Where are they now?
Published on May 13, 2007 at 2:44 pm.
6 Comments.
Filed under space exploration.
Five human-made spacecraft are on their way out of the Solar System. The most recent one, New Horizons, was launched only 16 months ago, yet it is already 5.13 AU from the Sun (One Astronomical Unit, or AU, is the average distance that Earth is from the Sun). New Horizons is the fastest spacecraft ever to be launched from Earth. Currently, New Horizons is in the general direction of the constellation Ophiuchus and is moving at 21.2 km/s. It takes radio signals over 43 minutes to reach us from New Horizons. New Horizons, like all of the other spacecraft to the outer Solar System is powered by radiothermal generators instead of solar panels because at its current distance from the Sun the Sun appears only about 2.5% as bright as it does from Earth, and New Horizons still has a very long way to go. It is on a mission to visit Pluto and the Kuiper Belt.
But, there are four other spacecraft leaving the Solar System. Depending on how you look at it, they either have left the Solar System or will soon leave it. If by “Solar System” you mean the system of planets around the Sun, then they have left the Solar System. But, the Sun is continually streaming material outwards from it, and these spacecraft are moving through this material. So, if by “Solar System” you include this material, then they are still in the Solar System, though Voyager 1 is right on the cusp of interstellar space. It is currently in the heliosheath, the region that acts as a boundary between the Sun’s influence and interstellar space. Most astronomers consider the outer edge of the heliosheath to be the boundary of the Solar System, and Voyager 1 is nearly there. Launched in the summer of 1977, Voyager 1 is now almost 103 AU from the Sun, also in the general direction of Ophichus. From this distance, the Sun appears only 0.009% as bright as it appears from Earth! Furthermore, radio signals from Voyager 1 take over 14 hours to reach Earth. Voyager I’s sister ship, Voyager II, is only 82.7 AU out, in the direction of the constellation Telescopium. Both Voyagers continue to function, though at much reduced capacity.
The Voyagers were to be our first comprehensive studies of the outer planets. However, there was some worry about what dangers they might face on the mission, so two much less expensive (and expendable) spacecraft were sent ahead to pave the way: Pioneer 10 and Pioneeer 11. They were launched in 1972 and 1973, and are no longer functioning. Pioneer 10 is 93 AU from the Sun in the direction of the constellation Taurus, and Pioneer 11 is almost 74 AU from the Sun in the direction of the constellation Scutum.
These five spacecraft have escape velocity, and they will leave the Solar System to wander through interstellar space. It wil be tens of thousands of years before then reach another star system, by which time they will long since have ceased to function. No one knows, even, what tens of thousands of years worth of exposure to radiation and particles in space will do to the craft, and we’ll likely never find out.
-Astroprof
Images courtesy of NASA, JPL
Spacecraft position data courtesty of HeavensAbove
Galactic Supah Fly on May 13, 2007 at 4:24 pm: 1
That’s intresting. I often wondered, when using the Solar System Simulator on the JPL website, what happened to the Voyager and Pioneer crafts!
A Ler…-- Rastos de Luz on May 14, 2007 at 8:51 am: 2
[…] “Where are they now?”, no Astroprof’s Page. […]
Dick Gorter on May 15, 2007 at 4:16 am: 3
Really nice to know!
Robert Clarke on May 15, 2007 at 10:18 am: 4
Thanks. Nice to know that Voyagers 1 & 2 are still functioning. Rather remarkable!
Sean on May 16, 2007 at 1:01 am: 5
very very cool. I was born in 1970 and had never heard of Pioneer 10 and 11. Thanks for taking the time to put this together.
Lars Andersen on August 7, 2007 at 9:06 am: 6
Does anyone know what star New Horizons will be passing (in thousands of years)?
I know it’ll probably be within a light-year’s distance. I assume that New Horizons hasn’t got the energy to chase Kuiper Belt Objects, and changing ”target star”.