RESULTS OF THE THIRD U.S. MANNED ORBITAL SPACE FLIGHT, OCTOBER 3, 1962

 

2. MISSION OPERATIONS

By John D. Hodge, Asst. Chief for Flight Control, Flight Operations Division; Eugene F. Kranz, Flight Operations Division; and John Stonesifer, Flight Operations Division

 

Summary

 

[13] A discussion of the detailed operational support provided during the MA-8 mission, including the prelaunch, launch, orbital, and recovery phases, is presented. Because the prelaunch preparation and the launch countdown for the spacecraft and launch vehicle were nearly identical to that performed for the first two U.S. manned orbital missions these activities are given only minor emphasis. The launch phase proceeded almost perfectly, except for a brief hold of 15 minutes' duration which occurred at T-45 minutes for repairs to the Canary Island radar. The countdown continued thereafter without difficulty. The powered flight phase was normal, and the spacecraft was inserted into a nominal orbit. The flight was satisfactorily monitored by personnel located at ground stations around the Mercury network, and their activities are presented chronologically. The only flight discrepancy which caused concern was a suitcooling problem during the first orbital pass. The astronaut corrected this problem by gradually increasing the flow of coolant water to the suit heat exchanger. The mission continued normally after the suit temperature had reached a more satisfactory value, and the astronaut's management of the onboard systems was excellent. The astronaut used the automatic stabilization and control system to perform successfully the retrofire and reentry maneuvers. Initial computations using flight data at retrofire indicated that the landing point would be very close to the recovery aircraft carrier, the U.S.S. Kearsarge. The spacecraft was observed visually during descent on the main parachute and, after landing about 4 nautical miles from the carrier, was placed aboard ship in approximately 40 minutes.

 

Introduction

 

In the present paper, the flight control and recovery operations for the MA-8 mission are discussed in detail. Since the launch support procedure was discussed in reference 1, it will only be mentioned briefly. A very limited number of changes in the operational support from the two previous missions was made. Most of these changes were instituted in anticipation of longer duration missions after MA-8. Based on the extended mission for MA-8, the recovery support was grouped in a general area south of Bermuda and a second support activity was provided near Midway Island in the Pacific Ocean. The flight plan differed significantly from those of the two previous missions, primarily because of the greater emphasis placed on the engineering aspects of the flight. Most of the flight activities conducted during the mission were designed to establish greater confidence in the operation of spacecraft systems for longer duration missions, to provide a detailed check of the long-term, operating characteristics of the automatic stabilization and control system (ASCS), and to determine if the spacecraft window would provide an adequate yaw reference under all conditions.

 

Prelaunch Activities

 

During the prelaunch period, a total of 7 days were spent in conducting simulation exercises. Two days were utilized in conducting launch simulations with the Mercury Control Center and Bermuda flight control teams and the astronauts in attendance. One day was spent in performing four reentry simulations, which involved the Canton, Hawaii, California, Guyamas, and Mercury Control Center stations. These simulations were conducted in an [14] effort to familiarize the personnel at these stations with reentry decision techniques and retrosequence procedures when faced with various spacecraft systems problems. Three full network simulations were performed in fast time. The fast-time procedure primarily consisted of a real-time mission from lift-off to a ground elapsed time (g.e.t) of 03:20:00. At this time, the computers used in the simulations were fast-timed until 07:10:00 g.e.t. when the mission was resumed in real time.

The flight control teams at the majority of the network stations included one or two new personnel, and all simulations were profitable in providing detailed training in network operations for these new flight controllers. A high level of performance was demonstrated by the flight control teams very early in the schedule. The flight controllers maintained this performance level throughout all of the remaining network simulations and during the actual MA-8 mission.

The countdown for launching the Mercury-Atlas vehicle is conducted in two parts. The first part, lasting approximately 4 hours, was conducted on October 2, 1962, and was completed satisfactorily. The second part of the countdown was initiated after the detailed hydrogen peroxide surveillance test, and the flight control team joined the spacecraft and launch vehicle countdown at approximately T-3 hours. The astronaut was suited (see fig. 2-1) and transported to the launch complex for insertion into the spacecraft. The countdown continued normally until T-45 minutes, at...

 


[MISSING] Figure 2-1.-Astronaut Schirra being suited prior to launch.

 

....which time the Canary Islands radar unit became temporarily inoperative because of a driver-unit failure, and the countdown was interrupted for 15 minutes to allow repair of this unit. The Canary Islands station is important during the initial phases of the mission, primarily because it is the first network station to establish radar contact after sustainer engine cut-off.

The resulting data provide an early confirmation of the orbital insertion conditions and trajectory. In the case of marginal cut-off conditions, the Canary Islands radar data provide enough information concerning the orbital capability to make any necessary go- no-go decision at the end of the orbital pass. With this unit inoperative, the decision from a later station regarding orbit capability would become time critical. After resuming the countdown at T-45 minutes, no further holds were experienced, and all systems were "go" during the remainder of the period prior to lift-off.

Lift-off occurred at 7:15:11 a.m. e.s.t. on October 3, 1962 and the powered flight phase was monitored routinely The quality of the air-ground (A/G) communications was reduced somewhat by the increased background noise near staging; however it improved rapidity and was satisfactory during the remainder of powered flight. Throughout- this phase, the astronaut was able to make all the communications and observations indicated in the flight plan. The "go" capability as indicated by the computers at the Goddard Space Flight Center, was confirmed and transmitted rapidly to the astronaut at 00:05:44 g.e.t.

Table 2-I presents the actual cut-off conditions orbital parameters and maximum conditions that were obtained. A comparison of the planned and actual times at which major events occurred is given in table 2-II.

 

Orbital Flight Phase

 

After separation of the spacecraft from the launch vehicle the astronaut was given all pertinent data regarding orbit parameters and necessary retrosequence times. As in the MA-7 mission, the Bermuda voice-remoting facility (see ref. 2) was utilized to extend the communications capability of the Capsule Communicator (Cap Com) in the Mercury Control Center.

 

 

[15] Table 2-I.

Cut-off conditions:

Altitude, ft

528,467

Space-fixed velocity, ft/sec

25,730

Space-fixed flight-path angle, deg

-0.0062

Orbital parameters

Perigee altitude, nautical miles

86.94

Apogee altitude, nautical miles

152.8

Period, min:sec

88:55

Inclination angle, deg.

32.55

Maximum conditions:

Exit acceleration, g units

8.1

Exit dynamic pressure, a lb/sq ft

964

Reentry acceleration, g units

7.6

Reentry dynamic pressure, lb/sq ft

458

a Based on atmosphere at Cape Canaveral.

 

 

From the A/G voice communications and summary messages received from network stations during the early portion of the first orbital pass, it became readily apparent that the suit-cooling system was not as effective as had been expected. The suit temperature, as indicated....

 

Table 2-II. Sequence of events.

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

Launch phase

Booster engine cut-off (BECO)

00:02:10.8

00:02:08.6

Tower release

00:02:33.8

00:02:33

Escape rocket ignition

00:02:33.8

00:02:33

Sustainer engine cut-off (SECO)

-

00:05:15.7

Tail-off complete

00:05:05.8

00:15:15.9

Orbital phase

Space seperation

00:05:06.8

00:05:17.9

Retrofire sequence initiation

08:50:21.8

08:51:30

Retrorocket (left) no.1

08:50:51.8

08:52:00

Retrorocket (bottom) no.2

08:50:56.8

08:52:05

Retrorocket (right) no.3

08:51:01.8

08:52:10

Retrorocket assembly jettison

08:51:51.8

08:53:00

Reentry phase

0.05g relay

09:00:20.8

09:01:40

Drogue parachute deployment

09:05:36.8

09:06:50

Main parachute deployment

09:07:02.8

09:08:12

Main parachute jettison (water landing)

09:11:33.8

09:13:11

 

....by telemetry, appeared to have increased from a value of 74°F at lift-off to a value of 90°F over the Muchea station. The suit-heat-exchanger dome temperature, a new parameter for this mission, remained at approximately 80° during this period. The astronaut had gradually increased the suit coolant valve setting to a scribe mark of approximately 7.5, which was almost twice the level of 4 established for lift-off. During most of the orbital phase, the onboard instrumentation indicated suit inlet temperatures from 6° to 10° less than values read out on the ground from telemetry. In most instances, flight controllers relied upon telemetered values during the first orbital pass. Consideration was given to terminating the flight at the end of the first orbital pass because of the elevated suit temperature. The environmental monitor at the MCC believed that the system should have been operating satisfactorily within the first hour and that the intended level of suit cooling might never be achieved. However, during the period between passes over Muchea and Canton, the ground readout of suit-inlet [16] temperature had begun to stabilize and indicated a tendency to decrease. The flight surgeon at the MCC was also concerned with the elevated temperature, especially since the body temperature instrumentation was at that time inoperative. But, since other aeromedical data and voice reports indicated that the astronaut was in good condition, the flight surgeon believed that it would be safe to continue for another orbital pass. All other systems performed extremely- well throughout the first orbital pass. The correlation between attitudes observed visually through the window and the readouts of the spacecraft gyros and the horizon scanners was good. This excellent performance continued throughout the remainder of the mission. The spacecraft was controlled by the ASCS in orbit mode throughout the first pass, except for brief periods when the astronaut used the fly-by-wire (FBW) mode, low thrusters only.

Because the suit-inlet temperature had apparently leveled off and the possibility that it had started to decrease late in the first pass, the flight director decided to continue the flight for at least one additional orbital pass in order to allow the suit cooling system more time to stabilize. Upon contact with Guyamas, the astronaut reported that he was feeling warm, but not uncomfortable, and that the suit-cooling system had apparently begun to function properly. He stated that all of the systems were performing perfectly, and the telemetry readouts on the ground confirmed this observation. Over Woomera on the second orbital pass, the suit temperature had decreased to a value of 72° F and remained in the area of 67° to 72° F, as reported by the astronaut, for the remainder of the mission.

Fuel management during the entire flight as exceptionally good. The spacecraft fuel tanks had been filled to capacity, and at the end of the first pass, the gages for both the automatic- and manual-system fuel supply tanks indicated that there was approximately 98 percent remaining. In the majority of the cases where maneuvers were conducted over network stations, the fuel usage was so slight that it was difficult to determine if fuel was being consumed at all. The fuel usage in both the automatic and manual systems was significantly less than had been estimated based on the flight plan. Oxygen consumption was almost exactly as it had been estimated prior to launch. The cabin air temperature remained reasonably constant, as evidenced by its operating range of 105° to 110°F. The 150 v-amp inverter temperature increased slowly to a value of about 110°F, and the temperature of the 250 v-amp inverter climbed gradually to a value of approximately 150° F until the power to the ASCS was turned off early in the fourth orbital pass. At this time, the temperature dropped steadily to a value of approximately 120°F within one orbital period, at the end of which the ASCS was again turned on. The 250 v-amp inverter temperature again increased gradually at a similar rate to a value of 18O°F at completion of the flight.

Minor difficulties occurred in the biological instrumentation system; the primary problem was the failure of the body temperature measuring system to read correctly on the ground during the early portion of the flight. However, over the Indian Ocean Ship during the second pass, the temperature readout was regained and continued to indicate a value between 97.7° F and 98.5° F throughout the remainder of the flight. The blood-pressure instrumentation had displayed minor difficulties prior to flight, in that the automatic timer used to conclude the measurement cycle had failed. The astronaut was therefore required to use the manual stop button to terminate each measurement cycle.

Activities during the first orbital pass were primarily- devoted to ASCS checks. Also, the manual proportional and the FBW, low, control modes were checked, and the high-frequency voice system was exercised. After receiving the go-no-go decision at the end of the first pass, the astronaut performed a series of maneuvers designed to test his ability to aline the spacecraft about the yaw axis during the daylight phase. These yaw- checks were entirely satisfactory, and the astronaut reported that he was able to determine a day yaw reference very accurately, After completion of the yaw checks at approximately 02:00:00 g.e.t., the astronaut selected the manual proportional control mode and began limited drifting flight within the limits of the horizon scanners. At approximately 02:20:00 g.e.t., the astronaut began a series of yaw checks on the night side, again using the FBW [17] low mode. He reported that these yaw checks were also satisfactory.

A minor clock error of +1 second continued throughout the second orbital pass. There was some indication that the error was very gradually increasing. At the end of the flight, a +5 second error, which is still within specified limits was evident in the clock. This error was routinely compensated for in the retrosequence time transmitted to the astronaut.

After having received the decision to continue into the third orbital pass, the astronaut turned off the power to the control system and the radar beacons and began attitude-free drifting flight at approximately 03:10:00 g.e.t. The powering down sequence was considered to be normal by the MCC, and the astronaut maintained the spacecraft in this configuration until the pass over the Indian Ocean Ship. The astronaut completed a power-up exercise over this station and all systems operated normally throughout the remainder of the third orbital pass.

Prior to lift-off, the retrosequence setting in the spacecraft clock for a retrofire during the sixth pass was set at a nominal value of 08:50:31 g.e.t. based upon nominal cutoff conditions. The astronaut was instructed to increase this setting, by about 1 minute when the spacecraft passed over the Cape Canaveral site during the third pass because of the overspeed condition at cut-off. At the end of the third orbital pass, the astronaut again powered down the spacecraft systems, began attitude-free drifting flight, and remained in this flight mode throughout the fourth pass. At the end of the fourth orbital pass, the fuel quantity indicators read 86 percent for the automatic system and 90 percent for the manual system. The clock during this period had increased to 3 seconds, and the suit temperature was stabilized at a value of approximately 70° F. The cabin temperature during the third and fourth orbital passes indicated a decrease to approximately 90°F, and all other systems appeared to be functioning normally.

Throughout the fifth orbital pass the astronaut mainly used the ASCS mode of control, and good correlation was maintained between the gyro attitude readouts and the horizon scanner outputs. The spacecraft-to-ground voice communications were somewhat inferior to those experienced during the previous flight; however, most of the stations were able to communicate during their preestablished contact period. Patching of the A/G voice communications into the Goddard conference loop was not as efficient as had been expected. In addition, the majority of the stations from the Pacific Command Ship to Kano were affected by the transition from daytime to nighttime frequencies. During the fifth pass, the Mercury Control Center was unable to communicate with the Indian Ocean and Pacific Command Ships in order to relay the decision to continue into the sixth orbital pass. The Cap Com aboard the Pacific Ship and the astronaut apparently had made this decision independently, and, as a result, the mission continued through the fifth pass and into the sixth.

During the fifth pass, Hawaii relayed the correct end-of-mission retrosequence time of 08:51:28 g.e.t., which was based upon the latest orbital trajectory data and the final estimated weight loss. This time did not include the +5-second clock error that was currently apparent. The clock was corrected to include this error over the California station, and the correction was confirmed by Guaymas. Thus, the final and correct clock setting was established as O8:51:33 spacecraft elapsed time.

The mission continued normally as the spacecraft passed over the remaining two stations during the sixth orbital pass. The Cap Com aboard the Indian Ocean Ship assisted the astronaut in completing his preretrosequence checklist. These communications were monitored by personnel throughout the network over the Goddard conference loop. Voice communications to both the Indian Ocean and Pacific Command Ships were acceptable at this time, and, as a result, the Mercury Control Center was able to monitor activities during retrosequence. Retrosequence was initiated by the spacecraft clock at approximately 08:51:28 g.e.t. Retrofire was initiated at approximately 08:52 :00, as observed in Mercury Control Center; but this time appeared to be about 2 seconds late. The attitudes at retrofire were nominal and remained constant to within ±2° during the entire retrofire interval.

 

Reentry Phase

 

The astronaut reported that the spacecraft attitude, as observed visually remained constant [18] at the desired values and that the retropackage had jettisoned automatically at 08:53:00 g.e.t. The retraction of the periscope and orientation of the spacecraft to reentry attitude occurred on time. The fuel quality indicators at the completion of retrofire showed the fuel remaining to be 68 percent in the automatic system and 84 percent in the manual system. Although the reentry trajectory is normally computed by Goddard based upon nominal conditions at retrofire, the Goddard computers were prepared at this time to receive the telemetered retrofire parameters in order to process the final landing-point computation. This computation is based upon the known time of retrofire, the telemetered spacecraft attitudes, and the estimated weight of the spacecraft. Other than voice communications with the astronaut and limited telemetry information received from the Watertown radar ship, no further trajectory data were obtained. The Watertown Cap Com gave the MCC an ionization blackout time which confirmed the initial reentry trajectory computation. The final predicted trajectory submitted by Goddard indicated a nominal spacecraft landing about 4 nautical miles from the primary landing point. A report from the carrier that the spacecraft had been sighted visually before landing provided final confirmation of the computed predictions. The communications relayed from the spacecraft by aircraft in the primary recovery area to the Hawaii station were extremely effective and provided communications with the astronaut almost continuously from the end of blackout until landing. These communications gave the Mercury Control Center and the entire network confidence that the mission had been terminated satisfactorily. Because of the excellent performance of the astronaut and spacecraft, the flight-control task during the second through the sixth orbital passes became one of the monitoring, gathering data, and assisting the astronaut in this completion of the flight plan. After the decision to continue the flight at the end of the first orbital pass, the remaining end-of-orbit decisions were made without hesitation, with the one exception previously mentioned regarding the loss of communications between Control Center and the Pacific Command and Indian Ocean Ships during the fifth pass. The operations conducted during the entire MA-8 mission made maximum use of experience gained in previous missions, and, as a result, was the best coordinated effort of the Mercury program to date.

 

Recovery Operations

 

Disposition of recovery forces for the MA-8 mission was very similar to that for the MA-6 and MA-7 missions. In addition, there were three planned landing areas in the Pacific Ocean to provide for landings from orbital flight during the fourth, fifth, and sixth orbital passes. The planned landing areas in the Atlantic Ocean were essentially unchanged from the two previous missions. As shown in figure 2-2(a) these areas were located to provide recovery capability during aborts from powered flight and for landing at the end of each of the first three orbital passes. The locations of the planned landing areas in the Pacific are indicated in figure 2-2 (b). Area 6-1 was the primary planned landing area. Recovery support was positioned in this area to provide for location and retrieval within 3 hours of landing. The disposition of the recovery forces positioned in the planned landing areas is indicated in table 2-III. The positions of all recovery forces were not static, in that certain ships and aircraft were required to provide recovery capability for more than one landing area during the course of the mission. As in MA-6 and MA-7, special aircraft were on alert at various staging bases in the event of a contingency landing at any point along the orbital ground track. These aircraft were positioned and equipped to locate the spacecraft within a maximum of 18 hours from landing and render pararescue assistance if required.

All recovery forces were in their planned positions at the appropriate times. Weather forecasts on the morning of October 2, 1962, indicated that Hurricane Daisy might be in a position to cause unfavorable recovery conditions in area 3-1. Therefore, the recovery ships in this area were relocated along the ground track approximately 215 nautical miles downrange from their corresponding original stations. At launch time, weather conditions were favorable for satisfactory location and retrieval of the spacecraft in all planned Atlantic and Pacific recovery areas, including those designated in case of a contingency Ianding. Although some redundant transmissions were not received, recovery communications were satisfac-

 


[19] Figure 2-2. Planned landing areas.

[20] Table 2-III. Recovery forces in planned landing areas.

Area

Number of search aircraft

Number of helicopters

Number of ships

Alloted access time, hr

Launch site

0

3

0

Short

A

2

0

3 destroyers

6

B

3

0

3 destroyers

9

C, E, F

1

0

1 destroyers

6

D

1

0

1 oiler

3

2-1, 3-1

a2

0

2 destroyers

3

4-1

2

3

1 carrier, 1 destroyer

3

4-2

b4

0

3 destroyers

3

5-1, 6-1

4

3

1 carrier, 3 destroyers

3

Total

17

9

23

a Two area B search aircraft deployed to area 2-1 after spacecraft passage of area B.
b Area 4-2 search aircraft deployed to areas 5-1 and 6-1 after spacecraft passage of area 4-2.

 


Figure 2-3.-Landing area details.

 

....-tory throughout the operation, and the recovery forces were given information regarding mission status during the launch, orbital, and reentry phases.

During the sixth orbital pass, recovery units in area 6-1 were alerted to expect a landing in their area. After retrofire maneuver at about 20 minutes prior to landing, recovery forces were informed that the retrorockets had operated normally, and the landing position was predicted to be nominal. Recovery units in area 6-1 made contact with the descending spacecraft before any calculated landing predictions, based on reentry tracking, were available from network support. Details of the recovery events in the landing area are shown in figure 2-3. The U.S.S. Kearsarge, the aircraft carrier positioned in the center of area 6-1, established radar contact with the spacecraft at a slant range of about 175 nautical miles and maintained this contact until the spacecraft had descended to an altitude of approximately 1,200 feet. Lookouts aboard the U.S.S. Renshaw, the destroyer positioned 80 nautical miles uprange from the center of the area, reported that they had heard the noise caused by the shockwave of the spacecraft during reentry. A few minutes after the "sonic boom" occurred, lookouts using optical aids on the recovery carrier reported having first sighted...

 


[
21] [MISSING] Figure 2-4. Spacecraft landing.


[MISSING] Figure 2-5. Motor whaleboat attaching lifting line to the spacecraft.

 

.....a contrail and then the spacecraft after drogue parachute deployment. Main parachute deployment and spacecraft descent and landing were observed to be about 4 nautical miles downrange from the U.S.S. Kearsarge (see fig. 2 4). In addition to visual sightings of the descending spacecraft by ship personnel, the search aircraft reported contact with the spacecraft recovery beacons at ranges of 60 to 280 nautical miles. The SOFAR bomb signal was received by the hydrophone net in the Pacific Ocean, and a "quick look" location fix was provided as a result of this reception 20 minutes after spacecraft landing. The final location fix from the SOFAR bomb signal was provided 45 minutes after landing. Both of...

 


[MISSING] Figure 2-6. Spacecraft being lowered to the deck.


[MISSING] Figure 2-7. Astronaut Schirra egressing from spacecraft.

 

...these fixes were within 2 miles of the actual spacecraft retrieval position (fig. 2-3).

After Ianding, the astronaut reported that conditions were normal, that he was comfortable, and that the spacecraft was dry inside and floating upright. Helicopters launched from the U.S.S. Kearsarge dropped a team of [22] three frogmen who installed an auxiliary flotation collar around the spacecraft. At this time, the astronaut reported he preferred to remain in the spacecraft and be retrieved by the recovery ship. As the carrier approached the spacecraft, a motor whaleboat towed a lifting line to the spacecraft, as shown in figure 2-5, and attached it to the recovery loop atop the spacecraft. The spacecraft was then hauled to a position beneath the U.S.S. Kearsarge boat crane, lifted clear of the water, and positioned on one of the carrier's elevators at approximately 40 minutes after landing. Figure 2-6 shows the spacecraft being lowered to the elevator. After spacecraft positioning on deck, Astronaut Schirra opened the explosive-actuated side hatch and egressed from the spacecraft (fig. 2-7). He remained onboard the U.S.S. Kearsarge (see fig. 2-8) throughout a period of about 72 hours and participated in medical and engineering debriefings. The spacecraft was transferred to an airplane at Midway Island for return to Cape Canaveral, Fla.

 


[MISSING] Figure 2-8.-Astronaut Schirra aboard the recovery carrier.


Reference

1. Staff of NASA Manned Spacecraft Center: Results of the First United States Orbital Space Flight, February 20, 1962. Supt. Doc., U .S. Government Printing Office (Washington, D.C.).

2. Staff of NASA Manned Spacecraft Center: Results of the Second United States Orbital Space Flight, May 24, 1962. SP-6, Supt. Doc., U.S. Government Printing Office (Washington, D.C.).


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