NASA Space Shuttle Launches iPhone to Test Radiation Effects

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Discussion Overview

The discussion revolves around the effects of radiation on memory chips, particularly in the context of a NASA experiment involving an iPhone launched on a space shuttle. Participants explore the sensitivity of different types of memory to radiation, the implications for satellite design, and the challenges posed by decreasing die sizes in modern electronics.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants question the sensitivity of memory to radiation, specifically regarding "single bit upsets."
  • Others assert that memory can indeed be sensitive to radiation, depending on the material used.
  • One participant notes that as die sizes decrease, the problem of radiation effects on memory becomes more pronounced, leading to the implementation of redundancy in satellite avionics systems.
  • A participant provides an example of a single event upset (SEU) causing issues in spacecraft, highlighting the vulnerability of systems like Voyager that operate in single string mode.
  • There is a distinction made between older memory technologies, such as ferrite core memory, which are less susceptible to radiation, and modern solid-state memory, which is more vulnerable.

Areas of Agreement / Disagreement

Participants express differing views on the susceptibility of various memory types to radiation, and the discussion remains unresolved regarding the extent of these effects and the implications for satellite design.

Contextual Notes

Limitations include the lack of consensus on the specific mechanisms by which radiation affects memory and the varying definitions of susceptibility among different memory technologies.

Sakha
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http://www.wired.com/wiredscience/2011/06/iphone-space-shuttle/" . Anyways, it says that it will look for radiation effects with "single bit upsets", is memory really that sensible to radiation?
 
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Depending on the material, yes!

http://www.eeherald.com/section/news/nws2011052512.html

http://www.ornl.gov/info/press_releases/get_press_release.cfm?ReleaseNumber=chip

http://academic.research.microsoft.com/Publication/19605323/radiation-induced-errors-in-memory-chips

http://www.simmtester.com/page/news/showpubnews.asp?where=5795186&num=135
 
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Absolutely, and the problem is in general getting worse as die sizes decrease. All but the very cheapest of satellites are now designed to have multiple avionics systems running in parallel. They vote on the incoming sensor data, vote on the outgoing commands, sometimes even on memory content. A computer that repeatedly steps out of line is voted off the island. This redundancy is danged expensive. It's there for a reason.

A somewhat recent example of an SEU causing a real problem: http://www.jpl.nasa.gov/news/news.cfm?release=2010-151. The Voyager spacecraft are particularly sensitive to SEUs because they are now running in single string mode (only one active set of avionics) to conserve power.
 
Old memory like ferite core are not, but those are massive (huge boards with a few hundred bytes) and slow. Modern memory is small and fast because it's solid state. Solid state devices are susceptible to radiation.

Thanks for the comments and questions. I wrote SpaceLab for iOS.
 

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