Safety For The Moon Expedition

Press, Volume CIII, Issue 30438, 12 May 1964, Page 11

Safety For The Moon Expedition

The greatest event of the next 10 years will undoubtedly be the landing of the first men on the moon. If they happen to be Russian cosmonauts there is little we can say about the precise course they will follow or the methods of landing they will adopt until their plans are divulged. However, the Americans have revealed many of the ingenious schemes by which their astronauts will make the moon trip in a manner that will be as safe as humanly possible for such a dangerous venture. From the moment the giant Apollo Saturn C-5 moon-rocket lifts off from Cape Kennedy until the Apollo capsule drops back into the Gulf of Mexico after returning from the moon it will be possible to call a halt at almost any time. The whole course of the expedition is so planned that there will be several opportunities to “mark-time” for a while in space and make unhurried decisions.

Let us suppose that the time has arrived for the Project Apollo expedition to depart. Before this time there will be manned test flights circling the moon but not landing. In fact all of the steps we are about to describe will—with the exception of the last, of course—be tested and proved before the great day when three Apollo astronauts are sealed in their capsule at the top of the 361feet high Saturn C-5 rocket and the count-down nears zero.

Even before the moment of lift-off, the escape rocket on top of the capsule will be armed and ready at an instant’s notice to haul the astronauts out of danger if something goes wrong and there is a risk of igniting the 2800 tons of fuel and oxidiser in the tanks of the Saturn C-5. Normally the escape rocket will remain in position until after the Saturn first stage

falls away and the second stage is burning properly. It is then jettisoned and other on-board rockets will provide a means of escape for the astronauts until the whole upper section of the Saturn is safely parked in earth orbit. As they circle the earth at a height of 115 miles (see diagram) the astronauts and ground controllers will confer and decide whether to proceed to the moon. If all indications are “go” the guidance computer in the Apollo command capsule will choose the correct moment to fire the Saturn third stage. This stage will give the expedition a 7000 miles an hour boost in speed, bringing its total speed up to 25,000 miles an hour, enough to carry it to the moon. Even so, the flight may be aborted at any indication of trouble and the expedition diverted into an elliptical orbit which will finally return everyone to earth, although the choice of land area in such circumstances will not be as good as otherwise.

Three days after departing from the parking orbit around the earth the expedition will arrive near the moon. A brief burst of power from the fourth stage (known as a service module) will be enough to drop the expedition into a parking orbit 92 miles above the moon (see diagram), otherwise they will flip around the back of the moon and head back to earth.

From the vantage point of the lunar parking orbit the decision will be made to transfer two of the three astronauts from the command capsule to the Lunar Excursion Module (LEM) which will land on the moon. A slight nudge of rocket power and the LEM orbit will be modified to almost graze the lunar surface.

At the lowest point of its orbit the LEM will pass only 50,000 feet above the pronosed landing region, but it

will reach its highest point at about 170 miles in order that its orbital period will exactly equal that of the command capsule. Thus the LEM and the command capsule will automatically meet once per revolution and furthermore they will remain in sight of one another. As the two astronauts in the LEM swing low over the moon they will seek out the most suitable landing site and decide whether to continue. Next time round, assuming everything looks good, the astronauts reignite the rocket on the LEM and come down to a hovering position above the lunar surface. They will have enough fuel to hover for something like a minute and travel, if need be, about a quarter of a mile in any direction to a suitable point for touch-down. If they don’t like what they see they can boost themselves back into a rendezvous orbit with the command capsule. If they decide to land they will make history. After three or four days on the moon the two astronauts will have to set about rejoining their fellow astronaut who has been patiently orbiting the moon in the command capsule. As he comes overhead the two on the moon have a six or seven minute “launch-window” in which to blast-off and climb into a suitable rendezvous orbit.

All throughout the ascent there will be radar and visual contact between the two vehicles and both .will be capable of altering course to home-in on the other. This provides complete redundancy for one of the most critical manoeuvres of the whole operation. When the trio is complete once again in the command module the L.E.M. is jettisoned (to remain forever as a satellite of the moon) and the computer figures out the departure time for the return trip to

earth. When this has been verified by the computer’s big brothers back on earth the astronauts get set to go. A short thrust from the rocket on the service module (still attached to the command capsule) and the threeday return journey is begun. Half-way back to earth, after the computer in the command capsule has chatted by radio with its terrestrial relatives, the vital midcourse correction will be made. Precise bursts of rocket power will guide the expedition into a narrow corridor which will be less than 20 miles deep at the earth end. If the final trajectory is too high they will get too little braking from the earth’s atmosphere ai!H remain in an elongated earth orbit—with another chance about a week later if they are lucky. Or they might miss the earth altogether. If the final trajectory is too low the expedition will perish in a ball of fire in the earth’s atmosphere. If the trajectory is correct they will survive the re-entry and the rest will be up to the recovery task force.