72-227 ALSEP - Lunar experiments to continue beyond Apollo 17
NASA Manned Spacecraft Center, Houston, Texas 77058
FOR RELEASE: UPON RECEIPT
F. Dennis Williams 713/483-5111
RELEASE NO: 72-227 ALSO RELEASED AT NASA HEADQUARTERS
ALSEP - LUNAR EXPERIMENTS TO CONTINUE BEYOND APOLLO 17
Though Apollo 17 and the last Americans to explore the lunar surface are scheduled to splash into the Pacific December 19, an extensive scientific network will continue to send live reports from the Moon for at least two years.
The network has been an important product ofthe lunar research program carried out by Apollo spacecraft since November 1969. Powered by nuclear energy, the $125 million system allows direct relay of data to scientists on Earth from experiments on the Moon.
Apollo 17 astronauts will establish the fifth independent experimental station, bringing the total number of operating experiments to nearly two dozen. The instruments in the network measure such things as tremors beneath the lunar surface, heat radiating from within the Moon, gravitational and magnetic forces, and particles in the lunar atmosphere.
Most of the experiments had a life design goal of one year, but four of the five instruments carried by Apollo 12 continue to return information more than three years after they began operating.
All five stations include seismometers to record tremors caused by meteoroids, tidal stresses, and internal changes in the Moon. Because the Moon is extremely quiet, the seismometers register shocks far smaller than would be noticeable on Earth.
The seismic network is providing a wealth of information about layers far beneath the Moon's surface.
Even though there is a nearly perfect vacuum on the Moon, a variety of instruments measure the constantly changing lunar atmosphere. Solar winds, gases escaping from beneath the surface of the Moon, and dust thrown up by the impact of meteoroids all contribute to matter in the atmosphere.
A third attempt to measure the heat flowing from the center of the Moon will be made with an experiment to be set up during Apollo 17. Sensors will be placed in holes drilled 2.4 meters (8 1/2 feet) into the lunar crust to provide regular readings.
Three new pieces of equipment will be added to the lunar network during the final mission. Devices to measure lunar gravity, the size and speed of micrometeroids, and the elements of the lunar atmosphere will complement earlier instruments.
In addition to the more sophisticated geophysical network, three arrays of retroreflectors specially constructed to reflect laser beams sent from observatories on Earth were placed on the Moon during Apollo 11, 14, and 15.
By aiming a laser beam at any of the arrays and timing its return to Earth, the distance to the Moon can be calculated with remarkable precision, now equal to 15 centimeters (6 inches).
This is giving information about the mass distribution and wobbles of the Moon about its center. In addition, measurements of the variations in distance with time are giving both an improved orbit for the Moon and an accurate check on the theory of gravity.
A new lunar distance observing station designed for 2.5-cm (1-in.) precision is being constructed on Mt. Haleakala in Hawaii. New observations concerning the Earth should become possible with this increased precision. If major earthquakes tip the Earth slightly with respect to its axis of rotation, this should show up in the lunar distance observations. Continental drift and fluctuations in the Earth's rotation should also be detectable in a fairly short period of time.
The final group of five experiments for the Apollo 17 landing site have a life design goal of two years, twice as long as the earlier packages. They may operate much longer.
No one knows when the five stations may stop sending back data from the Moon, but their nuclear-powered generators may still be providing energy well into the twenty-first century, far longer than the experiments themselves will survive the cycle of extreme heat and cold on the lunar surface.
- end - November 29, 1972