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Author
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Topic: Apollo hardware placed in heliocentric orbits
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Silent Sea
Member Posts: 36
From:
Registered: Mar 2015
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posted 11-19-2015 06:52 PM
  
Having read about the S-IVB (and the Apollo 10 lunar module ascent stage "Snoopy") in orbit around the sun, my question is simple:Why place these in such an orbit? |
Jim Behling
Member Posts: 1488
From: Cape Canaveral, FL
Registered: Mar 2010
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posted 11-19-2015 07:34 PM
Because it was an easy way of disposing them. |
Silent Sea
Member Posts: 36
From:
Registered: Mar 2015
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posted 11-20-2015 06:13 PM
Okay, easy makes sense. But what exactly makes it easy? Why orbit the sun? Why orbit anything? If it was pushed away in some general direction away from the CSM/LM so that it just goes off into endless space... is that more difficult than putting it into heliocentric orbit? I'm genuinely curious.
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chet
Member Posts: 1506
From: Beverly Hills, Calif.
Registered: Nov 2000
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posted 11-20-2015 07:48 PM
From what I've gathered the mission plan was to burn to depletion the remaining fuel in Snoopy's ascent stage so as to obtain further engine performance data. |
tfrielin
Member Posts: 162
From: Athens, GA
Registered: Feb 2007
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posted 11-21-2015 10:16 AM
quote:
Originally posted by chet:
...to obtain further engine performance data.
Also to collect data on which subsystems failed first as the batteries died — information that was useful during Apollo 13. |
Headshot
Member Posts: 891
From: Vancouver, WA, USA
Registered: Feb 2012
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posted 11-21-2015 11:10 AM
There were several possibilities for discarding unwanted Apollo S-IVB hardware. - Crashing it into the Moon
- Causing it to re-enter the Earth's atmosphere and burn up after a lunar fly-around.
- Putting it into a heliocentric orbit.
- Sending it into deep space (exiting the solar system).
- Sending it into the sun.
There was not enough remaining fuel on board the S-IVBs to accomplish Nos. 4 and 5. No. 3 was the easiest to accomplish until engineers decided on No. 1 to gain scientific data after seismometers were placed on the lunar surface. Limited battery life and frozen fuel lines would have precluded No. 2 from succeeding.As it was, an Apollo 12 S-IVB malfunction during its last burn (long after TLI) caused it to enter a large orbit around the Earth instead of going into a heliocentric orbit. |
tfrielin
Member Posts: 162
From: Athens, GA
Registered: Feb 2007
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posted 11-21-2015 01:01 PM
I don't think it was a burn (in the sense that the S-IVB's J-2 engine was re-ignited) but a propulsive vent of the residual propellants, that placed the Apollo S-IVB stages on their lunar impact trajectories.See also the deliberate re-entry of the four S-IVB stages that placed the three Skylab crews in orbit, plus ASTP. All those S-IVBs were de-orbited via propulsive vents of the stages' excessive propellants. |
SpaceAholic
Member Posts: 4494
From: Sierra Vista, Arizona
Registered: Nov 1999
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posted 11-21-2015 01:26 PM
quote:
Originally posted by tfrielin:
I don't think it was a burn (in the sense that the S-IVB's J-2 engine was re-ignited) but a propulsive vent of the residual propellants, that placed the Apollo S-IVB stages on their lunar impact trajectories.
APS engine burns after S-IVB separation provided the required impulse... |
Headshot
Member Posts: 891
From: Vancouver, WA, USA
Registered: Feb 2012
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posted 11-21-2015 02:19 PM
My bad. I always believed that the J-2 engine re-ignited to use up the remaining fuel. After nearly 45 years I am still learning. |
Silent Sea
Member Posts: 36
From:
Registered: Mar 2015
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posted 11-21-2015 06:27 PM
The Apollo 10 LM makes sense. I was just reading about that in Go, Flight! so it sounded familiar.  Headshot's and the following posts make things clearer for me. So (aside from ones crashed into the lunar surface) it's actually most efficient for the remaining fuel to send the S-IVB toward the sun to orbit than send them off into deep space. Am I understanding this correctly? |
Jim Behling
Member Posts: 1488
From: Cape Canaveral, FL
Registered: Mar 2010
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posted 11-21-2015 08:30 PM
quote:
Originally posted by Silent Sea:
Why orbit the sun?
Because it is already orbiting the sun, even while on the launch pad. If it is not in Earth or lunar orbit, it is by default in a heliocentric orbit. quote:
...to send the S-IVB toward the sun
It wasn't toward or away from the sun or deep space, it was just away from the Earth and moon. It is in a orbit of the sun that is similar to the Earth's. |
Space Cadet Carl
Member Posts: 225
From: Lake Orion, Michigan
Registered: Feb 2006
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posted 11-23-2015 12:06 PM
Starting in 2011, a group of British astronomers and students began searching for Apollo 10 LM Snoopy. NASA and JPL were to assist in the effort. Forty-six years later, it is the only formerly manned U.S. spacecraft still in space. John Young jokes about how somebody in the future is going to rendezvous with Snoopy and find all of his and Cernan's frozen "DNA waste" and other garbage stored onboard the craft. |
SkyMan1958
Member Posts: 880
From: CA.
Registered: Jan 2011
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posted 11-23-2015 09:20 PM
Here's the page from the Apollo 12 Flight Plan where they send the S-IV B on the so called sling shot maneuver. It occurred roughly 4:45 hours after launch. |
SpaceAholic
Member Posts: 4494
From: Sierra Vista, Arizona
Registered: Nov 1999
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posted 11-24-2015 06:08 AM
quote:
Originally posted by Headshot:
My bad. I always believed that the J-2 engine re-ignited to use up the remaining fuel. After nearly 45 years I am still learning.
Not re-ignited, but there was propulsive venting of propellant (in gaseous state) through the nozzle to supplement the APS. |
Silent Sea
Member Posts: 36
From:
Registered: Mar 2015
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posted 11-26-2015 09:37 AM
quote:
Originally posted by Jim Behling:
If it is not in Earth or lunar orbit, it is by default in a heliocentric orbit.
Now that it's put that way, it really makes a lot of sense. |
Tykeanaut
Member Posts: 2216
From: Worcestershire, England, UK.
Registered: Apr 2008
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posted 11-26-2015 11:21 AM
quote:
Originally posted by Space Cadet Carl:
Starting in 2011, a group of British astronomers and students began searching for Apollo 10 LM Snoopy.
So do we know exactly where LM Snoopy is? |
Robert Pearlman
Editor Posts: 43576
From: Houston, TX
Registered: Nov 1999
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posted 11-26-2015 01:18 PM
From what I understand, the 2011 efforts were unsuccessful and Snoopy's location remains unknown. |
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