Final Test Flight Soon For Lunar Vehicle

Press, Volume CIX, Issue 31986, 13 May 1969, Page 6

Final Test Flight Soon For Lunar Vehicle

As the American Project Apollo moves closer to its goal of landing a man on the moon a greater share of attention is being focused on a strange-looking spacecraft known as a Lunar Module—or LM for short.

It is designed to convey two astronauts from an Apollo capsule in lunar orbit down to the surface of the Moon and later return them to the waiting capsule—an exacting task with no room for error. . Built by the Grumman Aircraft Corporation, the 16-ton lunar module is the first true spaceship in the sense that it is designed to operate only in a space environment It lacks the strength and shielding to survive a re-entry into the Earth’s atmosphere. Despite its relative fragility and odd appearance the lunar module is really quite a powerful twostage rocket. The lower of •the two is called the descent stage and is equipped with four spidery landing legs which will support the entire module on the surface of the moon. The upper one is the ascent stage which contains the crew compartment and a rocket engine to boost it back into lunar orbit. The discarded descent stage remains on the moon. Odd Shape The ascent stage comprises the upper half of the complete lunar module. It is the oddest shape imaginable—not even Buck Rogers flew in such an ungainly-looking contraption. Even without its four clusters of thruster rockets and its dozen radio and radar antennae it looks like something a small boy might create from his construction toy. However it is thoroughly utilitarianin design, providing

not only transportation for the crew but also a complete life-support system and protection from the hazards of space. It has an oxygen supply and atmosphere revitalisation section which removes carbon dioxide, noxious gases, odours and excess moisture. It can supply both of the space-suits or pressurise the cabin depending on whether the outer hatches are open or closed.

Water for drinking, firefighting or food preparation is provided from a 36-gallon tank in the descent stage, supplemented by two 5-gallon tanks in the ascent stage. Thermal control is achieved by a waterglycol circulation system which transports heat from the space suits, batteries and electronic components to cold plates or radiators and if necessary heat can be dumped overboard by water evaporation. Ladder To Moon When the lunar and command modules are docked the astronauts can transfer internally to the ascent stage via a hatch which leads through a 32-inch diameter tunnel into the crew compartment. This compartment is surprisingly roomy even though it is only about six feet long and three and a half feet wide. The astronauts stand side by side in front of instrument panels. Below the panels is another hatch which opens out on to the platform and ladder to be used for egress on the moon.

Just above his instrument panel each astronaut has a

triangular window looking forward and downwards. Either astronaut can take over manual control of the lunar module as it makes its landing approach and steer it clear of obstructions or even abort the landing and guide the vehicle back to the orbiting command module, On the forthcoming Apollo 10 mission the lunar module will be given its final spacetest before the Apollo 11 lunar landing next July. The LM was first tested in space early last year when its guidance and attitude control systems performed beautifully and its descent engine demonstrated that it will easily brake the module's 3500 m.p.h. fall from orbit to the surface of the moon. The ascent engine likewise gave an assurance that it will boost the expedition back into lunar orbit with thrust to spare. Testing Systems In February this year all components of the Apollo spacecraft were ready for a trip to the moon. However, caution has prevailed and the Apollo 10 mission is therefore designed to test all systems in lunar orbit rather than merely in orbit round the earth. There are several reasons for adopting a cautious approach at a time when many are advocating that Apollo 10 should chase the honour and glory of the first manned lunar landing. In the .first place the moon’s gravitational field is not as thoroughly explored as that of our planet. Due to the presence of mass concentrations under the lunar “seas” or maria the lunar gravity field is distorted and rather bumpy. As a result it is difficult to compute a precise approach trajectory to the surface of the moon and be sure that it will not deliver the spacecraft to a point higher or lower than anticipated. The latter case could be disastrous. So Apollo 10 will follow a path taking it down to Within 50,000 feet of the lunar surface. At that altitude a discrepancy of a few thousand feet either way will not matter. If there is much of an error the information gained will enable an improved approach trajectory to be prepared for Apollo 11. Dress Rehearsal The uneven gravitational field of the moon will also affect the rendezvous between the command module and the ascending stage of the lunar module, but to a lesser extent. The ascent stage has rendezvous radar equipment with an operating range from 80 feet to 400 nautical miles as well as a flashing-light beacon visible with the naked eye to 130 miles in case the command module needs to come to its rescue. Nothing has been left to chance, nevertheless NA.S.A. officials want Apollo 10 to be primarily a dress rehearsal to ensure the success of the his-tory-making Apollo 11 flight. When Apollo 11 astronauts Armstrong and Aldrin become the first Americans to tread the desolate landscape of the moon the event will culminate the most ambitious and spectacular test-flight programme ever attempted by man or machine.