By Walter M. SCHIRRA, JR., Astronaut




[49] A personal narrative is presented by Astronaut Schirra of his flight experiences during the MA-8 mission. In many instances, his observations are coincident with those of the astronauts for the previous orbital missions. However, two notable differences should be mentioned. Astronaut Schirra observed a hazelike layer that was different in both character and size from that described by Astronauts Glenn and Carpenter, and, although both of these pilots spoke of the expended sustainer stage of the launch vehicle as silvery in appearance, Schirra described it as having appeared black. The pilot witnessed both types of space particles which had been observed by Glenn and Carpenter. After reviewing the details of the turnaround maneuver, the pilot discusses the possibility of rendezvous with the launch vehicle immediately after separation from it. Despite the fact that the MA-8 orbital phase was twice the length of the previous Mercury flight, Astronaut Schirra easily adapted to the space environment and suffered no ill effects from the long periods of attitude-free drifting flight. The astronaut's candid evaluation of the systems' performance throughout the flight is a reflection of the greater emphasis placed on the engineering aspects and was extremely valuable in making the postlaunch investigation of the flight results a comprehensive one.




One of the main objectives of this flight was an engineering evaluation of the spacecraft systems to determine their capabilities for an extended mission. In line with this objective, we wanted to demonstrate that the consumable supplies could be conserved sufficiently to permit longer duration flight in the future using the Mercury spacecraft. Of course, most of the consumables, such as water, electrical power, and contaminant filters, will have to be increased, but it is still important to determine the long-term consumption rates.

Since this was to be an engineering evaluation, the name chosen for my spacecraft was that of the mathematical symbol for summation, sigma, with the number 7 added to it for the seven-member Mercury astronaut team. Thus was derived the main and symbol that was painted on the spacecraft, Sigma 7.

The camaraderie of everyone concerned with the flight preparations and equipment meant a great clear to me. For example, it was certainly a thrill while entering the spacecraft on launch day to see a dummy "ignition key" on the control stick safety pin. This and other small gestures really helped to make me realize that there are many other people who were interested in what I was doing. We know this inherently, but these visible examples of it mean quite a bit. Here again, sigma symbolizes the summation of the great efforts exerted by each and every man in the vast Mercury team.

The following comments are my observations and impressions of the flight from the countdown to recovery. In the previous paper, the flight plan was described and my performance in completing the assigned tasks was discussed. In this report, I will amplify that discussion, as well as describe my own flight sensations. In the period since the flight, I have taken the opportunity to refine and analyze my flight experiences. In many instances, I will submit comparisons of my observations with those of astronauts who preceded me into space. It was their pioneering efforts which helped so much to make my flight a success.


[50] Countdown and Powered Flight


The countdown was conducted very successfully; there were absolutely no problems. The only delay was that resulting from a temporary loss of signal from the Canary Islands' radar system but waiting for what proved to be a rapid repair was worthwhile since they had good radar acquisition during the first orbital pass. The tracking task is critical at this time, because it provides early definition of the spacecraft trajectory.

The boosted flight} itself was disappointingly short. Considerable training was conducted to prepare me for emergencies which might occur during powered flight. We so often practiced system failures and aborts, either in the procedures trainer or by coordinating the trainer with the Mercury Control Center and Bermuda stations, that this practice made a very pronounced impression upon me.

This launch, in contrast, was a successful, normal flight where I encountered many new experiences. I still believe that the amount of practice we had for the period prior to insertion is important in that here the pilot must be prepared for reaction to an emergency, rather than thinking one out.

There is no doubt about when lift-off occurred. If anything, I was somewhat surprised because it occurred earlier than I had anticipated. I heard the vernier engines start, felt them thrusting, and then heard the main engines start. During ascent, the communications with the Cape Capsule Communicator were perfect except for the few seconds when the noise of maximum dynamic pressure triggered the voice-operated relay and prevented the ground transmissions from reaching me. I never felt rushed, and all the events during launch were in order.

I had more than the anticipated time available to me to make my system checks. My scan pattern of the instrumentation panel was developed to where it was instinctive. I thought from my training that I might have missed on making a good electrical check prior to 3 minutes but subsequent to tower jettison; however, I found that I had completed that in time. There was absolutely no question as to when booster engine cutoff (BECO) occurred. The change in acceleration was quite obvious; whereas in the trainer, I could only wait for the accelerometer indication to decrease. There is no doubt, whatsoever, when these forces decrease in actual flight. Since the beginning this mission, I had become familiar with checkoff points for various emergencies; for example a no-BECO abort, a no-staging abort, and an abort at 3 minutes and 50 seconds after lift-off. It was a very pleasant feeling to check each of these off and put them behind me.

I knew that the launch vehicle staged without having to wait for confirmation from the Cape Cap Com, which, by the way, did come in rapid order. You can see the flashback of smoke from the booster engines as they part from the sustainer stage, and you can see the escape rocket when it is jettisoned. Unfortunately, the escape rocket blast left a light film on the window.

It did seem that the buildup of acceleration during the sustainer period was rather slow. As I look back, the forces I experienced while being accelerated in boosted flight seemed to be much less than the later forces of reentry.

This comparison, l am sure, is best explained by the fact that you have a breathing point at BECO, in between the accelerations, while at reentry there is a long continuous buildup of accelerations which are equally as exciting as those during boosted flight.


Orbital Flight


At sustainer engine cutoff (SECO), the sequence panel light did not seem to help very much. All the lights were somewhat dim, and I was made aware of these events better by the feel and sound than by the sequence light itself drawing my eye to it. After SECO, I immediately selected the auxiliary damping mode knowing from my previous training that there was no rush, selected fly-by-wire, low, on the thrust select switch, and commenced turnaround. I resisted every impulse to look out of the window at this point, as I wanted to make this a fuel-minimum turnaround by strictly monitoring the gyro instruments. I was pleased to note that I got exactly the turnaround I wanted in the fly-by-wire low control mode, including approximately 4 degrees per second left yaw. I had no trouble with any of the low thrusters at this time or at subsequent tines during the flight. I attained retroattitude [51] at about 6 minutes and 50 seconds after lift-off and then selected ASCS, dropping into this automatic-pilot mode without any high thruster action.

After turnaround, I observed the sustainer stage right where it had been predicted to be, and I was very intrigued. I was somewhat surprised to see the sustainer engine pointing toward me. By this, I mean that it was basically in an attitude where it must have turned lengthwise 180°. It was moving very, very slowly in relation to its insertion attitude, although it had managed to make a 180° turnaround during the time I had made mine. I was also impressed with the fact that it was almost black in appearance, rather than the shiny silver vehicle that Astronauts Glenn and Carpenter had seen at this time and that I had observed on the launching pad. The white belly band of condensed moisture, the frost itself, was apparent to me. The sustainer followed the path that was predicted, and this knowledge helped satisfy me that the attitude gyros and horizon scanners were operating properly. I did not see any crystalline material exhausting from the sustainer engine which Scott Carpenter had described. The sustainer, in retrospect, appeared slightly to the right of the predicted position which indicated a slight error to the left in my indicated attitude about the yaw axis.

It was a very real satisfaction to receive the statement from the Cape Cap Com that I had at least a seven-orbit capability. As I proceeded on to the Canary Islands the flight was textbook already. I never did feel rushed; in fact I could send blood pressure, for example, and have little else to do. I got a good 10-minute check when the tower jettison and cap sep lights indicating spacecraft separation went out. I had loss of voice transmission with the Cape Cap Com just prior to 10 minutes. Although I had everything under control, I did store away all events and switch positions to transmit to the Canary Islands Station, since their relaying of' these data would in turn, update the flight director and the flight controllers back at the Cape.

At about 10 minutes 30 seconds, I went back to fly-by-wire, low, and tracked; the sustainer as it traversed down through the window, and it was a thrill to realize the delicate touch that it is possible to have with, fly-by-wire, low.

This touch is an art that a pilot hopes to acquire in air-to-air gunnery for getting hits. In this case the control system was so effective that it just amounted to a light touch and maybe a few pulses in either axis to get the response l wanted. I could point the spacecraft at anything I wanted to. I could see the sustainer and track it, but I do not believe the relative motion problem would be so easy to solve that I would be able to steam along and join up with it. Although the relative velocity was on the order of 20 to 30 feet per second, it was enough to cause a problem, particularly at a time when one is becoming acclimated to a new environment. These problems would be difficult to solve by one's own inherent trajectory analysis, since there were no systems aboard to aid the pilot in solving the problem. I think that when we build up to the rendezvous technique one will need more time than that just at the point of insertion to effect this rendezvous, even with proper training. The use of time while orbiting in space is only earth relative, therefore if a rendezvous is not hurried, the task should be relatively simple.

At the Canaries, the flight itself had settled into a very normal pattern. I was content with the autopilot function, although I was convinced by this time that I had a small discrepancy between indicated data and actual yaw attitude. During the sustainer tracking exercise, I had disabled the yaw reference system, and I knew that I had to wait for it to precess out the errors before I misjudged it. Having pitched up with manual proportional control, I was content that the system was exactly as I felt it would be. The greatest effect I did notice in manual proportional control was the tail-off in thrust, rather than the response to control input. As a result, you have the tendency to overshoot, and you cannot park the spacecraft in the attitude you want without having to counteract and then recounteract a tail-off. As a result of this effect, almost every time I went from manual proportional back to automatic mode, I switched to fly-by-wire, low to reduce these small rates to a level at which could effect this transition without using high thrusters.

I did not have much chance to assess Africa as a viewing sight; I was much more engrossed in what was happening within the spacecraft. I did, of course, notice the color of Africa's [53] desert terrain; it was difficult not to notice it. The country itself was exactly as I had anticipated from the orbital charts. At this time I was well aware of the fact that we were working up to a slight suit-system cooling problem. I decided then to devote my primary attention to solving this situation before it became necessary to end the flight prematurely. I was well aware of the fact that people on the ground were probably quite concerned and were thinking in terms of previous missions when cooling problems had persisted. Therefore I decided I had better solve this one.

I did not want to increase the valve setting for the suit circuit too rapidly. I had said before the flight that I wanted to increase the flow settings about half a mark every 10 minutes and this technique had been agreed upon by the system specialists. I had to go from a setting of 4 to 8, which represents about eight half marks. This procedure would therefore take about 80 minutes. At a setting of about 7, I had arrested the increase in the suit and dome temperatures, and I needed about another 10 or 15 minutes to get the cooling I wanted. I did not want to increase the setting too rapidly and freeze the system. I had everything monitored closely and while I saw the temperature was still going up as I increased flow, the rate of change of the temperature was decreasing.

Even though it seemed to me that the Mercury Control Center did not have as much information as I did on this temperature problem, their request that I decrease the suit setting back to 3 was valid. I later decided that they might have made an analysis that I had not and subsequently backed down to the number 3 position as requested. I gave the system about 10 minutes to respond and saw that both the dome temperature and the suit inlet temperature were increasing again, so I immediately went from there up to about 7.5, which again arrested the temperature increases.

Once the suit circuit temperature was under control, no other problems demanded such careful attention. Continually I metered the attitude control fuel and attempted to conserve its use. Electrical power, which is stored in six batteries, is another consumable that I wanted to conserve. There were scheduled periods during the flight where I powered down electrical systems. In addition I conserved electrical power by recording my observations with a voice operated relay "record-only" mode, rather than transmitting out of range of the Mercury tracking stations. Although we don't have a system for measuring the actual power remaining, battery voltage readings are a good indications, and I was very impressed that the voltage readings did not drop during the flight.

I do not believe I need to discuss the weather, the sun, or the stars. It seems more appropriate to discuss the events within in the spacecraft. Each network station got as much information as I had available to give them. Once we had solved the suit circuit problem and I had begun to feel cool, I knew we were in a "go" status and I had achieved my goal of using minimum fuel up to this point. I had stated long ago that I wanted to do some control maneuvers other than in fully automatic mode. I also had stated that I wanted to use the automatic mode when I did not need to employ manual modes or when I was too busy to fly the spacecraft since this is why we have an autopilot. Admittedly we have taken a system that was designed to be completely automatic and then tried to build some versatility into it and give the pilot the capability of controlling the vehicle as he desires. I had become satisfied with my capability of controlling the spacecraft before I got to the Canaries, a fact which I reported to the ground. From that time on, I merely wanted to make observations that seemed to have merit and to use the control system only during those periods when I had to reestablish the attitude within the limits required to drop back into the automatic mode.

I was discouraged by the tremendous quantity of cloud coverage around the earth and realized that it may always be a problem for certain space flight requirements. Africa, on the first and second passes, was ceiling and visibility unlimited (CAVU). The southwestern United States was also CAVU after I crossed over the ridge along the Baja California peninsula. I had a very good view, and I could easily determine yaw attitude by reference to the ground.

When I reestablished orbital attitude as I came over Muchea on the third pass, I was very pleased when I talked to the Muchea Cap Com and he and I agreed on yaw attitude exactly except for a possible 4° error in left [53] yaw, which was also indicated by my instruments. The telemetered scanner readings were coincident with the spacecraft attitudes, and I had just acquired these attitudes shortly prior to Muchea by using the Moon and planet Venus adjacent to it for visual references. They actually showed up over the Indian Ocean Ship and were very easy to work with. They both lined up to give me a roll, pitch, and yaw reference.

A smog-appearing layer was evident during the fourth pass while I was in drifting flight in the night side, almost at 32° South latitude. I would say that this layer represented about a quarter of the field of view out of the window, and this surprised me. I thought I was looking at clouds all the time until I saw stars down at the bottom or underneath the glowing layer.

Seeing the stars below the glowing layer was probably the biggest surprise I had during the flight. I expect that future flights may help to clarify the nature if this band of light, which appeared to be thicker than that reported by Scott Carpenter.

It was a real treat to pass over each station and realize that they were as excited as I was and as envious as anyone could ever be. I saw the particles that John Glenn reported, and I also saw what Scott Carpenter reported as having seen. I believe that both phenomena are varied in appearance because of lighting conditions at sunrise and during bright daylight.




I checked the high thrusters in fly-by-wire prior to retrosequence, and on the first demand for each high thruster in all three axes, they worked and reacted beautifully. It was a tremendous feeling to know that I had no problem with the high thrusters becoming cool. At the nominal retrosequence, the Pacific Ocean Ship Cap Com gave a perfect count. Sequence and attitude lights actuated on time. I was sitting there ready to punch the retrosequence button. I did have the safety cover off the button and put it back on again. At the time of retrofire, the delay by a fraction of a second in firing the first rocket seemed agonizingly long. This time is probably the most critical of the flight, at least subsequent to insertion; and you know that these rockets have to work. Again, I was poised to punch off the retrofire button to back up the automatic system. I had its safety cover off, and I guess I put it back on again sometime later. The rocket ignition was crisp, clean, and each one actuated with a definite sound. There was no doubt as to when each rocket was firing. The spacecraft did not seem to vary as much as half degree in attitude during the period of retrofire. I was also cross-checking out the window and had plenty of visual cues in case things did go wrong with the automatic mode. I could see stars that did not even quiver. Because of these cross-checks, I was aware that the ASCS was working well throughout this period and did not require any manual control inputs.

Subsequent to the retrofire maneuver, I controlled the spacecraft with fly-by-wire. I had the retrojettison switch armed in time, and the retropackage subsequently jettisoned. Control seemed somewhat loose. I guess I was probably excited about the fact that the retrorockets did ignite and did not have the cool head that I should have had. Therefore, I allowed the attitudes to drift off by perhaps 10° or 15° in roll and probably the same amount yaw and pitch. The flying was not really of poor quality, but it was not up to my usual standards. I then brought Sigma 7 up to reentry attitude on fly-by-wire and intentionally actuated some of the high thrusters to see what it felt like. They reacted very well. At this time, I did not want to stay in the rate command mode and use a large quantity of fuel needlessly. I have always believed, with regard to full consumption, that the rate stabilization control system (RSCS) was the most expensive mode of the spacecraft. I came into retrosequence with 80 percent of fuel in each tank, which was higher than my mark, and I was quite pleased that I had that much. After retrofire, the automatic fuel was somewhere around 52 or 53 percent. I easily got into reentry attitude and felt very confortable with it. The periscope retracted on time. I noticed that my control of the spacecraft was still loose, so I tightened it up and then went into ASCS orbit mode. I wanted to see if the logic had picked up for reentry, and it dropped right in and held beautifully. Then, I set up rate command to give it a small check. It responded very well, and I was satisfied that that the system was working.


[54] Reentry


The beginning of the actual entry into the sensible atmosphere, with the attendant cues was a very thrilling experience. Because my vision was somewhat obscured by perspiration on the inside surface of the visor, the cue for occurrence of the important event, 0.05g, was my visual sensing of the roll rate that was automatically induced by the control system rather than by the 0.05g event light on the panel. The spacecraft with a roll rate is something you just cannot effectively visualize in your mind. It is a very nice series of slow rolls and you really feel as if you are back in the old fighter seat, just playing games. Looking out at the sky and at the surface of the earth which was starting to brighten up, I observed that the roll pattern was very slow and deliberate. You could integrate your attitude out of this very easily and I knew that the spacecraft was as stable as an airplane.

The accelerations during reentry were not severe in the sense of bothering me, but it seemed to take much longer than I had anticipated. This was predictable but it is just one of those things that you cannot seem to approximate in real time even on the centrifuge which I had trained in just before the flight. It is difficult to store all these cues and inputs into your mind and just pull them out quickly. Physiologically I never felt any strain as far as the reentry went. Each event came into place as closely as I could have wished.

As the acceleration buildup began, I could see external cues which were of great interest. I missed the hissing that John Glenn and Scott Carpenter described, possibly because I was concentrating so much on how the RSCS system was performing. I was prepared at any time to throw it into the auxiliary damping mode. As expected, an enormous amount of fuel was consumed during reentry before the drogue parachute was deployed. After drogue parachute deployment, of course the fuel was jettisoned normally. But before the drogue parachute was deployed, that system must have been down to approximately the 20 percent level. This level corresponds to a total fuel consumption from the manual tank during reentry of some 60 percent, or approximately 14 pounds.

There were two occasions when I nearly switched from RSCS to the auxiliary damping mode. One was while I was monitoring the fuel gage; it looked just like a flowmeter. The indicator for the manual tank was visibly dropping. Yet, I continued with RSCS because I wanted to give it every chance to complete the reentry control task in order to evaluate it sufficiently. The second time that I thought about going to the auxiliary damping mode was when the yaw rate left the nominal 2.5 to 3 degrees per second and went off-scale (6°/sec) to the left. Soon after this occurrence, it held to about 5 degrees per second and then did the typical needle fanning that we have seen in the reentry training at Langley. Since it had started to hold again, I did not switch to auxiliary damping because I still wanted to allow the RSCS a full demonstration. However, I was perfectly content that the ASCS was working properly and it was good to know I had this powerful system ready to be switched on if needed.

I did see the green glow from the cylindrical section. It was a very pretty color probably best described as a shade similar to limeade (a little green and chartreuse mixed together). This shade included a slightly stronger yellow cast than I had anticipated from earlier descriptions. One opinion which was ventured that might explain the green-yellow color is the copper treatment on the beryllium shingles. In fact burning copper in a Bunsen burner flame is a good approximation to the effect that I saw. I did not see any distinctive color differences resulting from the different ablation panels that had been bonded to the beryllium shingles. There were no variances in color, such as a chromatic or a rainbow effect..

The altimeter came off the peg very nicely. I manually deployed the drogue parachute at 40 000 feet. There was a definite strong thrumming accompanied by the drogue deployment, somewhat like being on a bumpy road. Although it is of no consequence I was probably about 10 or 15 seconds slow in turning the hydrogen peroxide jettison fuse switch on, and this I can only blame on the intrigue and interest in looking at the drogue parachute up there straining and pulsating. The window definitely was further occluded during reentry.

[55] I armed the recovery arm switch at about 15 000 feet. The main parachute opened at about 10 500 feet, and it was just as pretty as astronauts of previous flights had described it. It sort of puts the cap on the whole thing. I prepared for landing but did not hook up the survival raft to the suit.


Landing and recovery


On landing, Sigma 7 seemed to sink way down in the water. It also seemed as if I were horizontal for a while. I allowed the main parachute to be jettisoned by punching in the main-parachute disconnect fuse. Then, I actuated the recovery aids switch to the manual position. The spacecraft seemed to take a long time to right itself, but again time is merely relative, and in actuality, the spacecraft righted itself in less than 1 minute. When Sigma 7 had finally started to right itself, it was a very, very pleasant feeling, and at this point I knew I could stay in there forever, if necessary. The suit temperature was 75°F or 76°F, and the highest point reached prior to egress was 78°F.

I had very good communications with the Cap Com at Hawaii. The recovery carrier, which was probably the nearest thing other than the recovery helicopter, was really "down in the mud" as far as communications as are concerned. Communications from the carrier were very weak, but legible, as evidenced by the fact that my request for permission to come aboard was immediately granted.

Sigma 7 deserves some engineering closing remarks. Aviators are know to acquire an affection for their aircraft when it performs well, and now, in the space age, an astronaut should convey his personal thoughts about his spacecraft. I definitely fell in love with Sigma 7 , and it is the first vehicle in my history of flight that finally replaced the F8F, a Navy propeller-type fighter, as the one on the top of the list. This spacecraft, the crew that prepared her, and the flight itself, truly combine to make this MA-8 experience the high point in my life.