We all know that when JPL (the Jet Propulsion Laboratory/ NASA) builds something, they build it well. If only everything, from washers and dryers to cars were designed and built by those engineers! Granted, few people could afford to buy the stuff, because you get what you pay for. Imagine a car that never needs an oil change, new tires or a battery! Sounds great, right? Apart from the prohibitive price you wonder why it never needs any maintenance.
You may remember grandma’s iron that somehow worked for 50 years of almost daily use, and you think, well, they don’t build them like that anymore. And for most things that’s true. But when things break you have to buy new ones, and that in turn is good for the economy. And an iron can be replaced any day.
When things break in space, they usually stay broken and the mission fails in that respect. On rare instances, like with the Hubble Space Telescope, a repair can be done. But by and large things just simply have to work. Quality control is of the essence, testing is mandatory, triple-checking everything is essential.
Many spacecraft have so-called redundant systems on board – components that can take over when the primary part fails. The Space Shuttle used to fly with five redundant computer systems!
If you have a mission like Voyager, you know there will never be a chance to fix anything, and the longevity of all working parts impacts the mission, ensuring its success.
Voyager 1 has been in space since September 1977 – over 40 years. A few years ago it passed through the outer boundary of the Solar System and slipped into interstellar space – that vast empty space between the stars. The spacecraft is so far away from Earth that it takes a radio signal over 19 hours and 35 minutes to reach us.
Over the past several years engineers have noticed distinct signs of aging in the spacecraft. Voyager uses tiny thrusters to orient itself in space, so its antenna always points at the Earth for data down- and uplinks. Those adjustments are short millisecond-long puffs from the thrusters, but lately it’s been taking longer and longer puffs to move the spacecraft. Clearly, they need a tune-up, but alas, there’s no way anyone could reach them, and there are no mechanics out there.
But wait! We have backup thrusters!
And those backup thrusters have been sitting there, dormant and unused for 37 years. It’s a huge risk, for sure. But the engineers didn’t have much of a choice: either use the primaries until they no longer work, or possibly have malfunctioning old machine parts blow up the whole spacecraft…
In addition – do you know what computer programs and programming languages looked like in the early 70s, when Voyager was built? Many of those programs and languages no longer exist, there is no equipment that runs them. How do you send commands in a language you don’t understand and don’t know what it does? The original engineers are no longer around, and none of the old equipment runs anymore.
But people working at JPL aren’t just average achievers – they are super smart, and they worked until they figured out a way to re-learn the old stuff and found a way to send those commands. Then they waited – 39 long hours. And the signal that came back was almost too good to believe. It’s as if Voyager had said “What now? Want me to fire thrusters that haven’t been used for 37 years? Okay, no big deal. Here you go.” Back on Earth there was much elation and relief: knowing that the backups still worked as if no time at all had passed gave the mission an additional 2-3 years of life.
The Voyagers have always been The Spacecraft That Could. After all these years they still report in almost daily, sending back data about science observations and receiving commands from us. Even though their signals are weak – a modern digital watch has about 20 BILLION times more power than what the Deep Space Network (DSN) picks up – they still keep coming.
And that by itself is impressive enough – for both Voyager and the giant radio dishes here on Earth!
Learn more about Voyager at http://ift.tt/2pq4zpS
Beate Czogalla is the Professor of Theater Design in the Department of Theatre and Dance at Georgia College & State University. She has had a lifelong interest in space exploration and has been a Solar System Ambassador for the Jet Propulsion Laboratory/ NASA for many years. She can be reached at our_space2@yahoo.com
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