Apollo On Board Computer Emulator

frankk74 writes "For those of you interested in Historical Computing and the Apollo manned spaceflights Ron Burkey has created a open source emulation of the Apollo Guidance Computer called vAGC. I use it as my desktop clock of choice. Note it only keeps mission time so after 24 hours you have reset the time :-). P.S. Another cool Apollo toy free and payware can be found here."

Comments

Amazing

[Nermal6693]

I'm amazed with some of the stuff people come up with. Not very practical of course, but I spend half my time doing stupid stuff - I spent most of today playing Super Mario 64!

Slashdotted

[dreamer8815]

In three two one... Huston, we have a problem.

Re:Slashdotted

[Metteyya]

I have a lot of respect for all the admins and webmasters for not banning their sites/servers from people-coming-thx-to-slashdot.

Re:Slashdotted

[Mr. Bad Example]

> Huston, we have a problem.

Not the least of which is that he's dead.

Re:Slashdotted

[gadget junkie]

........why, THEY have UIDs starting from 1 and going on!!!!!!!!!

The coolest project I've ever seen

[incog8723]

Forget Linux. Forget overclocking/unconventional CPU cooling. This is cool shit.

Re:The coolest project I've ever seen

[Anonymous Coward]

And for the second link:
Forget Linux, forget open-source software, download the shareware (yuck...) and order the full version.
This sux.

Warning

[poofyhairguy82]

From site: For Win32 users, it's much more work to get your computer set up to build Virtual AGC than it is in Linux, and the steps needed will be less familiar.

That made me feel good seeing as how this is the first week I've tried linux.

Re:Warning

[ricotest]

I hope that thought consoles you when you're struggling with the ATI graphics card drivers or recompiling your kernel :)

Re:Warning

[paranerd]

Ever try recompiling your kernel?

Re:Warning

[paranerd]

If the grandparent thread to this reply isn't flamebait, then neither was the parent. (Yet, I'll accept my previous response as offtopic!)

Re:Warning

[paranerd]

Well, I am from West Virginia.

Re:Warning

[Anonymous Coward]

Never had any problem compiling a kernel.

Never had any problem with the ATI drivers.

Never had any problem with this stuff. What's yours?

very simple processor

[ndevice]

Took a quick scan at the architecture of the machine, and I'm suprised that it's so simple.

People say over and over again that simple handheld calculators are more powerful than that thing, and it seems that the oft-parroted line is more accurate than they realize.

Add to that: RTL (before TTL) and magnetic core memory bring up the nostalgic value.

Re:very simple processor

[thhamm]

some of the "moon hoaxers" think thats why they could never get to the moon at all.
"though much faster, my pentium can barely run [insert 3d shooter here] at good FPS. how could it fly to the moon? so they never did."

logic?
clavius explanations.

Re:very simple processor

[RedWizzard]

People say over and over again that simple handheld calculators are more powerful than that thing, and it seems that the oft-parroted line is more accurate than they realize.

Or perhaps they repeat it because it's accurate and they know it?

Re:very simple processor

[Edward Teach]

In the Apollo 11 descent to the moon, you hear someone say "twelve oh one alarm." This was the alarm that told the LM crew that the computer reset because it ran our of memory.

Re:very simple processor

[Anonymous Coward]

No, it didn't 'run out' of memory, there was no OS capable of making that determination. There were simply too many real-time interrupts coming in. The time-slice approach of the Apollo system simply couldn't handle all those requests.

Re:very simple processor

[TheHawke]

Eh, Brute force. They needed the AGC to be as simple, yet programmable with all the steps necessary to get the boys on the moon and back.
So they took the PDP8 and squeezed it down into the size of a early 80's era Kaypro portable (now that's saying something about my age) and managed to get it to draw as much power as your coffeemaker.
THEORETICALLY, they could have done it with a sextant and a good clock, BUT! Their navigation skills had to be dead-bang on every time to the fraction of a minute.
So it was easier to shoehorn this colossus into the spacecraft and let it do the driving.

Re:very simple processor

[oogoliegoogolie]

...the computer reset because it ran our of memory.

That's because when the LM was being designed some engineer decided "640 Bytes should be enough for anyone."

Re:very simple processor

[Speare]

But somehow a few rafts colonized the polynesian islands. Somehow a compass, a sextant and a bunch of canvas guided boats across the Atlantic for centuries.

Re:very simple processor

[Archibald Buttle]

The hoaxers are dicks.

It is of course completely irrelevant that their pentium is a heap of crap, as you imply. These are the kind of idiots that don't believe that you could have a 3d game on a 20 year old 8bit micro - showing them Elite blows their minds.

They think that because a computer is slow it's worthless. Well, that's what Microsoft and Intel keep telling us so it must be true. Also their 3d shooter is damn slow. That's gotta be proof.

Conversely those of us with brains, real software development knowledge, and an appreciation of physics realise that you hardly need any computing power at all for an Apollo space craft. Indeed it's arguable that the computer they did have was overkill - a computer-less solution could have been engineered.

Re:very simple processor

[Daniel Dvorkin]

Look at just about any operation your computer performs. Not only is it all math, it's generally fairly simple math. You could do it all with a pencil and paper -- but you can't do it as fast. It's speed that's the issue. On a ship, you have time to correct your errors. When landing on the Moon ... you don't.

Re:very simple processor

[Kenshin]

Wow. The last thing you want on the descent to the moon is a BSOD...

Re:very simple processor

[morcheeba]

you haven't lived until you've programmed a computer with 544 bytes of memory. This computer was released in 1985!

The web page says program words, but those were equivalent to bytes. Tokenizing the BASIC keywords helped save memory, but line numbers were stored as ASCII, so "GOTO 5" took half the memory of "GOTO 500"

Re:very simple processor

[ultranova]

It's speed that's the issue. On a ship, you have time to correct your errors. When landing on the Moon ... you don't.

Wasn't the actual landing manual ?

Re:very simple processor

[kunudo]

Actually, with the FDIV bug, I wouldn't trust an old pentium to fly my to the moon. It proboably wouldn't make a diffrerence, but still.

Who am I kidding, if I had a chance to go to the moon, I'd go almost no matter what...

Re:very simple processor

[Teancum]

During the final few seconds, yes it was manual. But with Apollo 11 they had about 5 seconds of reserve fuel left when they actually set down. That was not 5 seconds to abort and go back up, but simply 5 seconds before they ran out of fuel.

While indeed there was actual piloting and people were clearly in the loop to run the spacecraft (and needed!), some of the critical timing issues for orbit insertion and lanuch windows simply have to be run with computers. There is no other way to ensure that you can hit the buttons at the precise time and stop in time.

While analog computers could have been used in this situation, this was the time period (late 1960's) when digital computers were finally widespread enough to be used in applications like this. The AGC was one of the first computers to use integrated circuits (IC's), and even then it was primarily 7400 series chips and a couple of specialized circuits. NASA at the time contracted something like 50%-70% of all IC production, which is where some people seem to think NASA was behind the development of some of the early micros.

BTW, this thread referenced the fact that sailors in the 16th through 19th Centuries used pretty much just a compass, clock, map, and sextant. The poster forgot to mention the clock, but it was indespensible back then...to give longitude data. Clocks still are very important even now, as that is all a GPS satellite really transmits anyway (the current time). All the rest of the positioning info is derived from the clock data.

Anyway, the sextant is actually a fairly sophisticated analog computer that is able to correctly identify your current lattitude with amazing precision. It tended to make the navigator go blind with one eye, which is why you see skippers and naval officers in depictions of the era wearing an eye patch. They litterally looked at the sun too long through the sextant. A good navigator using a sextant could get lattitude down to +/- 1/2 to 1/10th of a degree. Longitude you were usually considered very fortunate if you got it down to +/- 10 degrees (almost 600 miles when near the equator), which is why maps of the 18th Century are very accurate on lattitude but miserable with longitude, causing things like Minnesota's Northwest Angle.

Re:very simple processor

[shadowbearer]

IIRC correctly during the Apollo 11 landing they actually passed the "no-abort" point at about 60 seconds of fuel, when they were simply too low for a successful ascent stage abort.

OI isn't really that critical timewise unless you have to hit *precisely* the orbit you want; a few seconds either way (and there often was during the lunar missions even with the computer running things) meant merely that your orbit would have a few miles or tens of miles discrepancy in perigee/apogee, correctable with a short burn.

The Saturn rockets were pretty reliable wrt to launch windows, but as I recall with the Atlas and Redstone they often couldn't predict exactly how long the rocket would fire sometimes not even to tens of seconds; but they still achieved the trajectories they wanted. So it couldn't have been *that* critical.

De-orbiting to splashdown, now, that's a different matter, a few seconds difference in retrofire and you could under or overshoot your splashdown target by tens of miles. :) But then that's because after the retros were jettisoned they had little maneuverability, which wasn't true with LM deorbit.

Given that the Polynesians didn't have clocks (or sextants) they did most of their navigating using dead reckoning and knowledge of their local environment; which shows just how much they understood the local winds and their ability to move their rafts. ( * see below)

Without a clock determining longitude accurately was extremely difficult. One could approximate the time using star set/rise times and seasonal charts, but with the distortion near the horizon causing enormous errors in the actual location of the star, and especially given the inaccuracy of the charts at the time, this was pretty much a crap shoot.

Sextants are certainly incredible! While in college I had the opportunity to learn to use a modern one (with a sun filter) and on my first few tries I located the longitude of the observatory at SCSU to within 14 minutes of arc; not especially astounding by modern standards (see the link below), but astonishing given the basic simplicity of the device and my inexperience.

I didn't know that about the MN NW Angle, do you have a ref? Fascinating!

* There is a good piece available about the Polynesians and modern navigation here

Cheers,
SB

Re:very simple processor

[wjsteele]

Cool... I still use mine. ;-) But, I've since bumped the memory to 1k - through the serial interface no less!

Bill

Re:very simple processor

[Anonymous Coward]

Has anyone ported Linux to this archetecture?

Re:very simple processor

[Erbo]

Right...1201 was "Executive overflow - no vacant areas." The computer was simply unable to complete all its jobs in the course of a major cycle.

Gene Kranz's book Failure Is Not An Option talks about simulating the moon landing, and seeing 1201 alarms coming up and the controllers unable to deal with them. Kranz ordered an abort after a 1201 alarm...but it turned out that was the wrong thing to do. Dick Koos, the simulation supervisor, told him, "This was not an abort. You should have continued the landing. The 1201 computer alarm said the computer was operating to an internal priority. If the guidance was working, the control jets were firing, and the crew displays updating, all the mission-critical tasks were getting done." They wound up figuring out rules on which program alarms would terminate descent...and the list did not include the 1201 or 1202 (similar) alarms.

Good thing, too, because both of those alarms occurred on Apollo 11's descent. Buzz Aldrin reported that it seemed to happen when they had a computer display of time, range-to-go, and altitude up. They continued the landing, which was eventually successful; the alarms didn't seem to affect the LM computer performance any.

Re:very simple processor

[morcheeba]

I got the 1K memory module soon after I got it, so that's kinda cheating. Serial interface, wow! I kinda miss mine since I sold it a long time ago.

Re:very simple processor

[Teancum]

There was a fairly primitive sextant that the polynesians (and earlier with the Phonecians, who had something very similar) that ammounted to a card (or fishbone) that had a bunch of notches on it to mark the lattitude of various ports (or islands as it may be) with reckoning based on Polaris or the Southern Cross.

In reference to the MN NW Angle, it actually goes back to the Paris peace talks for the Revolutionary War, when all of the land east of the Mississippi River was given to the USA. As you are quite familiar with Northern Minnesota, obviously there was a minor negotiation regarding the area between Lake Itasca and the northern frontier with "Lower Canada" (now Ontario). The maps that were used in the treaty had Lake Itasca much further west than it was in reality, and the Lake of the Woods much further east. The boundary in the treaty specifically mentioned the northern bank of Lake of the Woods as being in the USA.

When the Louisana Purchase occured, a minor correctional treaty was enacted, but by then several much more accurate maps of the area had been made. It was decided at that time by the British surveyor to simply draw a line at a right angle to include Lake of the Woods, rather than renegotiate the entire Treaty of Paris all over again. England wasn't ready for yet another war against the USA after the War of 1812.

Some extra info can be found here.

Re:very simple processor

[Keebler71]

Holy crap! A 3-digit user ID!?

As an aside, how do you have suh intimate knowledge of the APG? Just curious...

Re:very simple processor

[shadowbearer]

Thanks for the link. Google had too much to search thru.

Interesting, had never heard that, although I'd wondered. Sounds like their major error was that at the time, nobody knew where the start of the Mississippi was (Lake Itasca is actually considerably further south, somewhat further south even from I was living :)

(I've been there by the way, it's a beautiful area and if you're ever in MN again make sure to visit it)

Dunno if I'd call that a sextant, it's more like an astronomical protractor :0 ... oh, wait :D

Cheers,
SB

Re:very simple processor

[Erbo]

3-digit user ID: Just lucky, I guess...

As for the knowledge of the processor, I did mention that I have Gene Kranz's book, Failure Is Not An Option. (A signed copy, yet.) He talked about the simulation run and the computer errors in the chapter entitled, "SimSup Wins The Final Round." (The book even discusses the software patch they had to make for Apollo 14 to lock out the abort switch--the one the author of the simulator gives as a "Final Exam"--but only in general terms.) But I've always been a nut for space stuff; I'm the sort of geek who gets misty-eyed at the end of Apollo 13, and who can follow along with all the major milestones of a Shuttle launch from T-9:00 to MECO.

(No, I never worked for NASA, if that's what you're thinking. Unfortunate for me. :-) )

Ahh, it's the Missing Piece!

[Anonymous Bullard]

Now the Chinese Communist Party can finally be confident that their Soviet-era space capsule can be launched at the moon, with one or two "People's Liberation" Army's faithful inside.

Like Deng Xiao Ping's 50-year plan towards (real) World Domination by using the capitalists' greed against their own long-term interests, this space-conquering plan began over 50 years ago when the "People's Liberation" Army invaded their peaceful neighbour Tibet, to be used as a back-up landing area. Well, Tibet can also be looted for their natural resources (oil, gas, uranium) and subjugation the hapless Tibetan people has been used as a great propaganda victory for Party jingoism, but clearly one of the main reasons to invade was to use the Tibetan territory as a back-up landing site.

Apollo On Board Emulator, running on Red Flag Linux and locally-built Dragon CPU... even Evil Invading Dictatorships can be pretty geeky when it suits their World Domination Plans... ;-)

Re:Ahh, it's the Missing Piece!

[Twirlip of the Mists]

Are the rights of a chinese worker worth less than the rights of an American worker?

To an American? Yes. To a Chinese person, it's the other way around.

I'm neither celebrating nor bemoaning this basic fact of human nature. But you seem to be either unaware of it or unwilling to acknowledge it.

Lots of bad things happen when people choose to ignore human nature.

12-bit Instruction set

[Anne Thwacks]

A quick inspection of the instruction set reveals why they only made 157 of these and made 6 million PDP8s.

Re:12-bit Instruction set

[Rosco P. Coltrane]

A quick inspection also shows that a PDP8 weighs as much as the Saturn V rocket, and weight is the last thing they needed to haul stuff on the moon...

Re:12-bit Instruction set

[kfg]

A quick inspection of an Apollo capsule reveals why they didn't just use a PDP8.

Think of three fat guys trying to move one of those things in a Mini Cooper.

KFG

Re:12-bit Instruction set

[hughk]

Not really, and it had an excellent reputation for real-time work. The thing is when NASA were shopping for processors a long time before the landing, the PDP-8 didn't exist in the compact form. By the time of the first landing it certainly did, but it was already too late. The PDP-8 and later the PDP-11 then just swept through the world of real-time computing.

Re:12-bit Instruction set

[melonman]

Also, it takes a long time to get electronic components approved for use in space, which is why the stuff in satellites is usually way behind what sits on your average desk. The university I attended designed and launched a series of very cheap satellites, which, apparently, ran some of the most advanced computing equipment in orbit, simply because it didn't matter too much if it blew up after 3 days.

Re:12-bit Instruction set

[gatkinso]

It also sucked more juice than the average house does today.

Re:12-bit Instruction set

[AndroidCat]

And they made Buzz Aldrin sit in the back. No wonder he gets cranky if someone says that he didn't go to the Moon!

Re:12-bit Instruction set

[Anonymous Coward]

On closer inspection, these are loafers!

Re:12-bit Instruction set

[Anonymous Coward]

I think I am not alone in wondering how long it lasted.

Re:12-bit Instruction set

[Anonymous Coward]

cranky?

Due to excessive bad posting from this IP or Subnet, anonymous comment posting has temporarily been disabled. You can still login to post. However, if bad posting continues from your IP or Subnet that privilege could be revoked as well. If it's you, consider this a chance to sit in the timeout corner or login and improve your posting . If it's someone else, this is a chance to hunt them down. If you think this is unfair, please email moderation@slashdot.org with your MD5'd

oh really?

Re:12-bit Instruction set

[hughk]

The PDP-8s were rack mounted. If you didn't have extra memory, the tape units or the high-speed paper tape reader, then the whole thing was about 4U high.

Re:12-bit Instruction set

[kfg]

. . .the whole thing was about 4U high.

Or a few inches larger in each dimension than an average full sized tower, but a hefty 100 pounds.

If you don't mind spending a week locked in a Mini Cooper (not a MINI) with one of those and three fat guys, well, enjoy the trip.

KFG

Re:12-bit Instruction set

[0racle]

I think you'll find that if it did blow up after 3 days someone would have cared.

Re:12-bit Instruction set

[hughk]

The panel on AGS is just the user interface. The main unit was much larger (see the MIT site for photos). A large part of the weight of systems in those times was the PSU, and this could be somewhat reduced for fitting somewhere with different rails.

A Mini Cooper is about the same size as a Mini but with a much better engine (note, we aren't talking the BMW version here). A friend had the hobby of rebuilding Minis, so I got to know them well and I'm old enough to remember the PDP-8a in the lab at Uni.

Re:12-bit Instruction set

[kfg]

The panel on AGS is just the user interface. The main unit was much larger (see the MIT site for photos).

Certainly. I've seen the device in person. I'm old enough to have seen it in Apollo 11. It's notably smaller than a PDP-8. Lighter too.

A Mini Cooper is about the same size as a Mini. . .

Well of course it is, the one being a modification of the other. Just like an Integra "R-Type" is built on the same chassis as the base model.

(note, we aren't talking the BMW version here)

Actually, if you go back you'll find that the only time I refered to a MINI I was.

KFG

Re:12-bit Instruction set

[melonman]

Well, yes, but, by memory, it was a $500,000 project (tucked in the space between a few commercial payloads). If it went down after 3 days, I'm sure there would have been a few drunk electronic engineers in the student union, and maybe there might have been questions about funding the next shoebox-satellite, but it wasn't going to leave half a continent without telephones or punch a hole in the CIA's spy network, let alone kill any astronauts (which is where we came in).

I remember seeing a documentary about space technology about the time the USA and USSR linked up. Apparently much of the life support system in the Russian vehicles ran on a pin wheel like a kids music box. There was much mirth about this, but, despite or maybe because of my programming credentials, I far prefer the idea of fixing the mechanical version if my life depended on it.

Re:12-bit Instruction set

[hughk]

I have also seen the device in person (not as part of Apollo 11, but as a standalone display) and several versions of the PDP-8. Most of the weight with the early 8s is in the PSU, this could be considerably reduced through a direct connection to the busses in the CM or LM. The other main element costing weight was the backplane, which was wire-wrapped, again relatively easy to reduce the weight by going to an alternate design. It should be remembered that th8 was a true general purpose computer whereas the AGS computer was designed specifically for the job.

It would easily fit in the standard Mini, after all, I seem to remember six students fitting in one with the doors closed.

Simulation - emulation environment

[Anonymous Coward]

What I would like to see is a complete Apollo computing system simulator, consisting of the hardware simulator, where you could realistically simulate the effects of increased core voltage, heat, power surges, fluctuations, etc. coupled with the hardware emulator capable of running native Apollo code, just like vAGC.

Do they have this at NASA? For them it must be easier and more reliable to just use an identical environment for testing purposes, but some Apollo enthusiasts would enjoy tinkering with such a combined simulation-emulation environment (SEE).

Re:Simulation - emulation environment

[thhamm]

then integrate the whole thing into Orbiter.
this would be incredible. not just simulating the whole spacecraft in such detail, but actually doing the whole flight.

i wasnt my fault. i they tell me to stir the tanks, i stir the tanks.

Re:Simulation - emulation environment

[Anonymous Coward]

Yep, that would be very exciting! I have a feeling someone is already working on making this happen, so I'm getting an astronaut suit to make the experience as realistic as possible when the time comes!

Oh man, can you believe there are no astronauts selling their suits on eBay?! What a bummer! It's easier to create the SEE + Orbiter system than get an astronaut suit, even a used one! *rolling eyes*

Re:Simulation - emulation environment

[cpuffer_hammer]

You could rent a copy from http://www.globaleffects.com/C_b02_frameset_links. html

Re:Simulation - emulation environment

[Twirlip of the Mists]

Oh man, can you believe there are no astronauts selling their suits on eBay?!

Astronaut suit? You mean space suit? Apart from the fact that the astronauts have never owned them, I doubt you could pay the million bucks one would cost, much less the hyperinflated auction price.

Re:Simulation - emulation environment

[Gordonjcp]

I wonder if you could model the electronics in Spice or something similar? The RTL logic was, if memory serves, made out of discrete components. You could actually build your own in hardware, although it would be very time-consuming. One for the dedicated electronics hobbyist, I think...

Re:Simulation - emulation environment

[dswartz]

I do not know about Apollo (I think that program might have had its funding cut), but I believe the ISS has (or will have) a complete simulator of the type you described, developed by the USA (not the country).

Re:Simulation - emulation environment

[hughk]

Didn't one of X-prize teams pick up an old Russian suit for about $10K or so? I understand that it needed some work but it theoretically would be usable.

Re:Simulation - emulation environment

[chrisatslashdot]

I think the NASA way would be to use an identical environment for testing purposes. To test the ability of the Saturn V and Shuttle to withstand the stresses of flight do you think they relied on simulation and model testing? No, they build the largest structure in the state of Alabama (at the time) to shake the heck out of full sized space craft.

See http://www.cr.nps.gov/nr/travel/aviation/sat.htm

How do they get to the moon...

[Purifier]

...without having a "Start" button? ;)

Re:How do they get to the moon...

[Anonymous Coward]

If they had had a 'Start' button they would never have made it to the Moon. Or haven't you heard of the Blue Screen of Death?

Re:How do they get to the moon...

[bytesmythe]

They just used LaunchPad... ;)

Re:How do they get to the moon...

[cammoblammo]

Where do you want to go today?

Re:How do they get to the moon...

[Anonymous Coward]

Haha. I work there. I wouldn't trust a spaceship launch to it. I wouldn't trust an Internet Explorer launch to it!

/really works for Digital River (online store) not Computer Associates (Software vendor) and therefore posting anonymously.

Slingshot

[Hypharse]

I tried to use this to run games. It didn't work at first, there just wasn't enough power. Then I used the gravitational pull of my neighbor's house as a slingshot and was running Doom 3 in no time.

I wonder......

[bhaynes]

......how long it will take someone to try and load it up with pr0n. "Huston, we have a REALLY BIG problem......"

Re:I wonder......

[Anonymous Coward]

Bah. Apollo computers only has a numneric display. The hottest pr0n that it can display is number "69" in all fields.

Re:I wonder......

[Anonymous Coward]

What is it with Slashdot readers and the inability to spell "Houston?"

I read that the first time and thought "what the hell is Huston? Ohhhh, Hou ston!"

Re:I wonder......

[Feanturi]

80085

Duh...

[Anonymous Coward]

> They put Internet Explorer in the Startup folder.

Where do you want to go today?

Re:Duh...

[AndroidCat]

If it gets infected with Gator/Claria, it'll probably take them somewhere that sells printer ink and toner.

Game anyone?

[NewtonsLaw]

Does someone have a copy of that old favourite: "Lunar Lander" which runs on this emulator? :-)

Hell, even my Texas Instruments card-programmable calculator played that game!

Re:Game anyone?

[Fallen Andy]

spits venom jealously. I had to key in all (let me see 96 steps?) out of 100 possible on my first programmable (a TI SR56) (c.a. 1976)
Oh and of course it forgot everything when you switched it off.

Re:Game anyone?

[mikelmoore]

Hey, I think I still have a copy of the Lunar Lander program from Control Data came with their 6000 series & Cyber 70/170/early 180 series mainframes and displayed on the system console. (I have to say from experience that there was nothing else like turning a supercomputer into a gaming machine)

Now if the 30+ year old tape is still good & I had a 9 track 1600 bpi drive to load it with, I could run it on this simulator...Cyber Emulator

Orbiter

[0123456]

"then integrate the whole thing into Orbiter."

Already being worked on:

http://mysite.wanadoo-members.co.uk/marui/orbite r_ agc.jpg

Re:Orbiter

[0123456]

Hmm, for some reason that link got screwed up: here's another try.

Re:Orbiter

[thhamm]

have you got more info than the picture yet? features? :)

Re:Orbiter

[0123456]

Currently the programs run, but the IMU hardware simulation isn't there, so it can't control the spacecraft...

Source is here.

Re:Orbiter

[Keebler71]

hmmm.... I have been playing in Simulink with a generic IMU that I modelled for the last couple weeks. I'd be curious if there is anyway I could help out with this...

MOD parent UP - see next post by Orbiter

[Anonymous Coward]

MOD parent UP - see next post by Orbiter about work being done as referenced in parent post!

How to build your own astonaut suit

[Anonymous Coward]

Well, at least you can build your own astronaut suit using this http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&cate gory=416&item=3927005923&rd=1

ouch my eyes

[mattr]

I feel sorry for the guys who have been spending a lot of time on tis yaAGC.. cool but is there a good reason for a light green on light grey simulated lcd display? I can barely make out what the figures are supposed to me and it would seem to cause fatigue. On the heels of the Siemens story.

Re:ouch my eyes

[Anonymous Coward]

You are not Astronaut material.

Hell, you are you not good enough to even drive a wheelbarrow in my back yard if that "contrast" is a problem for you. Goodbye.

Space Shuttle computers

[Veteran]

An engineer I work with at JSC has an actual - legally obtained Space Shuttle flight computer. The government declared it surplus, and he bought it from the surplus section, so he has the paperwork documenting that he is the legal owner. His box is an actual flight unit, which was in space, not a ground test unit or engineering sample. He has the paperwork documenting its complete history.

Every once in a while you can find some incredible things in government surplus.

Re:Space Shuttle computers

[TehHustler]

Can he do something with it at home to get it running? Not sure what he'd do with it at home, like, but it'd be cool nontheless.

Re:Space Shuttle computers

[Veteran]

I believe he has powered it up, and it does work.

Re:Space Shuttle computers

[Anonymous Coward]

I bought a 1GHz sampling scope plug-in from 1964 with a NASA-LANGLEY property tag on it, via eBay. Who knows what waveforms they were looking at back then with it??

Re:Space Shuttle computers

[Anonymous Coward]

Unfortunately, all the tiles fell off his roof ...

Linux

[schweini]

Darn. another platform to port linux to! Just when we thought we had most architectures covered :-)

But seriously: would it, theoretically (!), be possible to write a x86 emulator on something like that?

Re:Linux

[AndroidCat]

If you can write a Turing Machine on it, you're there. Just give it a long enough R/W tape, and let'er rip! (I will warn you that your FPS frame rate will suck.)

Re:Linux

[marcansoft]

Hmm... what about a Brainfuck sim?

Re:Linux

[Anonymous Coward]

We'll have to invent a new measure so we can properly benchmark it...

I propose Seconds per Frame.

Not comparable in any way to calculators

[panurge]

This machine is optimised for the acquisition of fairly real-time data; read the architectural description. Multiple channel counters are implemented in hardware, partly because in the days of discrete logic this was relatively easy to do (and, of course, the tube calculators with which people had gained experience used lots of counters, because it is relatively easy to make a counter tube, while binary tube logic is very hardware inefficient.)

Calculators have absolutely minimal I/O and need hardly any interrupt handling capability, and general purpose CPUs like the PDP-8 require a great deal of external hardware to give efficient programmed I/O. It was only really with integrated electronics that general purpose CPUs became appropriate for real time instrumentation and control.
It's also important that in a space environment, every added gate is a hazard because it can get flipped by radiation. The ideal is to have the minimum gate count, minimum memory cell count, and the shortest possible path between phyical I/O and computing. The computers used in the Apollo meet this requirement.

Sorry to restate what may be obvious to some people, but a lot of people here will never have had to implement a rad-hard design, and will not understand why simplicity and directness are such virtues in design for space use.

Re:Not comparable in any way to calculators

[Anonymous Coward]

I beg to differ ... ... why then, to all these geeks have SO much aluminum foil on hand, if not to stop radiation?

Re:Not comparable in any way to calculators

[Anonymous Coward]

Uh, so the MacIntosh that I flew on STS 46, 57, and 63, without any Radiation optimization was crap?

Ran OS-7 along with Labview to run an experiment in a mid-deck locker for 8 days.

Proved that a lot of the Rad hard design crap, is just that, crap. :)

Next step: hardware

[H_Fisher]

How long before somebody cobbles together a "system" this will run on - a re-creation of the hardware using today's components, or at least a neat-looking case for this emulator?

I'm sure somebody out there with more time than I have is working on it ... :)

Re:Next step: hardware

[Anonymous Coward]

A neat looking case? Uh, I think NASA did. Back in the 60s. I don't know. Something to do with the moon.

Re:Next step: hardware

[Anonymous Coward]

"...or at least a neat-looking case for this emulator?"

NASA has a neat case for one of these: its about 200 feet long, develops 15 million pounds of thrust, and was named after a Roman god...

Disaster waiting to happen

[Veteran]

I had occasion to look at the plans for the oxygen tank that blew up on Apollo 13. There is no great mystery why it blew up, the mystery is why they didn't all blow up.

Trying to figure out how much is left in a liquid oxygen tank in outer space is not an easy task. If you wanted to know that answer here on earth you would weigh the tank - which obviously won't work in free fall.

The idea they came up with was to have a sensor in the tank that could measure the level by resistive means. In order to have a 'level' to measure they had to create an artificial gravity inside the tank by swirling the contents with an internal electric motor and a blade. In the movie "Apollo 13" one of the astronauts talks about "stirring the O2 tank", that is what he is talking about.

Consider what this all means: you have a tank full of liquid Oxygen, you have several pounds of highly combustible aluminum and graphite parts which are soaked in liquid Oxygen, and you have a DC motor with brushes sparking up a storm inside the tank. Another name for such a combination is a "bomb".

NASA's - management driven - engineering has long been full of "Whir click, whir click - OK, Russian Roulette is flight certified as safe" thinking. Nobody does a "how could this all go wrong" analysis.

Re:Disaster waiting to happen

[Anonymous Coward]

That is really amazing. I'll look it up, of course, but it sounds about right. I would have used some ultrasonic transducers or beta probes or something to sense the level... Who knows what state those where in in the 60s but I know they used the beta probe approach to sense fuel level in airplanes back then.

Re:Disaster waiting to happen

[peawee03]

Not posting this as troll, flamebait, or anything other than a matter of engineering: could you do better?

Re:Disaster waiting to happen

[Veteran]

i would have suggested an external motor with magnetic coupling to an internal stirring blade - similar to what is done in chemistry labs.

Measuring how long the stirrer takes to come up to speed tells you the mass of what you are accelerating.

Re:Disaster waiting to happen

[wideBlueSkies]

Just thinking about this...could we not tell the mass of the liquid in a tank by shaking it slightly? The time/energy it takes to get the tank moving, combined with the momentum after turning off the shaker could probably determine how much stuff is in there.

Or another alternative...sonar...sound reflected off the contents of the tank.

wbs.

Re:Disaster waiting to happen

[Veteran]

Good idea, the problem you need to solve with it is potential for leakage from the fittings.

I think I would use a small Gamma emitter with a radiation sensor to measure absorbtion instead of sonar, since bubbles could affect the sonar.

Re:Disaster waiting to happen

[Beryllium Sphere(tm)]

Maybe a capacitive measurement? Liquid oxygen must have a different dielectic constant from gaseous oxygen.

Re:Disaster waiting to happen

[Anonymous Coward]

NASA engineering... it may be a bomb, but it's a *triply redundant* bomb.

Why look at the apollo flight computer

[stinky wizzleteats]

When you fly it?

The most recent version of the apollo spacecraft add-on (NASSP 5) has a partial working AGC built into the navigation system.

Re:Why look at the apollo flight computer

[Queuetue]

Actually, it uses *this* AGC.

Car-PC

[LakeSolon]

Does anyone else have a sudden urge to run this on the touch-screen of their car-pc? I can't wait...

~Lake

Re:Car-PC

[Dr. GeneMachine]

Just be sure to have a lot of space in your trunk for all the punched tapes containing the data for your navigation system....

Re:very simple processor 1201

[Tuna_Shooter]

Also, I beleive that they left the rendevous docking radar switch in the on position during decent (a no no) also contributed to the 1201's. Even though it was listed in the Flight manual as being in the on postion. A mistake i believe that wasnt tested in the simulators but was found by 2 engineers during a passing conversation in a hall.

Anyone get a good look at the code yet?

[today]

Humorous snippet from the landing module code...

P63SPOT3 CA BIT6 # IS THE LR ANTENNA IN POSITION 1 YET
EXTEND
RAND CHAN33
EXTEND
BZF P63SPOT4 # BRANCH IF ANTENNA ALREADY IN POSITION 1

CAF CODE500 # ASTRONAUT: PLEASE CRANK THE
TC BANKCALL # SILLY THING AROUND
CADR GOPERF1
TCF GOTOP00H # TERMINATE
TCF P63SPOT3 # PROCEED SEE IF HE'S LYING

P63SPOT4 TC BANKCALL # ENTER INITIALIZE LANDING RADAR
CADR SETPOS1

TC POSTJUMP # OFF TO SEE THE WIZARD ...
CADR BURNBABY

Re:Anyone get a good look at the code yet?

[Quatloo]

And its nice to see octal again too!

Re:Anyone get a good look at the code yet?

[Anonymous Coward]

Hey, that's the same code we've been using in SCO Linux. Now we've got to sue NASA, too.

Thanks for the tip.

-- Darl

Interesting time limit

[Chemisor]

> Note it only keeps mission time so after 24 hours you have reset the time

Yeah. 24 hours ought to be enough for everybody.

Re:Interesting time limit

[pknoll]

It doesn't have a 24 hour limit, you have to reset the time at 24 hours if you want to use it as a clock, because it doesn't wrap to 0:00, it keeps counting up... i.e. 23:59...24:00, and later, 24:59...25:00.

It will do this to ~31 days, at which point the timers overflow.

nope Re:Disaster waiting to happen

[WolfWithoutAClause]

In order to have a 'level' to measure they had to create an artificial gravity inside the tank by swirling the contents with an internal electric motor and a blade.

They didn't use artificial gravity to seperate the LOX; quite the opposite.

In fact, in zero gravity LOX tends to divide up into regions of gas and liquid. If the gas happens to float past the sensor, then they get an incorrect reading of the density, and hence they don't know how much is in there. This was a big problem on previous flights. Stirring the tank mixes it all up and makes it the same density; allowing a reliable reading to be taken.

you have several pounds of highly combustible aluminum and graphite parts

Aluminum, particularly bulk aluminum is *not* combustible in LOX. It's used on the Space Shuttle main tank fer heavens sake!

Graphite can't really burn either; for it to burn it needs to reach ~3000K, and the LOX is pretty keen on it not reaching that temperature.

LOX only really explodes in contact with greases- it's soluble in them, and they form a contact explosive.

and you have a DC motor with brushes sparking up a storm

Provided the brushes are carefully chosen, this need not be a problem.

That's not actually what caused the explosion anyway.

During testing a relay welded itself shut due to incorrect voltages. In flight, the wiring overheated- and the insulation burnt in the LOX. That caused the LOX tank to overpressure, and it blew away half the side of the vehicle.

Re:nope Re:Disaster waiting to happen

[Veteran]

They didn't use artificial gravity to seperate the LOX; quite the opposite.

In fact, in zero gravity LOX tends to divide up into regions of gas and liquid. If the gas happens to float past the sensor, then they get an incorrect reading of the density, and hence they don't know how much is in there. This was a big problem on previous flights. Stirring the tank mixes it all up and makes it the same density; allowing a reliable reading to be taken.

Yes and no. In zero g the bubbles and liquid have no reason to separate. In a gravity field the bubbles float just like the do in water - so you get a liquid without voids in it - which you can measure.

Aluminum, particularly bulk aluminum is *not* combustible in LOX. It's used on the Space Shuttle main tank fer heavens sake!

Aluminum will burn in air if there is enough energy to break through the surface layer of aluminum oxide which builds up on the surface. In fact aluminum is so reactive with oxygen that this layer forms instantly when the metal is exposed to oxygen. Anything which will burn in air will really burn in LOX.

Graphite can't really burn either; for it to burn it needs to reach ~3000K, and the LOX is pretty keen on it not reaching that temperature.

There was an experiment where a scientist used LOX and charcoal to see how fast it would burn - it esentially flashed in less than a second. DO NOT ATTEMPT THIS. IT IS RIDICULOUSLY DANGEROUS. Your statement is like saying Nitro Glycerin is safe to have in your house. NOTE FOR THE YOUNG AND INEXPERIENCED: DO NOT STORE NITRO GLYCERIN IN YOUR HOUSE. IT WILL BLOW UP AND KILL YOU!!!

Provided the brushes are carefully chosen, this need not be a problem.

This is exactly the sort of thinking which resulted in the original disaster. Brushes are mechanical devices - there is inductance in a motor - when the brush connection is broken the inductance of the motor will cause a spark. We have studied the ignition properties of such sparks in LOX in my group. There is a statistical probability of a given spark igniting the brush material.

That's not actually what caused the explosion anyway.

During testing a relay welded itself shut due to incorrect voltages. In flight, the wiring overheated- and the insulation burnt in the LOX. That caused the LOX tank to overpressure, and it blew away half the side of the vehicle

That is the official theory which was reached by people who knew nothing about the spark ignition problem. The voltage in the GFE power supply used in the test was not enough to weld contacts - the LOX would have cooled the wires so that they wouldn't have reached ignition temperature. The explosion didn't happen until the tank was stirred. The thinking behind reaching that official theory was "Well none of the other tanks blew up so the design was OK so it must have been someing which was done to that particular tank that caused the problem."

Thanks for demonstrating the "Whirr click, whirr click " mind set to everyone.

Re:nope Re:Disaster waiting to happen

[Anonymous Coward]

Your theory is all well and good, except that they actually tested this out on another tank they had around. The subjected the tank to everything that happened to Apollo 13's, and kept a watchful eye on it the whole time. Sure enough, after a couple of stirrings, the whole thing blew up.

Re:nope Re:Disaster waiting to happen

[thompson42]

In flight, the wiring overheated

No, the wiring overheated on the ground, as the test conductors ran the internal tank heater for hours to boil off the LOX inside. The tank contents did not empty as quickly as usual because the tank fill pipe had been dislodged when the tank was dropped two inches during installation some months before. Because the tank heater was built for 28V and the older ground test equipment delivered 65V, the heater thermostat failed, and the tank heater stayed on 100% of the time instead of cycling on and off. The intense heat that built up in the well-insulated tank damaged the wiring in the tank.

the LOX would have cooled the wires so that they wouldn't have reached ignition temperature

Ignition occurred when the wires with damaged insulation came into contact with each other and arced. The arc was hot enough to induce combustion in the wire insulation.

Re:nope Re:Disaster waiting to happen

[Veteran]

Yes the tank blew up. This could have happened either way - just statistical chance. Basing a conclusion on one test is rather dangerous.

Look, I am not interested in arguing - why? An argument is the intellectual equivalent of a fight. Fights do NOT go to the person who is right or wrong - they go to the person who is the best fighter.

This is the root of the basic intellectual falacy which pervades the academic world - that the winner of an argument is the person who is right.

I really understand fighting - I am a certified experet in the subject - so I know what a waste of time fighting is: people get hurt, and nothing gets achieved.

By the way the statement that sparks can cause ignition in LOX soaked material is not a theory - it is an observed fact - easily duplicated, verified and confirmed.

Re:nope Re:Disaster waiting to happen

[Veteran]

Thanks for the additional data. I had read this a year and a half ago and had forgotten it.

In LOX the wires themselves in the precense of a spark can ignite. This is dependant upon the size of the spark and the size of the wires; does the wire lose heat to the LOX bath faster than the combustion can provide it? If so there is no ignition of the wire - if not then the wire can ignite.

Breaking a wire which is carrying a current is one of the best ways we have found of causing a fire.

Regardless, the design of the LOX tank was a disaster waiting to happen: fly it enough and it will blow up.

The conclusion we have reached in testing is that it is not safe to spark in pure oxygen.

Re:nope Re:Disaster waiting to happen

[thompson42]

the design of the LOX tank was a disaster waiting to happen: fly it enough and it will blow up

No. The fan motor design that concerns you so was not at fault in this accident. This particular tank was damaged, with partially bared wires that touched when the tank was stirred; it was indeed a disaster waiting to happen. But there was nothing inherently unsafe in the tank design. Unless you have more specific information on the design of the fan motor than I do?

it is not safe to spark in pure oxygen

No argument there! Of course this would not have been news to the tank designers either.

Re:nope Re:Disaster waiting to happen

[the pickle]

There was an experiment where a scientist used LOX and charcoal to see how fast it would burn - it esentially flashed in less than a second.

Experiment? More like "let's see how fast we can light a barbecue grill!" ;)

p

Re:nope Re:Disaster waiting to happen

[WolfWithoutAClause]

You are right of course; in a more theoretical sense aluminum *can* burn in LOX. It's very difficult to get going because it conducts heat away like a mad thing; you need to vapourise or atleast melt metal to sustain a flame- but a big enough spark will get it lit, and the Shuttle tank 'fails the hammer test' with a non zero probability-the Shuttle engineers claimed that hammers were unlikely to strike the vehicle in flight and got a waiver- this was before Columbia :-(.

On the other hand, combustion chambers like Agena were built from aluminum, and flew many, many times without problems. I've also met people who built and ran alloy LOX cooled combustion chambers that developed cracks and leaked LOX straight into the combustion chamber- no problem. They also ran tests where they threw gravel into LOX and ran it through an alloy pipe- again no problem (the firemen present were upset at that.)

Graphite is rather more dodgy. There is a qualitive and quantitive difference between graphite and charcoal, which you are skirting around. Charcoal is much more fluffy stuff, graphite tends to be solid, and highly thermally conductive. That makes a *big* difference.

But I agree that the Apollo stirrer design is rather more risky than it needed to be. I still believe the official version; but I don't discount your theory totally either- but the official explanation seems more likely; given the abuse that the tank had been through.

Re:nope Re:Disaster waiting to happen

[Veteran]

No argument there! Of course this would not have been news to the tank designers either.
It may have been. There is currently a discussion between various groups at NASA on this very subject - is there some minimum value of spark energy which is safe in a pure oxygen athmosphere? We say no, others say there is.

This entire thread is highly instructive of how memory and the human brain work in the real world: When I read the original reports about a year and a half ago I knew and understood the cause of the actual accident - but I remembered the dangerous design of the tank better than I did the pedestrian causes of the actual incident. Why? as a design engineer the design problems were of more interest to me. Over time I forgot the actual cause of the incident and substituted what I did remember about it.

Learn from this error lest it happens to you at some point.As you get older this happens more since you have much more information stored as an older person than you do as a young person. This makes you slower to respond (it takes longer to search through more stuff), and the chances of 'bit errors' increase with the number of bits stored.

Nevertheless my original point can be modified to: "it was a poor design decision to have live electrical circuits inside of a LOX tank".
I think most of us can agree with that.

Re:nope Re:Disaster waiting to happen

[Veteran]

Please see my post earlier - the official explanation is probably the correct one.

As to the managment think problems at the root of shuttle disasters, the Columbia is another classic example of it. The shuttle was getting foam impacts since the very first flight (whirr click). This was NEVER safe - it needed to be corrected - instead it was accepted as 'normal' and ignored.Then for politically correct reasons the formulation of the foam was changed which roughly trippled the number of foam impact incidents. The engineers knew that it was dangerous and said so, but the managers won the argument - they weren't right but they thought they were because of the intellecutal falacy I outlined elsewhere. Same thing happened in the Challenger - the engineers were right but lost the argument to a manager.

This thread is an excellent example of the Internet being used correctly as a communication medium; everyone knows more now than they did at the start of the thread. Great work evrybody.
.

Re:nope Re:Disaster waiting to happen

[grozzie2]

Aluminum, particularly bulk aluminum is *not* combustible in LOX.

The british navy used to think this as well, so they built some ships from aluminum, and sent them down to the Falkland Islands to stem off an invasion. They discovered the hard way, if you heat a piece of aluminum to the correct temperature (achieved thru the ignition of an exocet missle) then the aluminum superstructure indeed will burn, and continue to burn, in a gas mix that's only 16% oxygen, with the rest relatively inert gasses (air).

It's used on the Space Shuttle main tank fer heavens sake!

There is an old saying in the aviation industry, 'Learn from the mistakes of others, you only get to make one yourself.' Aluminum + oxidizer + sufficient heat source = self sustaining combustion reaction. The rate of combustion will be controlled by the availability of oxidizer. LOX has a significantly greater percentage of oxidizer than air (a little more than 5 times as much, or one could say it's somewhat more pure).

I'll give nasa engineers enough credit that they probably understood this risk when designing the shuttle, but it was a tradeoff. The combustible nature of aluminum was considered an 'acceptable risk' when measured against the weight savings. The reality is, it wouldn't matter anyways, if the heat source is such that the aluminum was combusting, there would be plenty of liquid hydrogen in the general vicinity so as to make the combustible nature of the aluminum tank an insignificant variable in the overall disaster equation. Refer to the final challenger flight for empirical data thru observation to basically confirm this assumption.

The shuttle system is a great example of engineering compromise. Beginning with technology from the 70's, engineers began the balancing act of trading off function, weight, and safety in the process of coming up with a design that met the goal of re-useable launch vehicle. It can launch 40,000 pounds into low orbit, and do so on a fairly consistent schedule. With a mission failure rate on the order of 2%, it's pretty obvious that safety got the short end of the compromise in more cases than not. This is not necessarily a bad thing, just a fact of life. With the propulsion systems available, it's possible to meet the requirements for function and weight, just not possible to include a high safety margin into the same design. A series of compromises that resulted in an 'acceptable risk' at the time, which are today no longer considered acceptable.

Re:nope Re:Disaster waiting to happen

[WolfWithoutAClause]

Yes, but the Falkland island thing isn't quite the same- the aluminum structure was uncooled. What happens is that the aluminum gets hot and melts, and then droplets of it disconnect from the body- they can then easily burn and set off a self-sustaining reaction.

In a LOX tank or pipe, the LOX continuously cools the aluminum, and *cooled* aluminum is incredibly hard to melt, let alone ignite.

Re:nope Re:Disaster waiting to happen

[TheHawke]

The tank design itself was safe. The problem was voltages and the thermal limit switches.
Where the LOX tank was fabricated they used 24 volt power to test the tanks. At the Cape, they used 48 or 72 volts DC at the pad. When they did the forced LOX purge, the limit switches fused shut the instant they were subjected to the higher voltages, hence the temperature inside the tank rose to a nice 400 degrees F. The interior temperature gauges were not calibrated to detect the oven-like heat that occurred. The teflon insulation could not handle the heat, burned to carbon and thusly provided the fuel for the explosion.
When they stirred the tanks, the carbon residue from the telfon heated and the raw LOX saturating the material provided the cataylic reaction in which the high temperatures caused the supercritical LOX slush to flash to a gas. There was an explosion, but from a massive surge of gaseous oxygen, not from explosives.

Re:nope Re:Disaster waiting to happen

[Sciflyer]

Pure class :D

"By hooking into the World Wide Web, you can look at a variety of electronic "pages," consisting of documents, pictures, and videos created by people all over the world. One of these is a guy named (really) George Goble, a computer person in the Purdue University engineering department. Each year, Goble and a bunch of other engineers hold a picnic in West Lafayette, Indiana, at which they cook hamburgers on a big grill. Being engineers, they began looking for practical ways to speed up the charcoal-lighting process. "We started by blowing the charcoal with a hair dryer," Goble told me in a telephone interview. "Then we figured out that it would light faster if we used a vacuum cleaner." If you know anything about (1) engineers and (2) guys in general, you know what happened: The purpose of the charcoal-lighting shifted from cooking hamburgers to seeing how fast they could light the charcoal. From the vacuum cleaner, they escalated to using a propane torch, then an acetylene torch. Then Goble started using compressed pure oxygen, which caused the charcoal to burn much faster, because as you recall from chemistry class, fire is essentially the rapid combination of oxygen with the cosine to form the Tigris and Euphrates rivers (or something along those lines). By this point, Goble was getting pretty good times. But in the world of competitive charcoal-lighting, "pretty good" does not cut the mustard. Thus, Goble hit upon the idea of using - get ready - liquid oxygen. This is the form of oxygen used in rocket engines; it's 295 degrees below zero and 600 times as dense as regular oxygen. In terms of releasing energy, pouring liquid oxygen on charcoal is the equivalent of throwing a live squirrel into a room containing 50 million Labrador retrievers. On Gobel's World Wide Web page (the address is http://ghg.ecn.purdue.edu/), you can see actual photographs and a video of Goble using a bucket attached to a 10-foot-long wooden handle to dump 3 gallons of liquid oxygen (not sold in stores) onto a grill containing 60 pounds of charcoal and a lit cigarette for ignition. What follows is the most impressive charcoal-lighting I have ever seen, featuring a large fireball that, according to Goble, reached 10,000 degrees Fahrenheit. The charcoal was ready for cooking in - this has to be a world record - 3 seconds. There's also a photo of what happened when Goble used the same technique on a flimsy $2.88 discount-store grill. All that's left is a circle of charcoal with a few shreds of metal in it. "Basically, the grill vaporized," said Goble. "We were thinking of returning it to the store for a refund." Looking at Goble's video and photos, I became, as an American, all choked up with gratitude at the fact that I do not live anywhere near the engineers' picnic site. But also, I was proud of my country for producing guys who can be ready to barbecue in less time than it takes for guys in less-advanced nations, such as France, to spit. Will the 3-second barrier ever be broken? Will engineers come up with a new, more powerful charcoal-lighting technology? It's something for all of us to ponder this summer as we sit outside, chewing our hamburgers, every now and then glancing in the direction of West Lafayette, Indiana, looking for a mushroom cloud."

Re:nope Re:Disaster waiting to happen

[Anonymous Coward]

Worth noting that many people have nitro glycerine in their houses. It's a very common medicine for heart disorders, and small dosages have been shown to stop heart attacks. Although, we're talking about miligrams. If you extracted it from the pills, you might be able to crack the small glass bottle it comes in.

Parent is informative, deserves upmod

[Beryllium Sphere(tm)]

In addition, the incorrect voltages during testing were the result of failed communication between the contractor and NASA, a spectacular example of why the paperwork is important.

Curious about the computers back on the ground

[Beryllium Sphere(tm)]

Does anyone have the specs on the mainframes NASA used for orbit calculations, mission planning and so on? I was wondering when personal computers reached the equivalent power level, and whether my Prius has more computing power on board.

Re:Curious about the computers back on the ground

[hughk]

NASA was using IBM360s in those days. They really had little processing power in real terms (although they were quite good on I/O).

I have no idea what the Prius has as a processor, but a modern laptop would substantially exceed the processing power of the ground installation. Perhaps only if programmed in FORTRAN though (the NASA language of choice at the time).

Re:Curious about the computers back on the ground

[Anonymous Freak]

Well, I remember reading that a 386 has more computing power than all five flight control computers on the space shuttle combined. (This was before the space shuttle upgrade in the mid '90s, though.)

So I'm pretty certain a Prius has more computing power than the Apollo capsule. (And yes, I can easily believe that a modern laptop has more power than all of NASA in 1969.)

Should it ever need a new home

[wowbagger]

Should your friend ever decide that he needs to give that computer a new home, send it here.

Beowulf comment ...

[Alain Williams]

If we have a Beowulf cluster of these, do we have a space invasion on our hands ?

If so: who is invading who ?

Re:Beowulf comment ...

[Anonymous Coward]

Well I, for one, welcome our Beowulf cluster overlords.

Actually, that doesn't sound quite as daft as I'd hoped...

Draper Labs built the AGC

[dswartz]

I would just like to point out that Draper Labs in Cambridge, MA (the company I work for) built the AGC. An exact replica of the real AGC sits in our Simulation Lab.

Re:Draper Labs built the AGC

[Anonymous Coward]

I would just like to point out that Draper Labs in Cambridge, MA (the company I work for) built the AGC. An exact replica of the real AGC sits in our Simulation Lab.

Lemme have it! Please? Just for a day? Can I visit with you nice people? I'll bring my own sleeping bag.

Intuitive

[suwain_2]

Some people complain that the Linux CLI is too user-unfriendly. Have they tried using this thing?

Setting the time:
Press Verb 2 5 Noun 3 6 Entr. Then enter a + to indicate you're entering the time in decimal, not octal. Be sure to enter all 5 digits of the hour. Then press Entr, and enter minutes, and then repeat for seconds. And make sure you remember that the seconds are in 100ths.

V25N36E+00012E+00002E+04400E

Totally intuitive.

Re:Not comparable in any way to calculators AC11

[Anonymous Coward]

"The ideal is to have the minimum gate count, minimum memory cell count, and the shortest possible path between phyical I/O and computing. The computers used in the Apollo meet this requirement."

The design of the gates in the apollo computers is fascinating. They used *only* NOR gates, and these were designed with multiple redundancy - each one effectively contained three copies of all the components required for it to function!

Notes on compiling

[crucini]

I didn't immediately succeed with the author's instructions. Here's what worked for me:

cd yaAGC
./configure
make
sudo make install
cd yaDSKY
./configure
make
sudo make install
yaAGC --core=Validation.bin --debug
In another window, still in the yaDSKY directory: yadsky --cfg=src/LM.ini
(Note lowercase yadsky)
Congratulations, Ronald. Pretty cool. Does the contrast on the LED display have to be so low? The background is very light.

Am I the only one here who actually tried the program?

Re:Notes on compiling

[shadowbearer]

Probably... or else everyone else is still struggling with it. :)

Thanks, your instructions worked here while the original ones didn't. Lots of warning during compilation, but I have some weird lib versions on the box I compiled it on, gotta take it down for a few days to update libs (Gentoo is nice but time consuming :) and I run some software that requires custom beta libs, so that might have something to do with...

and now that I've blown the better part of two hours playing with this, it'll probably get shelved in favor of the priority items on my 2-do list :(

Sigh.

I'm not noticing any contrast problems with the 'LED' display; but I am seeing some weird window size problems. (might be due to fluxbox, dunno? but my X and X lib versions are somewhat old on that box)

Neat stuff, tho! I wonder if this will ever be integrated with a LM sim using Orbiter? Or has it already? I can't keep up with the massive amounts of 3rdMods to Orbiter as it is.

What dist are you running there?

If I find time tomorrow I'm going to do a totally clean install on another box.

Cheers and thanks!
SB

Re:Notes on compiling

[crucini]

I'm running Red Hat Linux release 9 (Shrike) - actually Pink Tie, a CheapBytes copy. And fluxbox 0.1.14 - love it.

Agreed about Gentoo. I run it at work, with much help from a nearby Gentoo expert, and frequently have to put too much time into fixing it. The benefit is that I can run recent Mozilla, etc.

I added apt-get to Red Hat and it gives me some of the functionality, but most applications I want aren't available. It is much faster than emerge, of course.

I don't know Orbiter - I'll take a look.

Weird Coincidence

[pyrrhonist]

This is just too weird a coincidence.

I just bought The Sky Moves Sideways, and I was listening to it while reading Slashdot.

By the time I had read through the articles on the home page, most of the album had played out. Then I read the AGC article and downloaded the code.

The weird part is that when I started reading the Luminary source code, the track playing was, "Moonloop", and hit the part at 13:18 where an excerpt of the Apollo landing broadcast is mixed it.

I am totally freaked out right now.

Re:Weird Coincidence

[Anonymous Coward]

Then you'll have a blast the next time you happen to be playing Dark Side of the Moon while watching the Wizard of Oz.

Re:very simple processor 1201

[Anonymous Coward]

You're right, the 1201 and 1202 occured because the rendez-vous radar was activated.
Steve Bales who was in charge of the DSKY in the control center pondered and decided to continue the final approach of the landing.

John F Kennedy's answer to this would have been:

[gd23ka]

"Darn. another platform to port linux to! Just when we thought we had most architectures covered :-)"

Ask not what Linux can do for your platform. Ask your platform what it can do for Linux!

Absolutely a super thread

[tjstork]

Thanks to everyone who posted on this thread. I really enjoyed learning everything here.

Re:Disaster waiting to happen - slightly OT

[MadHungarian1917]

Just think in your car there is a 12 volt DC motor submerged in gasoline with air and fuel vapor filling the void space in the tannk.

This is an even nastier mix than LOX in an AL tank
and we all drive around with it every day.

At least on apollo only the oxidizer was in the tank...