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Mr. Murphy, You’re Not Welcome in Space

During a recent conversation with my co-workers I was reminded of Murphy’s first corollary by my manager while discussing my most recent blog. Murphy’s first corollary goes like this: “Left to themselves, things tend to go from bad to worse.” I’m not sure how I missed this while researching Murphy’s Law for my last blog, but I found a very interesting website while looking for information on Murphy’s first corollary. You can find it here. I had no idea an entire website was set up and devoted to the origins and variations of Murphy’s Law! There are a lot of other neat topics to explore there as well, but I won’t discuss all those here. I would encourage you to take a look and explore the page to find out more about all the variations and corollaries to Murphy’s law.

Getting back to that conversation with my coworkers, we talked about how everything is constantly falling apart and requires continual maintenance to continue operating. We also discussed how scientists think up these great ideas and help to move technology forward but it’s the engineers who keep the technology from falling apart while working to make the next version more efficient and last longer. That is a large part of what we do in engineering. It is definitely not all of what we do, but it sure is a good portion of it. So if “Mr. Murphy” is against us with his laws and corollaries then what do we do as engineers when putting designs into space? A natural first response might be that Mr. Murphy is not welcome in space. Wouldn’t that be really nice? How great it would be if we could negate such ‘laws’ and send designs into space that would never fail! Of course that can’t be done because it would violate the laws of physics!

However, we can design products that are radiation hardened and offer high reliability for the harsh environments in space. At ADI we have certain specialized products that are designed to be tolerant to the radiation and harsh environment present in space. Products are also placed into hermetically sealed packages to keep out moisture as well as prevent outgassing. To find a particular product of interest simply go to Analog Devices’ Space Applications site which will open a page that has the diagram pictured below.

ADI Space Products Signal Chain Diagram

ADI Space Products Signal Chain Diagram

ADI Space Products Signal Chain Diagram

To find products for a particular function simply click on the desired component function in the signal chain diagram. Since I have a background in high speed ADCs I’ll use the ADC as an example here. Clicking on this brings up a menu below the diagram that lists all the space qualified ADC offerings from ADI.

Space Qualified High Speed ADCs from ADI

Space Qualified High Speed ADCs from ADI

Space Qualified High Speed ADCs from ADI

There are many more products available, but at least this provides a sampling to whet your appetite just a bit. Let’s look at how parts like these can be used in space applications. I imagine by this point you’ve likely heard about the Juno mission that is currently underway with NASA. Juno is currently in orbit around the planet Jupiter as of the time of this writing. Below is a photo of the model of Juno and the planet Jupiter.

Model of NASA Juno Space Probe and Jupiter1

Model of NASA Juno Space Probe and Jupiter1

Model of NASA Juno Space Probe and Jupiter1

In order to gain some perspective of the requirements for a mission of this nature I’ve included a mission overview from NASA’s webpage below. The mission life for Juno is actually relatively short by comparison to other requirements I have seen while working in the space products group at ADI. It is not uncommon to have a requirement for 15-20 years or longer for the mission lifetime for space applications. Juno’s requirement is about 7 years based on the mission timeline below provided from NASA’s website. You can find more details about Juno and its mission: here

Mission Timeline2

  • Launch – August 5, 2011
  • Deep Space Maneuvers – August/September 2012
  • Earth flyby gravity assist – October 2013
  • Jupiter arrival – July 2016
  • Spacecraft will orbit Jupiter for 20 months (37 orbits)
  • End of mission (deorbit into Jupiter) – February 2018

The mission lifetime may be relatively short by comparison to typical space applications, but the environment is arguably among the harshest. Jupiter has the most intense radiation of any planet in our solar system. Juno must have electronics inside that are radiation tolerant and hermetically sealed, but even still there is shielding designed into Juno to help prevent Jupiter’s intense and harmful radiation from causing damage to these electronics inside Juno. The infographic from NASA regarding these conditions provides some insight into the conditions Juno faces orbiting Jupiter.

Juno Mission Infographic from NASA (For a larger image see Reference 1 below1

Juno Mission Infographic from NASA (For a larger image see Reference 1 below1

Juno Mission Infographic from NASA (For a larger image see Reference 1 below1

Now let’s recall that first corollary from Mr. Murphy: “Left to themselves, things tend to go from bad to worse.” The engineers working to design the Juno space probe must have surely been planning ahead to avoid such problems since the Juno probe will be left to itself in the reaches of space orbiting the planet of Jupiter with its intense radiation. Juno must have been designed to be robust enough to handle the 7 year mission life in such a harsh environment. The engineers had to take into account not only the amount of radiation, but also the huge magnetosphere of Jupiter. For reference, the graphic shows that Earth’s magnetosphere extends 10 Earth radii while Jupiter’s magnetosphere extends 100 Jupiter radii! That is incredibly large! This magnetic field is part of the reason for the intense radiation around Jupiter. As I stated earlier, it would be nice if we could simply tell Mr. Murphy he is not welcome in space.

Unfortunately we cannot do that. We must put our engineering skills to work to put designs into space that last longer!

1 Image courtesy of NASA

2 Information courtesy of NASA

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