In 1961, President Kennedy set America on a path that would change the course of human history; to land a man on the moon by the end of the decade. 8 short years after that commitment and with only months remaining in the decade; America prepared for the final lap in the race to the moon.
In the wake of the Christmas flight of Apollo 8 around the moon, a return to earth orbit was almost anticlimactic, and yet, the flight of Apollo 9, an Earth orbital flight test of the combined Apollo spacecraft was the most crucial flight to date in the of reaching the moon.
Originally scheduled for the Apollo 8 mission in late 1968, the flight had, in the third quarter of 1968, undergone a radical transformation.
In September of that year, reliable CIA intelligence pointed to a Soviet attempt to reach the moon by years end. Reconnaissance photos appeared to show a newly constructed launch pad and a heretofore unknown super booster resting upon it. Unmanned flights with their Zond spacecraft around the moon had met with increasing levels of success. Zond 5B in September and Zond 6 in November had demonstrated lunar flight feasible with a live payload. With a new powerful Proton launch vehicle poised on a Baikonur launch pad and a 2 man crew lead by Cosmonaut Alexei Leonov said to be in training for a circumlunar mission; the moon was moving within range of Soviet space efforts.
The American effort by comparison was emerging from the flames of Apollo 1 and the loss of its crew on a Cape Canaveral launch pad in 1967. Three unmanned Apollo flights had met with varying success, the recent flight of Apollo 6 being beset by second stage vibration and issues with third stage ignition.
On Pad 34, the Saturn 1B for Apollo 7 was in the final stages of preparation for an October launch on an 11 day shakedown flight of the Apollo Command Service Module (CSM). The schedule beyond this last manned launch from Cape Canaveral was in considerable disarray. The manifested Apollo 8 mission, scheduled for a November launch would be the first manned flight of the Saturn V from the new Merit Island launch Complex (later the Kennedy Space Center) carrying the combined Apollo spacecraft on an Earth orbit dress rehearsal of the lunar mission, however, in October of 1968, Lunar Module (LM) development was months behind schedule, although the LM for Apollo 8, LM-3 had arrived at the Kennedy Space Center, in October its fault list still ran to over 100 separate items.
Unlike the CSM which could draw on the engineering experiences gained in the Mercury and Gemini programs, the development of the LM represented a departure from traditional spaceflight engineering. Contractor Grumman Aviation of Bethpage New York was tasked with the design and building of the first true spaceship; a craft designed on an Earth to which it could not return, the airless vacuum of space and the 1/6 gravity of the moon were its natural environment. Without the limitation of a heatshield or recovery aides, the LM was designed purely as a space taxi. To get two astronauts from an orbiting CM to a safe landing on the lunar surface, sustain them for a period of days and, most importantly, return them to orbit. Everything about the LM was new, every part from the smallest fittings were hand made. Weight was the single most important factor in its design. So thin were the skin panels of the LM that its skin would ripple to the slightest vibration, a blunt pencil could penetrate the inch skin.
A two stage spacecraft, the octagonal descent stage contained the fuel tanks and descent stage engine for the landing on the lunar surface. This TRW developed variable thrust gimballed rocket engine could be throttled at various percentages of thrust giving crews the ability to hover much like a helicopter in search of a landing site.
At four points, landing gear of a cantilever design consisting of struts trusses, a footpad and lock and deployment mechanism provided attenuation during lunar landing and prevent tip over on the surface.
The gear was released by the explosive release of uplocks allowing springs in the deployment mechanism to lock the gear into a deployed position. Sensor probes are flited to three of the gear to detect lunar surface contact. The forward gear contained the ladder and porch for ingress and egress of the LM cabin.
Compartments in two of the four descent stage quadrants contained experiments for deployment on the lunar surface, the United States flag and television camera. Attached to its outside were a canister of Plutonium 238 to power experiments on the lunar surface and, on later flights, the Lunar Roving Vehicle.
The ascent stage was the living and control quarters for the crew. Dominating the cabin was the cover for the single thrust ascent engine was designed to be fail safe with a simplistic ignition system. Once ignited the engine fired at full thrust for seven minutes to place the ascent stage into a low orbit from which the Command Module could affect a rendezvous. Two 45 degree angle windows at the front of the stage gave a view of the approaching lunar surface while the astronauts, secured by foot restraints and bungee cords stood before the display consoles, the Commander on the left and the Lunar Module Pilot on the right. Between them at floor level was the hatch leading to the descent stage porch and the lunar surface. Interior volume for the ascent stage was about the same as a public telephone booth.
As the Apollo 7 launch window approached it became clear that the LM would not make its planned 1968 launch window. With this knowledge and the intelligence from the Soviet Union, NASA Management made the boldest decision in the history of spaceflight. The Apollo 8 and 9 crews were switched, a new mission, C Prime, was created. The Frank Borman lead Apollo 9 crew would fly the Apollo 8 Command Module around the moon and the James McDivitt lead Apollo 8 crew would wait for the Lunar Module and fly on the Apollo 9 mission, tentatively set for early 1969.
The crew of the remanifested Apollo 9 consisted of two veteran astronauts and one rookie. Commander James McDivitt had Commanded Gemini 4 in June 1965 whilst Command Module Pilot Dave Scott had piloted Gemini 8 with Neil Armstrong in March of 1966. Lunar Module Pilot Russell Schweikart; a group 3 astronaut selected in 1963.
The flight plan for the revised Apollo 9 flight called for simulation of the most important aspects of the lunar landing in the relative safety of earth orbit: the first dual spaceflight of the combined Apollo spacecraft, repeated dockings between the Command and Lunar Modules, a solo flight by the Lunar Module in simulation of lunar descent and ascent, and a 2 hour spacewalk by Schweikart and Scott would highlight the 11 day mission. The walk would provide the sole opportunity to certify the Apollo Extravehicular Mobility Units (EMU’s) for use in space and on the lunar surface prior to the lunar landing.
March 3 1969, the countdown for the Apollo 9 mission nears its conclusion. As the crew board the CM atop the 110 metre tall three stage Saturn 5 Launch vehicle, a problem deep in the unseen LM threatens to delay the flight.
A helium tank pressure measurement in the descent stage of the LM is reading high. Should this reading persist or increase in value, the danger existed that the helium burst disc in the stage could blow. Should this happen, it would not be possible to fire the descent stage in space. As the count proceeds, Grumman engineers at Bethpage, in the Launch Control Center at Kennedy and Mission Control in Houston watch anxiously, the pressure remains high but stabilises. The decision is made: Go for launch!!
At 11:00 AM Eastern Standard Time (EST) , the Apollo 9 mission rose from Pad 39A and, following a successful 11 minute burn of all 3 Saturn stages, the Apollo spacecrafts attached to the third stage are injected into an orbit of 189 X 192 KM.
At 02:41:16 Ground Elapsed Time (GET) after spacecraft checkout, Dave Scott separated the CM from the combined Saturn third stage and LM. Following separation, the launch shroud atop the LM was opened like a flower and separated from the third stage revealing the docking cone in the roof of the LM ascent stage. Turning 180 degrees, Dave Scott guided the probe affixed to the nose of the CM into the docking cone (The drogue) on the LM in a simulation of the transposition and docking manoeuvre vital to the lunar mission. With a contact indication on the CM instrument display, Scott fired thrusters on the CM to effect a hard dock between the docking rings of both spacecraft. Scott then reversed thrust to spring the LM clear of the now defunct third stage.
Its primary mission complete, the third stage was, under ground command, fired multiple times to test the restart capabilities of the J 2 engine before final injection into the heliocentric orbit in which it remains to this day.
With the combined Apollo spacecraft now configured as for trans lunar flight, the crew prepared for the first flight of a manned lunar module in space in addition to testing of the Service Propulsion System Engine attached to the aft end of the Service Module to assess manoeuvrability of the docked craft.
Accessing the LM required pressurization of the lunar module to a point equal to that in the CM. Following this the connecting tunnel was cleared and the probe and drogue assemblies were removed and stowed. Opening the LM hatch required an adjustment in orientation for the crew. With the two craft docked nose to nose astronauts needed to turn 180 degrees to be correctly orientated.
First Entry to the LM was at 43:15 on Flight Day 3 with landing gear extension at 45:00. Aside from some floating washers and minor debris, the LM was in excellent condition and checkout and power up of LM systems began. 45 minutes later, McDivitt reported that Schweikart had been physically ill on two occasions, as such the crew was now behind on the timeline.
Schweikart’s illness called into question the EVA planned for Flight Day 4 and by consequence the solo flight of the LM itself. Under the current flight plan, Schweikart would don an EMU and, after checkout on the LM porch, spacewalk to the open hatch of the CM and retrieve an experiments package in a demonstration of crew transfer from a disabled LM should a docking not be possible on return from the lunar surface. With Schweikart having multiple episodes of vomiting, risk of further illness when suited could result in a life threatening situation. Faced with such a scenario, Flight Surgeons in Mission Control and mission managers demined that the walk, as planned would not proceed.
While debate on the safety of EVA continued, McDivitt and Schweikart continued LM checkout with the first burn of the LM descent engine with the spacecraft in a docked configuration occurring at 49:51 for 371 seconds.
Fight day 4 saw an improvement in Schweikart’s condition and with it came a modified plan for EVA. Schweikart would suit up and go out on the lunar Module porch to evaluate the suit and retrieve LM thermal samples. A space suited Dave Scott would meanwhile open the CM hatch and retrieve the experiments package. At 72:55 the forward LM hatch opened with CM hatch opening at 73:02. Attached only by a tether and connected to LM environmental systems, Schweikart completed a 1 hour seven minute evaluation of the EMU systems before returning to the LM cabin.
16 mm footage taken during the EVA by Schweikart of a suited Dave Scott in the CM hatch with Earth as a backdrop would become some of the most broadcast footage of the early space program.
Flight day 5 saw the most crucial test of the Apollo 9 mission. Solo flight of the LM before returning to dock with the CSM.
At 92:38:00 an attempted undocking was unsuccessful after capture latches in the docking mechanism failed to release. A further attempt at 92:39:36 was successful and the two spacecraft moved apart. A CSM burn opened the gap to 3.2 KM 45 minutes after separation. For the next three hours the distance between the two craft increased to a maximum of 154 KM.
With two craft now flying separately, identification on audio channels became an issue. To alleviate confusion, NASA, for the first time since Gemini 3, allowed the crew to personalise their spacecraft. Prior to the flight, the crew had chosen the name Gumdrop for the CSM and Spider for the LM, the names being derived from the look and shape of the respective spacecraft. With the craft now flying separately these names would be in effect until such time the spacecraft re-docked after which, identification would revert to Apollo 9
On the outbound coast McDivitt fired the LM engine to determine engine performance at varying thrust levels as required for the final stages of lunar landing. At 20% thrust the engine began to chug much like a car backfiring. Releasing the hand controller, the chugging, later determined to be excess helium in the fuel lines, stopped. Further tests at 40 % and 10 % resulted in smooth engine performance. Other than this one anomaly, descent engine performance was nominal.
Separation of the ascent and descent stages of Spider was initiated at 96:16:06 GET as explosive bolts separated the two stages and the ascent engine ignited. As the descent stage fell away, Grumman Engineers relaxed, the helium issue that had dogged them since launch had not eventuated and, as the descent stage was lost against the Earth, the burst disc had not blown.
The Descent stage of the Lunar Module re-entered the earth’s atmosphere on March 22 1969.
Three hours after stage separation, at 99:02:26 GET, with rendezvous and docking between the two spacecraft performed nominally, the crew transferred to the CSM after configuring the LM for its final, solo, flight.
At 101:22:45 GET with the crew reunited in the CSM, the LM ascent stage, with the crew watching through the CM windows, was jettisoned for the final time.

A 6 minute ascent engine burn to depletion (of fuel) at 101:53:15 GET placed the LM in an eccentric orbit of 6965 by 234 KM
The Ascent stage remained aloft until its decay on October 23 1981.

With the LM phase of the mission now complete the crew the final four days of the mission saw further tests of the SPS engine, a program of Earth photography and observation in addition to tracking of the Pegasus 3 satellite, launched with Apollo boilerplate spacecraft 9 on the Saturn 1 SA 10 mission on 30 July 1965, on two successive orbits beginning at 192:43 GET.
Separation of the Service Module at 240:36:03 GET preceded entry interface for the Command Module at 240:44:10 GET at 122 KM in altitude. Splashdown, 290KM east of the Bahamas came at 241:00:54 (12:00:54 EST), within sight of the recovery ship USS Guadalcanal.
The Service Module decayed in Earth’s atmosphere with a predicted impact point for any surviving pieces 324 KM downrange from the CM.
Apollo 9 would be the final mission to land in the Atlantic until the Crewed Dragon demonstration Mission exactly 50 years later. All remaining Apollo craft employed a Pacific recovery.
The Command Module Gumdrop, retrieved during Apollo 9 recovery, is currently displayed at the San Diego Air and Space Museum in San Diego California.
For McDivitt, Apollo 9 was his last spaceflight In May of 1969, he became manager for Lunar Landing Operations in the lead up to Apollo 11. Three months later, in August of 1969, he assumed the role of Apollo Spacecraft Manager at the Manned Spacecraft Center before leaving NASA for private industry in August 1972.
Russell Schweikart likewise would never fly in space again. Transferring to the Apollo Applications Program, he served as backup Commander for Skylab 2 before transferring to NASA Headquarters in 1974 before retiring from NASA in 1979. In later years he founded the Association of Space Explorers.

Dave Scott would command Apollo 15 in July of 1971, but his career and those of James Irwin and Alfred Warden would be tainted by a scandal surrounding postal covers carried illicitly to the Moon. Removed from the Apollo 17 backup crew as a disciplinary measure, he became Deputy Director and then Director of the Dryden flight Research Center Edwards Air Force Base before retiring from NASA in October 1977 to pursue private business interests.
The flight of Apollo 9, like that of Apollo 7 is largely forgotten in the history of the race to the moon, overshadowed by the more glamorous lunar landing missions that would follow, and yet were it not for the accomplishments of Apollo 9, succeeding flights could not have happened. The very next person to don and EMU backpack in flight was Neil Armstrong as the Lunar Module Eagle rested in the Sea of Tranquillity. Had Schweikart not tested the backpack on Apollo 9, further inflight testing would have been necessary before any attempt at a lunar landing could have been made. Had the LM not been so thoroughly checked out, improvements could not have been incorporated into later craft to preclude issues with fuel flow and tank pressures that exhibited themselves on Apollo 9.
The success of Apollo is hinged on these earlier flights. As we pause in this 50th anniversary year to remember the first steps on another world, let us not forget the flights and crews on whose shoulders we stood to make that One Giant Leap…
For without them, we may still be Earthbound.

Apollo 9 March 3 – March 13 1969