Voyager 1 & 2
Rsadeika
Posts: 3,837
I noticed that their was a news item about the spacecraft. The two are at the outer reaches of space, and they are still functioning after thirty three plus years.
This got me thinking about the computer(s) that are on board. Does anybody know what is on the spacecraft? Since the spacecrafts nuclear reactors only put out approximately 200 watts, they do not contain mainframes, I don't think?
I wonder if there is any comparison to be made with a Propeller chips functionality? A lot of questions, and not enough answers.
Thanks
Ray
This got me thinking about the computer(s) that are on board. Does anybody know what is on the spacecraft? Since the spacecrafts nuclear reactors only put out approximately 200 watts, they do not contain mainframes, I don't think?
I wonder if there is any comparison to be made with a Propeller chips functionality? A lot of questions, and not enough answers.
Thanks
Ray
Comments
As for the power state, the RTG (radioisotope thermoelectric generators) nomimally produced a maximum 315 watts... however they're currently only outputting about 270 watts due to the normal decay of the radioactive fuel. Each craft (which is identical) had 10 science instruments on board and about half are shut down on each due to the diminished power. They both use an optical alignment (star tracker) platform to stabilize the spacecraft, but also contain gyroscopic stabilizers as well.
Bill
to bad RTGs are frowned apon as a power sorce these days for space craft .
Peter
on these spacecraft even though they are billions of miles out!
It's cool just to be able to update firmware over the web...but OMG! doing it
to a computer out beyond the solar system..WoW!
I just love this stuff....
At their current distance, it turns out to be quite often that they don't actually receive the message. Usually only about 20% of the messages get acknowledged by the spacecraft. To me, the most amazing part is that their transmitters are broadcasting at only about 20 watts... think about that... our antennas are so good they can pick out the signal the power of a small light bulb out of the background noise from over 7 billion miles away!
Bill
I remember reading somewhere that the new Mars rover will use an RTG generator rather than solar like on the previous ones. It's a great idea since it'll enable a long service life.
http://voyager.jpl.nasa.gov/
OBC
Awhile back I read that if you added up the energy represented by every radio signal ever received in the history of radio astronomy, it would not equal the impact of a single snowflake hitting the ground.
I guess it depends on what you mean by the "radio signal" received by radio astronomy. I suspect the Arecibo dish picks up much more than a pico-Watt of astronomical microwave background radiation, but I might be wrong. Of course, if we're excluding the background radiation and just talking about radiation from stars and galaxies, then that is probably much less than the kinetic energy in a snowflake.
Yes, that is correct. The MSL (named Curiosity) will also use a very novel technique of landing instead of the equally novel airbag methods. It will actually be lowered to the surface via a crane off of a hovering platform. When it touches the ground, pyro charges will cut the cables and the "sky crane" will fly off.
The reason they're using both of these new technologies is due to the shear size of the new rover... about the size of a small car. The MER-A and MER-B (Opportunity and Spirit) rovers were about the size of a small riding mower... and the original Sojourner rover was the size of a toaster oven. The MERs were just about at the limit that a solar panel could power. Because the sunlight could only power the unit for a few hours a day, the observation times were very short. Interestingly enough, Curiosity is powered by a RTG with a nominal output of about 125 watts, but that is roughly continous throughout the mission profile of a year... so there is a whole lot more energy available to the system. On average, there should be about 4 times the power available to the Curiousity rover than was available for Spirit and Opportunity.
Using an RTG will also allow Curiosity to work 24 (or 28) hours per day (sol) and, more importantly, will allow the science to extend into the night time (climate observations, stellar observatory, etc.) which the MERs couldn't do.
Bill
In other news: The reason for avoiding RTG's is that they carry a hell of a lot of nuclear fuel, and should there be a launch or other sort of atmospheric re-entry accident they could cause a contamination incident comparable to a full-blown reactor meltdown. Cassini bothered a lot of people because of its particularly large RTG and the fact that it made several Earth fly-by passes to get the Solar angular momentum to shoot for Saturn; if a flyby pass had hit the Earth there is no technology known to Man that could have contained the radioisotopes. That furore is a primary reason Spirit and Odyssey are solar powered.
In better news though the Mars missions don't have to do slingshot flybys to get to their target so if they survive launch, there is no further risk.
From here:http://voyager.jpl.nasa.gov/faq.html
This whole project is amazing. I can't even get a signal from the DCF77 time transmitter 2000Km away:)
Two points of clarification. One, The MER-A and MER-B rovers DO contain several small radioisotope heat generators to keep the electronics warm (in addition to the thermal electric heaters.) As well, RTGs were never considered by the engineers designing them simply due to their size and the fact that they were simply "larger" versions of the Pathfinder mission, which also used solar panels. The solar panels were always the first design choice for powering them.
And second, the current design of RTGs (since the late 60's) are contained in a graphite aeroshell that is designed to withstand the most severe reentry possible without containment failure. They were actually tested during the Apollo 13 incident, where the Lunar Lander was jetisoned on the return trip to Earth. It reentered the atmosphere at such a great angle that the only pieces that remained were the RTG's containment vessle and a few of the larger components of the engine. It is safely at the bottom of the sea and continous monitoring shows no sign of breach.
Most of the scientists and engineers know exactly how safe these modern units are, however, it is more political and FUD that causes people to think they are unsafe. Cassini's use of 3 RTGs along with many many (well over 100) of the smaller heaters was a concern mostly during launch and was never really an issue on the flyby's. Several RTGs have been lost and reentered over the years, but all of them were the first generation designs (or poor Soviet designs) that wern't protected with the graphite casings. If I remember correctly, there is still one somewhere that crashed in South America that the Soviets lost, but all the others that were lost burned up in the atmosphere with minimal exposure.
Bill
Some of those soviet reentries were full reactors, not just RTGs.
I understand that there is some very old equipment that is hard to maintain needed to communicate and program the voyagers. I wonder why they don't make an emulator like the MESS project of something>
@Bill - are you coming to UPENE?
RCA 1802CDP MPU
http://www.websters-online-dictionary.org/definitions/RCA+1802?cx=partner-pub-0939450753529744%3Av0qd01-tdlq&cof=FORID%3A9&ie=UTF-8&q=RCA+1802&sa=Search#906
From the outset the 1802 has also been available fabricated in Silicon on Sapphire semiconductor process technology, which gives it a degree of resistance to radiation and electrostatic discharge (ESD). Along with its extreme low-power abilities, this makes the chip well-suited in space applications (also, at the time the 1802 was introduced, very few, if any, other radiation-hardened microprocessors were available in the market). The 1802 was used in the Voyager, Viking, and Galileo spacecraft, and has been widely used in Earth-orbiting satellites. The Voyager spacecraft have three 1802s running at 6.4 MHz. All these CPUs sent to space were operating at full military specification temperatures (-55 to +125 °C).
http://www.medical-answers.org/hd/index.php?t=RCA+1802
The RCA 1802 has a static CMOS design with no minimum clock frequency, so that it can be run at very low speeds and low power. It has an 8-bit parallel bus with a bidirectional data bus and a multiplexed address bus (i.e., the high order byte of the 16-bit address and the low order byte of the address take turns in using the 8-bit physical address bus lines, by accessing the bus lines in different clock cycles).
The RCA 1802 has a single bit, programmable output port, and four input pins which are directly tested by branch instructions. Its I/O mode is flexible and programmable, and it has a single-phase clock with an on-chip oscillator. Its register set consists of sixteen 16-bit registers. The program counter (PC) can reside in any of these, providing a simple way to implement multiple PCs, pointers, or registers. In addition to standard CMOS technology, the 1802 was also available fabricated in Silicon on Sapphire semiconductor process technology, which gives it a degree of....
http://www.decodesystems.com/cosmac/
Although the 1802 is now more than 30 years old, it continues to prove itself in many industrial and commercial applications. A persistent rumor identifies it as the furthest microprocessor from Earth, having been used on board the Voyager spacecraft. (Voyager 1 is now the furthest human-made object from the Earth, at more than 100 A.U. distance.) Certain versions of the chip were extremely resistant to cosmic ray upset, making it well-suited for use in space. However, design work for the Voyager and Viking series spacecraft began long before the 1802 was available; instead they used custom-engineered computers. The Galileo spacecraft, however, used several 1802 processors.
http://www.old-computers.com/museum/computer.asp?c=543
The CDP-1802 CPU was also used as the heart of the Voyager, Viking and Galileo probes ! Until recently the 1802 was quite popular (for alarm systems for example) thanks to its CMOS technology ideal for low power systems.
http://www.cpu-museum.com/180x_e.htm
Besides the chip is the heart of the Voyager, Viking and Galileo (along with some AMD 2900 bit slice processors) probes. One reason for this is that a version of the 1802 used silicon on sapphire (SOS) technology, which leads to radiation and static resistance, ideal for space operation.
http://slideshow.techworld.com/3201497/the-11-most-influential-microprocessors-of-all-time/5/
Breakthrough application: NASA Voyager 1 (1977) The RCA 1802 was the first microprocessor in space. Due to RCA's aggressive positioning of the 1802 in the late 1970s, the chip made its way into numerous probes and satellites most notably the Viking, Galileo, and Voyager missions. Its low power consumption and a radiation-hardened version made it ideal for the harsh conditions beyond Earth's atmosphere. Voyager 1 is currently 10.2 billion miles from Earth and hurtling toward interstellar space. If alien engineers do find Voyager 1, they could learn everything about Earth's computer systems by reverse-engineering the 1802, which would have to make it more influential than all of the other CPUs on this list combined.
Note: information from Wikipedia is not included here because it is in error
Dave Hein, several kit Solar and Jupiter radio telescopes are sold. I've been contemplating getting a Radio Jove http://radiojove.gsfc.nasa.gov/office/kit_requests.htm for a while now.
Yep... I plan on going to both UPEC as well as UPENE.
Bill
It was a falsity that was widespread on the web, but has been increasingly corrected.
This has been verified via design specifications and documentation from the project websites and other sources.
Quoting this site: (slightly edited and amended -- http://forums.hardwarezone.com.sg/92584562-post1.html )
(cached here: http://webcache.googleusercontent.com/search?q=cache:L0q8InmQ6REJ:forums.hardwarezone.com.sg/92584562-post1.html+&cd=13&hl=en&ct=clnk&gl=us )
The computer on the Viking Orbiter were General Electric 18-bit TTL machines (not 12-bit) with a bit-serial, single register accumulator and bit-serial access to plated-wire RAM (4096 words). It executed around 25,000 instructions per second. The Viking Lander computers (Honeywell HDC 402) were a different design with 18,000 24-bit words of plated-wire RAM.
The Viking probes are commonly mistakenly claimed to be run by an 1802, however their is no factual basis to this.
The actual processors were a 18bit design with 64 instructions. The Voyager probes used the same design for one of its computers.
Voyager 1 and 2 used the same computer as the Viking Orbiter in only one of its 3 computerized subsystems (the Command and Control Subsystem). The Attitude and Articulation Control Subsystem used an augmented version of the CCS computer that inserted a unit (the Hybrid Buffer Interface Circuit (HYBIC)) between the CPU and RAM, which intercepted instructions to add indexed addressing capability (at the expense of other instructions), and accelerated instructions that used idle cycles. The third computer, used in the Flight Data Subsystem, was a new custom design in CMOS with a 128 register, nibble-serial CPU and 8096 words of 16-bit RAM. It ran about 80,000 instructions per second.
The Voyager probes (like the Viking Probes) are commonly mistakenly claimed to be run by an 1802, however their is no factual basis to this.
Both Voyager probes are still operating, 35 years after launch (2012)
The Space Shuttles used Intel 8086 and RCA 1802 (display controller) - Later Intel 80386. The Space shuttle uses the APA-101S computer (5 of them for redundancy). They run at about 1.2MIPS and still use a couple megs of ferrite core memory (which is impervious to radiation). The entire control software for the shuttle is less then one meg. The new glass cockpit in the shuttle runs on Intel 80386s.
The Galileo spacecraft is the only known craft outside of Earth orbit to use the RCA 1802, for the Command and Data System. Sandia Labs Rad hard 2901s were used in the Attitude Control Computers.
The 1802s used in space are built using Silicon-on-Sapphire which is much more stable in a radiation environment. In the Gallileo Spacecraft a total of 6 (possibly 4) 1802s were used (2 for the High level modules, 4 for the low level modules). Combined they had 176k of memory.
The 2901s were configured as a 16bit processor (4x4bit2901s) and duplicated for redundancy for a total of 8x2901s.
Some Earth-orbit satellites used the 1802 microprocessor.
BTW They will not want to use the newer 22nm and smaller ICs on any long distance spacecraft. It has been reported that at the wire scale of these chips, the wires behave like they are molten and migrate over time. Life expectancy is only just over 10 years!
So most new laptops and phones will likely not be working in 10 years. That's progress
https://en.wikipedia.org/wiki/RCA_1802
That's disturbing, we are forced to upgrade systems every five years just to be on the safe side. Doesn't sound like progress to me, dependability is intentionally compromised for the almighty dollar. Like a hard drive failure, I would like to know when my laptop is going to be bricked. How about a doomsday timer in BIOS.
While Y2K was not the doomsday the media made it out to be, it did require companies to do an audit of all their production systems to ensure they would work after the rollover. One of the things companies often found was a forgotten systems tucked away in the corner of their data center doing something critical that no one knew about. This had the positive side effect of cleaning up much of that technical debt and getting a fresh start.
Unfortunately that's now 17 years ago and a new generation of technical debt is emerging. Having these legacy systems randomly fail is not going to be fun.
Vendor: We have new gadgets for you that are cheaper, smaller, faster, more power efficient. Or you can continue using your old C64 and IBM PC x86.
Consumer: Ooo...give me the cheap, fast, small, efficient stuff. I hate my clunky IBM PC battle ship.
Vendor: OK, here you are. By the way, we had to adopt a technology that will only last 2 years to do this, hope you don't mind.
Consumer: Thanks. That's OK, I throw all my old Smile into the land fill every two years anyway. After all you keep producing ever smaller, cheaper, more powerful, efficient gadgets. Why would I keep the old ones? Besides, running around with last years old gadgets makes one a social outcast.
The rest of us can continue using Propellers
If my own girls and their families are any example, one of the best jobs out there could be trash collection, it's the fringe benefits.
I wasn't raised that way, and we certainly didn't raise them that way. I always took care of anything I owned, not to think I could just replace it.