Thursday, December 23, 2010

Geostationary Orbits

Man’s ability to place objects in orbit provides us with spiritual object lessons. Our musings about radio and television satellites beaming their digital messages to our receivers at the speed of light raise some questions. We may observe our rooftop satellite dish and wonder why the installation technician pointed it in a precise direction. Early earth satellites circled the earth in low orbit in a little more than an hour. So what accounts for our rooftop dish always pointing in only one direction? The answer triggers a need to review the basics of what keeps satellites in orbit.

Earth satellites are launched into earth orbit at almost 18,000 mph. They must achieve an altitude high enough so the drag of the atmosphere will not slow the satellite sufficiently to cause it to fall back to earth. Once a satellite’s rocket reaches orbital speed, the rocket’s engine is no longer needed. The satellite continues to fly on its own. Inertia, the tendency of a moving object to continue moving at its current speed and direction, allows the satellite to continue moving forward on its own.

If inertia were the only factor, the satellite would continue straight into outer space. Earth’s gravity always tugs on the satellite, causing it to travel in a curved path. The satellite, therefore, is always falling toward the earth, but always missing, because the earth’s surface curves away precisely the right amount. In theory, the satellite could remain in orbit forever. Near earth satellites whiz overhead, out of range in only a few minutes. Low orbit satellites would not be useful for transmission of continuous radio and television broadcasts.

Scientists are able to boost satellites into higher orbits. These orbits do not require such high speeds. Because the gravity diminishes the farther we go away from earth, lower speed is required to maintain the desired orbital path. For example, a satellite 22,223 miles above the earth needs a speed of only about 7,000 mph to continue in orbit. Under these conditions the satellite revolves once around the earth in the exact time earth rotates once. As a result, the satellite remains in a fixed position with respect to one location on the earth’s surface. Your DirecTV dish antenna is fixed toward only one position in the sky to receive its continuous stream of audio or television signals. We receive our Christmas music, our religious broadcasts, or our favorite baseball team’s play-by-play almost instantly, relayed from earth to outer space and back to us.

The satellites described are termed “geostationary.” They must orbit directly over the equator in the same direction earth rotates--west to east. Other types of satellite orbits serve other purposes. A successful satellite is one which meets multiple criteria precisely in order to fulfill its mission. Some satellites have failed because of errant human planning or execution. They travel too fast or too slow, they orbit too high or too low, or their power is lost. Praise belongs to our teams of scientists who implement precision processes to keep our satellites operating at peak performance levels.

Man’s technological achievements have outpaced his achievements in the spiritual realm. As progress in science and application of technology has expanded, we do not see a corresponding improvement in man’s spiritual achievement. Perhaps this is a function of living in the “perilous” or “difficult” times described in various translations of II Timothy 3:1-5. Man’s mastery of technology has increased his sense of self-empowerment, but not his devotion to God. Man’s spiritual dish antenna is not fixed upon God. Adherence to God-ordained physical laws of the universe is necessary for successful outcomes in thousands of scientific applications. In a different realm of human experience, obedience to God’s standards for our behavior is no less crucial.