Sunday, September 15, 2013

Moving Up, Moving Out

(Picture from here.)

Remember Voyager 1? Tiny probe barely the size of a Geo Metro who gave us pictures of Jupiter and Saturn like we'd never seen them before? Brief acting career in Star Trek I but the less said about that the better.

Well, the little guy has all grown up and moved out.

That's right Voyager I has exited the solar system. (NASA announcement here.) I know he flirted with moving out before, hanging out in the heliopause for months. But this summer he finally cut the cord and went out to see the big wide world.

Voyager was launched by NASA in 1977. Usually, I like to talk about manned exploration of space-- which fits with my general biological point of view. Manned missions are like biology exploring the rest of the universe.

But I have to say NASA's unmanned missions have actually done far more than the manned missions have. I mean it's great we reached the moon and have the ISS. But manned missions, to me, are about space colonization and getting people off the planet. Exploration is a nice but secondary part of the goal. It's a perk.

The unmanned missions are about raw exploration and scientific data. And NASA has done a lot more of them than they ever put people into space. (Here's a NASA list. Here's a much larger list.)

NASA started with Explorer (There were 90 Explorer missions)  in 1958 and now it's just a little more than fifty years later and we have a mission that has actually left the solar system. That's about two and a half human generations.

We like to make fun of the old SF books that had people colonizing the moon in the 20th century. Heinlein had Luna City founded sometime in the nineties. (See chart here.) Nobody had a good grasp on how godawful expensive space would be or how really far the planets were-- much less how far the nearest stars were.

It's interesting that unmanned exploration wasn't much talked about in SF. I mean there are some stories about it. Certainly, James Cambias has written more than one suggesting that robots are the way to handle space. Meat is just too fragile.

Meanwhile, in 1958 (coincidentally, the publication date of Heinlein's Have Space Suit--Will Travel) we started populating nearby space with machines. These days we have better than two thousand satellites in orbit. Most of those either are studying earth, handling earth commercial needs or are military.

But it wasn't long before we started looking outward. I'm guessing the first serious off-earth probes were the Pioneer missions. The first Pioneers launched for the moon. Some got there. Some didn't. In fact, from P-0 to P4 (which included 10 probes, all of which aimed at the moon) most failed pretty spectacularly. Of them, only one (Pioneer 5, launched in 1960) aimed for Venus. Later Pioneer missions, starting in 1965, looked all over the place. Pioneer 10 (launched 1972)  reached Jupiter. Pioneer 11 (launched 1973) reached Jupiter and Saturn. The year after Voyager I was launched, the Pioneer Venus Project had its first launch with the Pioneer Venus Orbiter-- which continued to give us data until 1992.

Pioneer 10 and Pioneer 11 are on their way to escaping the Solar System, slowly following where their younger brother has gone before.

In parallel with Pioneer were the Ranger missions. Ranger was all about the moon and, like Pioneer, failed a lot in the early years. Ranger 7 made it in 1964 and we had our first close images of another planet. To give a comparison to the manned program, Alan Shepard launched in 1961 and by 1963 the Mercury program had ended with six successful missions and four missions that involved actual orbits. Man returned to space in later in the Gemini program by 1965.

The Mariner program ran in parallel with both Pioneer and Ranger. It began in 1961 and sent probes to Mars, Venus and Mercury. Again: initial problems with Mariner 1 and Mariner 2, both intended for Venus. Mariner didn't show success until Mariner 5, launched for Venus in 1967. Mariner 6 and 7 made Mars. Mariner 9 orbited Mars, sending back data for a year.

Then, there's Surveyor: those wonderful tiny probes that we actually dropped on the moon. Seven were launched. Five succeeded. One (Surveyor 6) actually managed lift off for several seconds and moved around a bit.

In 1974, just three years before Voyager was launched, the first Helio probe was launched to study Mother Sun. They sent data back to us for ten years.

Viking 1 touched down on Mars in 1976, one year before the Voyager I launch.

And these were just the NASA missions. There's the Russian Venera and lunar exploration programs. Not to mention the many, many Earth observatory satellites, some neither Russian nor American. Not all exploration need be done by a visit.

Then came Voyager I, the first probe to execute a Grand Tour of the Solar System. Voyager I let us see Jupiter and Saturn, so close and personal we could watch volcanic eruptions on Io and see the atmosphere of Titan. Later, the Grand Tour would be continued by Voyager II.

I don't know about any of the rest of you, but those first pictures of first the Jupiter approach and then-- oh, my!-- those pictures of Saturn are as strong in my mind as Neil Armstrong's first steps. This is the sort of thing we should be doing all the time!

Since then humans have had tremendous success exploring the solar system and elsewhere by probes and observatories. I won't dwell on them here-- this is about Voyager I.

In 1980, Voyager I performed a close flyby of Titan, spun around it with a gravity assist and left the Grand Tour towards interstellar space. In 1990, V-I gave us a Valentine's Day present of the Family Portrait, a mosaic of the Sun, Earth, Venus, Jupiter, Saturn, Uranus and Neptune.

The recent years have been one of getting closer and closer to the boundary of interstellar space-- the edge of the Heliosphere. In 2004 it passed the termination shock-- the boundary where the interstellar medium slows the outgoing solar wind to the point where compression begins to occur. At some point, it passed the termination shock and entered the Heliosheath, the area between the termination shock and actual interstellar space. In 2010, it reached the region of the Heliosheath where the speed of the solar wind dropped to zero. In 2011, Voyager entered a previously unknown area called the stagnation region or "cosmic purgatory," an area of particle turbulence where the wind actually curls inward back towards the sun. The dominant force here is interstellar particles and fields but the magnetic field of the sun is putting up a good fight.

Then, in 2012, it was thought Voyager I had exited the solar system. But in December it was decided it was a new region at the edge.

Then, 9/12/2013, NASA confirmed Voyager I had at last left the solar system.

Voyager I is getting old and cranky. Three different subsystems have had to be turned off in the last few years to conserve power. Two years from now the recording system will be shut down. Sometime in 2016 gyroscopic operations will be halted. Then, in 2020, the science instruments will be terminated one by one until sometime between 2025 and 2030, nothing will be working any more and it will go forward, cold and dark, on its way to Gliese 445.

It should get within a couple of light years in 40,000 years. And it left us with this cool, creepy sound.

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