A Million Miles a Day

Voyager 1 left Earth aboard a Titan III rocket on a bright summer day in September, 1977. It reached its first destination, Jupiter in 1979, then visited Saturn in 1980 before heading out of the solar system.

Currently traveling nearly a million miles every day (about 38, 400 miles per hour), even after 30 years of space travel, the barely 180 pound space probe is only 14 light hours away from home. Compare that to the nearest star, Proxima Centari, at 4.3 light YEARS away. There are 8760 hours in a year. That means it has taken Voyager 1 30 years to travel .015 percent of even a single light year. Multiply it by 4 and that’s how much further it is to the closest star from our Sun.

The Star Trek Enterprise, it isn’t.

And yet, Voyager 1 has traveled further than any other space ship that has ever left our planet. It is now more than 100 AU from the sun. That means, it is more than 100 times the distance from the sun that the Earth is: 9.3 billion miles, compared to the 93 million miles that separates Earth from the Sun. And Voyager is the best we can do just now. The gap between the fantasy of Star Trek and the reality of our current space faring capability is wide.

Running on nuclear energy, since the Sun just another bright star as far as Voyager is concerned, receiving considerably less energy than it would need to keep functioning, it will likely continue to have enough power to remain in communication with Earth until at least 2020.

Electrical power is supplied by three Radioisotope Thermoelectric Generators (RTGs). The current power levels are about 315 watts. As the electrical power decreases, power loads on the spacecraft must be turned off in order to avoid having demand exceed supply. As loads are turned off, some spacecraft capabilities are eliminated.

Uplink communications is via S-band (16-bits/sec command rate) while an X-band transmitter provides downlink telemetry at 160 bits/sec normally and 1.4 kbps for playback of high-rate plasma wave data. All data are transmitted from and received at the spacecraft via the 3.7 meter high-gain antenna (HGA). Compare this to dialup internet access of 56 kbps. Even my first Commodore 64 used a modem that connected at 300 bits/sec. But keep in mind, this is a very old spacecraft, launched before the Commodore 64 even went on the market. And, since it is 14 light hours distant, twenty-eight hours pass between sending a signal like “how are you?” and getting a response “fine.”

A more than five times larger, 1000 pound New Horizons space ship was launched on January 19, 2006 toward Pluto. It had an Earth-relative velocity of about 36,300 mph just after its last engine shut down, making it the fastest spacecraft launch ever. It sped past the moon only nine hours after launch and is already past the orbit of Uranus. It is scheduled to reach Pluto in the summer of 2015. But Voyager 1, with its 30 year head start, will still remain the furthest space ship from Earth until 2070. Only then, will the New Horizons space probe at last pass it to become the furthest human built outpost—unless, in the interim, humanity figures out a way to travel even faster. According to the fictional Star Trek timeline, Zefram Cochrane is supposed to launch the first warp capable space ship in 2063. But of course, Star Trek is only make-believe. Voyager 1 and New Horizons, however, are quite real.

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About R.P. Nettelhorst

I'm married with three daughters. I live in southern California and I'm a deacon at Quartz Hill Community Church. I spent a couple of summers while I was in college working on a kibbutz in Israel. In 2004, I was a volunteer with the Ansari X-Prize at the winning launches of SpaceShipOne. Member of Society of Biblical Literature, American Academy of Religion, and The Authors Guild
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