Archive for the Science Category

The Little Probe That Could

Posted in Science on May 10, 2011 by Sardonic Pariah

Well, there’s actually two of them, but pluralizing “Probe” would have wrecked my reference to a famous train.

These are our little voyagers to the stars.  Literally.  They’re the Voyager probes.  Also, when I say little, I mean comparable to a small car.  Each weighs about 800kg.  But as far as things that are flinging through the interstellar medium go, they’re pretty tiny.

Originally designed to observe Jupiter and Saturn up close, the probes were so successful that Voyager 2 was sent to look at two more planets, the gas giants Uranus and Neptune.  Since then the probes have continued on their course, and that’s the exciting part, as far as I’m concerned.  Not that the gas giants aren’t great; I mean, they’re freakin’ huge, and awfully pretty, but the exciting part for me is that human beings are now fledgeling interstellar explorers.  That’s right, you heard me.  We’re in the deep space now.

As we speak, Voyager 1 is approaching the edge of the heliopause, the area of space where the Sun’s influence on events wanes and outside influences have more of an effect than the solar wind.  It’s like the edge between a cold front and a warm one, except far grander and far less violent.  Once the probe crosses that hazy line, it will truly be outside of the solar system, and for the first time we will have an active craft in interstellar space.  That is, provided the battery holds out.  They’re expected to last until “at least 2020,” which in NASA parlance means “it could break at any time.”  NASA equipment sometimes explodes on launch, sometimes lasts vastly longer than the design lifespan of the vehicle, and it’s kind of a crapshoot.  Given that it’s in a region where a catastropic disaster is increasingly unlikely, their estimate may fall short.

If it does, Voyager 1 will pass the heliopause first, sometime between 2020 and 2030.  The edge of the region is not well understood, and it could be subject to change, based on the activity of our star and that of others in the area.  Though it’s speed of 17km/s is the fastest of any human craft, Voyager 1 is still a snail compared to the sheer size of space.  It will take it 40,000 years to get within two light-years of another star, the imaginitively named AC+79 3888.  I sincerely doubt it’ll have a battery charge when it gets there.  Voyager 2’s next “close” approach will be with Sirius, the brightest star in the sky; it should reach 4.3 light-years from the big Dog in 296,000 years.  For reference, the closest star in our own sky, Proxima Centauri, is also 4.3 light-years away, so really, Voyager 2 is not going to be all that close.

While the batteries will be dead long before either of these two doughty little probes make it to anywhere other than the middle of nowhere, they both carry plaques that will give any inquisitive aliens a glimpse into who sent the craft.  The Golden Records will tell our story, if their discoverers can decipher them.  It’s entirely possible that an alien species capable of detecting and intercepting a non-transmitting, tiny space probe won’t have much experience with 12-inch records.