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The Loyal Engineers Steering NASA’s Voyager Probes Across the Universe

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Re: The Loyal Engineers Steering NASA’s Voyager Probes Across the Universe

#31

Post by [deleted] »

marsRoverDev wrote: post #8
bitexploder wrote: post #6

Earlier quoted context omitted.

This is a good insight. Having read about NASA's culture some from books like "An Astronaut's Guide to Life on Earth", they tend to be very dedicated to documenting everything. Every last little detail goes into handbooks or manuals about how they fixed problems or things that could have gotten someone killed, adapting procedures to take into account even the smallest of practical details. These engineers come from a…

To give some kind of context on more "modern" methods, we use stupendous numbers of PDFs, DOORS for requirements traceability and tons of code commenting. At last count our project had 0.73 commenting lines per line of code (and we use Allman style bracketing). We are also putting non mission-critical information in a Wiki; basically as a tl;dr of the more dense documentation.

[deleted]

Re: The Loyal Engineers Steering NASA’s Voyager Probes Across the Universe

#33

Post by formerjpl »

laydn wrote: post #4

You know, getting these electronics systems ready, sending out to deep space and communicating with these systems is an incredible feat. But, for me, another amazing thing about these long term projects is the sheer amount of knowledge that needs to be maintained and passed on to new people, over the course of several decades. To pull it off, this need of knowledge management and transfer must be so deeply engraved i…

I used to work at JPL (and coincidentally was given an opportunity to work on Voyager to update some ground software, but ultimately I passed on it since I was way over committed at the time.)

JPL has a formal database that maintains all its requirements documentation. Though, it isn't very user friendly; and you generally have to know what you are looking for.

When I was there, most of the knowledge transfer happened by talking to the older folks around. As a result, I ended up developing close work relationships with people who had been there for 20-40+ years. The historical context they provided on current and past designs was incredibly useful, and not something you would find in a requirements document.

Software was a different matter. Until recently, when the internal GitHub was introduced, finding and digging through code was not as straightforward. Each team/section maintained their own repos. And there was very little consistency, some used subversion, others cvs, accurev, etc, so it made it difficult to find and read code for projects outside your purview. Naturally, this led to software fiefdoms. In contrast, I work at google now, which is the polar opposite: I can effectively read through the entirety of google3 and send a CL/patch to just about anyone.

Re: The Loyal Engineers Steering NASA’s Voyager Probes Across the Universe

#34

Post by pmcjones »

sehugg wrote: post #13

... its oscillator, which allows it to accept a wide range of frequencies, had quit, essentially shrinking the target for transmissions from Earth. Assuming a much narrower bandwidth, and manually subtracting the Doppler effect, they recalibrated their signal. It worked — but to this day, the same calculation must precede every command. IIRC from an old SciAm article, the temperature of the spacecraft's electronics i…

Yes, the article later says "(On Voyager 2, because of the broken oscillator, any change in temperature also tweaks the receiver frequency.)"

Re: The Loyal Engineers Steering NASA’s Voyager Probes Across the Universe

#35

Post by [deleted] »

yourapostasy wrote: post #12

> ...[the heliosphere] blocks 75 percent of cosmic radiation... It sounds like a solar system-scale Van Allen belt [1] when described like this. So we have at least three layers of cosmic radiation protection identified (heliosphere, outer VAB, inner VAB). If the heliosphere has implications for high-precision, high-accuracy independent-of-Earth interplanetary spaceflight similar to gravimetric and magnetic readings…

[deleted]

Re: The Loyal Engineers Steering NASA’s Voyager Probes Across the Universe

#36

Post by Retric »

1_2__4 wrote: post #30
rebootthesystem wrote: post #23

Earlier quoted context omitted.

Well, above all, you value experience. Seriously, the degree to which age discrimination is an accepted reality in tech today is a great failing, and one that has enormous hidden costs over time. Sadly I know a number of extremely talented older engineers who have been discarded like trash only to be constantly rejected in their search for new employment, until some of them just give up. It's remarkably ignorant and…

It's not short sighted. Most upper management in those sorts of companies isn't there for any kind of a long haul. They win if they can impress the VCs with what they shipped in the last few months, doesn't matter if none of it works, services are crashing and customers are unhappy. Imagine if organizations like NASA only recognized accomplishments like "added a button to such-and-such dashboard." It's laziness mixed…

> isn't there for any kind of a long haul

That's a 'reasonable' cause for being short sighted, but it still means they are short sighted.

Re: The Loyal Engineers Steering NASA’s Voyager Probes Across the Universe

#37

Post by mrunkel »

I read far too far into the article before I realized it was the mobile site. :)

In the mid 1980's I went on a tour of JPL in Pasadena and actually saw the computers that were (at the time) in charge of recording and storing the telemetry data. I'm vague on the exact details, but apparently the computers were donated from the US Army and were field models (early "portable" computers) and they operated on 48V DC power. So not only were the computers themselves large fridge sized units, they had near matching transformers that were fairly unreliable.

I recall reading that in the mid 90s NASA replaced all the mission control systems for the space shuttle with a single Sun Workstation, so I assume that JPL also at some point replaced the downlink computers for V'ger.

My hat is off to these many fine people who stuck it out with jobs that were probably long periods of drudgery interspersed with moments of sheer terror.

Re: The Loyal Engineers Steering NASA’s Voyager Probes Across the Universe

#38

Post by FireBeyond »

CocoaGeek wrote: post #32

Love the Sun workstation on Enrique Medina's desk 8)

At the tender age of 39, I vividly remember my first IT job, for a bus company of all things, where at age 20 I had a Sparc 5 on my desk. I still love those Sun keyboards.

(We used it to solve for the most efficient driver/ bus scheduling).

Re: The Loyal Engineers Steering NASA’s Voyager Probes Across the Universe

#39

Post by mynameisnobody »

rootbear wrote: post #14

A lot of what has been said here about software documentation and process is true of NASA flight projects, especially manned. Outside of flight, not so much. In some cases, it's a bit more like grad-school-project-that-escaped. An exception would be the modeling code used for things like weather simulation on supercomputers. The scientists need to know that their code actually matches the model they're testing and th…

Yup.

I worked in a satellite data office of NASA and there was no formal documentation process. Much of the code running in the facility had been written by a single developer over 20 years, and all of the knowledge left with him. Masterful Perl can be frustrating stuff without documentation or comments.

Re: The Loyal Engineers Steering NASA’s Voyager Probes Across the Universe

#40

Post by Nimitz14 »

bitexploder wrote: post #6
laydn wrote: post #4

You know, getting these electronics systems ready, sending out to deep space and communicating with these systems is an incredible feat. But, for me, another amazing thing about these long term projects is the sheer amount of knowledge that needs to be maintained and passed on to new people, over the course of several decades. To pull it off, this need of knowledge management and transfer must be so deeply engraved i…

This is a good insight. Having read about NASA's culture some from books like "An Astronaut's Guide to Life on Earth", they tend to be very dedicated to documenting everything. Every last little detail goes into handbooks or manuals about how they fixed problems or things that could have gotten someone killed, adapting procedures to take into account even the smallest of practical details. These engineers come from a…

Everything you described is just standard engineering practice. I've always found it funny how software developers call themselves "engineers" while working nothing like them.
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