Farthest Human-Made Object: First Quarter Century 405
An anonymous reader writes "The NASA Astrobiology Magazine reports today the 25th anniversary of the Voyager I launch, now the farthest human-made object at 93 Sun-Earth distances (93 AU), or 12 light-hours away. Expected battery life to 2020. The fascinating part is that gold record of civilization, which is a strange audio mix of sentimental kisses [wav file, let ET phone home that way] and perhaps the most dated picture of DNA. Some progress there. Voy 1 will likely confuse even modern earthlings-- much less ET. Case in point: In 2002, can we understand that 70's show, when the Polish greeting memorialized as "Welcome, creatures from beyond the outer world"? Unlike those ET creatures we meet daily from the inner world?"
That's Light Hours, not Light Years (Score:2, Informative)
12 light years would require it to fly at ½ the speed of light, which is not technichally feasible (unfortunately!)
Re:Battery life? (Score:4, Informative)
Looks like the isotope's power the battery.
Comment removed (Score:3, Informative)
Re:Carl Sagan and the stellar record. (Score:2, Informative)
Re:What has changed since 1970's? (Score:3, Informative)
Radioisotope Thermoelectric Generators (RTG's)
Three RTG's provide electric power to Voyager. The generators produce about 1800 watts of heat by the radioactive decay of plutonium. The heat is then converted to about 400 watts of electric power by thermocouplers. The RTG's are mounted on a boom to protect the scientific instruments from excess heat and radioactivity.
and this [nasa.gov], which discusses RTGs in the context of Cassini and safety.
Golden Record (Score:3, Informative)
How odd that the first human voice any aliens who could work the disc will hear is the voice of a former Nazi alleged to have taken part in war crime atrocities in the then Yugoslavia...
You have no idea what you're talking about. (Score:3, Informative)
Besides, your analogy falls flat. I presume your point was that the age of the technology is irrelevant when it comes to leaving the solar system? Then consider this: what is it that pushed the 1970s technology of the Voyagers out of the solar system? Answer: more 1970s technology. If your 16th century vase were propelled by 16th century rockets, then your analogy would be valid.
Re:Battery life? (Score:3, Informative)
My Polish is rusty, but... (Score:4, Informative)
I think it would be an equivalent of "Greetings, creatures from Outer Space," but they didn't intone it pretentiously, right before Ed Wood hovers the hubcap from a string and a theremin plays in the background as his boustier intrudes into the picture, as we are wont to do over here.
Useful purpose for 1 AU (Score:2, Informative)
First, as has already been pointed out in other replies, miles are also an absurd, arbitrary unit as far as science is concerned. We could get a 'round' unit if we took, say, about .65 AU, as the 'new' astronomical unit--exactly 10^11 m.
But then the AU would be a pretty useless yardstick. Earth's orbit is very nearly circular, which means that over a period of six months, the Earth moves a net distance of (almost) exactly 2 AU. Using this knowledge, it is possible to measure the distance to nearer stars. As the position of earth changes, the apparent positions of nearby stars will also appear to change relative to much more distant stars--a parallax effect. To get a precise measure of this distance, you want to move the Earth as far as possible, to get the maximum apparent shift in position. 2 AU is as far as we can readily move the earth.
There is even a unit of measure that is defined on this basis. The distance at which the apparent parallax shift of a star is equal to one second of arc is defined as one parsec. Parsec measures can be directly obtained from astronomical images taken six months apart, so they are the preferred unit of measure for some types of observational astronomy.
Of course, this also works backwards. If we could see a planet orbiting a star one parsec away (about 3.26 light years--this is a hypothetical case) and its orbital motion was across one apparent second of arc, we would know it orbited its sun at a distance of 1 AU.
Yes, for sufficient money (Score:2, Informative)
First cab off the rank is probably the Orion drive. Build a really big plate, attach it with really big springs and dampers to a heavily radiation-shielded spacecraft, and detonate atom bombs behind the plate. The basic technology exists right now, all you need is a pile of cash and be prepared to violate the space weapons treaty. Maximum speed is about 1-2% of the speed of light, so you're still taking a couple of centuries to Proxima Centauri.
Next option is a fusion engine. We can't generate power with controlled fusion yet, but ITER probably will if and when it gets built. ITER is, er, rather large and heavy, and doesn't really produce much net power, so a practical space fusion power plant is a fair bit of engineering development down the road. Anyway, the idea is quite simple. Release the "exhaust" of the reaction out the back of the engine, just like a normal rocket except the exhuast is a hell of a lot hotter and travelling a lot faster. Maximum speed maybe 10-12% of the speed of light.
Alternatively, use a light sail powered by a really big laser. All you need is to scale up laser and telescope technology a crapload (so, again, considerable engineering development required). Maximum speed? Somewhere between 10 and maybe 30% of the speed of light, depending on just how big you can make your mirror (and consequently how far you can keep accelerating).
The other big issue with interstellar spacecraft is the question of how much debris is out there. If there's a lot, as you go faster you'll need one hell of a shield to protect you.
Finally, there's there's also the possibility of using antimatter-matter reactions to power a ship. Antimatter is kinda powerful stuff to have around, and you could theoretically use it to power a ship to near the speed of light. However, there is no known natural source, and manufacturing it requires milllions of times more energy put in than you get back when you "burn" it. It, therefore, is a really long-term option from when humanity has such astounding energy generation capacity it can afford to use it to power antimatter-powered spaceships.
All in all, there are some possibilities, but most are still a fair bit of technological development away. Let's get to the rest of the solar system first :)
Re:What is the heliopause? (Score:3, Informative)
The sun emits a flood of mostly-charged particles that make up the "solar wind." The earth is shielded by its magnetic fields, but the interplanetary environment is quite harsh.
The heliopause is where this outward flow of solar matter becomes less than the general flow of matter through the galaxy. There isn't any good way to observe this from earth, which is why having a Voyager pass through the area is a good thing. Our current picture of the heliopause is based on physical modeling and simulation. Having any observational data to check these models against would be a major step forward.
Re:My Polish is rusty, but... (Score:2, Informative)
Re:Not the furthest mad-made object?! (Score:3, Informative)
See This page [enviroweb.org] for details about the real test (search for "Pascal-B").
Re:Stellar escape velocity (Score:3, Informative)
Escape velocity from the Sun at a given radius,r, is just sqrt(2*G*M_sun/r). Plugging in (G=6.67e-8 in cgs units; M=2e33 g; r=93 AU = 93 *(1.496e13 cm)), I get v_escape of about 4.4e5 cm/s, or 4.4 km/s. (About 15,800 km/hr, or 9800 mi/hr, safely less than Voyager's velocity.)
It was an interesting thought, though. :-)
Re:DNA is still DNA (Score:3, Informative)
I used to own the hardcover, but it disappeared one day, along with my copy of A House in Space [amazon.com], the story of the first space station, Skylab.