Paul Worked At North American Aviation Beginning 1965

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My Career Started Out by Going To The Moon


I always loved space flight but it was Buck Rogers as no one had really done it before.  In High School it was the rage to talk about missiles and satellites but there were no satellites yet!  The all of a sudden we woke up and the Russians were ahead!

Sputnik Was An Awakening

Let's set the stage. Mom, Dad and I laid in the back yard in Los Angeles looking up at the sky in 1957 while listening to the KFWB radio announcer tell us where to look for the first man-made satellite, the Sputnik!  Wow! Space travel in my lifetime! No longer was it a fantasy! It beeped? What was the secret code? Many were scared!

This stupid little device scared the heck out of us!

Sputnik was the first artificial satellite to be put into outer space. Launched into geocentric orbit by the Soviet Union on October 4, 1957, it was the first of a series of satellites collectively known as the Sputnik program.

The unanticipated announcement of Sputnik 1's success precipitated the Sputnik crisis in the United States and ignited the so-called Space Race within the Cold War.

It was scary to think the bad Soviets had something orbiting overhead while we Americans were caught flat-footed with no viable alternative!

We laid on our backs in the early evening with KFWB blaring the direction to look to see this amazing event take place 100  miles above our heads.  I can still see Mom, Dad, and I on the lawn peering up into the heavens.

NY Times
The headlines allover the country was scary!

Space Was The Name Of The Game

All us kids could think about was the space race and missiles and space men!  Science and math took on a new meaning. Everybody wanted to be some kind of an engineer.  All my science projects in school from that day forward dealt with space related activities!  Off to college I went to become an engineer.  It turned out slightly different than I expected but I still was able to contribute to our countries race to the moon.

I Joined The Apollo Program in My Senior Year In College

The Apollo Program
It was the most magnificent activity I could have ever
 had the pleasure of working on

I leapt at the chance to go to work on Apollo Program doing anything!    It's easy to write about this part as I am just now ending a forty-four year run with the Boeing Company.  I started with North American Aviation on the Apollo Program in 1965.

In all history, there has never been a prouder, bolder, or more demanding human effort than this nation's program to land men on the face of the moon. In its simplest terms, it is a plan to send three men in a tub farther from home than men have ever been, and then to bring them back to tell the story. But it is also a giant stride in the stretching of human horizons, achievement, and knowledge, a proud new spire on the human Tower of Babel.

The leap through space is at least five years away, but it has already captured the world's imagination - and it is already a national effort comparable to the building of Egypt's pyramids. For the conquest of the moon must be fought on earth, and it is only possible through a near-miracle of engineering and production.

Almost casually, the United States decided to spend more than $20 billion to reach the moon - enough to pay for all the houses built in the country last year. Project Apollo at its height will occupy more than 300,000 workers, enough to man the entire crude-oil industry. And 20,000 companies, in all 50 states, have joined in a tangled skein of contracts and subcontracts to design and produce the space ship for the National Aeronautics and Space Administration.

$3.19/Hour Was Big Money And I Had To Join The Union

Dang!  $3.19/hour for working in the space factory testing control panels for the Apollo Command Module was a lot of money!  I worked several months in the Manufacturing organization running Acceptance Test Procedures on the control panels astronauts would use to guide the Command Module to the moon.  I had never been in a union before and I will never again.  The people around me operated in slow motion with little regard or understanding of emergencies.

I remember one day we had a "hot job" come through and the engineer even came down to see if he could do anything to help.  It became 4:00PM which was quitting time but we only had a little more to do to finish the job, say 30 minutes.  The people around me dropped everything like a hot potato at 3:30 and began to "clean up" to go home.  I kind of did the same thing and at 4:00PM they ran out of the building literally.  I clocked out, came back the laboratory, finished the job in about 45 minutes, and moved it to the next station thinking I did something good.

The next morning I had every union weenie in the house yelling at me, cussing and threatening me for working to complete the job.  I was stunned and amazed at the attitudes of these people.  Later that day the engineer came down during the break, found me, and thanked me over and over for helping him keep the schedule.

Obviously I wanted out of the union as these were NOT by kind of people!

NAA President's office
The President's office was the rounded upstairs office area

I Looked For Other Opportunities

The company was so short of engineers that I applied in the Apollo Test & Operation group (called amazingly enough "ATO").  My friend the engineer pointed me to this group.

Bill "Hutch" Hutchinson, Power Distribution Chief Took A Risk And Hired Me

To be an "engineer" you needed and engineering degree.  I met Hutch and he interviewed me asking about troubleshooting, etc.  My experience with Ham Radio kicked in and Hutch was amazed.  He plopped down a schematic of the Apollo power system and pointed to a line on the drawing and said "What happens when this line breaks?"

I mentally traced the circuit  finding out that if power was lost, a relay would trip and another circuit would be brought on line.  I explained how it worked and he again was amazed. I was hired  to assist the engineers do testing and troubleshooting on the space vehicle.   My knack for troubleshooting  (finding out what was wrong through the use of logic and deduction while progressing through a pre-developed plan) was appreciated by the older engineers and I soon became one of the group even though I predated most of them by twenty years. 

I Met Ralph Raming In The Graveyard

Soon afterwards, since I was the young one and was still going to school, I was asked to go on graveyard. Most people would have said "No!".  Not me as graveyard meant working six and a half hours for eight hours pay.  The differential was supposed to make up for the terrible hours.  When testing was at a lull (we often had to wait for the union workers to saunter over and get tools) I was able to study for the next days class!  I always had my books with me in a bog old leather briefcase.

I went to school, I left USC at 10:00 PM and drove down the freeway to Downey checking in at 10:30 which was an hour early.  I would go to work learning what the evening shift had dome.  I'd clock in at midnight..  We worked all night as the plant was on a 24/7 schedule to get to the moon.  I would clock off at 6:30 and stay around until we handed off to the day shift usually around 7:30 and then drove back to USC to go to school from 8:00 until sometime mid-afternoon.  Sleep, study, eat and off to work again!

Went we went on twelve hour shifts, I would leave USC at 4:00 PM, check in at 5:00 PM and work all night until 5:30 the next morning.  Then I would leave for school, sleep in my car until the first class and repeat the steps the next day!

I Lived On Sam's Famous Steak Sandwiches And Submarines

Along Lakewood Boulevard in Lakewood there were two great places to eat.  Sam's and the Sub Shop (the name I now forget).  I'd often slip out at 9:00 PM and go get steak sandwiches or subs for the guys coming back with 20 or so sandwiches.  This was neat because the guys would buy my dinner for doing the ordering and pickup.  Great for a poor college boy!

The Apollo Fire Occurred In The Evening While I Was At Work

On January 27, 1967, tragedy struck the Apollo program when a flash fire occurred in command module 012 during a launch pad test of the Apollo/Saturn space vehicle being prepared for the first piloted flight, the AS-204 mission. Three astronauts, Lt. Col. Virgil I. Grissom, a veteran of Mercury and Gemini missions; Lt. Col. Edward H. White, the astronaut who had performed the first United States extravehicular activity during the Gemini program; and Roger B. Chaffee, an astronaut preparing for his first space flight, died in this tragic accident.

We in Downey were in terrible grief.  We knew and worked along side these guys when they came to Downey to test their spacecraft. The initial Apollo manned flight with the modified Block II spacecraft is scheduled for launch by an up rated Saturn I vehicle during the third or fourth quarter of calendar 1968, some 17 or 18 months after the scheduled launch of Apollo 204 in February 1967.

During the down-time while the next vehicle was being redesigned, they had to keep the testers bust and we reviewed schematics, specifications, and did many other engineering tasks.  This was a great period of learning for me and used the time wisely.  I read and studied the Stabilization and Control System (SCS) and Guidance and Navigation (G&N) specifications with vigor!

In short I was young enough to be able to absorb and retain an amazing amount of information of the systems that made up Apollo!

Wild Man Llorente Nearly Sunk My Career

2TV1 Space Chamber
2TV-1 inside the thermal vacuum chamber

It was late at night and all of a sudden this wild eyed Pilipino named Dave Llorente appeared at my desk!  He was official looking and wore a black badge, the Holy Grail of the common engineer. He was senior management!  He explained to me that he was the Project Engineer for 2TV-1, our thermal vacuum test vehicle that was due to ship out in the next few days to Houston.

He carefully explained that he needed to have 10 wires from the Caution and Warning  (C&W)system cut, capped, and stowed.  The reason was simple, inside the thermal vacuum chamber at Houston, the C&W would be continually going off unless these were stowed.  Further, if we did not cut, cap, and stow them now, Houston would have to rip the panels apart, do the work, and retest everything again... loosing several days or weeks schedule.  Dang, made sense to me.

Dave Llorente
Dave Llorente's now live in Texas

Dave told me "You will be covered, I will write the engineering authorization tomorrow morning at Houston and fax them in".  Geez, sounds like the guy is real.  So I did write out a Test Preparations Sheet (TPS) calling our the cut, cap, and stow procedures for these wires.  Testing was slow that evening and the panel was out already so the work was one within a few hours.  I went home to sleep.

Buss, ring-ring-ring went the phone.  Quite groggy as I was four hours into what I was expecting to be a good sleep and the bosses bosses boss was on the phone yelling his head off!  Norm Casson,  the Director of Apollo Test & Operations , told me, via my boss, to "get my ass back to work so he could fire me and send my ass home!! 

All the way to work I kept thinking to myself, what did I do!  The s..t  hit the fan when I got in.  I explained the story and they said "Dave who???"  "You don't listen to some Project Engineer you idiot" Blah blah blah.  I called Dave and no answer, oh oh!

However, true to his work Dave Llorente got the engineering authorizations sent in, jumped in the face for Norm Casson (Director of Apollo Test & Operations) and saved my job... making me a small time hero within certain communities of people!

Dave was a man I always looked up to as his word was his bond.  It was an honor to work with him over the years! 

An Email From The Past (After 40+ Years)

From: "Norman Casson"
Date: March 8, 2010 7:30:28 PM PST
To: "Paul Liles"

Subject: RE: David Llorente

Hello Paul:

Thank you for providing me the link to your story regarding Dave Llorente, that incidentally, also included yours truly. I certainly remember Dave Llorente as a fine Project Engineer on 2TV-1, and if it is within your willingness and ability please convey to him my best wishes. Thank you also for bringing back such precious memories of the "glory days" of the nation's lunar landing project. Your mention of the "Test Preparation Sheet" (TPS) brought back to mind many incidents such as this one you cited. I also appreciate your explanation of the true importance of 2TV-1, more specifically, how each ground and flight test actually "set the stage" for each succeeding Apollo mission.
On a more personal note, I do not recall your specific story, most likely only because there were so many engineers (in my area of responsibility), many of whom not only were modifying engineering with Test Preparation Sheets, but were getting the work done before the engineering was released as well.

Since all of this was against the policy of engineering and "APOLLO TEST & OPERATIONS," quite naturally I probably yelled my head off about it. But in reflection Paul, over the past several decades (and I must admit, even back during the actual TPS "violations") I arrived at the conclusion that if you and your fellow young engineers had always waited for the engineering documentation to be released prior to getting the work done, we would never have met president Kennedy's goal of getting man on the moon and returning him safely to earth prior to the end of that decade!
And so I congratulate, praise and thank all of you manned spaceflight engineers for your ingenuity, creativeness, persistence, determination and tenacity ...for it was these ingredients that elevated each of you several steps above average in the field of science and engineering, all-of-which led to the unqualified success of our nations lunar landing program THE APOLLO PROJECT!

In appreciation, I remain,

Norm Casson

I Did A Short Stint With Manufacturing Engineering Operations Under Bill Smith

Late in the night and on weekends which the spacecraft was being built, the shop would need "engineering" to be released to fix problems.  A small group of people were on staff around the clock on off-hours to do just that.  I was recommended for the position because I needed the hours and because of my overall knowledge of the shop operations.  This was a fantastic opportunity as I was writing engineering, albeit fixes to existing designs.  An example might be a technician "nicked" the coating on a wire.  What do you do? Replace it, repair it? How do you repair it?  I would have to write up an MR (Material Review), write up the process to repair the wire, point to the proper specifications and repair parts, get my bosses signature and turn it in to Manufacturing Planning so they could translate it to what the union technicians could understand.  I would monitor the repair and close the MR after the work was done!

After Three Years I Moved To The "Project Office" Under John Montgomery

ATO was good but I was always looking for something else. I was hired to be a Project Engineer by John as he was stretched and he needed someone young to do the running.  John, bless his heart, had little idea of what I could do although he had some recommendations form the guys in ATO.

While the ATO guys gave me an aerospace education (drawings, specifications, policies, procedures, the space vehicle, etc.) John gave me something more important.  He taught me to do it right the first time and think about all the ramifications!  John made me so mad because he wanted to read and internal letter I was going to release.  Damn John, I can write I told him.  He would read one of my works of gold and find so many holes in it I would be on the verge of tears for being so stupid.  To this day, John's peskiness I believe kept me moving forward in my career.  I was also the go-to man for solving problems and understanding the relationship between activities on the program!  One great man.

Apollo CSM
Apollo CSM

The Project Office Gave Me Access To The Leadership Of The Program

I was blessed to meet some of the greatest people I have even known.  Dedicated and intelligent leaders who had a goal and led the 30,000 man operation towards delivering a first class product that took man to the moon.  Here are some of the people:

Dale Myers

Dale Meyers Dale Meyers, (B.S. 1943) was president and chief operating officer of Jacobs Engineering Group, Inc. in Pasadena. He served as undersecretary of the Department of Energy, and as NASA associate administrator with responsibility for the Apollo, Skylab, and Shuttle programs. Prior to that he was corporate vice president of Rockwell International and president of North American Aircraft Operations. Myers has received the NASA and DOE Distinguished Service Awards, and was elected fellow of the AIAA and member of the National Academy of Engineering.

George Jeffs

George Jeffs George Jeffs, (B.S. 1945, M.S. 1948) is president of Rockwell International Corporation's North American Aerospace Operations and vice president of Rockwell. In addition to directing the company's Apollo program, Jeffs has been responsible for the design, engineering, and construction of the Space Shuttle. He has been a leader in the nation's space program since its inception and has received many honors for his work, including the Presidential Medal of Freedom, two NASA Distinguished Public Service Medals, and election to the National Academy of Engineering.

Charlie Helms

What a nice man!  Charlie was a gentleman who always provided smooth guidance and provided stability in the organization. When I met him, he was Manager of Change Project Engineering.  John Montgomery and I worked for Charlie.  One heck of a guy!

Edward Smith

What can you saw about the man who pulled 3,000 engineers into a single team with a goal to get a product defined and out the door.  Ed was truly amazing with a memory of a super computer capable to going into the archives and extracting a single bit of information from years gone by!  Ed ruled with an iron hand and made most of the significant decisions but this required him to be in the plant from 6am to 8pm six days a week and sometimes on Sunday's.  It's too bad we do not have leaders like this today.  The buzzword in the 2000's is delegate and hope for the best.  If Apollo and Shuttle were to have been build this way, we would still be trying to get to the moon.  Ed moved from Apollo to Shuttle and gave the Shuttle engineering staff the same leadership qualities.  He eventually became the Program Manager but I believe he was always a Chief Engineer at heart.  We need more Ed Smith's and a load fewer people who think they can run an engineering organization by remote hands-off hoping it works.  Wherever you are Ed, I'd wish you would come back and teach the new generation of people playing at being a chief engineer how to "chomp cigars" and run an organization!

Charlie Feltz

Charles Feltz
A brilliant country boy!

Charlie was country-wise.  He used his Texas upbringing wisely.  Charlie was bright and knew the Apollo systems like the back of his hand.  He came from Los Angeles Division of North American where he worked on the B-25 and the XR-72 vehicles. 

As Chief Engineer on Apollo he set up an organization that had nearly 20,000 engineers to design something that had never been done before... and he succeeded.  I can remember him strolling through the bays filled with engineers and he knew them by their first name, leaned over the drafting tables and discussed designs in intimate detail!

He created management schemes at North American in the late 1950's that are still used in 2008 at Boeing such as the Master Change Record (MCR), a method of keeping track of changes to complex aerospace vehicles.

He ended up running the Shuttle Program for a while and then moved on into the Corporate Management arena.  HE was called back after retirement many times when they wanted a country boys advice to solve complex problems.  He was one great man!

Donald Nakashima

Don was the Structures Senior Project Engineer for Apollo and Shuttle.  Done lived in West Los Angeles close to EP Smith.  Don was one great guy who knew how to get things done and how to assure the 1000's and 1000's of engineering drawings were released on a schedule that Manufacturing needed.  He was the interface between the big "E" and the big "O".  Engineering and Manufacturing always had some kind of a fight going on.  In retrospect I think it was planned for the benefit of the employees!  Don of course was of Japanese extract and every December 7th we would sneak into the plant in the dead of night and do something to Don's office.  I remember the desk going upside down, drawers getting glued shut, or other such nonsense.  Don expected and looked forward to it as he knew how much we all liked him!

John W. Montgomery

Apollo CSM
The open area in the Service Module
 was where we stuffed the scientific
experiments used on the Moon trips!

John was my second "Supervisor" at North American Aviation and he was a "Senior Project Engineer" for the Apollo J-Series Missions. John was a character so dedicated to his job he sometimes made other a bit angry.  I learned a load from John especially about being forceful, taking the initiative, and doing the job right!

You only came back with the "wrong answer" once or maybe twice with John and after that you would dig out every single piece of data available on any assignment and have that data available!

I wrote my first "Internal Letter" under John's able guidance and even got to sign my name and distribute it!  John read my letters for several months until I understood what "IL's" were all about!

We never became friends outside of work but we did have a respect for one another and over the years we would meet at the most interesting places!

One thing I do remember was a series of very important meetings with RCA on the Lunar Laser Altimeter.  John was to chair the three day long interface negotiations and I was to be there to take notes and get coffee (I'm joking about the coffee).  Anyway, for some reason John did NOT show up on the first two days which was not like John.  We were sitting in the Executive Conference Room in Downey and I took it upon myself to start and run the meeting.  Just like I saw John do many times.  The negotiations went well and we completed the technical meetings on the second day with RCA leaving for the east coast.  I cannot remember why John was gone but on the third day he showed up and asked what happened.  I told him and was instantly "killed" for my actions.  When he called RCA to apologize and set things straight, the RCA Program Manager apparently had accolades for my performance with strong statements about my running of the meeting, obtaining the necessary data, and skills at documenting the results. 

John "promoted" me to the Project Engineer for the Lunar Altimeter experiment! The laser altimeter, when operating independently, gave altitude data at a frequency of three data points per minute when the mapping camera was off and approximately 2.5 points per minute when the camera was on.

The last time I saw John W. Montgomery was on a classified project in 2002 while he was visiting Boeing.  He was getting ready to retire and wherever he is now, "Thanks John for kick starting my career and giving me the true aerospace basics!"

Doc Blosser

He was an old test engineer who was also a ham radio operator so we got along just fine.  Smart man and kind of a person to look up to!  He was in his 60's when I joined the Apollo Program and retired after several additional years on the job.

J-Series Missions

J-Series Missions
Stuffing this section of the Service Module and making it safe for the mission was a
major activity and kept us busy for several years!  Exciting times!.

ACE In The Hole

Acceptance Checkout Equipment
I studied all the training materials until I was considered an expert!

I had all the certificates that were needed to operate the ACE machines in Downey.

Apollo Test And Operations

ATO was the first organization I joined upon entering the engineering group.  I interviewed with Bill Hutchinson, the Chief of electronics testing.  The pecking order was Engineer --> Supervisor --> Manager --> Chief --> Director in those days.  My interview went well and I join ATO in 1965 working the swing shift so I could complete my education.

We did the final testing on the Apollo Command and Service Modules in building 6/290 in Downey.  One of my keys to success was ham radio!  In ham radio you get on the air and talk to people around the world and quite often you must talk in a large group carefully avoiding talking over people and having to remember their call signs and names!  While testing the Apollo we had almost 75 people on a network each with call signs and each having some responsibility to support the test.

As an example, I was SCS (Stabilization And Control) and I would get on the net and say, "CMP, this is SCS. Switch mode to manual".  CMP was the Command Module Pilot and he was sitting in the spacecraft 100 feet away and six stories up and would hear my order and make the switch change.  He would respond with "SCS, this is CMP, mode switch now manual". 

This was natural a natural for me as ham radio gave me years of training!  I rose through that organization fairly fast and because a CTC (Chief Test Conductor) even though I was in my early 20's, I was allowed to direct major tests on the spacecraft!  I remember OCP-0131 which translates to Operational Checkout Procedure #131 which was Integrated Vehicle Test.  It was about 1500 pages of procedures and took three weeks to complete working 24/7!

Black Badge Goes Away

The badges in those days were round and pinned onto your jacket (yes, we all wore coats and ties to work).  For most engineers there was a grey stripe across the badge with the persons name, title and organization on it.  A "black badge" was a member of management and their stripe was black with white writing on it.  I was promoted to a "black badge" and then two weeks later some goofus decided to change out the badges to plastic and get ride of the black badge so as not to make management so obvious. 

The Apollo System

Just amazing!

Apollo was a three-part spacecraft: the command module (CM), the crew's quarters and flight control section; the service module (SM) for the propulsion and spacecraft support systems (when together, the two modules are called CSM); and the lunar module (LM), to take two of the crew to the lunar surface, support them on the Moon, and return them to the CSM in lunar orbit.

The flight mode, lunar orbit rendezvous, was selected in 1962. The boosters for the program were the Saturn IB for Earth orbit flights and the Saturn V for lunar flights. 

I worked on the Command and Service Modules of the Apollo stack! We had almost 30,000 people in Downey working near round the clock to make all the pieces come together.


This was a complex vehicle made up of a million parts that had to be perfect!

Joining The Union Was An Eye-Opener

I had never been in a union before and I had to join when I came into North American Aviation.  I will never do that again!  If you work hard the union weenies get mad and come to see you and request you slow down!  I remember a hot job coming in one afternoon and I did not finish it so I clocked out, came back into the work area and finished it so it would be ready the next morning.  You would have thought I killed the union stewards dog!  That was the most terrible work experience I ever had.  I lasted six months and went into Engineering as a test engineer.

My First Trip

Business Trip My first business trip was exciting for a twenty something and never traveled alone before.  As you may have read above, I worked for John Montgomery and as a result of doing an unexpectedly good job with the RCA Laser Altimeter, John fought and got the OK to send me to the east coast to visit RCA and work out some interface details.  Sending a young "unknown" was just not done in those days but John had fait in me and I went and did a pretty good job.  I remember calling John several times to fill him in on the details.

The Laser Altimeter Experiment was performed on Apollo 15, 16, and 17. In this experiment, a pulse from a laser was aimed at the lunar surface. The reflection of the pulse from the surface was then observed with a small telescope. The length of time the pulse took to travel from the spacecraft to the Moon and back is related to the height of the spacecraft above the surface of the Moon. Measurements were made roughly every 30 kilometers across the Moon's surface. These measurements are sufficiently accurate to distinguish height variations of 10 meters between adjacent measurement points. On Apollo 17, measurements were obtained for a total of 12 orbits

Apollo Lunar Sounder Experiment

I worked the Lunar Sounder experiment and spent a fair amount of time in Canada working with their design on the deployable dipole antenna system.  I also got a chance to go to Goodyear in Litchfield Park Arizona and work our problems with the Optical Recorder device.

Apollo CSM The Apollo Lunar Sounder Experiment was performed on Apollo 17. This experiment used radar to study the Moon's surface and interior. Radar waves with wavelengths between 2 and 60 meters were transmitted through a series of antennas near the back of the Service Module. After the waves were reflected by the Moon, they were received using the same antennas and the data was recorded on film for analysis on Earth. The primary purpose of this experiment was to "see" into the upper 2 kilometers of the Moon's crust in a manner somewhat analogous to using seismic waves to study the internal structure of the Moon. This was possible because very long radar wavelengths were used and because the Moon is very dry, which allowed the radar waves to penetrate much deeper into the Moon than would have been possible if water were present in lunar rocks. (A radar experiment on the space shuttle has been similarly used to map ancient river valleys beneath the Sahara Desert .) This experiment also provided very precise information about the Moon's topography. In addition to studying the Moon, the experiment also measured radio emissions from the Milky Way Galaxy.

This experiment revealed structures beneath the surface in both Mare Crisium and Mare Serenitatis. These layers were observed in several different parts of these basins and are therefore believed to be widespread features. Based on the properties of the reflected radar waves, the structures are believed to be layering within the basalt that fills both of these mare basins. In Mare Serenitatis, layers were detected at depths of 0.9 and 1.6 kilometers below the surface. In Mare Crisium, a layer was detected at a depth of 1.4 kilometers below the surface. The bottom of the mare basalts were apparently not detected by this experiment. However, in Mare Crisium the Lunar Sounder Experiment results were combined with other observations to estimate a total basalt thickness of between 2.4 and 3.4 kilometers.

The Lunar Sounder Experiment also contributed to our understanding of wrinkle ridges on the Moon. These long, low ridges are found in many of the lunar maria. Most lunar geologists believe that these ridges formed when the Moon's surface was deformed by motion along faults ("moonquakes") in the Moon's crust more than 3 billion years ago. The weight of several kilometers of mare basalt in these areas caused the Moon's surface to sag somewhat, and this motion caused the surface to buckle in some places, forming the wrinkle ridges. However, other scientists suggested that these ridges are volcanic features, formed by the flow of magma either on the Moon's surface or within the crust. The Lunar Sounder Experiment studied several wrinkle ridges in southern Mare Serenitatis in detail, providing information about both the topography of these ridges and about structures in the crust below these ridges. These results support the idea that wrinkle ridges formed primarily by motions along faults