7/24/2023 0 Comments Mars 2020 droneIf you want no risk, you stay on the ground, it's that simple. NASA's Perseverance Mars rover used one of its navigation cameras to take a series of images of drifting clouds just before sunrise on March 18, 20. More generally, reviewing the result of your action and make corresponding corrections to your assumptions is fundamental to literally everything human does, it's the foundation of the scientific method, calling it "Hindsight" and "meaningless" is ignorant non-sense.įinally, nobody is pretending there's no risk, taking calculated risk is what spaceflight is all about. This animation shows the progress of NASA's Perseverance Mars rover and its Ingenuity Mars Helicopter as they make the climb up Jezero Crater's delta toward ancient river deposits. So why don't you tell NASA "Oh don't worry, even if a bigger lander has been demonstrated, it's just hindsight and meaningless"? Cost-plus keeps having cost overruns, that's what prompted NASA to prefer fixed cost contract, again that's not hindsight, that's called learn from your mistakes.Īnd that's just some examples from the policy side, from the technical side the examples are everywhere, like why do you think NASA changed MSR from one lander to two landers? It's because a single lander for 2 rovers would be too big, it would exceed what has been demonstrated to work before. Thus, in addition to sticking with designs like the PPC750 because they’re tried and true, older processors are also quantitatively more resistant to radiation than newer ones.Oh really? So you think post action review/report and lessons learned are meaningless? You do realize this is what NASA does all the time, both in terms of technical reviews and more general policy reviews? And what do you think "heritage" and TRL is, if not getting assurance from flight history?ĬOTS and CRS was successful, that's what prompted NASA to go all in on the commercial procurement, that's not hindsight and not meaningless at all, that's called learn from your successes. Any changes to a MOSFET which decrease the amount of charge needed to change the state – such as shrinking it, or designing it for a lower voltage – mean that it will be more sensitive to ionizing radiation. If this happens near a MOSFET gate, the charge can change the state of the MOSFET, leading to effects like SEUs, or worse, latchups. Radiation primarily affects electronics by ionizing an atom, and thus depositing some charge. Unfortunately, all of these things negatively affect radiation tolerance, one of the key requirements for space electronics. Similarly, CPU core voltages are decreasing: 5 V and 3.3 V used to be common, then went to 2.5 V, and are now down to 1.6 V or so. “14 nm process”) allows you to fit more transistors on the same area of silicon, decreases the gate capacitance, and decreases speed-of-light delay (although that’s a much less significant factor). Second, you can design the transistor to operate at lower voltages, so that fewer coulombs have to be shoved into the gate to turn it on.Īltogether, this means that as time goes by, processors get smaller and lower-voltage. Jezero Crater, Mars /mars2020 Joined February 2020. First, you can make the transistor physically smaller, directly decreasing the gate capacitance. NASA Mars rover, exploring since February 2021. One of the fundamental limits to how fast MOSFETs can switch on and off is gate capacitance: the higher the gate capacitance, the longer it takes the gate to “charge up” and switch on. However, there are also solid technical reasons.ĭigital processors fundamentally work by turning transistors on and off. When your device costs a billion or two USD, you can’t afford to have a previously unknown error mode or radiation upset ruin the mission.Įngineering conservatism and flight heritage are definitely part of the reason that spacecraft processors tend to be antiques, compared to mainstream commercial hardware. 1, 2019 inside the Space Simulator, a 25-foot-wide (7.62-meter-wide) vacuum chamber at NASA's Jet Propulsion Laboratory in Pasadena. Members of the NASA Mars Helicopter team attach a thermal film to the exterior of the flight model of the Mars Helicopter. You’ll find most processors used in spacecraft are a few generations behind cutting edge consumer tech. NASA's Mars Helicopter Completes Flight Tests. The RAD750 is radiation hardened and flight proven.
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