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12

The restrictions you are quoting only apply to the LGC, the computer in the Lunar Module. The Command Module Computer does not have these restrictions (compare the section about the Coasting Integration Routine you quote with the same passage from the document about the CMC: https://www.ibiblio.org/apollo/Documents/R-577-Colossus2-Martin-5.2.pdf). The CMC ...


14

You actually ask a really good question. And the answer is, we do both, depending on the needs. NASA tends to go for the ultra-reliable, and radiation tolerant components are more reliable, thus it is their preferred way. Many commercial satellites, however, use non-space grade components that are shielded lightly, and with software and hardware built in a ...


2

Throwing some rough and ready math at the question, happy to be corrected by anybody with actual numbers. Hardening increases the radiation level to trigger errors by several orders of magnitude, call it 1000 for this. Dropping the radiation by a factor of 1000 to a 10cm cube would take about half a mm of lead, adding up to something like 250g. Most ...


0

Modern PHP runs on a Virtual Machine: A guaranteed environment that will exist regardless of underlying operating system or hardware. That is, core library functions that depend on features of an OS are not part of the VM, such as getting the PID of a child process after performing a pcntl_fork() in a Posix environment. Rather, language constructs like ...


73

Because shielding against radiation is heavy, and weight is the enemy of getting things into space. CPUs are quite sensitive to radiation, and some types of radiation (cosmic rays) are not only quite good at penetrating most things, as they do, they cause a cascade of secondary radiation. To protect a device form any of this radiation getting through is not ...


5

Developing software for space applications is quite different from "regular" software development, especially when we're considering human spaceflight. If you want to develop critical software (i.e. software that, in case of a failure, can lead to loss of life, mission, and/or facilities) for ESA, you need to comply with the applicable standards defined by ...


4

Let's have a look on a 1998 paper on real time systems from CMU (Carnegy-Mellon Univeristy). Typical examples of real-time systems include Air Traffic Control Systems, Networked Multimedia Systems, Command Control Systems etc. In a Real-Time System the correctness of the system behavior depends not only on the logical results of the computations, but ...


3

What exactly makes PHP CLI fundamentally unsuitable to power all the math on board a space craft? ... What, exactly, is it about this that is so "crazy"? You seem to be taking the unsuitability of PHP as a given premise here. Why is that? PHP has two major deficiencies that are relevant here. One is that it's not very performant; the ...


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