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Forum:Mercury - Gemini - Apollo
Topic:May 18-26 1969: Remembering Apollo 10
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This material is taken from Spacecraft Films 2-DVD set on the Apollo 10 mission.

Robert PearlmanThe Oklahoman: 40th anniversary of Apollo X: How an Oklahoman made history
Disaster fell upon Apollo X astronauts Thomas P. Stafford and Eugene A. Cernan 40 years ago this month when their lunar module began spinning wildly during a low pass over the moon's surface. No humans had ever been so close to another celestial body, and yet in that defining moment, the mission -- and their lives -- appeared in jeopardy.

The world listened anxiously to the spacecraft's radio transmission to NASA's Command Center in Houston. As the lunar module pitched and rolled in "wild gyrations," Cernan bellowed his now-famous, "Son of a b----!"

Stafford mumbled something inaudible in his Oklahoma drawl and took action.

"When you see the surface of the moon flash before your eyes eight times in 15 seconds, it's a bit unnerving," recalled the retired Capt. Cernan, now 75 and living in Houston. "Luckily, Tom was able to shut it down completely and take over full control of the lunar module manually and get us back under control."

Stafford and Cernan -- with command module pilot John W. Young flying separately above -- completed a successful reconnaissance of the moon's cratered and rocky surface. Their work paved the way for Apollo XI's mission to land. Two months later, astronaut Neil Armstrong would become the first man to walk on the moon.

"We made Apollo XI possible," retired Gen. Stafford said simply. "We did our job. We did what we were sent to do."

ObviousmanApollo 10
18 May 69
(The launch date was actually on 19 May 69 in Australia, but I'll stick with the US dates for convenience)

After the success of the Apollo 9 mission, most of the pieces were in place for the first lunar landing attempt. The last test would be to do a practice mission to close to the lunar surface, to test all the equipment except the hazardous actual landing. For this important flight, NASA had its first 'all veteran' crew. The spacecraft commander (CDR) was Tom Stafford, who had flown on Gemini 6 and commanded Gemini 9. The Command Module Pilot (CMP) was John Young, also a veteran of two Gemini flights (Gemini 3, Gemini 10). Joining Tom Stafford in the Lunar Module would be Gene Cernan, the Lunar Module Pilot (LMP) who conducted a spacewalk during his flight on Gemini 9. The term Lunar Module Pilot was actually a misnomer. Although they were the LM systems expert and were in fact trained to fly the LM, it was always the commander who flew the LM. The LMP was a co-pilot.

(L to R: Cernan, Young, Stafford)

At 1549 GMT, the hold-downs were released and the Saturn V, known as launch vehicle SA-505, slowly rose from Launch Complex 39B. After clearing the service tower, the rocket changed its direction - the pitch and roll - for the correct path to reach orbit. Gene Cernan, obviously impressed and excited by the launch, shouts "We're going!" and "What a ride, Babe, what a ride!". It was indeed a ride, when at 2 minutes into the flight, the Saturn began to shudder, experience a known but not fully understood problem called pogo. The pogo was relatively mild however, and the rocket continued skyward.

Twelve minutes after launch, Apollo 10 was safely in a roughly 100 mile orbit. For nearly two hours the crew tested systems on the spacecraft, confirming all the systems were healthy and ready for the ultimate challenge - a flight to the Moon. All seemed well, and Houston gave the call "Apollo 10, you are go for TLI (Trans Lunar Injection)". TLI was the second firing of the J-2 engine on the S-IV-B, which would send spacecraft stack on its way from Earth orbit towards a lunar orbit. The engine fired for 8 minutes and Apollo 10 took the next step on its journey.

The crew now prepared to remove their LM - callsign Snoopy - from the S-IV-B. Housekeeping duties included reporting the dose of radiation received so far:

CAPCOM: "Roger Tom. Did you get a chance to get the radiation survey meter out?"

LMP: "Yes I did, Charlie, and I read zero on every scale".

A little after 3 hours from launch, the Command / Service Module stack (the CSM) separated from the S-IV-B stage.

Snoopy as seen from Charlie Brown, prior to undocking

The CSM - callsign 'Charlie Brown' turned around, and John Young guided them towards a successful docking with the LM. The docking probe was removed from the docking tunnel, and the hatch to the LM removed. As the hatch was removed, a flurry of small particles entered the CM. This turned out to be small pieces of fiberglass from the hatch, and was to cause the crew irritation during the flight.

At 3 hours 56 minutes Ground Elapsed Time (GET, the time since lift-off), the LM was withdrawn from the S-IV-B. CMP John Young carefully moved the stack away from the now redundant S-IV-B, increasing the distance away from what now was a hazard to them. Half an hour later, the crew fired up the Service Propulsion System (SPS) engine on the service module and moved them further away from the S-IV-B but closer to their goal.

The crew had set up the television camera prior to docking with the LM, and now commenced a dedicated broadcast back to the Earth, describing the Earth and showing what it looked like from Apollo 10.

Things were going so well on Apollo 10 that Houston advised that the first of three mid-course corrections, designed to refine the spacecraft trajectory, would not be required. The crew began preparations to get some rest after a hard day, and everyone was feeling good. So good, that a little risque chatter appeared:

CAPCOM: "And 10, if you'd be interested, there's just a possibility of a waste-water dump during TV"

CDR: "Okay, great. We could substitute another kind if you want to..."

(Tom Stafford was referring to a overboard dump of urine...)

The crew settled into sleep, trying to get as much rest as possible before what were bound to be a very hectic following few days.

(more follows tomorrow)

Obviousman19 May 69

Despite some problems with the thrusters maintaining the Passive Thermal Control (PTC) roll, the crew of Apollo 10 were awakened at 21 hours and 31 minutes GET and reported an excellent nights sleep. The PTC, otherwise known as "BBQ mode", was a slow roll of the CSM / LM stack, designed to evenly distribute the heating and cooling of the spacecraft. Spining at roughly 3 revolution per hour, this was a very important manoeurvre. The problem was not so much keeping the roll going, but the thruster firing if the roll started to spin off the axis - a wobble. The spacecraft computer would keep it stabilised, but Houston had been a little worried that the thruster firing would wake the crew. They need not have worried.

The normal routine of Apollo spaceflight then set in: preparing for "star shots" to confirm and refine the guidance systems understanding of where they were in space, course corrections, and waste water dumps. The latter could interfere with the former, as the ice crystals could look like stars in the sextant sight, so there was discussion about separating the two to ensure there was no interference.

Once again, radiation dosimeter readings were given:

CDR: "For your friendly man on the left, my dosimeter reads 26021."

LMP: "Okay Charlie. Mine is 15030."

"And mine is 05027."

NOTE: Each dosimeter was started at a random number. The figures do not indicate the total dose received during the flight.

Tom Stafford even commented at 21 hrs 46 min GET:

CDR: "These are very small numbers."

CAPCOM: "Roger. It's pretty early."

The crew were then read the news items of the day. These included their own historic flight, Leonard Bernstein leaving the New York Philharmonic Orchestra, sports news, the daily horoscope, and news of a Siamese cat in Vancouver, Washington who was raising three orphaned skunks!

What were the crew horoscopes?

Tom Stafford (CDR): You should concentrate on things already started. Today's pace will be moderate; use this time to take inventory.

John Young (CMP): You will have a slow day today. This will give you time to concentrate on the work ahead. You will enjoy your surroundings and companions.

Gene Cernan (LMP): Give careful thought to your working and driving habits. Do something nice for your friends.

NOTE: The origin of these horoscopes is not mentioned!

Tom Stafford then reported how he received a highly chlorinated slug of water, when his crewmates drinks had been fine. There was discussion as to the reason

for this and a resolution found. Houston asked them to also clear the water lines before mixing the water with their (dehydrated) food. Despite this, the

crew were obviously in good spirits. At 23 hrs 5 mins GET, they gave a serenade to Houston: a pre-recorded tape of the crew singing "Up, up and away!"

(Australians might recognise that tune from the old TAA commercials. Yes, I'm showing my age).

Gene joked: "We had trouble stowing the bass drum aboard, but other than that it came out pretty well!"

They were not asked for an encore. Then at 25 hrs and 58 mins, the crew report the first sighting of the Moon. At 26 hrs 32 min GET, a small midcourse correction was made. The crew then commenced another TV transmission, showing life aboard the spacecraft. Shortly after, Houston reported that the spacecraft had passed the midway point and that based on current projections, no further mid-course corrections would be required before LOI (Lunar Orbital Insertion, the rocket burn to change them from a free return trajectory around the Moon into a lunar orbit.)

When reporting that his meal tasted like a chicken salad sandwich - which it was meant to be - Gene made mention of a "corned beef sandwich". This was in reference to Gemini 3, where John Young (aboard Apollo 10) pulled out a genuine corned beef sandwich and offered a bite to the spacecraft commander Gus Grissom. The sandwich came from the astronauts favourite deli, called "Wolfies". The incident initiated various negative comments from a number of sources,
but the "contraband" was actually approved by Chief Astronaut Deke Slayton.

Finally, the crew reported medical and radiation dosimeter status, and once again closed their eyes in the blanket of space. At 1 day, 9 hours and 51 minutes, Houston wished the crew a good night.

Obviousman20 May 69

The crew started their day, again reporting an excellent night's sleep. Houston had been monitoring the spacecraft systems overnight, and reported to them that systems in both the CSM and LM look to be in good shape, something the crew would be pleased to hear. At 154 221 miles from the Earth and moving at 3853 feet per second, Apollo 10 was still almost perfectly on the planned trajectory, and the next mid-course correction was canceled. Amongst the news items passed up to the crew was the report of Ogalala Sioux Chief Winnie Red Fox, of Philadelphia. He requested that the astronauts leave the man in the Moon alone as it was ruining the rainfall.

"It doesn't seems to rain much anymore since man started messing around with the Moon" he said.

Houston discussed minor problems with the onboard sextant, but apart from this the only items were the fibreglass from the initial docking and air bubbles in the drinking water system.

Forty seven hours into the flight, and there was another TV broadcast back to Earth. This was not a live broadcast as such, but a test transmission prior to a broadcast later in the day. The transmission was recorded at the Madrid ground station and watched by NASA later. The later broadcast would be sent through the Goldstone ground receiving station.

Meanwhile, the crew gave descriptions of the Earth, both seen through the naked eye and through the sextants small magnifying monocular lens. LMP Gene Cernan even reported seeing light reflected of the discarded S-IV-B stage nearly 4000 miles away.

Houston also passed up some changes to the LM operational procedures, which caused concern amongst the crew. After discussion with Houston about the changes and the rationale behind them, Tom Stafford was satisfied with the intent and execution of the changes.

At 52 hr 15 min GET, Apollo 10 did another overboard waste water dump and the crew waited to see if the water - which would freeze into ice crystals and reflect light - could be seen through Earth-based telescopes.

So overall it seemed that it was a pretty lazy trip to the Moon... but John Young wanted to dismiss that notion:

53 hrs 49 min GET

CMP: "Okay. It may sound like we've been loafing for the past couple of days, but we haven't. We've been real busy, and every spare minute we get we study our flight plan. So you see that pretty soon we're going to be going into orbit, and we'll have a completely different set of operations to go into that shows our pitch profile all around the Moon, for the first revolution. Tomorrows a big day, and we're very much looking forward to it. Even though we're about 180 000 miles away from Earth, you never get away from studying."

The day finished off with systems status reports, initiating the PTC roll, and preparing for the next day's activities: going into lunar orbit and preparing Snoopy for a flight to the Moon.

Obviousman21 May 69

69 hrs 57 min GET. The crew are awoken to Barbra Streisand singing "On a clear day" from the popular 1970 movie of the same name. John Young, who along with Gene Cernan were Navy officers (Stafford was Air Force) - gave a Navy wakeup call to the rest of the crew:

CMP: "Reveille! Reveille! Up all hands, heave out, trice up, clean sweep down fore and aft!"

Shortly afterwards, though, Apollo 10 lost communications with Houston. For nearly 5 minutes, Apollo 10 and Houston called but neither hearing the other.

Eventually a technician from the Madrid ground station was able to talk to the CSM, with Houston joining in shortly afterwards. There is absolutely no truth to the rumour that Barbra Streisand's singing caused the spacecraft radios to fail. The crew were then given a number of flight plan updates, one of which was yet another cancellation of a mid-course correction; Charlie Brown and Snoopy were sailing down the middle of the road. The lack of mid-course burns had another effect: the firing of the SPS engine for Lunar Orbit Insertion (LOI) would be done 11 minutes later than originally planned. This also meant that all of the orbital activities would also be delayed by 11 minutes.

The crew were then read the latest news - including the sports roundup. LMP Gene Cernan had some questions about the results:

LMP: "What was the name of that town up north?"

CAPCOM: "Let's see.. C-H-I...Chicago. Chicago."

LMP: "Oh yes - I was looking at it yesterday. I saw them out there practicing. Speaking of Chicago, did the Cubs play ball?"

CAPCOM: "Hmm - I don't have them listed, Gene; do they play ball?"

LMP: "Oh you're bad, you're really bad..."

Final preparations were then made for lunar orbit. Three days, three hours, and fifty minutes after launch, Apollo 10 began its first orbit of the Moon. If the crew were to do nothing further, they would swing around the far side of the Moon and then 'slingshot' back towards the Earth. This was known as a 'free return' trajectory, designed so that if there were a failure of the SPS engine, the spacecraft stack would simply swing around the Moon and be on the correct path to return them to Earth. This though, was not the plan. In order to enter an orbit around the Moon, the big SPS engine need to fire - or burn - twice. The first would slow the spacecraft down and place it into an elliptical orbit around the Moon. The second burn would then change the orbit to an almost circular orbit. Since the Moon itself was moving in orbit around the Earth, each day a further small burn would be required to keep the orbit circular (or nearly circular).

The mechanics of spaceflight meant the first burn of the SPS engine would occur when Apollo 10 was behind the Moon... and thus out of contact with the Earth. The controllers on Earth could only tell if the burn had been successful by being told by the crew - or by the time the crew made re-contact with the Earth. If all went well, Apollo 10 would appear from behind the Moon at a pre-determined time and regain contact with Earth. If the engine did not fire, then the spacecraft would still be traveling at a higher speed and therefore re-appear from behind the Moon much earlier than expected.

Mission control waited, wondering if the burn had been "nominal" - as engineers were prone to say. The moment approached... then passed, with no contact from the spacecraft. They now knew the engine had fired... but had it fired with the correct thrust, for the correct length of time? The spacecraft could appear at any time. If it was earlier than the predicted time, then rapid calculations would be needed to determine the corrections required. Of course, if they
were to off the planned time it meant that the engine did not produce the planned thrust, or did not burn for the required time. In either case, investigation as to why would be needed.

At 76 hrs 24 mins, Houston heard:

CDR: "Roger Houston, Apollo 10. You can tell the world that we have arrived!"

The timing was perfect. The crew immediately began to report their visual observations of the lunar surface, particularly of one spot: Site 1, the first of three possible sites for the first lunar landing. They began taking numerous photographs of the surface. The LMP also reported that the fibreglass (actually Mylar) residue was continuing to be a problem. The day ended with the crew continuing to prepare the two spacecraft for the challenges of the following day.

Obviousman22 May 69

The days started with the crew still conducting system checks from the previous day; they were grateful for the rest they got prior to lunar orbit. There were tasks to be finished before resting, though. Gene referred to the 'snow' in the spacecraft: the debris from the hatch when they originally docked with the LM. He was still in good spirits, though:

84 hrs 42 min GET (Revolution 5 of the Moon)

LMP: "I didn't have to worry about inhaling it; I ate my way through it!"

LMP: "That should be a space first: snow on the Moon!"

Gene continued with reports of the Lunar Module's 'state of health'.

84 hrs 46 min GET

LMP: "Okay. When I deactivated the COMM and shut down APS, battery 1, 2, 3, and 4 had 37.8 volts. I don't know how that's possible, unless I misread it. And the commander's bus and the LM's bus are at 72.2."

CAPCOM: "Okay, we understand."

LMP: "That's not possible, is it?"

CAPCOM: "Roger. Everybody is shaking their head yes, Ed."

LMP: "The names Gene, Joe."

CAPCOM: "Okay Bill!"

They continued the spacecraft housekeeping duties, gave radiation dosimeter readings and medical reports, and then settled down to sleep.

85 hrs 35 min GET

CAPCOM: "You did a good job today, and have a big day tomorrow, so Deke says let's go to sleep."
(Deke Slayton was the Chief Astronaut)

CDR: "Yes, we concur that. We're just getting a little bushed up here, and we're just about to turn in and fix breakfast."


During lunar revolution 8 and after about 7 hours of rest, the crew were awakened for their big day. This day was the reason they had sent, and would determine if the next lunar mission would be landing or not.

93 hrs 50 min GET - Begin lunar revolution 10

Despite some communication problems between Charlie Brown, Snoopy and Houston, preparations continued for Snoopy's solo flight. Snoopy's systems were activated, checked, and double checked. Everything looked good with the LM in terrific shape. Then the first of the problems began to appear...

In preparation for the separation of Charlie Brown (the CSM) and Snoopy (the LM), the tunnel between the two needed to be sealed and vented; but the tunnel would not vent. Houston worked on the problem whilst checks proceeded, and a modified procedure developed. After testing the pressure of the tunnel, it was decided that there was no major problem and that the two spacecraft could still be undocked with the tunnel pressurised to 3.5 PSI. The undocking, however, would occur behind the Moon and out of contact with Houston.

At 98 hrs 11 min GET, the spacecraft successfully separated. Snoopy maneuvered around the CSM, allowing John Young to visually inspect the LM. All appeared well and so the LM prepared for the DOI - the Descent Orbital Insertion burn. The DOI would allow the LM to start the descent towards the lunar surface.

While Snoopy headed towards the surface, John Young in the CSM would keep close watch on Snoopy, ready to swoop down and rendezvous with the LM if a problem occurred and the LM could not return to a higher orbit to dock with the CSM.

The next problem was the signal from the CSM, which would allow the LM to home on it. Even though they were only 1000 feet apart, the LM could not detect the CSM's transponder signal. Without that signal, the descent was a definite NO-GO. The crew recycled systems and the LM picked up the signal. Once again they were ready. At last Houston told Snoopy that they were GO for DOI. The LM fired the Descent Propulsion System (DPS) and commenced its descent to 50,000 feet above the Moon whilst the CSM remained in an about a 60 nautical miles orbit.

Some involved in the lunar programme questioned the necessity of a dress rehearsal for a lunar landing. After all, why take the risk of sending a crew almost to the surface and then telling them to come home? If you accepted that much risk, why not go a step further and actually land? There were a couple of reasons for this. Firstly, NASA wanted to test the systems in lunar orbit, where conditions might be a little different. Although there were simulations, controllers had to get used to the time delay in - and problems with - communications. The major reason, though, was the LM itself. The most critical factor for the LM was weight. In fact, Grumman - the LM builders - received a bonus payment for shaving ounces off the LM weight. Snoopy, or LM number 4 as Grumman knew it, had been part of the weight saving programme but it was not quite light enough. The fuel required for a landing left insufficient reserves for NASA's liking. Risk was part of spaceflight, but this risk was not justified. LM5 on Apollo 11 would be light enough to make a landing; in the meantime Snoopy would have to be content with paving most of the way. Although 50,000 feet sounds high, there were mountains on the Moon that extended up to nearly 20,000 feet. LMP Gene Cernan certainly believed that they were very close:

LMP: "We is GO and we is down among them Charlie!"

CDR: "Also Charlie, it looks like we're getting so close all you have to do is put your tail wheel down and you're there."

The LM tested the landing procedures and systems such as the landing radar, which would give the spacecraft an accurate height above the surface. All these procedures would be vital in conducting a successful lunar landing. So far, everything was working well; the only problem occurred with the camera, where a film pack jammed and a battery camera went dead. The next major event would be the staging or separation of the descent and ascent stages. This would not only simulate an aborted approach to the surface, but also the liftoff from the Moon after a lunar exploration mission was complete. Snoopy prepared for staging...

102 hrs 44 min GET

LMP: "...We'll do it this way. You ready? okay... SON OF A BITCH!"

The LM began to spin wildly, apparently out of control.

LMP: "Okay! Lets... let's make this burn on AGS (the Abort Guidance System), babe. Make this burn on the AGS!"

CDR: "Got a good staging. Let's make it on the AGS... get into gimbal lock? She didn't go... got a good stage.. somethings wrong with that gyro..."

CAPCOM: "Snoop, Houston. We show you close to gimal lock!"

The crew regained control, the descent stage having being jettisoned.

CDR: "Yes. Something went wild during that staging but we're all set. We didn't lock it..."

Part of the test routine was to test the AGS. It had two modes: AUTO and ATTITUDE HOLD. In AUTO, the system would start searching for the CSM and try to rendezvous with it. Since the CSM was on the other side of the Moon at the moment, this is not what you wanted. Instead, the AGS would be in ATTITUDE HOLD.

During the preparations for the staging the AGS mode switch had been set to ATTITUDE HOLD, but the other crewman set it into AUTO, thinking they were moving it from AUTO back into the correct mode. When in the incorrect mode, the LM was surging towards the lunar surface. If the problem had not been corrected within 30 seconds of when it was, the LM would have crashed into the lunar surface.

(Note: A collector bought the original Apollo 10 checklist from Gene Cernan; on it it shows instructions to place the AGS mode control to AUTO)

The emergency averted, Snoopy's ascent stage completed the rendezvous with Charlie Brown. The CSM docked with Snoopy, and the LM crew transferred back into Charlie Brown. The day ended with activities prior to sleep.

Obviousman23 May 69

With all the Apollo 10 crew now back in the CM, it was time to cast Snoopy adrift. The LM ascent stage would have its ascent engine started by remote control and run until depletion. This would provide valuable engineering data on engine performance. The engine burnt for 249 seconds and Snoopy was launched into a heliocentric orbit about the Sun. Of note, Snoopy is the only one of the flown LMs that survived. The others either burnt up in Earth orbit, or crashed into the lunar surface (this was done deliberately for some, to provide data for the seismic sensors on the lunar surface). The crew farewelled their spacecraft.

108 hrs 56 min GET

LMP: "Is he really going to the Sun?"

CAPCOM: "Well, he's going in that general direction."

LMP: "God, I feel sorta bad about that, because he's a pretty nice guy; he treated us well today."

As they passed behind the Moon on their 18th orbit, they packed away the spacesuits they had been wearing and squared away the cabin. The crew was tired after a long and busy day.

110 hrs 20 min GET

LMP: "And the crew status is tired, and happy, and hungry, and thirsty, and horny, and all those other things."

CAPCOM: "Roger, we copy everything, and we've got solutions or pills for everything except item 4 [sic]."

Houston informed the crew that they would be given an additional four hours of sleep time, given them about 11 hours. Final flight plan changes were made, and the crew settled down to sleep.

When Houston called to wake the crew, they had already been awake for some time, getting an early start on the day. They were updated on their orbital parameters and told that Snoopy was now 23,000 miles away. Gene Cernan had an extensive consultation with Houston regarding the Hasselblad camera. He discussed how there were circumstances when the film pack appeared to jam, and then lens could not be removed. This was the same condition that had happened the previous day, when he reported that the camera batteries had died and / or the camera had malfunctioned. The cameras were very important to the mission; part of the Apollo 10 tasks were to take numerous photographs of the lunar surface, to further help with the selection of landing sites.

There was also the continuing problem of the Mylar "snow", this time from part of the LM's insulating blanket. Although the LM was gone, the Mylar remained. The problems on Apollo 10 lead to the insulation being removed from the tunnel hatches of future CMs, and modification being made to the insulating blankets of LM5 and beyond. There were no further problems with the Mylar on future missions.

The CAPCOM brought the crew up to date with the latest news and sports, and of course... the horoscopes:

John Young (CMP) - Keep all operations above board. Confidential transactions are apt to blow up later with considerable embarrassment to all. Travel is better postponed; the people you would go to see are not yet set for the visit.

Tom Stafford (CDR) - Your natural tendency for moderate, sparse consumption serves you well. Your system is a little more sensitive to strange foods.

Gene Cernan (LMP) - Conditions are bewildering. There are so many odd and unfamiliar details. Just curb your impatience; question everything and put things into place, one at a time.

The photographs of the lunar surface continued, and preparations were made for a return to Earth. On the 26th orbit, after the spacecraft had passed behind the Moon, Apollo 10 came back with an interesting report. They saw a star they couldn't identify. They then realised it was in orbit with them. Eventually, they passed close enough to see it through sextant monocular and saw... the descent stage of Snoopy, left behind after staging. It would eventually crash into the lunar surface, but for the moment it was in orbit around the Moon.

A short day, and the crew once more entered a rest period before the following day's TEI burn; the Trans Earth Injection, the firing of the SPS that would propel Apollo 10 on its way back to Earth. If the SPS engine did not fire, however, Apollo 10 would remain in orbit around the Moon with no chance of rescue.

Obviousman24 May 69

131 hrs 59 min GET - Rev 29

The crew continued with the normal mission updates, including yet another report of the LM descent stage below them, tumbling end over end. Tom Stafford asked the FIDO (Flight Dynamics Officer) to once again examine the trajectory, to make sure there was no possibility of collision.

132 hrs 17 min GET

CDR: "Seeing what I saw, John, yesterday - but we sure don't like being around here playing footsy with that rascal."

CAPCOM: "Roger that. You treated him so bad on staging, he's out to get you."

They continued to take photographs of the Moon, discuss the position the LM descent stage, and report problems with spacecraft. They were taking so many photographs that they were nearly out of colour film. They still wanted to save some fir the voyage home, though.

One of the problems was fuel cell No2, whose exhaust temperature was going up and down, causing the spacecraft MASTER ALARM to sound about every 5 mins. They weren't overly concerned about the fuel cell, but they could not afford to ignore an alarm, thinking it was the fluctuating fuel cell. The fuel cells were also responsible for spacecraft power, taking hydrogen and oxygen and mixing them together, giving electricity and water as the products. If one fuel cell was not operating correctly, a revision of the spacecraft power configuration for the TEI burn might be called for. Fuel cell No1 had a problem earlier, overheating and was kept functioning by disconnecting it when temperature limits were reached. Also, the waste water from No1 fuel cell could not be properly removed, and would shorten the fuel cell's useful life. For the moment, however, it was producing the required power. The No2 fuel cell later settled down, and things looked good for a nominal burn. Houston would continue to monitor the fuel cell problems. Later ground analysis would show the No1 fuel cell problems were caused by an extended hydrogen purge, and this procedure was dropped from future flights. The problem with the No2 fuel cell was not confirmed, although similar behaviour had been seen.

Final instructions were passed, and Apollo 10 passed behind the Moon on its 32nd orbit. The TEI - Trans Earth Injection - burn would take place behind the Moon. Houston waited for the expected AOS - Acquisition of Signal time.

At the appointed time, contact with the spacecraft was regained, and the crew reported a good burn; they were on their way home. Another TV broadcast was done, showing the Moon as Charlie Brown sped away.

137 hrs 50 min GET

CDR: "Houston, 10. I hope the Aussies have their sets tuned in because it's absolutely fantastic here."

CAPCOM: "Roger that Tom, I'm sure they're all watching."

The crew continued to make reports about the appearance of the Moon as they sped away at about 6000 feet per second. They began the PTC roll, and commenced the pre-sleep checklist. CDR Tom Stafford reported that all the crew were very tired, having been awake for over 22 hours. Now that the TEI burn had been successfully conducted, and systems check, all they wanted to do was sleep.


After an all too brief 6 hour sleep, the crew of Apollo 10 was again awakened. While the crew were asleep, the spacecraft had stopped decelerating. The spacecraft had now slowed during the flight, but now at 187 300 miles away from the Earth, they began to accelerate again and were traveling at 4800 feet per second, and on course. The first planned mid-course correction was canceled.

As always, the latest news was passed to the crew: Thor Heyerdahl was leaving Morocco to cross the Atlantic aboard the Ra, a craft built of papyrus and based on designs from ancient Egypt. The Houston Astros baseball team beat the New York Mets, 7 to 0, with pitcher Tom Griffin striking out 13 batters. Boxer George Foreman signed up a manager and would make his professional debut as a boxer at Madison Square Garden in June. And the horoscopes?

LMP - Discussion fills much of the morning, and you'll learn a great deal that would never have come to your attention. That is, if you listen well.

CMP - Keep your attention focused on your own affairs Saturday. The necessary chores are quite enough for the time being, and leave the thrills for another time and place.

CDR - Problems tend to get out of hand, and logic is not quite enough. There is nothing to do but ride it out with a certain amount of leniency.

This was followed by another TV broadcast, where the crew explained that the spacecraft axis was actually aligned about 90 degrees to the direction of travel. They showed images of the Earth and the Moon as each passed by the spacecraft windows. The ground also had a procedure to rid the food bags of air bubbles, a problem which occurred when they added water:

147 hrs 54 min GET

LMP: "Go ahead with your procedure there, over."

CAPCOM: "Well good. I don't know if you wanted that or not. First off it's quite lengthy. It's a full page. I'll try to go through it slowly, and then we can talk it through and ask some questions. First off, fill the entire bag, both top compartment and bottom compartment, about half full of water. Then work the water and the gas to the lower compartment by either spinning it or by just kneading it down. Then after you get it all in the bottom, spin it up and then let it come to rest slowly; and if possible, squeeze the gas - if you have any gas in the upper compartment - squeeze the gas out of the upper compartment. Then, if the bubble is present in the lower compartment and top compartment is empty, add some more water to the approximate size of the bubble. Then you want to spin it again, as in step - well, as in step 3. Now, after you spin it up again, you should have gas in the top or partially gas in the top, and gas and water in the bottom, and repeat the procedure. Add more water to the approximate bubble size and spin it again. And by the time you get finished, you should have all the gas in the top and - compartment that is, and then the bottom compartment should be just about full of water. Now, if you fill it too full, so you've got the bottom full of water and the top full of water - partially full of water, then the only way you can get the bubble out of there then is to squeeze out the bubble and the water in the top compartment. The object is to get the bottom compartment completely full of water and the gas in the top compartment, and then you can vent it off by pinching off the lower compartment. If that sounds reasonable to you guys, you can try it. It's going to take a lot of spinning, but that's what they recommend in the back room after 3 days. Over."

LMP: "Hey Charlie. With all due respect, would you play back Glynn's tape recorder in there on his desk and listen to yourself, and then give us a call?"

CAPCOM: "Okay, I guess you couldn't understand that."

LMP: "No, we understood it."

CAPCOM: (Laughing) "I told you, you might not want this!"

LMP: "Listen babe, I'm glad that's all we've got to worry about at the moment!"

For the next 15 minutes, the crew tried the procedure without success. They eventually gave up. Spacecraft commander Tom Stafford then discussed the staging problem they had with the LM, recognising they had accidentally put the mode switch into the wrong position. There was also some initial debriefing about the performance of the LM's steerable antennas.

At 152 hrs 21 min GET, Apollo 10 was 168 375 nautical miles from the Earth, and speeding along at 5000 feet per second. Yet another TV broadcast, yet more medical and radiation reports, and the crew prepared for sleep. In two days they would be home.

Obviousman(I'll combine the days until the end of the flight, as I'll be away for the next couple of days)

25 May 69

Today was a day with a twist: the crew of Apollo 10 gave a wakeup call to Houston! First was the song "Come fly with me" followed by a chipper and DJ-like "Geno" Cernan:

162 hrs 54 min GET

LMP: "Good morning, good morning! This is Tom, John and Gene from WAP-10, broadcasting again from approximately 140,000 miles out into the universe. It's a beautiful day out here, and it appears that it might be a beautiful day down in Mother Earth country. For those of you who are not just ready for work or are just getting up: GET UP LAZY BONES! It's time you got up! A big day ahead! And the thought for the day is: Remember - National Secretary's Week was last month!"

CAPCOM: "Good morning Apollo 10! You managed to wake everyone up early down here, and thank you for your brief program. And we'll be giving your advice due consideration down here. And we've got a little bit of music for you..."

(Plays: Zippity Do Dah)

(Applause from spacecraft)

CAPCOM: "Roger. Thank you for the applause. And watch out for migratory bird season!"

LMP: "That was a couple of seals up here."

CAPCOM: "You might have recognized Deke Slayton, as solo, on that song we just sent up, 10"

(Deke Slayton was the Chief Astronaut, often referred to - by the astronauts and not in his presence - as "Mother Slayton". He was a primary force in crew assignments)

CDR: "Roger."

LMP: "If he's eating that food, he's zippity-do-dahed all right!"

As per normal - and looked forward to every day by the Apollo 10 crew - was the horoscope:

LMP - This Sunday may find you in some quandary over home conditions. There should be some help available. Don't make smart remarks about Marines.

(Gene had been making jokes about Marines to CAPCOM Jack Lousma during the flight. Jack subsequently flew on Skylab 3 and shuttle mission STS-3)

CMP - Your money has to be spent today on institutions and the use of them for various purposes. Take the time to check everything out before doing anything drastic. Finding out the "why" in a situation may be more important than any other determination.

CDR - Your relatives and neighbours expect to see you this Sunday. Do the amenities gratefully. Make the rounds; there are gifts for you here and there. Then seek solitude. Reprimand all those in your command who make smart remarks about Marines.

This was followed by the news, and updates on the weather in the recovery area. The weather would be the determining factor; there was a prime recovery area chosen, but NASA had to have contingency plans in case the weather was unsuitable. This meant an additional 2 or 3 areas, each requiring a suitable recovery force of US Navy ships and aircraft.

At 164 hrs 33 min GET, Apollo 10 was about 130,000 miles from the Earth and travelling at a speed of 5700 feet per second. Their course (with a mid-course correction) put them on a re-entry angle of 6.52 degrees, almost exactly in the middle of their corridor. The "nominal" corridor was between 5.4 and 7.4 degrees. (Even without a mid-course correction, they were headed for an angle of 6.95 degrees).

The flight continued with the day-to-day routine of spaceflight: reports on radiation, oxygen and fuel remaining, flight plan updates or corrections, and word of the "unemployed philosopher", who continually gave his (or her) update on the effect of Apollo 10's colour television broadcast on the world. This wavered between a return to B&W television because of the crew's appearance, through to the current report: colour TV was making a comeback. It would make a real splash around here soon! The crew also reported that a new fangled invention called 'shaving' was working well aboard the spacecraft, and they all expected to look good upon splashdown.... but did they?

The crew concentrated on discussing spacecraft performance reports, and passing visual reports of the Earth. Because of the important re-entry to Earth's atmosphere, the crew asked for an early wake-up call... and an order of bacon & eggs. What's a CAPCOM to do?

At 177 hrs 18 min GET, Deke Slayton came on the comm channel to quickly talk to the crew before the crew slept for the final night in space. At 177 hrs and 50 min, the crew said goodnight and went to sleep.

26 May 69

A little over 6 hours later, the crew of Apollo 10 was awakened with a bugle call. Today, the return to Earth would be a big day. Firstly, the course of the spacecraft would be checked. Too shallow and it would bounce off the atmosphere, with no hope of recovery. Too deep and the capsule would go through excessive heating, burning up the capsule despite the heatshield.

After the Service Module (SM) had been jettisoned, the Command Module (CM) would only have very limited ability to change course. There was only a corridor of 2 degrees for a safe re-entry.

The capsule would enter the atmosphere, slowing down and generating tremendous amounts of heats. A little know fact was that the CM would then actually change its attitude and climb, further slowing and reducing the heat generated. It would then pitch back towards the Earth and once again re-enter the atmosphere.

Weather reports for the recovery area were discussed. The prime recovery area looked good. Before the re-entry, the crew of Apollo 10 recounted the achievements of the mission.

After 7 days 23 hours and 33 minutes from liftoff, Apollo 10 jettisoned the service module. The CM, no longer connected to the SM fuel cells, had a limited time on its internal batteries. Apollo 10 was on its way home. The spacecraft now started its descent. As they fell, the force of Earth's gravity exerted its force. Last reports were passed: about 2 miles from their target point. Plasma began to envelope the capsule, blocking communications.

Mission control waited anxiously for the first reports, either from the capsule or the helicopter from the recovery force.

8 days, 3 minutes and 25 seconds from launch, Apollo 10 splashed down.

Apollo 10 after splashdown

The crew of Apollo 10 aboard the recovery vessel USS PRINCETON (Young, Cernan, Stafford)
Apart from a minor switch problem with the LM, Apollo 10 was a success. Everything was in place for the next attempt: Apollo 10 was a green light for a lunar landing of Apollo 11. Less than 2 months later, man would be walking on the Moon - or have died trying.
golddogDo you know what is the badge on John Young's right shoulder? It does not appear to be on either Cernan or Stafford's flight suits?

(Thanks to Obviousman, enjoyed greatly reading the accounts.)

ObviousmanThat patch has "NASA MSC" on the bottom, and what looks to be a silhouette of a T-38.

You can see it more clearly in this image.

Originally posted by Obviousman:
LMP - This Sunday may find you in some quandary over home conditions. There should be some help available. Don't make smart remarks about Marines.

(Gene had been making jokes about Marines to CAPCOM Jack Lousma during the flight. Jack subsequently flew on Skylab 3 and shuttle mission STS-3.)

To further flesh out the joke, the prime recovery ship, USS Princeton, was an amphibious assault ship (converted from an aircraft carrier). As part of the "Gator Navy" (and thus conducting operations with Marines a lot of the time), not making smart remarks about them would be especially wise while aboard!
capoetcThis week, during the 45th anniversary of the Apollo 10 mission, I thought it might be worthwhile to post this playlist of CBS news coverage of the Apollo 10 mission. There are 57 parts to the playlist, plus a 58th part which contains ABC's coverage of the Apollo 10 launch.

So, grab some popcorn and absorb the historic news coverage!

moorougeIt's worth pointing out that the '10' crew was the only one where two members went back to the Moon to walk on its surface, whilst one became the only astronaut to fly in the LM twice.

I don't believe that Young took a bra with him on this trip though.

onesmallstepTo give the 'mascots' and LM/CM callsigns of the mission their due, here is an article on an exhibit at the Charles Schulz Museum in California.
Rick Teklits
Originally posted by moorouge:
...the '10' crew was the only one where two members went back to the Moon to walk on its surface
Good points... and those two returned to the moon as mission commanders!

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