Mercury-Atlas 7, launched May 24, 1962, was the fourth crewed flight of Project Mercury. The spacecraft, named Aurora 7, was piloted by astronaut Scott Carpenter. He was the sixth human to fly in space. The mission used Mercury spacecraft No. 18 and Atlas launch vehicle No. 107-D.
The flight was for three Earth orbits, essentially a repeat of John Glenn's Mercury-Atlas 6. However, a targeting error during reentry took the spacecraft off-course, delaying recovery of Carpenter and the spacecraft for an hour. Carpenter was held responsible, at least in part, for the landing error. Carpenter left NASA for the Navy SEALAB program in 1964.
Pilot
The original pilot selected for Mercury Atlas-7 was to have been Deke Slayton, with Wally Schirra as his backup. However Slayton was removed from flight status after the discovery of idiopathic paroxysmal atrial fibrillation during a training run in the g-loading centrifuge. Slayton had chosen the name Delta7 for the spacecraft, as this would have been the fourth crewed flight and Delta (Δ) is the fourth letter in the Greek alphabet. Instead of using Schirra, who was backup, it was decided to give the mission to Carpenter, who was the backup crew for Mercury-Atlas 6, had trained with John Glenn, and was considered the best-prepared astronaut. When Carpenter was given the mission, he renamed it Aurora 7 for the open sky and the dawn, symbolizing the dawn of the new age. The number Seven was also chosen for the Mercury 7 astronauts. In addition, Carpenter's home address in his childhood was the corner of Aurora Ave. and Seventh St. in Boulder, Colorado, although at a talk he gave at the Boulder Theater in 2003, Carpenter admitted that he never made the connection between the Aurora 7 spacecraft and the address of his youth until friends pointed it out to him after he made the flight.
- Apogee: 162 mi (260 km)
Changes made to Atlas 107D over Glenn's booster were minor. It had been agreed that the insulation blanket in the tank bulkhead was unnecessary and would be removed on subsequent Mercury-Atlas vehicles, although MA-7 would still retain it. The LOX tank skin was thickened still further due to the growing weight of the Mercury capsule as missions grew longer and more ambitious. A meeting of the Flight Safety Review Board on May 16 discussed the 12 Atlas flights since Glenn's launch and any anomalies on them that were of concern. There had been four major Atlas in-flight malfunctions during this stretch, but three were caused by random quality control defects unlikely to be a concern in the much more tightly supervised Mercury program. More concerning was Atlas 11F, which had exploded almost immediately at liftoff on April 9 and the static firing test of Atlas 1F, which exploded at Sycamore Canyon on May 13. Alan Shepard was the CAPCOM at California.
During flight
thumb|left|Astronaut Scott Carpenter leaving the White Room for the launch site to begin his Mercury-Atlas 7 (MA-7) mission.
Carpenter was awakened at 1:15 AM on the morning of the flight and ate a breakfast of orange juice, filet mignon, eggs, toast, and coffee.
Launch vehicle performance was overall excellent with one small anomaly in that one of the sustainer engine's hydraulic switches registered a loss of sustainer hydraulic pressure and moved to the abort position at T+265 seconds. Normal hydraulic system performance was substantiated by other flight data and as two hydraulic switches had to be tripped to signal an abort to the ASIS system, nothing happened and the flight proceeded as planned. The malfunction of the hydraulic switch was believed to be the result of cold temperatures due to nearby LOX lines; on subsequent flights thermal insulation would be added to prevent a recurrence. BECO was effected at T+124 seconds and SECO at T+305 seconds. The Atlas's flight path was so accurate that Aurora 7 reached almost the exact orbital parameters planned for the mission.
thumb|upright|MA-7 launch
Carpenter had solid food items for the first time, in the form of freeze-dried cubes in a plastic bag, instead of paste squeezed out of a tube, which produced problems with loose crumbs floating inside the cabin. The food cubes had been coated with an anti-crumbling agent, but may have accidentally been crushed prior to launch, breaking the coating. Carpenter expressed concern about crumbs being sucked into ventilation intakes in the capsule in addition to posing a possible choking hazard if ingested. In addition, a candy bar included in the food supply melted from high cabin temperatures (up to 102 °F). By the end of the second orbit, he informed Mercury Control that most of the food was a mess and he would avoid touching it for the rest of the flight aside from taking a xylose capsule.
It was then suspected that the fireflies were either steam from the life support system turning into ice crystals when exposed to open space or debris on the exterior of the spacecraft being shaken loose, however, the former was considered the more probable explanation. Steam generated by the life support system formed condensation between the spacecraft bulkhead and the heat shield which then escaped into space and froze.
Noting a disagreement between his attitude indicators and what he could see from the window and the periscope, Carpenter established retrofire attitude visually; Aurora 7 was in fact aimed 25 degrees right of the true retrograde vector. In addition to the attitude error, Carpenter also activated the retrorockets three seconds late, adding another 15 miles (24 km) or so to the trajectory error. Following retro jettison, Aurora 7's fuel gauges indicated 20% in the automatic tank and 5% in the manual tank. Carpenter intended to use his remaining manual fuel to establish reentry attitude, but found that the gauge was inaccurate and the manual tank was actually empty. Due to compounding issues and lack of fuel, Carpenter overshot his planned reentry mark and splashed down from the target.
thumb|Scott Carpenter is received on board USS Intrepid
After nearly an hour of searching, Carpenter was located in an area northeast of Puerto Rico. USS Farragut was the first ship to arrive at the spacecraft nearly forty minutes after splashdown had occurred. Two helicopters dispatched from the aircraft carrier reached the scene and transported Carpenter back to Intrepid and over the next several hours Farragut remained on the scene watching the spacecraft until USS John R. Pierce arrived with special equipment enabling her to tow Aurora 7 to Roosevelt Roads Puerto Rico where it was then flown back to Cape Canaveral.
Other than slight exhaustion, Carpenter was in good health and spirits and post-flight medical exams did not find any significant physical changes or anomalies. Kraft, however, was unhappy with the astronaut's performance due to his needlessly high expenditure of attitude control fuel, which resulted in reentry and landing taking place well off-course. As a result, Carpenter was sidelined for future missions. He left the space program in 1964 to participate in the Navy's SEALAB program.
Aurora 7 is displayed at the Museum of Science and Industry in Chicago, Illinois.
Mercury-Atlas three-orbit flight events
{| class="wikitable"
! T+ Time
! Event
! Description
|-
| T+00:00:00
| Liftoff
| Mercury-Atlas lifts off, onboard clock starts.
|-
| T+00:00:02
| Roll Program
| Mercury-Atlas rotates along its axis 2.5 deg/s from 30° to 0°.
|-
| T+00:00:16
| Pitch Program
| Mercury-Atlas begins a 0.5 deg/s pitch from 90° to 0°.
|-
| T+00:00:30
| Radio Guidance Lock
| General Electric-Burroughs guidance system locks onto radio transponder in Atlas booster to guide the vehicle until orbit insertion.
|-
| T+00:01:24
| Max Q
| Maximum dynamic pressure ~980 lbf/ft² (47 kPa)
|-
| T+00:02:10
| BECO
| Atlas Booster Engine Cutoff. Booster engines drop away.
|-
| T+00:02:33
| Tower Jettison
| Escape Tower Jettison, no longer needed.
|-
| T+00:02:25
| Atlas Pitchover
| After tower separation, vehicle pitches over further.
|-
| T+00:05:20
| SECO
| Atlas Sustainer Engine Cutoff, spacecraft reaches orbit, velocity 17,547 mph (7,844 m/s).
|-
| T+00:05:24
| Spacecraft Separation
| Posigrade rockets fire for 1 second giving 15 ft/s (5 m/s) separation.
|-
| T+00:05:25
| 5-Second Rate Damping
| ASCS damps spacecraft rates for 5 seconds in preparation for turnaround maneuver.
|-
| T+00:05:25
| Turnaround Maneuver
| Spacecraft (ASCS) system rotates spacecraft 180 degrees, to heat shield forward attitude. Nose is pitched down 34 degrees to retro fire position.
|-
| T+00:05:30<br>T+04:30:00
| Orbital Operations
| Orbital operations and experiments for 3 orbits.
|-
| T+04:30:00
| Retro Sequence Start
| Retrofire in 30 s; (ASCS) checks for proper retro attitude −34° pitch, 0° yaw, 0° roll.
|-
| T+04:30:30
| Retrofire
| Three retro rockets fire for 10 seconds each. They are started at 5 second intervals, firing overlaps for a total of 20 seconds. Delta V of 550 ft/s (168 m/s) is taken off forward velocity.
|-
| T+04:31:00
| Retract Periscope
| Periscope is automatically retracted in preparation for reentry.
|-
| T+04:31:50
| Retro Pack Jettison
| One minute after retrofire retro pack is jettisoned, leaving heatshield clear.
|-
| T+04:33:00
| Retro Attitude Maneuver
| (ASCS) orients spacecraft in 34° nose down pitch, 0° roll, 0° yaw.
|-
| T+04:40:30
| 0.05 G Maneuver
| (ASCS) detects beginning of reentry and rolls spacecraft at 10 degrees per second to stabilize spacecraft during reentry.
|-
| T+04:50:20
| Drogue Parachute Deploy
| Drogue parachute deployed at 22,000 ft (6.7 km) slowing descent to 365 ft/s (111 m/s) and stabilizing spacecraft.
|-
| T+04:50:25
| Snorkel Deploy
| Fresh air snorkel deploys at 20,000 ft (6 km). ECS switches to emergency oxygen rate to cool cabin.
|-
| T+04:51:55
| Main Parachute Deploy
| Main parachute deploys at 10,000 ft (3 km). Descent rate slows to 30 ft/s (9 m/s).
|-
| T+04:52:00
| Landing Bag Deploy
| Landing Bag Deploys, dropping heat shield down four feet (1.2 m).
|-
| T+04:52:30
| Fuel Dump
| Remaining hydrogen peroxide fuel automatically dumped.
|-
| T+04:57:10
| Splashdown
| Spacecraft lands in water.
|-
| T+04:57:10
| Rescue Aids Deploy
| Rescue aid package deployed. The package includes green dye marker, recovery radio beacon, and whip antenna.
|}
See also
- Splashdown
References
External links
- Results of the Second U.S. Manned Orbital Space Flight, May 24, 1962 NASA report - (PDF format)
- This New Ocean: A History of Project Mercury - NASA report (PDF format)
- Project Mercury: A Chronology - NASA report (PDF format)
- NASA NSSDC Spacecraft Details