AURORA 7 - MA7

Mercury Spacecraft artwork by Cece Bibby

Launch:

May 24, 1962. 7:45:16 EST. The launch countdown proceeded almost perfectly, with only a last-minute hold of 45 minutes occurring at the T-11 minutes mark in anticipation of better camera coverage and to allow aircraft to check the atmospheric refraction index in the vicinity of Cape Canaveral. The launch vehicle used to accelerate Carpenter and the Aurora 7 spacecraft was an Atlas D. The differences between the Atlas 107-D launch vehicle and the Atlas 109-D used for MA-6 involved retention of the insulation bulkhead and reduction of the staging time from 131.3 to 130.1 seconds after liftoff. 

The performance of the launch vehicle was exceptionally good with the countdown, launch and insertion conforming very closely to planned conditions. At sustainer engine cut off (SECO) at T+5min10sec, all spacecraft and launch vehicle systems were go and only one anomaly occurred during launch. The abort sensing and implementation system (ASIS) Hydraulic switch No. 2 for the sustainer engine actuated to the abort position at 4:25 minutes after liftoff. Pressure transducer H52P for the sustainer hydraulic accumulator was apparently faulty and showed a gradual decrease in pressure from 2,940 psia to 0 between 190 and 312 seconds after liftoff. Another transducer in the sustainer control circuit indicated
that pressure had remained at proper levels so the switch did not actuate until the normal time after SECO. 
 

Landing:

May 24, 1962. 12:41 p.m. EST. 19deg 29min North 64deg 05min West. 

Spacecraft overshot intended target area by 250 nautical miles. After landing, Carpenter reported a severe list angle on the order of 60 degrees from vertical and post flight photographs of the spacecraft taken after egress indicated approximately a 45 degree list angle. An Air Rescue Service SA-16 amphibian aircraft established visual contact with the spacecraft 39 minutes after landing (1:20pm) and the USS Farragut, located about 90
nautical miles southwest of the calculated landing position was first to reach the capsule. 

Carpenter was picked up by HSS-2 helicopters dispatched from the aircraft carrier USS Intrepid (CVS-11) while the destroyer USS Farragut (DLG-6) watched the Aurora 7 capsule until it could be retrieved with special equipment aboard the USS John R. Pierce about 6 hours later. A Considerable amount of sea water was found in the spacecraft which was believed to have entered through the small pressure bulkhead when Carpenter passed through the recovery compartment into the life raft. The spacecraft was delivered by destroyer to Roosevelt Roads, Puerto Rico with subsequent return to Cape Canaveral by airplane. 

Mission Highlights:

Total time weightless 4 hours 39min 32sec. The performance of the Mercury spacecraft and Atlas launch vehicle was excellent in nearly every respect. All primary mission objectives were achieved. The single mission critical malfunction which occurred involved a failure in the spacecraft pitch horizon scanner, a component of the automatic control system. This anomaly was adequately compensated for by the pilot in subsequent in-flight operations so that the success of the mission was not compromised. A modification of the spacecraft control-system thrust units were effective. Cabin and pressure-suit temperatures were high but not intolerable. Some uncertainties in the data telemetered from the bioinstrumentation prevailed at times during the flight; however, associated information was available which  indicated continued well-being of the astronaut. Equipment was included in the spacecraft which provided valuable scientific information; notably that regarding liquid behavior in a weightless state, identification of the airglow layer observed by Astronaut Glenn, and photography of terrestrial features and meteorological phenomena. An experiment which was to provide atmospheric drag and color visibility data in space through deployment of an inflatable sphere was partially successful. The flight further qualified the Mercury spacecraft systems for manned orbital operations and provided evidence for progressing into missions of extended duration and consequently more demanding systems requirements.
 

At 7:43 a.m. on May 24, 1962, Carpenter became only the second human to ride an Atlas rocket into space and only the second American to orbit the earth, piloting Aurora 7 three times around the planet. The mission was to corroborate MA-6, but mission planners also wanted to explore and experiment—without jeopardizing, of course, either the pilot or the mission.

In the six weeks leading to the launch, the MA-7 flight plan was therefore repeatedly refined and modified to include experiments with fluids in zero-G and tests of various kinds. A tethered multicolored Mylar balloon was both an experiment in drag (that Cooper would repeat during MA-9) and a test of human visual acuity in space The latter would help engineers with techniques and navigation studies then being developed for Gemini and Apollo rendezvous and docking operations. The plan also called for a heavy maneuver program, more extensive observations and measurements, and more photographs of the earth from space, requested by the Weather Bureau and by MIT, which provided special film and filters.

It was hoped, in addition, that Carpenter would resolve the mystery of John Glenn’s “fireflies,” the term Glenn used to describe the swarm of luminous particles that surrounded his ship at times. Such was the dearth of knowledge at the time that, after MA-6, serious academic “fireflies” conferences were convened. Were they living organisms perhaps posing a threat to astronauts and their capsules during spaceflight? No one knew. It was Carpenter’s job to find out.

The flight of Aurora 7, while busy and at times quite hot for the pilot, was largely without incident. Carpenter worked through his experiments methodically, combating both balky suit temperature settings and cabin temperatures that peaked at 108 degrees F. Although he could not jettison the Mylar balloon (one of the experiments), he was able to take some drag measurements and to report that, of the five colored lunes, the day-glo orange and the aluminum paints were the most visible in space, with the former by far the most brilliant.

Low fuel readings created some concern, by the end of the second circuit, and necessitated a long period of drifting flight during the third and final orbital pass of Aurora 7. According to the NASA history, this “vehicle control relaxation maneuver” would be an extremely valuable experiment, if successful, for mission planners then devising rest and sleep periods for the longer-duration Mercury missions.

Manned spaceflight in 1962 had not yet, however, become a routine business, and so the flight of Aurora 7 produced some dramatic moments. At retrofire the Automatic Stabilization and Control System (ASCS) failed.

Some explanation here: on autopilot on several occasions (evident in the mission transcripts), Carpenter noted and reported erroneous attitude readings. Postflight analysis found that the errant attitude readings were caused by a malfunctioning pitch horizon scanner (PHS). As an intermittent malfunction, however, the misbehaving PHS resisted troubleshooting efforts. No one during the flight, not in Mercury Control, nor the pilot himself, tied the occasionally errant readings to the mysterious rates of fuel consumption during the first two circuits. With fuel conservation measures in place during the third and final circuit, according to This New Ocean, it was considered unwise to conduct “an adequate checkout of the ASCS before retrofire.”

As Aurora 7 approached retrofire, Chris Kraft, directing the flight from the Cape, wrote that he “considered this mission the most successful to date; everything had gone perfectly except for some overexpenditure of hydrogen peroxide fuel.” But because Carpenter had spent most of his third circuit in drifting flight, Kraft observed with approval that the pilot had successfully maintained more than 40 percent of his fuel in both the automatic and the manual tanks. According to the mission rules, this ought to be quite enough, reckoned Kraft, to thrust the capsule in the retrofire attitude, hold it, and then to reenter the atmosphere using either the automatic or the manual control system.

As he began to work through his pre-retrosequence checklist, Carpenter reached for equipment to stow and accidentally rapped the walls of his cabin. The force of the blow produced a swarm of fireflies, which Carpenter had observed throughout the flight. But this time, the astronaut experienced a “Eureka!” moment. The Glenn “fireflies” mystery was resolved. The fireflies were, Carpenter explained in his voice report, capsule-emanating “frostflies”—particles of ice and frost that posed no danger to the vessel or crew.

Returning quickly to his pre-retrosequence tasks (equipment stowage, establishing retroattitude, etc.) and working with the Hawaii capcom, Carpenter reverted to autopilot, reporting: “Wait a minute. I have a problem in—”

Thirty-three seconds passed until, finally, the pilot of Aurora 7 confirmed the malfunction: “I have an ASCS problem here.”

The ASCS would not hold the 34-degree pitch and zero-degree yaw attitude required at retrofire. The pitch horizon scanner, hewing to a false read of the horizon, had jerked the spacecraft off proper retroattitude in both pitch and yaw. Quickly resuming control of his craft, Carpenter manually established proper pitch attitude, with easy reference to the horizon. But he was unable, in the time available, to bring the spacecraft to the required 0 degrees in yaw.

Postflight analysis showed that at retrofire the capsule was yawed to the right about 25 degrees. Meanwhile, the retrorockets had failed to fire automatically. The three seconds it took to fire them manually, combined with underthrusting retrorockets (and the error in yaw), produced a 250-mile overshoot of the planned landing zone—with no recovery forces nearby. Before loss of communication, Gus Grissom, capcom at the Cape, informed Carpenter that he could expect forces to pick him up an hour after splashdown. “Understand,” Carpenter replied, “One hour.”

He landed 135 miles northeast of Puerto Rico at 12:41 p.m. EST, 4 hours and 58 minutes after his 7:43 a.m. launch from Cape Canaveral, Florida. Because the actual landing took place outside NASA’s line-of-sight radio range, Aurora 7 was unable to communicate with the Cape. In the 55 minutes it took to locate the astronaut, network newscasters openly speculated that Carpenter had been lost, fueling the public’s mounting concern for the astronaut’s safety.

Yet NASA radar had tracked the capsule during reentry, pinpointed his landing site, and received intermittent voice reception, while a P2V airplane pilot in the area had picked up the Aurora 7 beacon “from a distance of only 50 miles,” Mercury Control neglected, however, to share this glad information with both the press and the astronaut’s wife and four children, who were watching the television news coverage in a beach house near the Cape.

After egressing through the nose of his spacecraft, Carpenter, resting in a life raft, was joined about an hour after splashdown by air force pararescue divers. Two hours later he was winched aboard a recovery helicopter and flown to the USS Intrepid. There he took congratulatory calls from Vice-President Lyndon B. Johnson and President John F. Kennedy and underwent a cursory medical examination. He was found to be in excellent condition, if mildly dehydrated. He had lost more than seven pounds during his five-hour flight—mostly through perspiration.

Carpenter was flown to Grand Turk Island for two days of debriefings, additional medical tests, and an afternoon of scuba diving. He returned to Patrick A.F.B on May 26 for a reunion with his wife, Rene, and their four children, Scott, Jay, Kris, and Candy.

The overshoot, the hour-long silence, and public concern for Carpenter’s well-being combined to make the flight of Aurora 7 one of the more dramatic U.S. spaceflights.

A Postscript

News coverage for MA-7 ended about a week after the flight—in early June 1962. Yet the vexing PHS malfunction was diagnosed weeks later. It was first described in NASA’s bluebook report, The Results of the United States Second Manned Orbital Mission, which concluded among other things that the pilot overcame a “mission critical malfunction” of the pitch horizon scanner and “achieved all mission objectives,” and proving once more how essential humans are in manned spaceflight.

But the NASA findings were lost on most journalists covering Project Mercury, and therefore among the reading public. The overshoot therefore became a lingering mystery somehow connected (incorrectly) with vague recollections about a last-minute fireflies discovery, a crowded flight plan, etc.

As nature abhors a vacuum, so mysteries give rise to fancy. Over time, fanciful accounts of the flight of Aurora 7 moved in to fill the story-telling vacuum. The hypertechnical explanations were forgotten (or ill understood), giving way to less-than-accurate versions, which with repetition over the years morphed into imaginative accounts that assumed the status of legend. As legend, these counterfactual versions of the flight of Aurora 7 began to appear in print, taking on even greater apparent authority.

For the facts about the flight of Aurora 7, the following histories, technical reports, biographies, and other nonfiction books are recommended:

Loyd S. Swenson, Jr., James M. Grimwood, Charles C. Alexander, This New Ocean: A History of Project Mercury (Washington, D.C.: NASA, 1998), pp. 443–460.