Voyager 2 Detects Odd Shape of Solar System's Edge

[Professur]

Voyager 2 could pass beyond the outermost layer of our solar system, called the "termination shock," sometime within the next year, NASA scientists announced at a media teleconference today.

The milestone, which comes about a year after Voyager 1's crossing, comes earlier than expected and suggests to scientists that the edge of the shock is about one billion miles closer to the Sun in the southern region of the solar system than in the north.

This implies that the heliosphere, a spherical bubble of charged low-energy particles created by our Sun's solar wind, is irregularly shaped, bulging in the northern hemisphere and pressed inward in the south.

Scientists determined that Voyager 1 was approaching the termination shock when it began detecting charged particles that were being pushed back toward the Sun by charged particles coming from outside our solar system. This occurred when Voyager 1 was about 85 AU from the Sun.

One AU is the distance between the Earth and the Sun, or 93 million miles.

In contrast, Voyager 2 began detecting returning particles while only 76 AU from the Sun.

"This tells us that the shock down where Voyager 2 is must be closer the sun than where Voyager 1 is," said Ed Stone, Voyager project scientist at the California Institute of Technology in Pasadena.

The researchers think that the heliosphere's asymmetry might be due to a weak interstellar magnetic field pressing inward on the southern hemisphere.

"The [magnetic] field is only 1/100,000 of the field on the Earth's surface, but it's over such a large area and pushing on such a faint gas that it can actually push the shock about a billion miles in," Stone explained.

Both Voyager spacecrafts were launched from Cape Canaveral Air Force Station in Florida: Voyager 2 headed out on Aug. 20, 1977, Voyager 1 on Sept. 5, 1977.

Currently, Voyager 1 is about 8.7 billion miles from the Sun and traveling at a speed of 3.6 AU per year while Voyager 2 is about 6.5 billion miles away and moving at about 3.3 AU per year.

IMHO, the best science money ever spent.

source

 

[unclehobart]

I'm shocked that early 70s tech radios and the power supply are still pumping out data 30 years down the road... data that we can still intercept and use. I guess its a little late to do a firmware bios flash to get that Commodore64 brain it has up to V1.1.

 

[Professur]

I'm not. Back then, NASA was the Golden child of the nation. Now the penny pinchers and politics have scrubbed them down to where they're getting beaten by private industry, and the Chinese. Christ, have you seen what's being put forth as the new orbit (and soon lunar) vehicle? An Apollo style capsule. That puts the russians and the chinese ahead of them in R&D, since both of them already have a working one. Hell, they're not even gonna reuse the shuttle engines, but fall back on a modified Saturn engine.

 

[chcr]

I'm shocked that early 70s tech radios and the power supply are still pumping out data 30 years down the road... data that we can still intercept and use. I guess its a little late to do a firmware bios flash to get that Commodore64 brain it has up to V1.1.

NASA would love it if that onboard computer was as powerful as a Commodore 64. Think Altair.

 

[MrBishop]

I'm surprised that we're not pitching out more of those space probes. Small, inexpensive and hardy. Send them off every which way. Toss a few into orbit of our planets to act like signal re-transmitters. Hell, send off basketball sized probes with a beeper, an antennae and a transmitter and see if we can bump into an ET signal.

IMHO, contracts and the exorbitant price for parts is killing the budget for real exploration more than politics.

 

[unclehobart]

I keep looking online for the specs of the Voyager craft. Theres plenty of resources talking about the antennas and power and whatnot... but nothing on what the actual computer brain is. I'd really like to know what kind of comp has been going on like the Energizer bunny for thirty years in space and 3-4 years of ground trials and tinkering.

 

[Professur]

You're not gonna find any specs like that on it. It was a hand built, transistor brain, not unlike what flew on the apollo missions. The average digital watch has it beat for processing power. But ..... it was the cat's whiskers at the time.

" A Voyager has the electronic circuit complexity of some 2,000 color TV sets, NASA says."

 

[unclehobart]

Yeah.. It probably has something comparable to a 2k memory stick the size of a Hershey bar.

I wonder if they will ever have the nads to make a modern probe for deep exploration with a cutting edge tres snazzy Alienware grade computer to run it. I also wonder if theoretical propulsion has ever hit the application stage ... sloar wind sails and the like... get that sucker up to perpetual 2,3,10 G acceleration until its up to about 1/10 the speed of light.

 

[HomeLAN]

It's not a question of nads. It's largely a question of durability. No one's been able to test the lifespan of anything juicier than a 486 in the vaccuum and zero temperatures of space. At least not to the extent that they can base a mission on its reliability.

 

[Professur]

What kind of computers are used on the Voyager spacecraft?

There are three different computer types on the Voyager spacecraft and there are two of each kind. Total number of words among the six computers is about 32K.

Computer Command System (CCS) - 18-bit word, interrupt type processors (2) with 4096 words each of plated wire, non-volatile memory.

Flight Data System (FDS) - 16-bit word machine (2) with modular memories and 8198 words each

Attitude and Articulation Control System (AACS) - 16-bit word machines (2) with 4096 words each.

According to my calulations, that's a total of about 541KB, or small potatoes compared to today's microprocessors. We probably could perform all functions with one of today's boards and still have room for solid state data storage and much more fault detection software. We would still need a second unit for redundancy. Today's microprocessors are also much faster than the 1802 derivatives used on Voyager and a comparative system would use less electrical power. On the other hand, software might be more complicated as opposed to that used in an interrupt type system, but it would be much more capable and more flexible.

Let's look closer at the CCS. The CCS has two main functions: to carry out instructions from the ground to operate the spacecraft, and to be alert for a problem or malfunction and respond to it. Two identical 4096- word memories contain both fixed routines (about 2800 words) and a variable section (about 1290 words) for changing science sequences. The CCS issues commands to the AACS for movement of the scan platform or spacecraft maneuvers; to the FDS for changes in instrument configurations or telemetry rates and to numerous other subsystems within the spacecraft for specific actions. Fault-protection algorithms are also stored in the CCS, occupying roughly 10 percent of the CCS memory.

The main functions of the FDS are to collect data from, and controls the operations of, the scientific instruments; and to format engineering and science data for on-board storage and/or real-time transmission. The FDS also keeps the spacecraft "time" and provides frequency references to the instruments and other spacecraft subsystems.

The Voyager spacecraft computers are interrupt driven computer, similar to processors used in general purpose computers with a few special instructions for increased efficiency. The programming is a form of assembly language.

There is no clock chip, as such, in the spacecraft. The "clock" is really a counter, based on one of several electronically generated frequencies. These frequencies, based on a reference, generated by a very stable oscillator, are converted and fed to different locations in the spacecraft as synchronization signals, timers, counters, etc. The "clock" signal is part of the information telemetered to the ground and it is with ground software that we convert to day of year, time of day Greenwich Mean Time.

Voyager was built in-house at JPL; the computers were manufactured by General Electric to JPL specifications.

Source

There ya go, Unc. All you had to do was ask.

 

[unclehobart]

I wonder if they could do something like a piggyback op to the international space station.

Shoot the payloads to orbit and have a meatier rocket assembled up there, make sure it is stable to the rigors of space, then launch it in the right direction. A less intense g force rocket could probably used to insure better suvivability since it wouldn't have to break Earth surface gravity.

 

[HomeLAN]

I wonder if they could do something like a piggyback op to the international space station.

Shoot the payloads to orbit

Potential issue #1. Can the components survive the stress of launch?

and have a meatier rocket assembled up there, make sure it is stable to the rigors of space, then launch it in the right direction.

Potential issue #2. Vaccuum and extreme cold. Will, say, an athy 64 survive that?

A less intense g force rocket could probably used to insure better suvivability since it wouldn't have to break Earth surface gravity.

Potential issue #3. How long is the mission? How long can a modern machine cope with the conditions out there?

All that shit (and more, I'm sure) has to be tested. By the time you've done that, your computers are waaaay outdated. I hear they'll be progressing to the equivalent of pentium 2's soon.

 

[Inkara1]

I'm thinking an Athlon of any kind would do quite well in the extreme cold. I would even go so far as to say it would still need a heatsink.

 

[HomeLAN]

You think? Don't foresee any brittleness issues at absolute zero?

 

[highwayman]

The waffers wouldn't be effected but a slight bump might do something to wires or a printed circuit...

 

[Professur]

Hey HL, do ya suppose we could get these guys into a poker game sometime? They smell like money to me. Easy money.

 

[Inkara1]

You think? Don't foresee any brittleness issues at absolute zero?

fa·ce·tious ([FONT=verdana,sans-serif] P [/FONT]) Pronunciation Key (f

-s

sh

s)
adj. Playfully jocular; humorous: facetious remarks.

 

[unclehobart]

Can't they dovetail this with the international spacestation? Build a vessel up there that wouldn't need to take all the launch stresses of an earth-based mission? That might expand the possibilities a lot.

 

[alex]

Anyone ever see the Star Trek episode where they find the voyger craft stranded on some planet...or was that one of the movies?

 

[unclehobart]

I believe it was one of the middle Star Trek movies that showed a Klingon vessel blowing it apart for target practice. It was the one with Spock's emotional brother.