Apollo 5 Certified the Lunar Module Safe for Astronauts

‘America to the Moon’ Part 4 – The Lander Works in Orbit

By Bob Granath

The year 1967 began with the tragic loss of the Apollo 1 crew, but ended with the successful launch of the first Saturn V rocket. NASA hoped to make it two successes in a row with the first unmanned flight of the lunar module, or LM, the spacecraft designed to land Americans on the Moon before the end of the decade. A successful flight would be crucial in meeting President John F. Kennedy’s goal.

But, time was running short.

The Apollo 5 flight test of a lunar module would kick off an exceptionally successful year for the Moon landing program, culminating on the first flight of humans to the lunar orbit.

Apollo 5 lifted off from Cape Canaveral Air Force Station’s Launch Pad 37B on Jan. 22, 1968. The 11-hour mission was designed to establish the ability of the lunar module to perform as designed. It also would help certify that the spacecraft could safely fly with astronauts on its next mission.

Tests during Apollo 5 included verifying that both the lunar module’s descent and ascent engines would ignite as planned Allowing NASA to evaluate the strength of the spacecraft’s overall structure. The mission also would confirm the LM’s ability to separate the ascent stage from the descent section. The descent engine would become the first throttleable rocket engine fired in space.

Once in Earth orbit, a planned 39-seconds firing of the descent propulsion system (DPS) engine was stopped after only four seconds due to overly conservative programming of the flight software. The burn was designed to simulate deceleration for descent to the lunar surface.

Using an alternate flight plan, flight controllers at NASA’s Manned Spacecraft (now Johnson) Space Center in Houston fired the DPS engine for 26 seconds at 10 percent thrust and then for seven seconds at full throttle.

A third DPS firing involved a 26-second burn at 10 percent thrust and two seconds at maximum thrust. This was followed by a burn to simulate an abort during the landing phase in which the ascent propulsion system (APS) was ignited at the same time the DPS engine was shut down.

The ascent propulsion system burn lasted 60 seconds, followed by a six-minute, 23 second firing depleting the remaining APS fuel.

At the end of the flight test, both LM stages were left in orbit eventually to disintegrate on reentry. The mission was deemed a success in spite the descent engine programming error. A second unmanned flight test using LM-2 was canceled. This cleared LM-3 for the first manned LM flight, Apollo 9, taking place in March 1969.

U.S. Air Force Maj. Gen. Samuel Philips, director of the Apollo Program Office, said that the lunar module’s maiden flight completed testing of the last major piece of Apollo flight hardware. All other Apollo hardware elements had been tested throughout the previous two years.

“The Apollo program is in good shape and we are getting back into a mission sequence,” he said. “The LM’s maiden flight during Apollo 5 was very critical and constituted testing the last major piece of Apollo flight hardware. “

Between late 1968 and the end of 1972, nine manned Apollo missions were flown using the lunar module, eight going to the Moon with six landing on the lunar surface.

EDITOR’S NOTE: This is the fourth in a series of feature articles marking the 50th anniversary of NASA’s Apollo missions to the Moon. During the 1960s and early 1970s, the space agency and its contractors sent astronauts from Earth beginning a period of exploration that will lead to pioneering flights planned for the 21st century. Next, read about the first piloted mission of Apollo.

111

111

111

© 2019 SpaceAgeChronicle.com All Rights Reserved.