Apollo CSM Apollo CSM with Launch Escape Tower Credit: © Mark Wade. 4,184 bytes. 609 x 174 pixels.

Follow the technical development of Apollo spacecraft systems and configurations. Entries from official NASA project chronologies, rearranged according to topic:

• Apollo CSM Original Specification

• Apollo CSM Source Selection

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• Apollo Mode Debate - How to get to the moon? It may seem strange, but the Saturn V booster and Apollo CSM were under contract before this basic decision was made. There was much controversy, with equally expert committees supporting either of the three methods - earth orbit rendezvous, lunar orbit rendezvous, and direct landing. The final lunar orbital rendezvous decision did not turn out to be the great weight and schedule saver that it was supposed to be...... but, that's 20-20 hindsight....

• Apollo LM Original Specification

• Apollo LM Source Selection

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• Apollo CSM Block I - In 1964 it was decided to build Apollo spacecraft in two 'blocks'. Block I spacecraft, designated by serial numbers below '100', would carry no rendezvous and docking equipment and would be used for earth-orbital missions only. Delays in the project and the death of astronauts in the on-pad fire of Block I CSM 012 resulted in no manned Block I mission ever being flown.

• Apollo CSM Block II - Apollo Block II spacecraft were flight-ready vehicles with the final design configuration for the lunar missions. They were substantially different from the Block I Apollo and finally incorporated many changes resulting from the Apollo fire.

• Apollo CSM Communications - There were quality problems with the S-band antenna, but in general development of the Apollo communications systems were one of the least troublesome areas.

• Apollo CSM Crew Station - Follow the course of decisions that resulted in the Apollo cabin you see in the movies...

• Apollo CSM Docking - Read of some of the wilder early ideas for how to dock two spacecraft in space...

• Apollo CSM ECS - The early decision to save 30 pounds by using an all-oxygen cabin atmosphere would lead to terrible consequences in the Apollo fire...

• Apollo CSM Electrical - Not a point of too much controversy during development, the Apollo fire investigation revealed huge problems in the spacecraft wiring....

• Apollo CSM Fuel Cell - The Apollo fuel cells were specified from the dawn of the program.....the explosion of a fuel cell tank on Apollo 13 would nearly result in the first in-flight loss of life in the American space program

• Apollo CSM Guidance - Guidance was considered the biggest problem for Apollo, and MIT was contracted to start work on it even before the spacecraft contractor was selected...

• Apollo CSM Hatch - Apollo originally might have had an airlock - and the size of the hatch varied considerably during development. At one point transfer of the astronauts by space-walking from the CSM to the LM was considered (as was done in the Russian program). Finally, the hatch was implicated in the Apollo fire, leading to a complete redesign and large weight increase in the CM.

• Apollo CSM Heat Shield - Developing a heat shield to withstand the vacuum of space and re-entry at twice the energy of orbital vehicles would seem to be a great challenge. But NASA's biggest problem turned out to be having a shield that didn't crack apart on landing....

• Apollo CSM LES - The Launch Escape System was one of the earliest items developed and tested. It gave rise to an interminable debate about the best way to guide it during its brief mission of pulling the capsule away from an exploding booster.

• Apollo CSM Parachute - Getting the parachutes to work correctly turned out to be a major problem, resulting in several demolished boilerplate capsules. See why the 'simple' low-tech things are often the ones that give the most trouble.

• Apollo CSM RCS - The reaction control system thrusters provided orientation of the spacecraft. But an early design requirement was that they be able to deorbit the CSM in the event of a main engine failure.

• Apollo CSM Recovery - For some time recovery of the Apollo on land was considered. If you thought only Soyuz used soft landing engines, read here of those planned for Apollo, and how the spacecraft was designed to allow the crew to survive a 'land landing'.

• Apollo CSM SPS - If you always thought the Apollo CSM Service Propulsion System engine looked too big, it's because it was originally sized to lift a much larger CSM off the lunar surface and send it toward earth in the original direct-landing scenario. The design was frozen early, but development went relatively well compared to the lunar module's engines.

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• Apollo LM Ascent Propulsion - The Lunar Module Ascent Engine had to work - otherwise the crew would be stranded on the moon, and there was no backup. It was difficult to develop, and was qualified for flight only a few months before the first manned mission.

• Apollo LM Communications - The lunar module had to communicate with the CSM, the astronauts on the surface of the moon and Houston - while being nested in the S-IVB stage, in flight around the moon, and on the surface. No wonder there were constant problems and compromises....

• Apollo LM Crew Station - How to arrange the LM so that the crew would have good landing visibility, good docking visibility, be able to determine their landing point -- and the decision for the crew to stand, contrary to all prior aerospace practice.

• Apollo LM Descent Propulsion - The LM Descent Engine - which had to be throttled in flight to make a soft landing on the moon - had enormous development problems, and it was necessary to have two companies develop competing designs in parallel.

• Apollo LM Electrical - At first the LM was to use fuel cells, like the CSM. But problems during development led to their abandonment and replacement by an 'all battery' LM.

• Apollo LM Hatch - Originally the LM was to have two docking ports, at the top and front. But during development it was decided to change the front port to a hatch only, saving weight but making docking very uncomfortable for the crew...

• Apollo LM Landing Gear - The landing gear had to be designed without knowing what the lunar surface was actually like. How to do this, and the changing configurations and tribulations during development...

• Apollo LM RCS - The LM and CSM reaction control system jets were the only item NASA could actually convince the two contractors to use in common.

• Apollo LM Structural - The LM had to be as light as possible but still survive rough launch environments.

• Apollo LM Television - Use of television on Apollo naturally was a big issue for management. Here's how the decisions were made.

• Apollo LM Weight - The LM was originally to weigh 24,500 pounds. It grew and grew and grew, until it seemed that Apollo could not be launched towards the moon by the Saturn V. It was only the above-specified performance of the Saturn V that allowed the final 32,000 pound spacecraft to make its voyage.