suitable lighting conditions at the landing site.<br /><br />I *think* you'd have a similar situation with a 28.5 degree orbit, if it was a fixed orbit (e.g. that of a space station). If you are launching in one shot then you can do it every day, even from a 51 degree inclination, because by choosing the launch time you can alter the plane of the parking orbit.<br /><br />I am not absolutely 100% sure on the above.<br /><br />IMO the main disadvantage in carrying out lunar missions from a 51 degree orbit is not the relatively minor loss of efficiency in going *from* that orbit to the moon, it is the more significant reduced payload that can be taken from the *surface* to a 51 degree orbit compared to a 28.5 or equatorial orbit for a given launch vehicle.

 

[scottb50]

No it couldn't take significant acceleration, but an ion engine could move it to lunar orbit, given enough time. Maybe the best idea would be to move it to and equatorial orbit and use it as an assembly Station for the vehicles that will go to the moon. <div class="Discussion_UserSignature"> </div>

 

[henryhallam]

The plane change requires enough propellant and engines (even ion engines) that it would probably be easier to build a new station in an equatorial orbit.<br /><br />New lunar missions will almost certainly be launched from the Cape so they will be going into a 28.5 degree orbit not an equatorial one.<br /><br />Why do you even need an assembly station at all?