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About DerekL1963

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    Rocket Scientist

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  1. SpaceX SFR: The Small Falcon Rocket

    "Accurate within 10%" is equivalent to not being accurate at all. You might as well pick numbers out of a hat at that point rather than pretending that your math has any validity. And it's not just about tank mass, it's also about engine mass, and structural mass (the thrust web and interstages) - the last in particular doesn't scale in any easily predictable way.
  2. SpaceX SFR: The Small Falcon Rocket

    SpaceX jumped from Falcon 1 to Falcon 9 because there was no market for the Falcon 1 - GEO is where the money is. The Falcon 5 was cancelled for the same reason, insufficient payload to GEO.
  3. Camera system for Mariner 4

    Correct. Mariner 4 had neither the onboard processing power nor the bandwidth to send images in real-time. In fact, the whole system was so slow that it only took 22(!) images during the entire flyby.
  4. Camera system for Mariner 4

    It was a television camera. The analog signal was converted to digital and transmitted to Earth via radio.
  5. Mars Colonization Discussion Thread

    The lander and rover teams who had to build insulation and heating into their vehicles to prevent them from freezing would be surprised to learn that.
  6. Should We Launch a Kid to Space?

    Both of these are eternal truths. By my version was close enough for the purpose of correcting the people working backwards from a conclusion rather than forwards from the data.
  7. Should We Launch a Kid to Space?

    0.o I wouldn't claim a ship that flooded and sunk subsequent to a huge internal explosion as being sunk due to flooding either. In fact, it's actually quite common to describe accidents in terms of their cause (skidded on ice) rather than effect (hit a light pole). Well, common except when people are twisting definitions in order to reach a preordained conclusion. But the problem with that pre-ordained conclusion is that it doesn't jive with the numbers. If heat was the cause, the Columbia would have been destroyed on her first flight. If heat was the cause, then Shuttle wouldn't (all by itself) represent such a high percentage of successful landings. In this case, the cause of the accident wasn't due to higher peak heating - it was damage to the heat shield. A capsule with a damaged or flawed heat shielding would suffer the same fate.
  8. Should We Launch a Kid to Space?

    Given that safe space plane reentries account for 40% of all manned flights to date... the claim that spaceplane re-entries pose some especial danger due to heating seems unsupportable. (Especially given that the one unsuccessful re-entry wasn't due to heat.)
  9. Mars Colonization Discussion Thread

    The why did you even reply in the first place? If you don't want to talk about something, don't quote it, don't add a non-sequitur. Just scroll on by. Um, no, you weren't. "If life is better" relates to people's desire to move - not to the logistics thereof.
  10. Mars Colonization Discussion Thread

    It's not an argument it's a non sequitur that fails to address either part of my statement. It has nothing to do with the costs of sustaining the colony. It has nothing to do with logistical challenges of moving millions people.
  11. Mars Colonization Discussion Thread

    Even though space travel is cheap, that doesn't mean sustaining the colony is cheap. And while millions of people moving are (theoretically) possible... It's so wildly improbable as to be laughable.
  12. NASA SLS/Orion/DSG/DST

    Which is about the 227th time in my lifetime that Congress, or the Administration, or a Blue Ribbon panel constituted by one of those two has demanded that NASA present a Brave New Plan for human exploration. Precisely none of them have amounted to much. So, I wouldn't get too excited.
  13. Mars Colonization Discussion Thread

    Certainly it's a fun thought experiment - but only if, like any experiment, it sticks to reality. Otherwise, it's just an exercise in writing collective fiction.
  14. Mars Colonization Discussion Thread

    Quoted for truth. A colony is place of lifelong residency with a certain degree of economic self-sufficiency (and often a certain degree of legal and political self sufficiency as well) and generally an economic role as part of a larger polity. What people are describing in this thread are mostly outposts or stations. Places of temporary residency where people are generally hired by the operators or assigned to a tour of duty by outside authorities. That is, like a military base, or one of the facilities many nations maintain in Antarctica, or one of the resource extraction facilities in Canada's far northern regions. One key indicator of the difference (for example) is that the citizens of a colony cannot be forced to remove themselves from the colony without the force of Law and a formal legal process. The transient contractors of an outpost or station can be given their pink slip and be on the next ship out of Chryse with little to no legal recourse. (Sure, sure, there are going to be dictatorial colonies. But a dictator is the force of Law by definition.) Which is not to say that an outpost or station can't become a colony as people settle nearby and live independently of (even if economically dependent on) the outpost or station and it's transient residents. This happened in many places in the New World over the centuries. Heck, it's even happened as late as the late 19th century - the town I live in would be a miniscule fraction of it's current size if the Congress hadn't selected the area for a Navy Yard. (If it even existed at all.) But it almost certainly won't happen on Mars - because you can't just clear a few acres, plow a field, and then sell carrots or cattle or whatever to the outpost. You can't plop down a simple shack, import a little yarn or catch local furbeasts, and start selling blankets and hats to the transient residents of the outpost. And all this presumes that Mars doesn't end up like Antarctica, where private residence is forbidden and you'll simply be placed on the next ship outbound (in cuffs if need be) if you try. But, to be honest, people are to be forgiven not understanding this. When it comes to space and space travel, science fiction and the popular media have been misusing the term colony for over half a century.
  15. Lunar atmosphere?

    He specified that said calculation was a naive assumption, which to me means that it's not meant to be taken (as you seem to be doing) as a model of reality. He's said so many times - you even quoted and replied to a message where points out the difficulties of creating said model. You're arguing with something nobody claimed as fact. He keeps telling you that you're correct (it's a complex situation), and you keep telling him he's wrong.