RESULTS OF THE SECOND U.S. MANNED ORBITAL SPACE FLIGHT, MAY 24, 1962

 

3. MISSION OPERATIONS

 

By John D. HODGE, Asst. Chief for Flight Control, Flight Operations Division, NASA Manned Spacecraft Center; Eugene F. KRANZ, Flight Operations Division, NASA Manned Spacecraft c enter; and William C. HAYES, Flight Operations Division, NASA Manned Spacecraft Center

 

[27] Summary

 

A discussion of the detailed operational support provided during the MA-7 mission, including prelaunch, launch, flight, and recovery phases, is presented. Since the launch vehicle countdown and prelaunch phase was nearly identical to that for MA-6, this activity is given minor emphasis. The launch phase proceeded almost perfectly, with only a last-minute hold for weather. Powered flight was normal, and the Mercury spacecraft was inserted into a nominal orbit with exceptional precision. The flight was satisfactorily monitored by the ground stations of the Mercury Network, and their activities are presented chronologically. No major flight discrepancies were evident during the orbital phase until just prior to retrofire, when it was discovered that the automatic control system was not operating properly. The astronaut was instructed by ground personnel to effect a manual retrofire maneuver. Radar tracking data subsequent to this maneuver indicated that the spacecraft would land 250 nautical miles downrange of the planned landing point. Following contingency recovery procedures, the astronaut was recovered by helicopter some 3 hours after landing, and the spacecraft was retrieved by a recovery destroyer approximately 3 hours later.

 

Introduction

 

In the present paper, the flight control and recovery operations for the MA-7 mission will be discussed in detail. Since the launch support procedure was discussed in the MA-6 flight report (ref.1), it will be only discussed briefly. Some small changes from the MA-6 operational support were made, most of which were associated with the development of appropriate support procedures for the future missions of longer duration. Network support is discussed in detail in paper 2. Based on previous experience, it was found that the total recovery support used for MA-6 could be slightly reduced for MA-7. The flight plan was basically the same as that for the MA-6 mission with two significant differences: the astronaut was given a greater amount of manual-control tasks to perform; and a large number of experiments were to be accomplished.

 

Prelaunch Activities

 

During the prelaunch period, four flight controller network exercises were performed. A new network countdown was used, and a high degree of confidence was established in the countdown format during this time. These drills were very similar in content to those performed for the MA-6 mission. Flight controllers quickly obtained a high degree of confidence in various site and network procedures and reached a high level of performance very early in the schedule. They maintained this performance level throughout all the network simulations and during the actual MA-7 flight. The countdown for launching the Mercury-Atlas vehicle is conducted in two parts. The first part is conducted on the day before the launch and lasts approximately 4 1/2 hours. This part of the countdown was conducted with no major problems or delays. The second part of the countdown was probably as close to perfect for the launch vehicle, spacecraft, and network as could ever be expected. There were some minor problems throughout the network; however, none of these resulted in the necessity for a hold, and the coordination between the various agencies involved was excellent. A hold of about 45 minutes at T-11 minutes [28] in anticipation of better camera coverage and to allow aircraft to check the atmospheric refraction index ill in the vicinity of Cape Canaveral for the launch-vehicle guidance equipment.

 

Powered Flight Phase

 

The occurred at 07:45:16 a.m. e.s.t. in May 24, 1962, Sustainer engine cutoff occurred at 5 minutes 10 seconds ground elapsed time (g.e.t.) The "go" capability as indicated by the Goddard Space Flight Center computers was obtained and transmitted to the astronaut at 5 minutes 32 seconds. The powered portion of flight was completely normal, and the astronaut was able to make all of the planned communications and observations throughout this period. The Mercury Control Center go-no-go decision at cutoff was made rapidly, and there was no doubt that conditions very close to normal had been achieved. Table 3-I presents the actual cutoff conditions that were obtained. A comparison of the planned and actual times at which the major events occurred are given in table 3-II.

 Table 3-I. Actual Flight Conditions.

Cutoff conditions:

Altitude, ft

527,859

Velocity, ft/sec

25,717

Flight-path angle, deg.

-0.0004

Orbit parameters:

Perigee altitude, nautical miles

86.87

Apogee altitude, nautical miles

144.96

Period, mn:sec

88:32

Inclination angle, deg

32.55

Maximum conditions:

Exit acceleration, g units

7.8

Exit dynamic pressure, a lb/sq ft

967

Entry acceleration, g units

7.5

Entry dynamic pressure, lb/sq ft

429

a Based on the atmosphere at Cape Canaveral.

 

 

Table 3-II. Sequence of Events During MA-7 Flight.  

Event Preflight predicted time,
hr:min:sec
Actual time,
hr:min:sec

Booster engine cutoff (BECO)

00:02:10.1

00:02:08.6

Tower release

00:02:32.2

00:02:32.2

Escape rocket firing

00:02:32.2

00:02:32.2

Sustainer-engine cutoff (SECO)

-

00:05.09.9

Tail-off complete

00:0505.3

00:05:10.2

Spacecraft separation

00:05.06.3

00:05:12.2

Retrofire sequence initiation

04:32:25.6

04:32:36.5

Retro (left) No.1

04:32:55.6

04:33:10.3

Retro (bottom) No.2

04:33:00.6

04:33:15.3

Retro (right) No.3

04:33:05.3

04:33:20.5

Retro assembly jettison

04:33:55.6

04:34:10.8

0.05 g relay

04:43:55.6

04:44:44

Drogue parachute deployment

04:50:00.6

04:50:54

Main parachute deployment

04:50:37.6

04:51:48.2

Water impact

04:55:22.6

04:55:57

Main parachute jettison

04:55:22.6

04:56:04.8

 

 

Orbital Flight Phase

 

After separation of the spacecraft from the launch vehicle, the astronaut was given all pertinent data involved with orbit parameters and the necessary retrofire times were transmitted. A remoting facility for transmitting air-to-ground voice for the Mercury Control Center through the Bermuda site transmitters was implemented for the MA-7 mission. This facility enabled the Mercury Control Center Capsule Communicator (Cap Com) to transmit spacecraft systems data and orbital information to the astronaut in real time; therefore, much of the requirement for relaying information between the Canaveral and Bermuda Flight Controllers was eliminated. From the summary messages received from the African sites, it became readily apparent that the suit cooling system was not correctly adjusted and that the astronaut was uncomfortable. However, the [29] suit temperature began to decrease when the astronaut increased the water flow in the suit cooling circuit. By the end of the first orbit it had reduced to n satisfactory value. Other than the slight discomfort due to the high suit temperature, the astronaut was obviously in good condition and performing satisfactorily throughout the first orbit. The Canary Island site transmitted r radar data to the Goddard computers, and these data confirmed the orbital insertion parameters and all extremely good orbital definition was obtained. Over the Woomera station, the astronaut reported that he took four swallows of water and that his bite-sized food tablets had crumbled in the container and some particles of food were floating free in the cabin. He was able to eat some of the crumbled food.

Toward the end of this pass, a slight increase in body temperature was noted. The Canton Island site then reported a body temperature of 102°. However, the Mercury Control Center surgeon felt such a rapid increase was not probable and that the transducer had either failed or had been affected by the telemetry calibrate command transmitted from the Muchea site. The only other problem was the large amount of automatic control system fuel being used by the astronaut during the first orbit. He was cautioned against further excessive usage of this fuel during the orbital pass over the United States. The air-to-ground transmissions relayed via the Goddard voice loop during the first orbit were of good quality and provided the Mercury Control Center with information available from the air-ground voice communications of the astronaut. The network air-ground voice quality, although not as good as the previous MA-6 mission, continued to be usable throughout the remaining orbits and provided one of the best tools for maintaining surveillance of the flight. The spacecraft clock performed satisfactorily throughout the entire mission. The initial clock error of -1 second remained constant throughout the mission and was compensated for in the retrosequence settings that were transmitted to the astronaut. During the first orbit, the network radar systems were able to obtain excellent tracking data and these data, together with the data obtained at cutoff, provided very adequate information on the spacecraft position and orbit. As an example, the retrosequence time computed at insertion was changed only 11 seconds by the Bermuda data, and thereafter, the time varied within ± 1 second throughout the mission. The balloon was deployed during contact with Cape Canaveral 1 hour 38 minutes after lift-off. During the first portion of the second orbit, the suit temperature indicated a rise from 70° at Cape Canaveral to approximately 90° during contact with the Indian Ocean Ship, but again showed a decrease in trend before acquisition by the Muchea and Woomera stations. It was obvious throughout the flight that he pilot was having difficulty in achieving the proper waterflow setting for the suit-cooling system. There is about a 30-minute lag in the cooling system in response to a change in the valve setting and as a result it was difficult to determine adequate setting. However, when the loss of signal (LOS) occurred at Woomera, the suit temperature had decreased to approximately 82° and during the remaining one and one-half orbits the suit temperature indicated a steady decrease to a value between 64° and 67°. Cabin- air-temperature readings were slightly higher with the MA-6 flight. A maximum of 108° was monitored by the Hawaii station near the end of the second orbit. This temperature decreased and tended to stabilize at about 100° during the remainder of this orbit and the first portion of the third orbit.

Over the Woomera site, the astronaut reported that he could temporarily change the spacecraft attitude by moving his arms and body. The mission continued normally throughout the remainder of the second orbit. The astronaut was behind the flight-plan schedule by several items, and it was noted at California acquisition that the astronaut had used rather large amounts of manual fuel and was down to approximately 42 percent as he began the third orbit. The low automatic and manual fuel quantities caused considerable concern on the ground and resulted in a further request to the astronaut to conserve his fuel in both the automatic and manual systems. Site evaluation of telemetry recordings during the first and second orbits indicated considerable high thruster activity. These indications generally occurred while the astronaut was in the fly-by-wire mode, and it appeared that he was employing [30] high thrusters excessively during attitude changes.

Throughout the flight the astronaut made a number of voice reports regarding visual observations and various experiments carried out in the flight. These reports are explained in more detail in paper 7.

The Mercury Control Center made a go decision for the beginning of the third orbit at 2 hours 55 minutes g.e.t. The astronaut was cautioned to conserve his fuel and it was suggested that he increase his water flow to the inverter cold plates. The inverters had indicated an increase in temperature similar to the previous MA-6 flight. This caused no major; however, the increased water flow reduced the rate of this temperature increase to an acceptable level. As a result of the request to conserve fuel, the astronaut entered a period of drifting flight at 3 hours 9 minutes g.e.t. while he was in contact with Cape Canaveral. Over Mercury Control Center during the third orbit, 45 percent of the fuel in the automatic system and 42 percent of the fuel on the manual system remained. Over the Indian Ocean Ship, the astronaut attempted to jettison the balloon manually and reported that he was unable to accomplish this although the switch was cycled several times.

During the third orbit, all systems appeared to be normal. The clock was reset to 04:32:34, the retrofire time for the end of the third orbit, by the astronaut while in contact with the Muchea station.

 

Reentry Phase

 

Upon contact with Hawaii at the end of the third orbit, the astronaut was instructed to begin his preretrosequence check list and to revert from his present manual control mode to the automatic mode in preparation for retrosequence. The retrosequence check list was started but when the astronaut returned to automatic control, he reported having trouble with this system and, as a result, was unable to complete the list. The capsule communicator at Hawaii continued transmitting the remainder of the preretrosequence check list after loss of telemetry contact, and most of the transmission was received by the astronaut. However, the ground was unable to confirm that it had been received because of the limited UHF range of the spacecraft. From both astronaut reports and telemetry readouts during the periods in which the astronaut was using automatic control over remote sited during the mission, it appeared that no major difficulty was experienced while using this system. The astronaut reported the automatic stabilization and control system (ASCS) to be performing satisfactorily on several occasions. Although some differences between horizon scanner outputs and the spacecraft attitudes had been noted, they were not considered to be any reason for concern because of the control configuration at the time. Therefore, the failure of the ASCS system to maintain proper attitudes when engaged by the astronaut over Hawaii was unexpected. When voice communications were established with the California station, the astronaut continued to have problems on ASCS and, with advice from the capsule communicator, elected to perform the retrofire maneuver using manual control. During this period the astronaut used a combination of window reference, periscope, and attitude displays.

The astronaut was directed to initiate retrofire manually and to bypass the attitude permission circuit. The countdown was transmitted from California, but it was apparent that the retrofire had taken place several seconds late. Initial reports from the astronaut indicated that the attitudes had been held fairly well during retrofire. The California station reported that the velocity change indicated by the integrating accelerometer was normal. The radar data from California indicated an overshoot but the indication was suspected to be in error because of previous reports. However, as additional radar data became available from other sites, it was obvious that the California radar data were correct and that the landing point would be approximately 250 nautical miles beyond the planned position. Because of the small amount of automatic fuel remaining following retrofire and the complete depletion of manual fuel, the astronaut was instructed to use as little fuel as possible in returning the spacecraft to reentry attitude and to conserve the fuel for use during reentry. He was also instructed to use the ASCS auxiliary damping [31] mode during the atmospheric reentry portion of the flight.

Upon contact with Cape Canaveral just previous to the loss of communications as a result of ionization blackout, the astronaut was queried as to his face-plate position. He indicated that it was still open, and proceeded to close it. The communication blackout occurred about 40 seconds late, an occurrence which lent to further evidence to the longer reentry range predicted by the radar. The astronaut was told that his landing point would be long and would occur at approximately 19°23' N., 63°51' W. From this point no voice communications were received from the astronaut; however a brief period of telemetry data was obtained after blackout. A number of communications were attempted with the command voice system and the normal UHF and HF voice system on the chance that he might receive this information. All operating C-band radars at Cape Canaveral and San Salvador tracked the C-band beacon until the spacecraft went below the local horizon indicating that he spacecraft had reentered satisfactorily, and these radar data continued to predict approximately the same landing point.

 

Recovery Operations

 

The operation of recovery forces for this mission was very similar to that for the MA-6 mission. Planned landing areas were established in the Atlantic as shown in figure 3-1 to cover aborts during powered flight and landing at the end of each orbital pass. The disposition of....

 

 Table 3-III. Disposition of Recovery Forces in Planned Landing Areas.

Area Search aircraft Search and rescue aircraft Helicopters Ships Maximum recovery time, hr

Aa

4

2

0

9

3 to 6

B

1

0

0

1

6

C

1

0

0

1

3

D

1

0

0

1

6

E

1

0

0

1

6

F

0

0

3

2

3

G

1

0

3

2

3

H

2

1b

3

3

3

Total

11

3

9

20

-

a Launch site recovery forces consisted of 3 helicopters, several amphibious vehicles, and small boats.
b Launched as a precautionary measure when the astronaut began the third orbital pass.
 
 


map of planned landing areas

Figure 3-1. Planned landing areas.

 

...the recovery forces in the planned landing areas is shown in table 3-III. Area H is the planned landing area for the end of the third orbit, and recovery in this area could be effected within 3 hours of landing. Special aircraft were deployed on a standby basis to locate the spacecraft and render pararescue assistance within 18 hours of landing at any point along the ground track. During the entire mission, all recovery forces were informed of the flight progress by the Recovery Control Center. Shortly after the astronaut began the third pass, an Air Rescue Service SC-54 aircraft with a specially trained pararescue team aboard was dispatched as a precautionary measure from Roosevelt Roads, Puerto Rico, and assigned a position at the downrange end of landing area H. As soon as the calculated landing position was established about 250 nautical miles downrange of the center of area H, all units in area H were instructed...

 

 [32] Table 3-IV.- Chronological Summary of Post-Landing Events.

e.s.t.,
hr:mn
Elapsed time
from landing, hr:mn
Event

11:18 a.m.

-

As a precautionary measure, Air Rescue Service SC-54 was launched from Roosevelt Roads, Puerto Rico, to take station on downrange. end of Area H. The SC-54 had specially trained pararescue team aboard.

12:22 p.m.

-

Retrorockets were ignited

12:33 p.m.

-

Calculated landing position was reported as being 19°24' N. latitude, 63°53' W. longitude. Air Rescue Service SA-16 (amphibian) was launched and instructed to proceed to this point.

12:35 p.m.

-

All units in area El were proceeding to calculated landing position.

12:41 p.m.

00:00

Spacecraft landed.

12:44 p.m.

00:03

Contingency recovery situation was established at Recovery Control Center. Recovery commander in area H (embarked on U.S.S. Intrepid was designated mission coordinator. Positions of vessels in vicinity of landing point were requested from Coast Guard and other Naval commands (see fig. 3-2).

12:47 p.m.

00:06

Search aircraft reported possible UHF/DF contact with spacecraft at 04:54 g.e.t.

12:58 p.m.

00:17

Destroyer U.S.S. Farragut was proceeding to calculated landing position.

12:59 p.m.

00:18

All search aircraft were executing search plan. Had positive UHF/DF contact with spacecraft.

1:20 p.m.

00:39

Search aircraft reported visual contact with green dye at 19°29' X. 64°05' W. (Spacecraft employs flourescein sea-marker.)

1:21 p.m.

00:40

Search aircraft reported astronaut in liferaft attached to spacecraft.

1:27 p.m.

00:46

Search aircraft reported that astronaut appeared to he comfortable.

1:34 p.m.

00:53

The SC-54 descended to deploy pararescue team and auxiliary flotation collar.

1:40 p.m.

00:59

Pararescue team was deployed

1:40 p.m.

00:59

Two HSS-2 helicopters were launched from U.S.S. Intrepid with Mercury Project doctor and specially equipped swimmers aboard.

1:50 p.m.

01:09

The SA-16 arrived on scene.

1:56 p.m.

01:15

The SA-16 descended to evaluate sea state condition for possible landing.

2:15 p.m.

01:34

The SA-16 reported sea condition satisfactory for landing and take off.

2:21 p.m.

01:40

Astronaut appeared normal, and waved to aircraft. Pararescue team was in water Helicopters were enroute to spacecraft. The SA-16 was instructed not to land unless helicopter retrieval could not be made.

2:39 p.m.

01:58

Auxiliary flotation collar was attached to spacecraft and inflated..

2:52 p.m.

02:11

Astronaut and pararescue team were in water. There was no direct communication with astronaut. Astronaut appeared to be in good condition.

3:30 p.m.

02:49

Helicopter arrived over spacecraft.

3:40 p.m.

02:59

Astronaut was in helicopter. Doctor reported astronaut in good condition.

3:42 p.m.

03:01

Helicopter retrieved pararescue team. Astronaut Carpenter reported, "Feel fine." Destroyer U.S.S. Farragut was 18 miles from spacecraft.

4:05 p.m.

03:24

Helicopters returned to the U.S.S. Intrepid accompanied by SA-16 and search aircraft.

4:20 p.m.

03:39

U.S.S. Farragut had spacecraft in sight.

4:52 p.m.

04:11

Astronaut arrived aboard U.S.S. Intrepid .

6:16 p.m.

05:35

U.S.S. John R. .Pierce had U.S.S.. Farragut in sight.

6:52 p.m.

06:11

U.S.S. Pierce had spacecraft onboard.

7:15 p.m.

06:34

Initial medical examination and debriefing of astronaut was completed onboard U.S.S. Intrepid . Astronaut departed for Grand Turk Island.

 

[33] ...to proceed to this point. (See table IV for a chronological summary of post- landing events.) An Air Rescue Service SL-16 amphibian aircraft was also dispatched from Roosevelt Roads and instructed to proceed directly to the calculated landing position.

Since the landing was outside of a planned landing area, recovery procedures set up for such an eventuality were followed in the Recovery Control Center. The recovery commander in area H aboard the aircraft carrier, U.S.S. Intrepid was designated as mission on coordinator. Various United States Naval Commands and the Coast Guard were interrogated as to the location of merchant and naval ships. other than those assigned to recovery forces, to establish their availability for possible assistance in the recovery operations. The location of units available to assist in recovery operations at the time of spacecraft landing is shown in figure 3-2.

Search aircraft from area H quickly obtained a bearing on the spacecraft UHF/DF electronic location aids and proceeded to establish visual contact with the spacecraft about 40 minutes after landing. The astronaut was reported as seated comfortably in his liferaft beside floating spacecraft. The SC-54 aircraft arrived shortly thereafter and deployed the pararescue team with a spacecraft auxiliary flotation collar and other survival equipment to render any necessary assistance to the astronaut and to provide for the continued flotation of the spacecraft. A photograph of the spacecraft in the flotation collar is presented in figure 3-3.

Information received from the Coast Guard and Navy indicated a Coast Guard cutter at Saint Thomas, Virgin Islands; a destroyer, the U.S.S. Farragut, located about 90 nautical miles...

 


map depicting landing area

Figure 3-2.- Landing area details.

 


[MISSING] Figure 3.3.- Spacecraft in flotation collar.

 

....southwest of the calculated landing position; and a merchant ship located about 31 nautical miles north of the calculated landing position. It was determined that the Farragut could arrive at the spacecraft first, and it was directed to proceed at best speed. Two twin-turbine HSS-2 helicopters were launched from the carrier Intrepid to retrieve the astronaut. The first helicopter carried a doctor from the special Mercury medical team assigned to the Intrepid for postflight examination and debriefing of the astronaut. The recovery helicopters also contained two specially trained divers equipped with a second spacecraft auxiliary flotation collar. The SA-16 then arrived at the spacecraft and prepared for landing in the event such action would be required before the arrival of the helicopters. Although the landing point was outside the planned landing area, the astronaut was retrieved by helicopter, as shown in figure 3-4, in slightly less than 3 hours after landing.

 


[MISSING] Figure 3.4.- Astronaut being retrieved by helicopter.

 

[34] He was returned to the U.S.S. Intrepid for medical examination and debriefing and was later flown to Grand Turk Island.

The destroyer U.S.S. Farragut arrived at the spacecraft and kept it under close surveillance until the destroyer, U.S.S. John R. Pierce, arrived with special retrieval equipment to make the pickup as shown in figure 3-5. The spacecraft was delivered to Roosevelt Roads by the destroyer, with a subsequent return to Cape Canaveral by airplane.

 


[MISSING] Figure 3.5.- Spacecraft retrieval by destroyer.


Reference

1. ANON.: Results of the First United States Manned Orbital Space Flight, February 20, 1962. NASA Manned Spacecraft Center.


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