Zond/Soyuz circumlunar-orbit question

Status
Not open for further replies.
G

gunsandrockets

Guest
Before Apollo 8, the Soviets were planning a lunar flyby mission with a cut-down Soyuz spacecraft launched by a Proton booster. More recently the Russians have spoken seriously about a lunar flyby tourism mission in a Soyuz at the price of around $100 million per seat.<br /><br />http://www.astronautix.com/craft/soyz7kl1.htm<br /><br />http://www.astronautix.com/craft/dsealpha.htm<br /><br />Now unlike the Apollo 8 mission which braked into orbit around the moon, the Russian circumlunar missions would just swing-by the moon and head back towards Earth on a free-return trajectory. Ordinarily the Soyuz descent-capsule would do a skip-reentry at Earth arrival. <br /><br />But what if the Soyuz spacecraft didn't aim for Earth return? What if the spacecraft was aimed to swing-by the Earth and head back out again? Could the orbit be adjusted so it would swing out again towards the moon? Could such an orbit be adjusted so that the spacecraft would swing back and forth between the Earth and the moon in a perpetural figure 8 orbit? How stable could such an orbit be? And if unstable how much Delta-V would such an orbit require to maintain?<br /><br />Anyone know the answers to these questions? Please help.
 
S

strandedonearth

Guest
I've been meaning to ask that question for some time now.
 
D

davf

Guest
A few years back, Buzz Alrdin crunched some numbers and put together orbital parameters for a 'lunar cycler' that did exactly that. Is it possible? Providing Buzz's work was accurate then I'd say yes. Would it be suitable for Zond or a modified Soyuz? That I can't answer. Incidentally, Buzz also put together the numbers for a Mars cycler.
 
T

tomnackid

Guest
As Jim alluded to you would need a propulsion system to constantly adjust the orbit to keep it going. Most "cycler" systems that I have read about propose using low thrust, high impulse systems like ion drives to keep the cycler on course. I doubt that an already stripped down Soyuz could be outfitted with such a propulsion system, anyway a single trip to the moon and back would be straining the Soyuz's life support capabilities.
 
V

vogon13

Guest
Apollo 13 was (IIRC) looking at an earth miss distance of 40,000 miles on it's first pass through the figure 8 orbit.<br /><br />They had the LM descent engine to correct (and hasten) their flight. <br /><br />It takes a major burn (and a heap of fuel) to correct 40,000 miles in just a few days.<br /><br /> <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>
 
R

rybanis

Guest
Heh, I was just thinking of Apollo 13...then I thought of the movie. Heres a question: I remember in the movie when the flight controllers were trying to decide what to do about getting the crew home, and some were advocating free-return around the moon. The opposing view was that they should make a burn and reverse course from the point at they at. <br /><br />Now, there is no way they would have enough propellant to actually "turn around", right? <div class="Discussion_UserSignature"> </div>
 
J

jimfromnsf

Guest
"Now, there is no way they would have enough propellant to actually "turn around", right?"<br /><br />nope, there were many points in the trajectory that allowed the spacecraft to return without reaching the moon.<br /><br />From the Apollo 11 press kit:<br /><br />Translunar Injection Phase --<br />Aborts during the translunar injection phase are only a remote possibly, but if an abort became necessary during the TLI maneuver, an SPS retrograde burn could be made to produce spacecraft entry. This mode of abort would be used only in the event of an extreme emergency that affected crew safety. ………. Another TLI abort situation would be used if a malfunction cropped up after Injection. A retrograde SPS burn at about 90 minutes after TLI shutoff would allow targeting to land on the Atlantic Ocean recovery line<br /><br />Translunar Coast phase --<br />Aborts arising during the three-day translunar coast phase would be similar in nature to the 90-minute TLI abort.……… When the spacecraft enters the Moon's sphere of influence, a circumlunar abort becomes faster than an attempt to return directly to Earth.<br />
 
S

scottb50

Guest
Now, there is no way they would have enough propellant to actually "turn around", right?>>><br /><br />Turn around would not be an option. The option would be changing the orbit around the Earth. The route to the moon is simply an elongated orbit around the Earth an object would not disappear into deep Space if it missed the moon it would eventually complete the orbit.<br /><br />What would happen is the apogee of the orbit would be altered the outbound leg shortened. It would also change the perigee of the orbit making it more circular and require a further burn to enter the atmosphere. <div class="Discussion_UserSignature"> </div>
 
J

jimfromnsf

Guest
Read my previous post,<br /> turnaround was possible and an option. The route to the moon wasn't an earth orbit; some of the S-IVB's went into solar orbit. Also if the turn around did happen, another burn is not required. The turnaround burn included targeting for reentry
 
D

drwayne

Guest
It should be noted that the turn-around scenario, at the point that the Apollo 13 explosion happened would have required that the LM be jettisoned, and would have required using a SM engine, whose operational health was not known at the time. (I don't think anyone knows today if it would have lit and burned properly for what would have been a long burn)<br /><br />Wayne <div class="Discussion_UserSignature"> <p>"1) Give no quarter; 2) Take no prisoners; 3) Sink everything."  Admiral Jackie Fisher</p> </div>
 
P

PistolPete

Guest
Which brings up another question. If Houston knew that the SM was little more than a "dead elephant on their back" then why didn't they just dump the SM before the first burn? It would have solved the CG problems later on and would have allowed them to conserve fuel during the course correction burns. <div class="Discussion_UserSignature"> <p> </p><p><em>So, again we are defeated. This victory belongs to the farmers, not us.</em></p><p><strong>-Kambei Shimada from the movie Seven Samurai</strong></p> </div>
 
D

drwayne

Guest
They were reluctant to leave the heat shield exposed to the temperature variations that having it uncovered would induce - especially in light of the fact that they had no idea if if was cracked.<br /><br />Wayne <div class="Discussion_UserSignature"> <p>"1) Give no quarter; 2) Take no prisoners; 3) Sink everything."  Admiral Jackie Fisher</p> </div>
 
G

gunsandrockets

Guest
<A few years back, Buzz Alrdin crunched some numbers and put together orbital parameters for a 'lunar cycler' that did exactly that. Is it possible? Providing Buzz's work was accurate then I'd say yes.><br /><br />Thanx for the response. Your clue lead me to find some interesting information...<br /><br />http://adsabs.harvard.edu/abs/1991sfm..proc..163U<br /><br />http://www.moonminer.com/lunarcycler-orbits.html<br /><br /><Would it be suitable for Zond or a modified Soyuz? /><br /><br />Not relevant. I only brought up the Zond/Soyuz flyby missions for illustrative purposes, to help describe the kind of orbit I was interested in. <br /><br />
 
G

gunsandrockets

Guest
I have a new question about the Zond circumlunar-flyby free-return orbit. <br /><br />Did the Zond have Earth escape velocity? Did the orbit require the moon to swing the Zond back towards Earth? Or was the Zond velocity low enough that, absent the moon, it would have sped outward from Earth but still returned some weeks later?
 
P

PistolPete

Guest
The velocity of the Zond spacecraft was not enough to reach escape velocity. In fact, Zond 4 was purposely launched away from the Moon as a test to see if the spacecraft could last for the length of the journey. Because there was no Moon to block the signal from the spacecraft, telemetry could be monitored uninterrupted for the entire length of the flight. <div class="Discussion_UserSignature"> <p> </p><p><em>So, again we are defeated. This victory belongs to the farmers, not us.</em></p><p><strong>-Kambei Shimada from the movie Seven Samurai</strong></p> </div>
 
G

gunsandrockets

Guest
Interesting stuff, thanx! Do you have a figure for the orbital period of Zond 4? Days, weeks, ...?
 
C

CalliArcale

Guest
According to astronautix.com, Zond 4 blasted off on March 2, 1968 and returned March 7 (whereupon it unfortunately was self-destructed because the guidance system failed, prohibiting a landing on Soviet territory). So that's five days. <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>
 
P

publiusr

Guest
Zond would only be good for one man however--unlike the recent Soyuz to the moon concepts--
 
J

JonClarke

Guest
Actually it was good for two.<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>
 
P

publiusr

Guest
I seem to remember a single dummy cosmonaut--but there were other small payloads that took the rest of the space--that's right.
 
Status
Not open for further replies.

ASK THE COMMUNITY