In this video I m going to show the problems the Apollo 14 crew had with the initial docking
between the command module and the lunar module which nearly resulted in another
aborted attempt at a moon landing coming not long after apollo 13s problems.
If you need a recap on the operation of the docking system, I ve put it in the link here
Apollo 14 was crewed by Alan B Sheppard jr , Stuart A Roosa and Edgar D Mitchel.
Al Sheppard, the first American in space, was grounded after his first flight
due to Meniere s disease which is a disorder of the inner ear causing dizziness and Tinnitus.
He went on to have experimental surgery which later restored his flight status in May 1969.
With his Rookie crew they were selected for Apollo 14
Stu Roosa was the Command Module Pilot and was keen after many hours in the Simulator,
to do the most efficient docking yet. This he would have achieved
..if the docking probe had worked first time. After apollo 13 s aborted attempt at landing on
the moon, all eyes were on Nasa and Apollo 14 to make a successful, problem free trip.
Apollo 14 launched without incident on 31 January 1971. This was 9 months after Apollo 13 which
gave the engineers a chance to rectify all the problems encountered on the previous mission.
Everything ran smoothly, and after entering TLI, Trans Lunar injection the Command
Module separated, and initiated the docking manoeuvre. This was 3 hours after launch.
Stu Roosa guided the Command Module using the RCS, Reaction control system
A text book approach using the minimum amount of fuel.
The system is designed to capture with closing velocities
of between 0.03 and 0.305 metres per second.
Unfortunately, Ed s Mitchell s call was premature, the Probe did not engage with the Drogue.
Stu added some thrust and a second attempt was made
Still no latching A third attempt this time when contact was made
0.55 seconds of thrust was applied to hopefully force the probe head home.
Still no latching Finally, a fourth attempt. This time
with 1.95 seconds of thrust on contact. Again, without success.
Another attempt was made this time a faster velocity
And again.
These attempts relied on the forward velocity and no extra thrust was applied on contact.
At this point they back out and discuss possible solutions. They verify the docking probe circuit
breakers are all on and the probe extend retract switch is showing the correct indicators.
All these are okay. With the switch set to extend Houston asks them to try the docking again,
this time Houston advises that when contact is made 3 seconds of thrust is added.
The actual amount of thrusting was 6.2 seconds but still no joy
. Stu Roosa reports that he can see scratch
marks on the drogue about an inch and a half long 120 degrees apart. The latches should retract when
entering the Drogue head but the scratch marks are indicating that the latches are stuck out.
Once again, they check the retract swich which is indicating Gray and the nitrogen bottle will
not fire to retract the probe. This tells Houston that the capture latches are cocked but there is
something stopping them from being released. If we look at the cut away you can see when
the latches enter the drogue, they are depressed which pushes down on the spider.
Then when they go through the top of the drogue they spring out and lock into position. Something
seems to be stopping the spider from moving and therefore the latches are staying out.
Houston then advises them to go to extend release and hold it for 5 seconds.
Then return to retract and try the docking again
with a normal closing rate. This they do.
The time elapsed since the initial Docking attempt is an hour and a half. Houston now have a docking
probe brought into the control room and Astronauts Gene Cernan, John young, and the engineering team
discuss possible solutions. At this point it is looking more
and more likely that they will have to do some hard suit work. This involves all the
crew being fully suited up and then opening the spacecraft up and retrieve the probe.
This They would then bring it into the Command module which would allow them
to do a close inspection of the latches. However, this would be a last-ditch attempt
to try and save the mission. If they can t dock with the Lunar Module then the moon landing would
have to be aborted and after Apollo 13 it would be another high-profile failure for NASA.
To try and avoid this scenario Gene Cernan comes back on the comms with one final idea.
He asks them to go ahead and go through a normal docking procedure. Once there is contact keep
a plus x, i.e., continue thrusting. Which should help with the alignment.
Then blow the nitrogen bottle and retract the probe. The probe once retracted should enable
the lunar module to connect with the command module docking ring and get some latches.
They are hopeful that even getting one latch should be enough. The rest of them can be done
manually from inside the spacecraft. In normal operation a minimum of 3 latches
are required for hard dock, the rest can be manually activated.
One problem they envisage though is that electrically, there might be a series path
that stops them from actually retracting the probe.
It seems the thoughts in Mission control
were that the probe would not retract but they felt they would rather attempt this first
rather than going to a Hard Suit scenario. They start then 6th Attempt.
Contact, they attempt to retract the probe without success. Stu Roosa continues applying thrust.
Then after 6.9 seconds the latches depress .
The probe retracts and then 5 seconds later latching is successful.
Once the tunnel was pressurised and they could remove the hatch they found
all of the latches had activated, just 2 needed a slight push to lock them in place.
The crew then continued on their mission.
Instead of jettison the probe in the Lunar Module as would be the normal procedure, the
probe is returned to earth so the NASA engineers can do a thorough investigation on it.
During the probe inspection and tests, various particles were found but none large enough to
stop the mechanism from working. The focus was therefore on the items
that could influence the position of the spider. If something was impeding the
travel of the spider then the latches could not depress and go into the locked position.
There was talk of various foreign materials in the probe head, I ve shown it with ice and you can see
how it would prevent the spider from moving. The conclusions were that either a foreign
material that was subsequently lost, restricting the mechanical operation of the probe or
jamming of the cam. Therefore, on subsequent missions cleanliness was increased, a cover
was applied to the probe head prior to launch and There were design changes to the Cam.
On Apollo 14 The docking mechanism performed flawlessly for the rest of the mission.
And as they approached the moon for an historic third landing,
Al Sheppard made sure all the essentials were packed for the Lunar
surface!