SP-402 A New Sun: The Solar Results From Skylab


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xii]

OFF TO THE SUN! Astronauts Carr, Gibson, and Pogue blast of from Cape Kennedy on November 16, 1973, to rendezvous with Skylab, 435 km above Earth.

OFF TO THE SUN! Astronauts Carr, Gibson, and Pogue blast of from Cape Kennedy on November 16, 1973, to rendezvous with Skylab, 435 km above Earth. They were the third and final crew to man the scientific space station and their stay of 84 days set an endurance record for man in space.


 

Introduction

by Edward G. Gibson *

 

 

What you can do or dream you can, begin it: Boldness has genius, power, and magic in it.
 
- Goethe

 

[xiii] It is November 16, 1973. We are 435 km above Earth, traveling over it at 8 km/sec. Slowly, our command module moves in and docks with Skylab. We have arrived at our country's first space station, a 91-Mg laboratory in orbit around our planet Earth.

Two crews have been here before us-they repaired the damaged laboratory, performed their programed observations successfully, and returned home. Now it is our turn. Peering through the command module windows, we can see the immense workshop, its solar-panel wings standing out starkly against the black sky. We anticipate with excitement (and to some degree, awe) our planned 56-day sojourn here. It turns out to be 84 days- nearly 3 months.

Looking back, I can again feel the excitement, the sense of challenge and adventure, of those first moments. Skylab offered the first two crews and us an opportunity to do what none had done before-to study the Sun from space. For one of the most exciting parts of the Skylab challenge was the operation of the great battery of solar telescopes on the Apollo Telescope Mount (ATM), part of the orbiting space station. For over 7 years I had been closely involved in the design, testing, and planning for these telescopes, and now I was to use them and to see the Sun as it could not be seen from Earth. Judging from the successes of the first two manned missions, we could anticipate discoveries.....

 


SKYLAB looked like this to astronauts Carr, Gibson, and Pogue as they approached it on November 16, 1973, ready to begin their record 84 days in space.

SKYLAB looked like this to astronauts Carr, Gibson, and Pogue as they approached it on November 16, 1973, ready to begin their record 84 days in space. A cloud-covered Earth lies below. On the distant horizon curves the thin band of atmosphere that is blue sky for those below. The color comes from sunlight scattered by molecules of air. Above it is the endless reach of Skylab's black sky.


 

[xiv] .....of hitherto unknown and interesting features of the Sun.

Once settled onboard Skylab, our daily operation of the ATM began. In both a visual and intellectual sense, it was very similar to the extensive training we had on our ATM simulator in Houston. In a physical sense, however, we were in the world of zero gravity, a constant reminder of the reality of our situation. Mass without weight was gradually accepted as a normal way of life. New habits in living and new methods of work developed: floating replaced walking, levitation replaced falling, and up was any direction that you could convince your mind was up.

While waiting on the dark side of Earth for our first look of the day at the complex and everchanging Sun, we received a briefing from Scientist-Astronaut Bill Lenoir in Mission Control in Houston:

A couple of words here on the Sun. The first is, I've just gotten word from the back room that we presently have an active prominence on the southwest limb. It is out to 0.03 solar radii now and is growing. You may want to be taking a look at that as the Sun comes over the hill. In active region 33 we show a few bright points coming out today in the plage. That may indicate that we're going to get some resurgence of activity there. Based on what we have seen here over the last few days and some speculation, there are obvious connections between active regions 31 and 32, which are up in the northern hemisphere, and 33, which is in the southern hemisphere.

These words were typical of the many interchanges between ground and crew. They were most welcome because they established a rapport that made the observatory's operation much more productive and enjoyable.

The Skylab solar observatory combined the best of many worlds. First, in terms of resolution in space, wavelength, and time, the instruments of the ATM were the most advanced ever put into operation. They could resolve the fine detail of the solar surface much better than those used in previous unmanned satellites; being above Earth's atmosphere, they could observe the Sun in wavelengths that are not visible from Earth; they watched the Sun, particularly the outer corona (the Sun's very faint outer atmosphere, only visible from the ground during fleeting moments of total eclipse) nearly continuously for 9 months.

Second, the controls and displays for the instruments were arranged so that we could use our on the-spot scientific judgment in managing the experiments. We could watch TV displays of the Sun and the corona as they appeared in ultraviolet light, in X-rays, white light, and inCapital H, subscript Greek letter alpha, (visible light from hydrogen atoms). We were able to make a good many of the decisions about where to point the instruments and when and how to operate them. The complex and dynamic nature of the Sun, the many and often diverse scientific objectives of each instrument, the limited amount of film available, and even our growing experience meant that a good deal of judgment could be exercised in taking the data. We realized that this provided great leverage for multiplying the efforts of all of the people who had worked on the ATM for many years. We also realized, however, that this exciting opportunity was not without risk. There were also numerous incorrect ways of operating the complex observatory that often required great care to avoid.

Third, our operation of the solar observatory centered around cooperative observing programs that specified just how we should operate each instrument to yield the best data. These programs.....

 


THROUGH THE DOOR, headfirst, comes Astronaut Gibson, floating freely from one of Skylab's rooms to another.

THROUGH THE DOOR, headfirst, comes Astronaut Gibson, floating freely from one of Skylab's rooms to another. Room-to-room travel in Skylab's weightless environment was more like swimming than walking, and much more fun.

 

[xv] ....were planned in great detail many months before Skylab was launched, and we had practiced them on a simulator at our training facilities in Houston. We started out with 26 programs, and others were added during the missions. They proved to be an excellent means of organizing our work so that the observatory was used as efficiently as possible.

The fourth factor that helped make Skylab a particularly powerful observatory was our close contact with a well-informed ground-support team-we were not just a lonely island in the sky. Each day scientists responsible for each instrument developed and sent to us on our teleprinter an operating plan for the ATM-a minute-by-minute program for the daylight parts of each orbit. They also sent general information on the changing characteristics of the Sun, gathered by the National Oceanic and Atmospheric Administration (NOAA) facility in Houston. This plan provided us with a good starting point, and we usually followed it unless we judged that the changing conditions on the Sun made other plans more productive. Houston routinely received data from many observatories as well as from other operating satellites. Some of the data from the ATM television displays and the telemetry from a nonphotographic instrument was assembled in Houston for "quick looks" so that solar scientists there could update the observing plan every day and send us more specific information for each of the instruments.

Fifth, in the same way that we in our orbiting observatory were in constant contact with the ground, the whole Skylab team was always in touch with other working solar astronomers throughout the world. Nearly 150 scientists in 17 countries were daily made aware of our planned observations. Some were notified on an hourly basis of changes in the schedule. These scientists then sometimes coordinated their own observations with ours so that more complete sets of data were obtained on many solar features.

In the planning stages we wondered sometimes whether such an intricate worldwide network could respond quickly to sudden changes on the Sun. Because of its size, would this network be slow to react? Let's take a look at some specific events.

On January 17, 1974, while I was looking at some very hot spots in an active region, a call came from Houston saying that the observatory at Mauna Loa, Hawaii, had just seen a large prominence, a spectacular cloud of dense gas, lifting off....

 


IN SHIRTSLEEVES, Gibson operates Skylab's solar telescope array from the control console in the multiple docking adapter.

IN SHIRTSLEEVES, Gibson operates Skylab's solar telescope array from the control console in the multiple docking adapter. One hand grips the table to keep him from floating away; he needs no chair. At lower left an unused electrical connector floats freely in Skylab's weightless environment.

 

.....the surface of the Sun. Houston recommended one of our planned programs of observing "coronal transients." I started into this new observing program and became excited as I got my first look at the prominence speeding outward through the corona. It was compact, exceptionally brilliant, and quite unlike any coronal structure we had seen before. Fascinated, and with an overwhelming sense of awe, I watched this new feature grow. In less than an hour it was several hundred times as large as Earth, and still moving outward toward the planets. Not until we had slipped into Earth's shadow, and could no longer see it, did I realize how quickly the total ATM team had reacted: Mauna Loa observatory had rapidly contacted NOAA in Houston, and they had immediately relayed the news to the scientist on duty in the ATM support room. He had requested through the ATM representative in Mission Control that we observe the prominence. The Flight Director had approved the request, and it was radioed to us as soon as we came into contact with the tracking facility at Goldstone, Calif. It was only a matter of 9 or 10 min. between the Mauna Loa sighting and the start of our observations.

Four days later, on January 21-less than 3 weeks before our mission would be over-I was at the ATM console watching a moderately active Sun. One active region in particular was very hot, and sporadically releasing small but brilliant bursts of radiation called subflares. By now continuous monitoring of our console displays had allowed us....

 


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SKYLAB was the modernistic home for three astronaut crews. A multiple docking adapter was attached to the end of the workshop, and to it was fixed the solar telescope array called the Apollo Telescope Mount. Finally assembled, it made up an orbital laboratory 36m long and weighing, on Earth, about 91 Mg.

SKYLAB was the modernistic home for three astronaut crews. A multiple docking adapter was attached to the end of the workshop, and to it was fixed the solar telescope array called the Apollo Telescope Mount. Finally assembled, it made up an orbital laboratory 36m long and weighing, on Earth, about 91 Mg.

 

[xvii] Some Facts About Skylab

Skylab 1

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Launch date

May 14, 1973

Launch site

Cape Kennedy

Total manned operational time

171 days

Total operational time (manned and unmanned)

251 days

Date to reenter Earth's atmosphere (estimated)

1980/1981

Overall length

36 m

Overall weight

about 91 000 kg

Length of orbital workshop

8.2 m

Diameter of orbital workshop

6.7 m

Orbit altitude (average)

435 km

Orbital velocity

8 km/s

Period to circle Earth

93 min

Earth orbits completed during operational time

3900

.

Astronaut crews

.

Skylab 2-first manned mission (May 25 to June 21, 1973):

28 days

Charles Conrad, USN

Joseph Kerwin, M.D., USN

Paul J. Weitz, USN

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Skylab 3-second manned mission (July 28 to Sept. 24, 1973):

59 days

Alan L. Bean, USN

Owen K. Garriott, Ph. D.

Jack R. Lousma, USMC

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Skylab 4-third manned mission (Nov. 16, 1973, to Feb. 8, 1974):

84 days

Gerald P. Carr, USMC

Edward G. Gibson, Ph. D.

William R. Pogue, USAF

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First manned mission backup crew:

Russel L. Schweickart

Bruce McCandless II, USN

Story Musgrave, M.D.

.

Second and third manned mission backup crew:

Vance D. Brand

Don L. Lind, Ph. D.

William B. Lenoir, Ph. D.

 


THE NINE ASTRONAUTS of the three Skylab crews posed for this postflight portrait in a training simulator at the NASA Johnson Space Center near Houston, Tex.

THE NINE ASTRONAUTS of the three Skylab crews posed for this postflight portrait in a training simulator at the NASA Johnson Space Center near Houston, Tex. This unique 360° view, made by photographer Michael Lawton for the National Geographic Magazine, shows the bottom floor of the four-story living space where these men lived and worked for a total of 171 days during the Skylab mission. Bean, Lousma, Conrad, Weitz, Kerwin, and Carr stand in the experiment compartment where medical tests and physical conditioning were performed; Gibson stands in the ward room (kitchen-dining room); Pogue at the door of the waste management compartment (bath); and Garriott in the sleep compartment (bedroom).

 

[xviii] .....to develop a feel for the Sun's level of activity-in a sense, to take its pulse. We had been disappointed that neither our crew nor either of the previous crews had managed to observe the very beginning of a flare, a short-lived explosion on the Sun's surface.

We hoped that by observing a flare's birth we could find keys to the mechanism by which the Sun releases great quantities of energy from a very small volume in a fraction of a minute. But every time we realized that a flare was taking place, and started the instruments, we were too late to observe the initial energy release.

Owen Garriott, Scientist Pilot of the previous Skylab mission, had suggested that when a tiny bright point appears on the extreme ultraviolet image of the Sun, it may be an early signal that a flare is beginning. So, as the active region shown on my TV display seethed with small energy fluctuations, I practiced the exact control panel procedures I would use if a flare erupted. (I had done this many times before, but to no avail.)

Suddenly, a small bright point appeared right in the center of my screen. As I started the instruments taking data rapidly in their flare modes, I was elated to see the bright point blossom into a full-blown flare.

My most interesting and challenging day on Skylab was January 26, 1974, when Houston asked me to develop and implement most of the plans for one full day's observations. They did this as an experiment, to see how an orbital observatory could be run on future NASA Space Shuttle missions when experimenters themselves will fly. Using the teleprinter, they sent up a general statement about the scientific goals and limitations of each experimenter and their knowledge of the state of the Sun. The rest was left to me.

I had a fascinating day, completely involved, entirely committed. Laying out the schedule was relatively straightforward. Routine data-gathering formed the framework that filled in with observations of the Sun's most interesting features. Knowing the experiments' objectives, the degree to which they had already been met, and the current state of the Sun, I could do all the short-term planning and make all the real-time changes in the observing program that were required. By now the matching of scientific objectives with the operation of the console had become second nature and the

ATM could be played like a piano, by ear, with cumbersome sheet music put away. On the other hand, this day's work also demonstrated the importance of an even closer link than we had between ground scientists and in-flight observers. I found that I sometimes missed the wisdom of the ground personnel in forming my decisions. Two heads are certainly better than one, especially if they can exchange knowledge freely.

The ATM contributed a staggering quantity of new data on the Sun. It also showed us how to use man to greatest advantage on long-duration space missions.

We realized this during our 84 days in flight, as we assumed many roles: observers, doctors, scientists, space pilots, cooks, housekeepers, space walkers, and technicians. In filling these roles we recognized that man makes his best contributions and is in his best psychological health when his tasks let him be creative and intellectually challenged. As our mission ended, we were still becoming more and more proficient, and we were still increasingly interested in what we were doing. Skylab demonstrated the value, to us and to the scientific world, of giving the onboard observer a high degree of freedom, letting him lend his mind and his creative abilities to the tasks at hand. We left Skylab with the first-hand knowledge of how to plan the operation of the space station of the future, perhaps a permanent national or international facility.

Significant dividends will result from heavy reli....

 


HOME AT LAST, after a record stay in orbit, Gibson steps to the deck of the U.S. aircraft carrier Wasp

HOME AT LAST, after a record stay in orbit, Gibson steps to the deck of the U.S. aircraft carrier Wasp. Still inside are Carr and Pogue and a heavy cargo of precious film. Their trusty command module, scorched by air friction on reentry into the atmosphere, was the same that had carried them to Skylab nearly 3 months before. For 84 days it wet parked outside Skylab's door, waiting for the trip back home.

 

[xix] .....ance on the judgment of the observer inside a science or technology laboratory, another solar observatory, or an Earth observatory.

This volume presents the highlights of the new and exciting picture of the Sun that has come from Skylab. Turning the vast amount of data into knowledge has really just begun, and will continue for many years. Behind the data lie the mechanical and scientific complexity of Skylab, the people and resources that made it a success, and the many years of planning.

Although Skylab was not as visible and dramatic, perhaps, as our first lunar landing, I hope that as you read you will share with me the feeling that it was an exciting, meaningful, and most productive step in our exploration of the universe.


* Scientist Pilot of Skylab's third manned mission.

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