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Everything posted by Steel

  1. For those who might be interested, ESA have just launched the second year of the "Space Explorations Masters" Challenge [1]. This is essentially an idea generator competition whereby you can submit you ideas to solve key problems in the space industry for a chance to have funding and collaboration opportunities with big industrial players in the sector. Seems like an interesting opportunity for any of you who might have some creative ideas lurking in the back of your mind. [1]
  2. Electron degeracy pressure is a quantum effect as a result of the Pauli exclusion principal, rather than a fundamental force.
  3. Mass accretion which pushes the mass of a white dwarf over the Chandrasekhar limit. At this point the electron degeneracy pressure can no longer balance against gravity and it collapses.
  4. Depends on the type of supernova. The mechanisms that trigger then aren't that well understood, but they generally form from white dwarves or massive stars.
  5. Radiation pressure [1] in normal stars, or electron degeracy pressure [2] in white dwarves. [1] [2]
  6. "Approximately 26 inches tall and roughly estimated to be around 1700 pieces. Designed to match the scale and asthetic quality of the Saturn V."
  7. Yes, that constant is actually dependent on the mass of the central body
  8. I think we all already knew, but I guess Mr/Mrs J. Average member of the public has heard no official announcement on the subject from SpaceX since they announced they were going to do it.
  9. Well no, they'll just need to validate the heatshield again. I would imagine that the reentry data they collected on that flight will also have helped them make this change. This is a late program change no doubt, but ETF-1 will still have produced a wealth of data on all other aspects of the spaecraft
  10. I don't know if anyone has mentioned this yet, but I think everyone should read the excellent waitbutwhy article on AI from a couple of years back. It's a 2-parter and quite lengthy, but more than worth the time to read. Really thought provoking, certainly gave me (an AI advocate) reason to pause and think about some of the implications and dangers that many people seem to dismiss quite quickly.
  11. Yes, but these improve survivability of a crash, they have absolutely no effect on how likely a crash is to happen to the vehicle That (I think) is the distinction @YNM was trying to draw. Manufacturers focus of safety features because that sell cars and improve drivability, however the chance that an accident happens to any given car is much more dependent on external factors. Therefore, it's a little silly to say that Teslas are safe based on their crashes per millions km, because that's mainly due to factors other than the car.
  12. You're quite right... Clearly my particle physics is a little rusty
  13. We actually understand the properties of antimatter quite well - it's surprisingly easy to find, it just doesn't stick around very long, but if you know where to look you can study it's properties. It obeys the laws of gravity the same as regular matter
  14. To quote Wikipedia (don't worry, I did check its source on this) "Antimatter may exist in relatively large amounts in far-away galaxies due to cosmic inflation in the primordial time of the universe. Antimatter galaxies, if they exist, are expected to have the same chemistry and absorption and emission spectra as normal-matter galaxies, and their astronomical objectswould be observationally identical, making them difficult to distinguish" This result just seems to add strength to that line of reasoning.
  15. "has been shown to work" is a strong statement. From what I've read, METs are in the same sort of shape as EM drives. Some people report seeing small thrusts, others report measuring no measurable thrust at all, several tests conclude that external factors and interference is likely to be skewing the results.
  16. Not quite. The problem here is that neither party can actually control what state they measure. Let's say we have two entangled particles with Z spin equal to 0 - so if one has up spin the other has down spin. Alice has particle A and Bob has particle B. However, because these are quantum particles, each one has a non-zero probability when measured to have either up spin or down spin. So Alice measures the spin and gets up, so she knows that Bob will measure spin down if he measures it now. However when Bob goes to measure, there's no way for him to know whether he is measuring the opposite spin to the one Alice has already measured, or whether he has measured too early and now Alice is just measuring the opposite of what he has measured. The only way to know for sure is to have another communication channel between the two.
  17. Let's break this down a bit. First, quantum particles do not have multiple positions. When measured they have one position (with some uncertainty). As @p1t1o mentioned above, you might be thinking about entangled particles, where two particles are "linked". The properties of entangled particles do correlate superluminally (i.e when one changes, the other appears to change instantaneously). However, as also mentioned above, you cannot transfer information this way.
  18. Because the US government says rockets are a defense/military technology, therefore they don't allow foreign people to work on them. Unfortunately that's just the way it is. EDIT: I know it's slightly more complicated than that, but it is frustrating for us non-US nationals
  19. In answer to your question in the title: is it hard to become an astronaut? Yes. It's probably the single hardest job to get into, simply because there are so few astronauts. You also have to be in very good condition both physically and mentally. Usually you need to bring some other skills with you too - most astronauts are engineers, scientists, doctors e.t.c as well as being astronauts. Also, not being from either the USA, China or Russia there is less chance of being selected for flights. Most astronauts are from these three nations because they are the only ones with active crewed space programs. I'm from the UK, and despite having been involved in spaceflight since the 1960's, we have no crewed space programs, so there have only ever been 11 British astronauts. But at the end of the day, this doesn't mean it can't be done. If you are truly passionate about things in life, why not chase after them? Find out what requirements there are, and work towards achieving them. Even if you don't end up becoming an astronaut, you'll still learn and experience a whole lot of new stuff that you never would have done otherwise. In terms of jobs in the wider space industry, it's a lot easier. The aerospace industry employs over 500,000 people across Europe in a variety of jobs from engineering to accounting.
  20. I have a feeling that whoever did those calcs has a very poor grasp of the physics, seeing as they keep confusing acceleration and velocity. Anyway, they've missed the fact that the equation they've used gives the velocity squared, not the velocity. So the the actual velocity is root(6159) which is about 78 m/s
  21. Unfortunately, once you get beyond simple Hohmann transfers - which can be solved pretty simply and analytically - usually the only way to accurately come up with an answer is to solve the equations numerically.
  22. Which way are they all pointed? If they all point along the tangent of the ring the ring would spin (no net thrust, only a net rotation) and the ring would then break apart from the strain, unless it is a magical unbreakable ring
  23. Being stood on top of a space tower at geostationary height would feel exactly the same as being on your own in geostationary orbit at the same place
  24. From a practical point of view, maybe. From the point of view of not needlessly killing anything that strays into the path of the beam, definitely not.