#sla-7

The Douglas-built S-IVB upper stage intended for Apollo 1 SA-204 mission was erected at Launch Complex 37B, Cape Kennedy, Florida. It was repurposed for Apollo 5 to send the unmanned Lunar Module (LM-5) into Earth orbit later that year.

Date: April 10, 1967

Apollo 5 Saturn IB (LM-1/SA-204) at night on LC-37B.

Date: January 19, 1968

A schematic highlighting the major milestones of the Apollo 5 mission to test LM-1.

Diagram of the Saturn IB used for the unmanned LM-1 test flight.

"A nearly perfect performance by the Saturn IB placed the S-IVB-204 stage and its LM-1 payload into an initial 163 by 222 kilometer orbit with an inclination of 31.6° following 10 minutes and 3.3 seconds of powered flight. After 35 seconds in orbit, the nose cone was successfully jettisoned with the four panels of the SLA deployed 9 minutes and 15 seconds later. LM-1 used its RCS to separate from S-IVB-204 at 23:38:58 GMT about halfway through its first revolution and into a 167 by 224 kilometer orbit. After separation, LM-1 changed its attitude to cold soak its propulsion system for the next two orbits.

Diagram showing the configuration of LM-1 inside of its Spacecraft Launch Adapter (SLA).

With its primary duties concluded, S-IVB-204 performed a number of engineering tests including the dumping of residual cryogenic propellants and helium pressurant through the stage’s J-2 engine. This procedure would help lighten the stage for easier control in orbit and prepare future S-IVB stages for use as a 'wet' orbital workshop as proposed for the Apollo Application Program which was planned to follow the initial Apollo lunar landing missions (a program which later evolved into Skylab). After the propellant dump was successfully completed at 01:19:33 GMT on January 23, the stage was in a 155 by 223 kilometer orbit. Although it was not tracked, the orbit of S-IVB-204 was expected to decay ten revolutions after the separation of LM-1 about 15½ hours after launch.

An artist conception of LM-1 separating from its spent S-IVB stage.

Following the three-hour cold soak of LM-1, a pair of burns were planned for the descent propulsion system (DPS) followed by two burns of the ascent propulsion system (ASE). The first 39-second burn of the DPS would start at a throttle setting of 10% then ramp up to full thrust for the last 12 seconds to simulate the initial deorbit burn which would start the descent towards the lunar surface. The second firing of the DPS would last for 739 seconds and use a series of throttle settings representative of an actual descent to the lunar surface. Immediately afterwards, the abort staging would be tested with an initial five-second burn of the APS. A subsequent firing of the APS would continue until the stage’s propellants were depleted after about 445 seconds completing the primary mission about 6½ hours after launch. Because the LM ascent stage was expected to be left in a comparatively long-lived 315 by 815 kilometer orbit after the completion of the last APS burn, extended mission activities were planned until the ascent stage depleted its consumables about seven hours later.

-Animation of LM-1 in orbit

At 02:47:49 GMT on January 23 (just shy of four hours after liftoff), LM-1 was commanded to start the first of two planned burns of the DPS but the engine unexpectedly shutdown after firing for only four seconds leaving the spacecraft in a 170 by 222 kilometer orbit instead of the planned 215 by 330 kilometer orbit. After examining the telemetry, ground controllers quickly located the source of the problem. The LM’s guidance computer had been programmed to abort the maneuver and shutdown the DPS if it did not provide the expected acceleration level after four seconds – a situation which would normally indicate a problem with the DPS. Because the pressure-fed propulsion system was purposely running at lower than nominal pressure for these tests, it would now take six seconds to reach full thrust. It was this oversight which resulted in the premature shutdown of the DPS.

Cutaway diagram of LM-1 used for the first unmanned test flight of the Lunar Module (LM)

As a result of the problem, a preplanned alternate mission was adopted by ground controllers which would meet the minimum mission requirements while keeping LM-1 in touch with tracking stations for key maneuvers.

An artist conception of the firing of the LM descent propulsion system (DPS) during the Apollo 5 mission.

With the guidance system deactivated, the DPS was ignited by ground command for a 33-second burn at 04:58:49 GMT during the fourth revolution. The second burn of the DPS for the alternate mission sequence was commanded at 04:59:54 GMT for an abbreviated 28-second burn.

This was followed by the abort staging test and a 60-second burn of the APS. All systems worked as intended during this alternate mission’s three burns. The 228 meter per second total change in velocity from these three propulsive maneuvers boosted LM-1 into a 172 by 961 kilometer orbit.

-Animation of LM-1 Ascent Stage in orbit.

After these first three firings of the propulsion systems, the primary control system was reactivated for the balance of the mission. Unfortunately the guidance computer, which had been in a passive mode during the abort staging, had not taken into account the change in spacecraft mass and used excessively long burns of the RCS to control attitude as if it had a fully loaded descent stage still attached. This resulted in higher than expected RCS usage and eventual propellant depletion after only about an hour. Fortunately the RCS could be configured to draw from the APS propellant supply to provide attitude control during the mission’s final burn. Because of the timing and other requirements of the burns in the alternate mission plan, this second burn of the APS would be in the retrograde direction which would send the spacecraft into Earth’s atmosphere ending the Apollo 5 mission.

Flight Director Gene Kranz (left) and Dr. Gilruth (right) shown in the Mission Control Center at the conclusion of the Apollo 5 mission

With the ground track of LM-1 beginning to drift beyond the mission’s tracking stations due to the one-orbit delay to implement the alternate mission, the remainder of the mission had to be completed by the next revolution. The second burn of the APS started at 06:32:20 GMT during the fifth revolution. As planned, the sequencer automatically closed the valves supplying the RCS with propellant about 161 seconds later. Without attitude control, the ascent stage began to tumble as the APS continued to fire for another 190 seconds before its propellants were finally depleted. The last telemetry was received from LM-1 at 06:40:18 GMT on January 23 ending the Apollo 5 mission 7 hours, 52 minutes and 10 seconds after launch. The LM-1 ascent stage reentered the Earth’s atmosphere and was destroyed over the Pacific Ocean some 640 kilometers off the coast of Central America. The inactive descent stage of LM-1 fell from orbit on February 12.

"Map showing the ground track of the Apollo 5 mission as flown and the location of tracking stations supporting the mission.

Although the Apollo 5 mission had encountered problems forcing a switch to an alternate mission plan, the overall performance of LM-1 was good enough to satisfy the mission’s main objectives. And with the requirement to certify the LM for crewed test flights satisfied, a potential second unmanned test flight with LM-2 was cancelled allowing one more mission to be cut from the Apollo program’s increasingly tight schedule. With LM-2 being unsuitable for manned flight without significant reworking to meet new requirements in the wake of the Apollo 1 fire, it was set aside as work continued on LM-3 for the first manned LM test flight on Apollo 9."

"SA-204, the fourth Saturn IB launch vehicle, developed by the Marshall Space Flight Center (MSFC), awaits its January 22, 1968 liftoff from Cape Canaveral, Florida for the unmarned Apollo 5 mission. Primary mission objectives included the verification of the Apollo Lunar Module's (LM) ascent and descent propulsion systems and an evaluation of the S-IVB stage instrument unit performance."

Date: January 1968

"On March 15, 1968, NASA announced that the planned second unmanned test flight of the Lunar Module (LM) was not needed given the success of the LM-1 flight during Apollo 5 in January. The decision to not fly LM-2 resulted in a significant cost and schedule savings to achieve the goal of landing a man on the Moon before the end of the decade. And while LM-2 never got to fly in space, it’s use as an important ground test vehicle helped clear the way for the first Moon landing. Because LM-2 was configured for an unmanned flight, it would have been too costly to reconfigure it for a manned flight, primarily to fireproof the cabin. As a result, the first manned test would utilize LM-3, then planned to be launched aboard a Saturn V in late 1968.

The Lunar Module (LM-2) Ascent Stage during vibration tests.

The decision at first put LM-2 and its Saturn IB rocket into storage, but NASA managers decided to use LM-2 as a high-fidelity ground-test vehicle since it contained flight-like systems. After a short time in storage, LM-2 was shipped to the Manned Spacecraft Center in Houston, where engineers used it for dynamic testing in the Vibration and Acoustic Test Facility (VATF) to better understand the effects of the Saturn V pogo oscillations seen during the Apollo 6 mission in April 1968. The results of those tests contributed to NASA engineers clearing the next Saturn 5 to carry a crew. After the attachment of landing gear, between March and May 1969 engineers in the VATF used LM-2 to conduct drop tests to verify the structural integrity of the vehicle and its subsystems. Because LM-2 contained flight-like vehicle systems, the results of these high-fidelity tests helped clear the Apollo 11 LM-5 to land on the Moon just two months later.

LM-2 ascent stage on display at the 1970 World’s Fair in Osaka, Japan.

After its ground testing days were over, LM-2 continued to be useful. In 1970, its ascent stage spent several months on display at the US Pavillion at 'Expo ’70' in Osaka, Japan, mated to the descent stage of Lunar Test Article-8. When it returned to the United States, it was reunited with its descent stage, modified to appear like the Apollo 11 Lunar Module 'Eagle,' and transferred to the Smithsonian in 1971 for display. In 2016, curators restored and relocated it to the new Boeing Milestones of Flight Hall in the National Air and Space Museum. The Saturn IB rocket that was planned to launch LM-2 came out of storage in May 1973, when it launched the first crew to the Skylab space station."

LM-2 modified to appear like the Apollo 11 Lunar Module "Eagle," on display at the National Air and Space Museum.

NASA ID: link, LM-NOID-09

An artist conception of LM-1 separating from its spent S-IVB stage.

Date: January 22, 1968

The Apollo 5 Saturn IB launch vehicle (LM-1/SA-204) lifts off from LC-37B. This unmanned mission verified the ascent and descent stage propulsion systems, including restart and throttle operations of the Lunar Module.

"A schematic highlighting the major milestones of the Apollo 5 mission to test LM-1."

"The Lunar Module-1 payload was boosted into Earth orbit by a launch vehicle composed of a Saturn IB first stage and a Saturn S-IVB second stage. The Apollo lunar module's first flight test was called a complete success. Ascent and descent propulsion systems and the ability to abort a lunar landing and return to orbit were demonstrated."

Apollo 5 mission patch (earlier design on the left).

Date: January 22, 1968

NASA ID: S68-19459, 6862755, S68-19460, 68-H-42, S68-19402, link

The Descent and Ascent Stages of Apollo AS-206 Lunar Module (LM-1) (later Apollo 5) on the work stands at the Manned Spacecraft Operations Building, Kennedy Space Center, Florida. This was after its arrival and transfer via Hanger AF.

Date: June 23, 1967