Jump to content

Piscator

Members
  • Posts

    155
  • Joined

  • Last visited

Everything posted by Piscator

  1. Actually, the atmosphere of Venus super-rotates in about four days, so the day length for anything carried along by the winds would not be crazy long. 48 hours of daylight at twice the insolation would be somewhat harsh but probably not the most difficult of the technical problems you would have to solve.
  2. Exited to see them trying out their time machine, too!
  3. According to Wikipedia there seem to have been at least four distinct periods of mountain-building (and subsequent erosion). So while some of the rock formations are indeed over a billion years old, the process that created the actual mountains (as in something that can be seen rising above the surrounding area) happend only some tens of millions of years ago. At least, that's how I understand it from my casual read.
  4. Not in a hurry, indeed. The ISS's solar panels have a power output of about 240 kW in direct sunlight. 50 Starlink Gen 2 ion thrusters (you can of course choose any brand you like, but I thought I go with something you might have 50 spares lying around somewhere) need about 210 kW and have a combined thrust of 6.5N (according to Wikipedia). For a mass of 450 metric tons, this translates to an acceleration of whopping 14.4 µm/s² or 1.25 m/s per day (so no worries about structural integrity, yay!). Since a trip to the moon requires a delta-V budget of about 4000 m/s you'd arrive in somewhat less than 9 years. This obviously ignores the mass of the required fuel and the fact that you would only get about half of the power output while still being in earth's shadow periodically. So better assume a decade, I guess. Speaking of fuel, with a mass-specific impulse of about 25000m/s for the engine of choice, we get a wet to dry mass ratio of ~1.17 for this trip, by the way. This translates to 78 metric tons of - in this case - argon, which doesn't sound that bad actually.
  5. I was doing some quick back of the envelope math, fully expecting to kill the international space zeppelin idea right there, but the basics seem to check out. The ISS has a mass of about 450 metric tons. Helium has a buoyancy of about one kilogram per cubic meter at standard conditions. Therefore, you need about half a million cubic meters of helium to balance the mass of the ISS. This is equivalent to a sphere with a diameter of about 100 meters, which fits the dimensions of the ISS nicely. It's also well within the available helium budget of the world and would just cost about 10-20 million dollars (if I read the pricing information correctly). So absolutely doable. Right? Right ..?
  6. Would the FTS even work while not in flight? I was under the impression that the aero forces do much of the actual destruction when it's triggered. (But then again, they might have installed a 'float termination system' as well ;).) That said, I would assume they have to send out a crew anyway. If not to make a visual inspection of the hardware before scuttling it, then at least to check if the self destruct worked properly and it is indeed sunk.
  7. Seeing how little the flaps were used (and how little of the flaps was used at times), I wonder if you could get away with just using attitude control or some kind of grid flaps.
  8. Not quite sure what you are referring to, but there's a nice shot of what remains of the heat tiles along the edge of the flap at 01:05:52. PS For context: replying to JoeSchmuckatelli
  9. It will be interesting to see how accurate the predictions will turn out to be. Apparently we only have good observational data for the last two events, which is surprisingly little to go on.
  10. Well, no "giant dot in the sky" then if you prefer to be needlessly specific. The point I was trying to make is that, while the event is certainly rare, cool and something to watch out for, it's still something you might very well overlook if you wouldn't know it was there.
  11. It's also not exactly expected to be giant. More like something of the magnitude of Polaris. Which is a lot, considering it's usually about magnitude 10, but not quite enough to put the sunglasses on.
  12. I would love to see missions like these. Your timeline might not work out though. I have no idea when Jupiter would actually be in a suitable position for a gravity assist, but to launch probes in two opposite directions you would presumably also need Jupiter in two roughly opposite spots along its orbit. So it would seem more realistic for your "second" mission to launch in 2036 (assuming your launch date in 2030 for the first mission works out), three years after the "third" mission.
  13. Let's try to avoid steering into ad hominem territory, but so far problems with the Raptor engine seem to either originate from side effects of being struck by debris, likely issues with the fuel supply or not being started up at all due to faulty attitude control. I don't see how testing the engine for minutes instead of seconds would solve these issues, since Raptor seems to be quite reliable once it's running.
  14. Repeating that something is a mistake over and over again doesn't make it a mistake though.
  15. In fact, the main form of propellant you lose is the bombs. Which, as has been pointed out, are used very inefficiently.
  16. I guess they could try it, but they would end up with a bunch of satellites with reduced life-expectancy (very reduced if they don't dispense properly). I'm not sure that's a good deal.
  17. If you're building this many satellites you probably get a few rejects you can use to test the dispensing mechanism. I agree though that it wouldn't be very sensible to release operational satellites on a suborbital trajectory and that trajectories will likely remain suborbital until a deorbit burn is demonstrated.
  18. To expand on point 2 in the start post, using milligrams of antimatter in a photon drive probably won't get you to Mars. Assuming a 10 ton spacecraft, every milligram of emitted photons will only accelerate you by about 3 cm/s. To reach Mars, you would be well into gram territory.
  19. 3. You are a tardigrade. Ideally made from antimatter. 4. You're buying the trip from someone who accepts antimatter as a currency.
  20. A higher atmospheric pressure would not necessarily lead to heavier winds, since wind speeds would likely be lower. Atmospheric circulation is mainly powered by the sun, so if you have to move a larger amount of atmosphere with the same amount of energy, it would move more sluggishly. On Venus, for example, wind speeds constantly decrease with rising atmospheric density.
  21. While it is highly doubtful that any rain of sulphuric acid reaches the surface (since it would boil away long before), the sulphur compounds in the Venusian atmosphere still contribute to its overall corrosiveness in a major way if you can believe this paper. Unfortunately, it doesn't say anything about titanium, but any copper wiring would have turned into a mass of dendritic copper sulphide crystals long ago, it appears. Aluminium seems to be fairly stable but traces of alloyed magnesium oxidize quickly. Steel in general doesn't fare very well either, slowly reacting with the simulated atmosphere to iron and chromium oxides and nickel sulphide, depending on the original composition. PS According to the follow-up study, titanium seems to be quite stable under Venusian surface conditions.
  22. Methane is actually non-toxic, but I would keep an eye on the hydrogen cyanide, carbon monoxide and other trace components of the atmosphere. Also, some of the tholins on the surface are probably not exactly healthy.
  23. How would you arrage a natural number of digits in a grid with a non-natural number of rows and columns? The idea behind the Arecibo message seems to be that you send out a signal with a number of digits that immediatetly shows you how to arrage it into a two-dimensional pattern since there are only two neat ways to do it (73x23 and 23x73). If you received a message with 4463 digits (the last one a little smudged) you wouldn't have an immediate clue how to arrange the content of the message. Even if you made a grid with pi columns work somehow. You would have to try out any number of mathematical and natural constants first. And more importantly, 1420.4 is only a natural constant if you happen to use the second as a unit of time anyway.
  24. I guess they could either keep more engines burning during separation or delay the full restart until the fuel has had time to settle again. Might be easier to just change the flight profile than rearrange the plumbing. Might be not though, in the long run.
×
×
  • Create New...