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33

It isn't the actual level of charge (potential) that causes electric shock. but being connected to two things (like your iron and the ground) that are at different levels. Hence why birds can sit on a 750kV overhead line and not fry. The earth wire in a domestic system exists to keep all exposed metal at the same potential. Grounding everything to the frame ...


30

Can you have a spacecraft based on an Arduino? Sure you can! ArduSat was two kickstarter funded cubesats that were eventually launched from the International Space Station in November 2013. When you think about it, an Arduino easily outperforms for instance the over forty year old Apollo Guidance Computer All of your requirements should be doable, if it is ...


23

Almost every premise of your question is wrong, unfortunately. Earth is not the only celestial body with a magnetic field — Jupiter, Saturn, and essentially every star (including the Sun), to name a few, all have powerful magnetospheres and north and south magnetic poles accordingly. (Mars and Venus are examples of planets that do not have ...


23

This answer addresses only the US side of the ISS. Like everything else on the ISS, it's complicated. Fuses are not commonly used on the ISS. There are fuses within the battery subassemblies, to protect against internal battery shorts. The common circuit protection device on the ISS is the Remote Power Controller (RPC), a commandable "smart circuit ...


22

From the Rosetta wake-up FAQ (pdf): Q. Was Rosetta completely shut down? Almost. Only the computer and several heaters remained active. These have been automatically controlled to ensure that the entire satellite doesn't freeze as its orbit took it from 660 million km from the Sun out to 790 million km and back between 2011 and 2014. Everything else on ...


21

You can, but it will suffer from a number of problems. These problems can probably be overcome with a short term mission. Problems include: Radiation- Degrading the long term effect of the electronics. Single event upsets- This is probably the biggest danger, a high energy cosmic ray strike could cause a bit flip, potentially changing the code running in a ...


20

Solar panel technology seems to have caught up with power requirements on the satellite. Since price of components is really no object when building a system like this, super expensive panels with efficiency ratings of up to 40% can be used. The trick to engineering something properly is using just the right amount of materials, as the old maxim goes "Any ...


19

"Soyuz: A Universal Spacecraft" says the electrical system produces 23-34 volts. I saw a reference to a nominal 28VDC supply to the spacecraft in the Soyuz launcher manual; 28VDC is a global standard for aircraft power supplies. I think "906V" is a part number, not a voltage; the source for that section of the WP page says (my bolding): Finally, the ...


19

"Earth" doesn't work the way you might think. In any case, on a vehicle of almost any kind, "earth" is replaced by "metal chassis". Your question is based on a very common misconception: that electricity wants to return to earth. Actually, electricity wants to return to source. For instance, electrons at a battery's negative terminal want to return to ...


18

I am guessing VxWorks but I haven't found any sources to validate this. Close, but no cigar. If New Horizons flight software was built by Jet Propulsion Laboratory (JPL), then I guess Wind River's VxWorks RTOS would have been their first choice (it's also a popular choice for hardware on Mars - Pathfinder, Sojourner, Phoenix lander, Spirit, Opportunity, ...


18

The frame of the spacecraft is used as a common ground. See this diagram from this handbook.


17

For rockets it's normally batteries since they only need to operate for minutes, maybe hours at most when it comes to upper stages. An example power budget and description of the hardware for one of the largest launch vehicles out there, the Ariane 5, can be found here. It's a bit outdated (2002) but you can get a feel for the numbers. Ariane 5 used to ...


17

There was no single DC voltage useful for the whole electronic system. A lot of different voltages were needed, for very noise sensitive systems dedicated DC sources were used to avoid interference. Using three phase 400 Hz AC current was a well established method used in aircrafts before. Providing 400 Hz AC enabled the use of aircraft instruments within ...


16

I concur with Hohmannfan's response. This answer addresses the wider issue of computers in satellites. Who needs a computer? I don't think there is anything about the mission that you have described in the question that actually requires any "digital computer" at all. It might seem as if image handling and navigation are highly demanding in computing terms,...


15

This paper describes the Juno telecomm system in detail. It is a standard deep-space X-band system with a 2.5 m high-gain antenna, a 25 W traveling-wave tube amplifier, and concatenated convolutional and Reed-Solomon or Turbo 1/6 rate error-correcting codes. It will get 18,000 bits per second down to a 34-m antenna on Earth at maximum range (6.459 AU) at a ...


15

The laptops on the ISS can only be used for non-time critical uses. Those laptops are used for some mission critical tasks, but only if the task can handle the time needed to replace a toasted laptop with another. Those laptops are commercial off-the-shelf, and they do not fare well against cosmic rays. Most cosmic ray hits result in a "single event upset", ...


12

Batteries usually. They're charged on the ground and discharged during flight. Sometimes fuel cells are also used, although that's more typical for manned spacecraft such as Apollo and the Shuttle. And in the case of the Shuttle the orbiters also required hydraulic power to actuate their flight surfaces, provided by hydrazine fueled auxiliary power units (...


12

The wake up is triggerred by the onboard timer in Rosetta. It is something like an alarm clock. When the timer triggers the start command, the system wakes up and runs a set of procedures. Here is an illustrative video which explains Rosetta's wake-up process. You can easily learn how the wake-up process works in the probe from this video.


12

NASA Built-in Hardware The dedicated mission computers are tested extensively for vibration resistance, resistance to cosmic and solar radiation (both particulate and EM), magnetic fields, and are also prioritized for low energy consumption and high reliability. Generally, this results in processors a generation or three older than current desktops, and ...


12

Generally speaking, all "air-tight" containers leak to some small degree. On Earth this manifests itself as an inability to maintain a vacuum indefinitely; in space, it manifests itself as an inability to maintain an atmosphere indefinitely without a source of replenishment gases (which themselves are going to leak over time, so you are really only delaying ...


10

Often, electrical systems prone to whisker growth are coated with a 2-3 millimeter layer of polymer (called a conformal coat); this not only prevents growth of whiskers, but also prevents any loose electrical contacts from creating short circuits. There are many benefits that are associated with doing this. Another likely cause of crystalline whisker growth ...


9

The probability is, simply, zero. Lightning is the heavy discharge between two electrically charged bodies that have enough electrostatic potential to ionize that medium. Where lightning occurs: Within the clouds Between two different clouds with different charge Clouds to earth Why cloud to earth not cloud to space? Wikipedia article states: In ...


9

TL;DR: The medical accelerators are not suitable. There are basically two effects of radiation on electronics: Single event upsets (SEUs) RAM Memory cells are usually small capacitors (caps) which are charged or not to represent a 1 or 0. If an ionizing particle crosses the dielectric between the cap plates, it forms a channel of ionized, and so ...


9

It should be possible. ESA has tested the rad-hardness of some cousin processors to that used in the Arduino and they turned out fairly well, at least for a relatively short mission. Some current stuff is actually using ancient 8051-architecture chips. There would be enough processing power to do navigation, maybe even enough to stream out recorded fake ...


9

Kepler has a 16 GigaByte synchronous dynamic random access memory solid-state recorder, so that would be a kind of DRAM. However, note that this is not the processor's main memory. The RAD750 used in Kepler is a 32-Bit processor, and wouldn't be able to address 16 GB of main memory. In practice, memory for RAD750-based systems is more in the range of 128 MB ...


9

Eight solar array wings, eight power channels. My answer to this question shows one power channel: How does electrical safety system work on ISS? You can read about the gory details of each channel in section 3.1.3.2 and subsequent of this document This diagram shows how the eight channels can be interconnected through the four main bus switching units (...


8

Specification Control Drawing/Document or Source Control Drawing page 9: Source Control Drawing (SCD) - Provides an engineering description (including configuration, part number, marking, reliability, environmental, functional / performance characteristics), qualification requirements and acceptance criteria for commercial items or vendor developed ...


8

Others have covered the hardware difficulties, but I would like to mention the software difficulties. Getting enough margin (CPU and memory) is difficult on arduino class processors. Spacecraft I have worked have required anything between 50% and 90% margin that means that you only get to use between 50% and 10% of the processor. The margin is for things ...


8

The answer is given in the thread linked in @KaushikGhose's comment: The space station solar arrays operate at 160 VDC. When the arrays are producing power, the station structure will also tend to float to a voltage close to the array voltage. Under these conditions, the space station could be subjected to problems like arcing from its ...


7

For general purpose electronics, such as the processors, memory, etc, there is actually a fairly broad market for radiation tolerant devices. These are often used for military electronics, people who just want to be cautious, weather balloons, etc. Of course, some of these don't meet the long term radiation requirements that satellites are forced to endure, ...


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