Our First Moon Scout Heads for the Pad
February 1965 Popular Mechanics

May 1968 Popular Mechanics
May 1968 Popular Mechanics - RF Cafe[Table of Contents]

Wax nostalgic over early technology. See articles from Popular Mechanics, published 1902 - 2021. All copyrights are hereby acknowledged.


Our First Moon Scout Heads for the Pad

Its three feet planted on rugged test terrain, with pantograph arm extended, TV humming and high-gain antenna oriented toward distant target, this is how Surveyor might look after making a soft landing on the moon.

This year a talented robot will try to "check out" the moon. Called "Surveyor," he's got three legs, electronic eyes and chemical senses

By Thomas E. Stimson, Jr.

Before we try to place human explorers on the moon, we are going to send up mechanical men who will land on their three feet, look around and tell us what they see.

After one of them has touched down, he'll report what the lunar surface is like. He'll scratch the ground with one hand to learn whether it's hard or soft. He'll reach out with another hand to feel if micrometeorites are showering down.

This mechanical American will be pretty human in other ways, too. His eyelids will close during landing, to keep dust out of his television eyes. If he suffers too much from the searing heat of the lunar day, he'll adjust his interior temperature. He'll go to sleep when the sun goes down, shutting off all of his senses except his sense of feel for moonquakes, and use stored-up battery energy to avoid freezing to death.

As a photographer, this extraordinary American will take stereo pictures and transmit them back to earth so we can see what he sees, in three-dimensional color.

The name of this mechanical man is Surveyor. And, to carry the simile one step further, his father is Caltech's Jet Propulsion Laboratory and his mother is Hughes Aircraft Company. Both parents expect great things of their offspring.

The first Surveyor, in a planned series of at least seven attempts, will leave for the moon later this year. The project is the last exploratory step before Apollo, the manned space-craft that is scheduled for a moon landing in the early '70s.

Surveyor's role is to provide us with answers to questions such as these:

• Is the moon covered with a laye1· of dust? If so, how deep is it? (Despite radar information and close-up photos taken by Ranger VII, this question continues to generate controversy. Several scientists connected with the Ranger project maintain that the lunar surface is essentially firm. Other scientists with equally good credentials say just the opposite; they think the dust is deep enough to swallow up a space vehicle.)

• Will moon dust clog mechanical purrs or even turn an Apollo spaceman into a walking dust ball? (There's some evidence that dry dust in a high vacuum tends to collect and cling to any surface.)

• Are tiny meteorites constantly raining down on the moon? (With no atmosphere to slow them down, the high speed particles could slice through a space suit or even the spaceman himself.)

But the first four Surveyors won't come up with all the answers. Instead of carrying the full "lunar laboratory," they'll be outfitted mainly with flight instruments designed to report the accuracy of the approach to the moon, how successful the landing is and, if some-thing goes wrong, exactly what the nature of the trouble is.

Landing strength is tested by dropping Surveyor from various heights. Tether arrangement is used to duplicate the one-sixth earth gravity of moon

Eugene Giberson, Surveyor project manager for JPL, explains that without these pioneer flights there would be no way of correcting a malfunction. So, first the vehicle will be proved out, then the full laboratory will be transported.

Giberson compares the job of making a soft landing on the moon to performing a launch at Cape Kennedy in reverse. That is, the vehicle approaches at high speed, at an angle. Then it must tilt tail-first toward the surface, slow itself down while maintaining perfect balance, then drop in at almost zero speed into the preselected site. And, adds Giberson, Surveyor must do all of this by itself after having spent 66 hours in the hostile environment of space.

Anatomy of an Atlas-Centaur. Drawing shows Surveyor cocooned inside nose fairing atop Centaur upper stage, first rocket to use liquid hydrogen fuel

After 66-Hour Trip (left panel), Surveyor will get command from earth to turn and point big retrorocket straight down (right panel). Sixty miles above target, rocket will ignite to slow craft from 6000 to about 400 m.p.h.

Even the blast-off from earth will be more critical than were the earlier moon shots. Ranger VII was first put into parking orbit around the earth, then was fired toward the moon at exactly the right time. This called for relighting the rocket's second stage while in orbit, a tricky operation by remote radio command.

To avoid possible failure, the first Surveyors will be fired at the moon by direct ascent. Each will travel toward a point in space that will be occupied by the moon at the moment the vehicle gets there. The period of time in which the rocket can be launched (the "launch window") is no more than an hour per day at best, on no more than four or five days per month.

When Surveyor closes to within 1000 miles of the moon the craft will turn (on command from earth) so that its big retro-rocket points straight down. At 60 miles altitude the rocket will ignite and push backward with enough thrust to slow Surveyor from its earlier 6000-mile-per-hour speed to less than 400 m.p.h. Explosive bolts that hold the retro case (now burned out) will then free the case and allow it to drop away.

Now RADVS goes to work. (Pronounced "radviz," the initials stand for Radar Altitude Doppler Velocity Sensor.) One RADVS beam projects straight down to measure the altitude and the vertical drop speed. Three other beams, at angles, will measure the craft's speed and direction of travel across the moon's surface. RADVS automatically operates three small vernier gas jets that will cut horizontal travel to zero, at the same time reducing the drop velocity to 12 feet per second. The jets shut off at 15 feet altitude to avoid stirring up moon dust, and Surveyor impacts at parachute speed.

Cutaway shows one of Surveyor's two TV "eyes." They are designed to take close-ups, scan the horizon and produce stereo pairs for viewers on earth

Technician tests arm. It can whack at the lunar crust like a pick and is strong enough to break a half-inch concrete slab or dig hole 20 inches deep

Being realistic, Giberson expects there may be failures. "If only one of the first four craft makes a successful soft landing, that will be a spectacular achievement," he says.

Surveyor is eight feet tall and its hinged, shock-absorbing legs spread out to a diameter of 13 feet. It is designed to land softly on slopes of up to 15 degrees and has actually landed safely, in rehearsals on earth, on 30-degree slopes.

The first thing Surveyor will do after landing is a little "housekeeping." It will tilt its solar panel to the sun to begin acquiring more electric energy. Then it will orient its high gain antenna toward earth for maximum radio strength.

These chores attended to, it will begin accepting and decoding radio commands from earth: "Take a good look at yourself with the wide angle TV vidicon so we can see if you received any landing damage. Now, look down at your legs so we can see whether they are buried in dust."

One Job After Another

Meanwhile, on a different frequency, Surveyor will be transmitting a telemeter report from its 24 touchdown sensors, on such things as time of contact of each foot pad and the force with which each one struck, and whether any sliding or rolling occurred after impact.

From the start, Surveyor has been an exciting challenge to its designers at Hughes Aircraft. To develop a machine that can determine the nature and strength of the lunar surface, provide information for maps, determine seismic activity and even if the moon has a liquid core, analyze the chemical composition of the surface, and do a score of other jobs-this is a tremendous task. Then add three complications: The scientific payload cannot exceed 65 lbs., everything that Surveyor learns must be relayed a quarter of a million miles to earth, and the moon craft must be able to "live" in a 500-degree temperature range.

All this seems like an impossible assignment and yet, by combining pure science and down-to-earth engineering, the Hughes' staff has reached solutions that appear simple, once they are explained.

Built-in Temperature

How, for instance, can the electronics equipment be kept at between 0 and 125 degrees F. when the outside temperature climbs to 260 degrees F. during the day, and then plummets to minus 240 degrees at night?

"Actually, battery energy will maintain a comfortable inside temperature at night," explains Sheldon C. Shallon, Hughes' chief scientist for Surveyor, "and thus the real problem is daytime heat dissipation.

"So, for once, the electronics 'black boxes' are pure white, for maximum reflection of the sun's heat. Inside the white skin there's a super-insulation of 75 layers of aluminized Mylar, crinkled so that one sheet touches the next only here and there.

"If the inside temperature still climbs too high, bimetallic switch buttons will click together and provide a metal heat channel to a glass window that has a mirrorlike one-way coating. The window admits very little outside heat, yet can radiate a great deal of interior heat."

Does the system work? The electronics white boxes have been "baked" under a solar simulator (heat lamps) in a vacuum chamber. And they have been chilled with liquid nitrogen until their temperature was that of the utter cold of the lunar night. The system works perfectly.

Can Break Concrete

Again, how would you design a device to "determine the mechanical characteristics of the lunar surface?"

On Surveyor the answer is simple and direct. The "soil sampler" is merely an instrumented pantograph arm that has a reach of four feet, extended, and that swings left or right on command. Spring-loaded, it can whack at the surface like a pick (it's strong enough to break half an inch of concrete). It can dig a hole 20 inches deep, can claw a furrow by retracting itself and meanwhile measure the drawbar pull.

These operations will be performed upon radio command from technicians stationed in Jet Propulsion Lab's operations room in Pasadena, who will watch the results on television. If small rocks happen to be in the way, the mechanical arm can push them to one side and then attack the material below.

To analyze the composition of surface materials, a beam of alpha particles from radioactive curium is used. The "scattering" of the alpha particles provides a rough measurement of the elements that are present, such as calcium or iron. The device can distinguish between meteoritic and igneous rocks.

A seismograph bolted to the spacecraft's frame not only will detect moon quakes, if any, it will also determine if there is much expansion and contraction of the surface because of temperature changes and will even pick up the impact of meteorites hitting at a distance.

Cameras' "Eyeball" Moves

-One of the most sophisticated portions of the lunar lab is its television section and, in particular, a pair of "survey" TV cameras. They can look almost all of the way around the horizon and take stereo picture pairs of about a third of the adjacent area. The cameras are actually stationary: they peer into pan-and-tile mirrors in their hoods. It is the hood and mirror "eyeball" that moves, guided by tiny motors.

Obeying radio commands, the cameras will change from close-up wide angle to semitelescopic, will change lens apertures from f/4 to f/22 and will even change filters to permit construction of true color photos on earth. By stereo-ranging, distances to features such as cliffs and craters will be measured so accurately that topographic maps can be prepared.

Blood Will Boil

A century or so ago, "civilized" nations used to deport some of their worst criminals to awesome parts of the earth where the heat, insects and disease soon killed them off. Today, paradoxically, we are planning to dispatch three of the fittest, bravest Americans to a hell far worse. On the moon the daytime temperature is above the boiling point of blood. At night, without protection, you would freeze in a microsecond. There is no air, no water.

To fire men out into space toward the moon, land them there and then bring them safely back to earth, will be the most fantastic undertaking yet attempted by mankind.

Surveyor, the "mechanical American" will lead the way.