Slashdot Mirror
Voyager 1 Passes 100 AU from the Sun
An anonymous reader writes "Yesterday, Voyager 1 passed 100 astronomical units from the sun as it continues operating after nearly 30 years in space. That is about 15 billion kilometers or 9.3 billion miles as it travels about 1 million miles per day. Scientists still hope it will find the edge of the solar system and get into interstellar space."
I recall some time ago reading that the total-return-time for an ICMP_ECHO_RESPONSE from voyager 1 was something in the scale of 29 minutes. I'm hoping we're still getting useful data from these devices.
Informatus Technologicus
http://g-fav.blogspot.com/2006/07/hey-linguists-a
(and now I must wait 49 seconds to amend it, ferfuxsake. slowdowncowboyslowdowncowboyslowdowncowboy)
If Jesus wants me it knows where to find me.
These RTG generators are compact, robust, and long-lived. However, they are not cheap, do not deliver huge quantities of power, decay slowly over time, do not respond to peak load requirements, and are not really efficient. (They use raw heat from radioactive decay, and thermoelectric conversion.)
On Earth, we can pile up a large amount of radioactive material to cause a controlled chain reaction. We can then convert it on an industrial scale to AC electric power for distribution over many miles. You may have seen something called an "electric outlet", where you can pay pennies for a kilowatt hour? And lead-acid batteries to tide you over if the electric grid goes out?
Umm... Read more fellow. They use Plutonium... They are radioactive and could be used to make at least a dirty bomb if not an outright fission device.
They uses some in the old Soviet Union at some remote sites but they used Strontium 90 which while it will still kill you can not be used to make fission devices.
Not something I would want in my basment but dang handy in space and maybe some remote applications like ocean monitoring or even antarctica.
See my blog http://ilovecookes.blogspot.com/ for light hearted technical information.
Damned near everything is dead, and it's sending back only the most basic scientific information to conserve energy levels that are already well beyond their expected date of exhaustion. I read an article not long ago (that I can't be bothered to find again) stating that only a small percentage of its original devices of science have worked at all since the 80s.
Long story short -- at this point, she's basically running flat out to see how far she can go while running on fumes. The same article stated that the new projection of its fuel exhaustion is roughly 2020.
-
Inventor of the term 'pardon my French'.
Space is VERY empty.
It's only slightly less non-empty when you're real close to a star or other big mass of stuff. Right now Voyager is the farthest from a star that any man-made object has ever reached, so the chances of it hitting into stuff are nearly zero.
But to answer your original question though, no, it doesn't have any kind of stuff-avoidance ability. Even if they had designed it to have that ability, by now it wouldn't have any power left to do that.
I respond to your sigs
Damned near everything is dead, and it's sending back only the most basic scientific information to conserve energy levels that are already well beyond their expected date of exhaustion.
Umm, no.
I read an article not long ago (that I can't be bothered to find again) stating that only a small percentage of its original devices of science have worked at all since the 80s.
The Scan platform was turned off in the early 21st century. That's when cameras were turned off to save power.
See http://voyager.jpl.nasa.gov/science/thirty.html and scroll to the end of the page.
VOYAGER 1
1998 DOY 316 - Reduction in Scan Platform power - preserve UVS and Elevation Actuator temperature (+11.0 W)
* WA Vidicon Heater OFF (+5.5 W)
* NA Vidicon Heater OFF (+5.5 W)
2002 - Terminate UVS operations - turn-off all Scan Platform loads (43.9 W). Date expected to change.
* WA Electronics Replacement Heater OFF (+10.5 W)
* IRIS Replacement Heater OFF (+7.8 W)
* NA Electonics Replacement Heater OFF (+10.5 W)
* Azimuth Actuator Supplemental Heater OFF (+3.5 W)
* UVS Power OFF (+2.4 W)
* UVS Replacement Heater OFF (+2.4 W)
* Azimuth Coil Heater OFF (+4.4 W)
* Scan platform slewing power OFF (+2.4 W)
So, until 2002, V1 was used for searching UV sources among the stars, among other things. However, that doesn't tell much, since most of the work is done with particle, plasma and wave detectors and those will be working well into the 2020's.
Too bad the CDP1802's architect, Joe Weisbecker, didn't live to see his microprocessor become the first in interstellar space. Coincidentally, this month also marks the 30th anniversary of his Popular Electronics article on the COSMAC ELF; Nuts and Volts magazine is covering it.
Technology has improved a great deal in the last thirty years. Unfortunately, some of the constraints on deep space exploration are physical, rather than engineering problems.
.0001 G over a matter of years). You get more milage per mass of fuel as you increase the exhaust velocity (the speed of the exhaust relative to the craft), but then you're up against power requirements - it takes more and more energy to accelerate the reaction mass to higher and higher speeds. That power has to come from somewhere, and any generator system will increase the overall mass of the spacecraft, decreasing the acceleration.
The limit with any engine, high or low thrust, is fuel. Essentially, any reaction drive that carries fuel with it will eventually run out (whether it's making ten Gs of acceleration over a few seconds, or
Combining an ion drive with, say, solar panels will work wonders in the inner solar system, since you're getting your power for free, and firing off your fuel in small quantities at extremely high speed. In the outer system though, solar power isn't an option and radiothermic generators (RTGs) like those used on voyager are heavy, at least relative to their power output. Most other power technology we have available today would add fuel and/or maintainance constraints. RTGs and solar panals are used for precisely those reasons - because they have neither signifigant fuel limitations nor many moving parts to break down.
Plus, the engines themselves will undoubtably have a limited working lifetime - extending that lifetime to operate for years or decades will involved increasing the mass of the engine, which kinda puts you back at square one.
Something like a light sail would work better (over long distances the lower thrust is offset by the lack of fuel requirements), but that's still more in the realm of science fiction. Nuclear drive technology could also fill the gap, but the political constraints involved in putting anything fission based in orbit are huge, and we won't have fusion for decades at least (longer, if you factor in the need for miniaturization).
Erotic is when you use a feather. Exotic is when you use the whole chicken.
That's actually the exact design philosophy behind ion thrusters.
The U.S. Constitution needs to be ammended with a "separation of business and state" clause.
Not heliopause. It passed the Termination Shock, where Solar wind changes from supersonic to subsonic speeds. It's still in solar wind. Heliopause will be coming up later.
You've just shown that you have no understanding of this issue. For example: your 145,000 tons of uranium is an isotope with a half-life of about 4 billion years. (The small amount of U235 has a half life of 700 million years, and doesn't change the overall total much.) Thorium is similar: it has a half-life of 14 billion years.
An RTG is filled with plutonium 238, which has a half life of 88 years, so it decays about 49 million times as fast as U238. So the total radioactivity of all that coal-based uranium is similar to that of 3 kilograms of Pu238, which is only enough fuel to provide a few kilowatts of RTG power. So it's no wonder environmentalists bitch and moan about a few kilograms of material: that few kilograms is about as radioactive as the total annual emissions of the entire coal industry.
So bottom line, to provide their electrical energy from RTGs, each household would need to manage an amount of radioactivity which is a significant fraction of the grand total emitted by all US coal burning plants. Coal plant heavy metal emissions are dangerous, but mainly because heavy metals are toxic chemicals, not because of radioactivity.
A more practical problem is the fact that Pu238 is outrageously hard to collect and there are only a few kilograms in existence worldwide. Other kinds of radioactive waste isn't generally hot enough to create a useful amount of work; otherwise, they would have left it in the reactor longer to generate more power.
100 AU is nowhere near the Oort cloud. Sedna's orbit is highly eccentric ranging from around 92 au out to around 850 au. The Oort cloud is even further out at 50,000 au.
Wouldn't it be 6.28 AU per year?
1AU=distance from earth to sun (radius of orbit), 2AU=diameter of orbit
2AU x pi = ~6.28AU * 30yrs = ~188AU
Voyager has travelled a lot further than 100AU over the years. It's just that now it is 100AU away from the sun in terms of radial distance.
It still kept the tangential velocity...we just added radial velocity.
Think of it traveling in a spiral, while we're going in a circle. Eventually we end up far apart.
Scientists still hope it will find the edge of the solar system
What's to find? It's not like it's hidden. Just keep going and you'll trip over it.
I think the term you're looking for is "slingshot orbit". Basically, the probe travels towards the sun at first, then uses the mass of one or more of the inner planets, or perhaps the sun itself, to alter its trajectory to take it out of the system. The pathway of the craft becomes something like a parabolic orbit, starting at the earth and ending on an escape trajectory.
Coupled with a solar/ion propulsion system, this would indeed work. You accelerate along a pre-planned trajectory, building up speed, and then use the mass of, say, Venus to launch the probe out of the system. By the time you're outside the range where solar power is a useful option, you've already used up all the fuel you're carrying for your ion drive. You then simply switch to a small RTG to provide power to the communications system, computer and scientific instruments, and coast out of the solar system.
However, the person I replied to specifically asked if it was possible to maintain an outward bound acceleration for a decade or so, and I said probably not. What we're talking about here with the slingshot idea would still be closer to what the original Voyager probes did (except that they used chemical propulsion, and their slingshot bodies were the outer planets instead of the inner ones, IIRC).
Erotic is when you use a feather. Exotic is when you use the whole chicken.
To the best of my knowledge, friend, there is more than one definition of "edge".
There's the magnetopause, where the magnetic influence of other stars predominates that of our own... to my knowledge, both Vger's are beyond this point.
There's the heliopause, where the outward flow of solar gases finally doesn't have enough pressure to overcome whatever's coming its way... to my knowledge, neither Vger has hit this point yet.
And considering that both Vgers were both launched basically along the ecliptic, neither one is likely to be headed towards the closest heliographic star, which is in the Southern hemisphere (Terran, not ecliptical; but if something's never north of one, it's probably never north of the other.) Neither is the shape of either 'pause likely to be spherical; they would depend upon the distances, relative magnetic field strength, and relative gaseous flux of every star around us.
Finding these things out, in some small way, is one reason I'm very glad the Voyager spacecraft have lasted so long beyond their design dates.
--
I don't want to rule the world... I just want to be in charge of mayonnaise.
There's a nice article on the flight team from a few years ago here.
Taking an educated stab in the dark (I've done satellite operations for NASA, but not on Voyager), I'm guessing that you've got a couple that deal with trajectory (where it is in space), one that handles the scheduling of time on the Deep Space Network downlink stations and queing command activities on the spacecraft itself, and maybe 3 that handle sustaining engineering on vehicle hardware systems like electrical, communications, attitude control (including momentum wheels and propulsion), and science instruments. Maybe 1 or 2 that handle the onboard computer and flight software. Finally, probably 1 or 2 maintain the ground data retention system and support workstations, plus a manager for the whole shebang.
It's also almost certain that most or all of these 10 people work on other JPL projects, too.
Worst...sig...ever!
Who do you get to be an expert to tell you something's not obvious? The least insightful person you can find? -J Roberts
As discussed before, Voyager is powered by radioisotope generators which derive power from the heat produced by radioactive decay. It's not a very efficient power source but it is reliable and long term the two neccessities for a mission of this type.
The answer to the second question is that it's an ordinary radio transimitter using the X-band frequency as I recall. The key to our reception is not Voyager's radio but the fact that we have very powerful tranceivers that can both receive it's very weak signal and transmit with enough boost so that Voyager's receiver can pick up commands.