When an explosion rocked Apollo 13‘s service module on April 13, 1970, the automobile’s important position, and that of the hooked up command module spacecraft, out of the blue turned crystal clear.
The astronauts lost one oxygen tank instantly, and the opposite was badly broken. The important engine that was speculated to deliver the astronauts again house was knocked out of fee. The three crewmembers did make it house, however barely — and solely by utilizing the hooked up lunar module as a lifeboat.
Positive, the lunar module had oxygen and water and energy. However it did not have sufficient to simply maintain three individuals for the 4 days wanted to get house. And positive, the lunar module carried an engine capable of get the astronauts to Earth orbit from the moon’s neighborhood. However this was removed from what the lander was designed to do, and doing so was a tough enterprise.
So, whereas the Apollo program’s lunar landings, which began 50 years ago this July 20, shall be entrance of thoughts within the coming weeks, the command module deserves its time within the highlight. It was the spacecraft astronauts sat in whereas rocketing to house, and generally, on the experience house once more. In any case, solely the command module had a warmth protect.
Some historians, like Mike Neufeld, a senior curator on the Smithsonian Nationwide Air and House Museum, have argued that the command module can’t be described as its personal spacecraft, as a result of it was the hooked up service module that had all of the gear that allowed the command module to operate. (Neufeld thus prefers the time period command and repair module, he advised House.com, a utilization that NASA has additionally employed incessantly.)
However whether or not in isolation or working with its accomplice, one factor was for positive: The command module was impressed by each NASA spacecraft that got here earlier than it. The large distinction? Apollo’s command module was greater and capable of stand up to extra warmth because the astronauts got here into the Earth’s ambiance at larger speeds.
Apollo was the final of three spacecraft applications that regularly received NASA to crewed lunar missions. Mercury was a easy, one-person spacecraft that primarily ran on autopilot, though an astronaut may take over at essential moments, similar to throughout touchdown.
Gemini, which was developed after engineers began engaged on Apollo, a step bigger than Mercury, carrying two astronauts. Spacecraft within the Gemini collection examined important lunar-mission milestones, similar to docking and facilitating spacewalks whereas nonetheless in Earth orbit.
However it might be Apollo’s command module that will fly to the moon. It was developed by North American Aviation. (That firm was later often called North American Rockwell and is right now a part of Boeing.)
The command module had a wider, flatter cylindrical nostril in comparison with the Mercury or Gemini spacecraft, Neufeld stated. The Apollo design was utterly coated in warmth protect, though the thickest half was on the again finish. Apollo’s computer, although simply outpowered by right now’s cellphones, was a marvel of the day, based mostly on the fast-calculating built-in chip, somewhat than the semiconductor transistors used throughout Gemini.
Virtually talking, the command module flew by itself solely through the few hours earlier than reentry, working on batteries at these instances. In any other case, it relied on the service module, which used gas cells for electrical energy, a Gemini innovation that Apollo carried on, Neufeld stated. These gas cells generated water as a waste product, which astronauts have been capable of drink, in a primary for U.S. spaceflight.
One of many command module’s distinctive options in comparison with earlier spacecraft was a navigation station outfitted with a tv and a sextant, Neufeld stated. “This was so that the astronauts, in theory, could navigate their way back home if they lost contact with the ground,” he stated.
However the association wasn’t good. The navigation station had a steering platform based mostly on gyroscopes, which are inclined to “drift” or lose accuracy over time. So, throughout most missions, astronauts needed to realign the steering platform every now and then.
This turned one of many lesser-known issues of Apollo 13. After the preliminary explosion, the ensuing particles and oxygen from the destroyed tank clung across the spacecraft in a nasty demonstration of gravity’s attraction. The clutter made it difficult for the astronauts to align their guidance platform for the journey house. As an alternative, in session with mission management, the crew used measures similar to aligning with the road between day and night time on Earth to securely return.
The command and repair module underwent three main design modifications throughout its lifetime, Neufeld stated. The primary got here after Apollo 1, when a deadly floor hearth killed three crewmembers on Jan. 27, 1967, whereas they have been working a observe liftoff on the launchpad.
Apollo 1 used the earliest “Block 1” model of the command module, which used nested outer and inside hatches for a tighter seal. When a fireplace broke out contained in the spacecraft, the crew was unable to get out. Worse, the within was stuffed with flammable objects held in flammable situations. These have been hearth hazards that NASA and its producer hadn’t thought of.
Within the wake of the accident, North American Aviation redesigned the spacecraft “to eliminate the dangers of wiring,” Neufeld stated, and take away flammable supplies from the module. NASA additionally switched to the Block 2 model of the spacecraft, which had a hatch that may very well be opened in seconds.
Apollo 13 prompted one other change. The explosion itself, NASA later realized, was attributable to a collection of wiring and dealing with issues on the bottom. These points triggered to a fireplace within the service module, which blew up one of many oxygen tanks and tore away the connection to the opposite, Neufeld defined.
Oxygen was important not solely to maintain astronauts respiration, but additionally for energy, as a result of it provided the gas cells. So, after Apollo 13, a 3rd oxygen tank was added to the service module on the alternative aspect of the bay from the oxygen tanks by the gas cells, Neufeld stated. “It provided some backup oxygen if there was ever a problem that knocked out the other two oxygen tanks,” he stated.
The final main change to the command and repair module got here in including a quadrant to the service module for Apollos 15, 16 and 17. These final missions to the moon have been closely centered on science. That precedence meant a busy schedule for the astronaut who remained behind within the command module whereas the opposite two crewmembers explored the moon.
The command-module astronaut would take footage and carry out experiments whereas nonetheless contained in the spacecraft. Then, on the way in which house, that astronaut would carry out a spacewalk to retrieve movie from a digicam photographing the floor of the moon from exterior the spacecraft, in addition to anything that wanted to return to Earth, Neufeld stated.
Today, the command module’s legacy lives on in new spacecraft being designed to fly inside the subsequent couple of years. These embrace two business crew automobiles, SpaceX’s Crew Dragon and Boeing’s CST-100 Starliner, every designed to deliver crews to the Worldwide House Station. NASA is constructing its personal successor to the command module as effectively, a lunar spacecraft known as Orion, scheduled to be examined on its first round-the-moon journey no sooner than 2020.