Comments by "H. de Jong" (@h.dejong2531) on "NASA's Plan to Build A Telescope on the Moon" video.

  1. There is nothing "supposedly" about the Apollo missions. And Exide is still around.
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  2. An area the size of this telescope is hit by one object less than 1 cm3 in size once every 1000 years.
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  3. Indians have proven that the US did land on the Moon in the 1960s. Chandrayaan-2 has photographed the Apollo landing sites.
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  4. Because that will be more complex and expensive, and it loses the advantage of having a telescope that never faces Earth and its radio transmissions.
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  5.  @jayrajdani  The largest antenna we've deployed in space has a diameter of 50-100 m (this is on a classified satellite, so very little is known about this). The LCRT is proposed to have a diameter of 350 meters. JWST has a mirror only 6.5 m in diameter.
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  6. The Apollo project was not 'free money' in any way, shape or form. There's an extensive audit trail that shows where the money went: it was exchanged for actual goods and services. Rockets were designed and built. People walked on the moon.
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  7. Apollo was the biggest engineering program in history. NASA was able to get to the moon so quickly because it was seen as a national priority, with huge funding allocated to it. They could employ 450,000 people to build everything at once. The budget for Artemis is tiny by comparison, and its goals are more ambitious: instead of putting two humans on the lunar surface for 3 days, they want 4-man crews to spend weeks on the surface, plus a manned station in orbit of the moon. Artemis also can't get away with a design that has a 50% chance of failure (as Apollo 11 had).
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  8. They did that 50 years ago.
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  9. the moon is tidally locked. This means that Earth's tides apply a torque to the Moon, and over time this forces the moon's rotation to sync up with its orbit: the same side of the moon always faces Earth. This is called the near side of the moon. The far side is sometimes called the "dark side". This phrase was used because before spaceflight, we'd never seen that side of the moon, so we knew little about it. This term has nothing to do with light levels. The day and night on Earth are determined by Earth's rotation: at any time of Earth's day, half the planet is in sunlight, the other faces away from the sun. Similarly, the light level on the moon is determined by the Moon's rotation. One rotation takes 28 days, so each part of the moon gets sunlight for 14 Earth days, then 14 days of darkness.
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  10. No. A meteorite would punch a small hole in the reflector, making it a tiny bit less effective.
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  11. NASA does not hide anything. Raw photos for every mission are easily found. JWST cannot take photos of the moon because that would expose the primary mirror to sunlight and ruin the telescope by overheating it.
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  12. We weren't ready to do that back then. Automation not advanced enough to build a radio telescope, and anything small enough to fit on a lander in one piece would be too small to be useful.
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  13. That won't work. A satellite "halfway between Earth and Mars" is in orbit around the Sun, and its orbital period is halfway between the 1 year of Earth's orbit and the 686 days of Mars' orbit. I.e. this satellite is almost never actually halfway between Earth and Mars: it's somewhere else in its orbit. You'd need a dozen satellites per orbit to make a difference. There's a much easier way to speed up data transfer between Earth and Mars: place satellites in orbit of each planet, and use an optical link between them instead of the radio links used now. This increases the bandwidth enormously.
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  14. There's no point in building or storing bombs on the moon for use on Earth: you'd have days of warning time before one arrives here, instead of the 10 minutes you get from an ICBM launch. The hydrogen on the moon is a possible resource for fusion, once we figure out how to build a fusion reactor.
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  15. There's about one meteor strike per km2 per 1000 years. Not an issue.
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  16. An area the size of this telescope is hit by one object less than 1 cm3 in size once every 1000 years.
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  17. Those craters were created over 4 billion years. The current impact rate is so low this telescope would be hit once every few thousand years.
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  18.  @RobertCro  You're overlooking that it's dozens per day spread over the Moon's entire surface. I'm talking about the impact rate per km2.
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  19. To answer a common question I see in the comments: What about meteor strikes? While the moon gets hit a lot more than Earth, meteor strikes are still pretty rare. There's about one meteor strike per km2 per 1000 years, and the majority of those are smaller than 1 cm3.
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  20. We've left Earth's atmosphere hundreds of times.
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  21. That's a bunch of nonsense. JWST provides real science, not CGI. A human eye on the moon can't see stars during the daytime if the lunar surface is in view. A telescope with a decent lens hood can photograph the stars during daytime on the moon. This project is a radio telescope, which isn't bothered by sunlight at all. Radio telescopes on Earth work during the day. The computer you wrote that comment on is a side effect of NASA investing enormous sums in chip fabrication in the 1960s.
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  22. All of the evidence shows that humans are the only ones to have set foot on the moon.
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  23. There are no dust storms on the moon, because there's no atmosphere. Meteor strikes are rare enough not to matter.
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  24. NASA has lost or deleted no valuable data. They deleted the stuff that had become worthless when Apollo ended. No more Saturn Vs meant that the Saturn V telemetry records no longer had value, so the tapes that held those were reused. NASA made it to the lunar surface 6 times with manned missions, and a bunch more unmanned missions. Since then, they've launched LRO, which still orbits the moon and which has photographed the Apollo landing sites. Orbiters from other countries have also photographed those sites.
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  25. by not looking at one emission/absorption line, but at several of them that are a known distance apart. When the whole pattern shifts, you know you're looking at redshift.
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  26. Every year, NASA produces tons of scientific papers, advancing the state of the art of physics, astronomy, earth observation and other sciences. Every year, NASA achieves significant milestones, like today's sample return from Bennu. We can in fact prove we've been to the moon. Apart from the data produced by the Apollo missions themselves, we have observations of the Apollo spacecraft on their way to the moon, we have photos of the Apollo landing sites from lunar orbit (made by later orbiters from multiple countries). Anyone can ping the laser reflectors left on the moon by the Apollo missions.
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  27. There is no "bombardment". The area of this telescope gets one hit every few thousand years.
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  28. Look at the sky tonight. You'll see satellites pass overhead, at altitudes far greater than where the "firmament" is claimed to be.
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  29.  @rongee3707  There is no evidence that any solid barrier exists anywhere above us. We can freely fly to any altitude we want: we've sent spacecraft all across the solar system. We can measure the distance to objects in the solar system, and find they're all at different distances, not projected on a dome (which would give them all the same distance). Projection glitches in a planetarium are just that. They are not an accurate representation of the structure of the sky.
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  30. No.
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  31. The plan is to use large solar arrays and batteries.
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  32. No. An area the size of this telescope is hit by one object less than 1 cm3 in size once every 1000 years.
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  33. You'll have to wait a long time for that. There's about one meteor strike (average size of a golf ball) per km2 per 1000 years.
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  34. hello, scammer.
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  35. There's about one meteor strike (average size of a golf ball) per km2 per 1000 years.
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  36. That sentence is missing a word.
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  37. While more meteors reach the ground on the moon than on Earth, the rate is not problematic: less than one per km2 per 10,000 years.
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  38. not really. The area of this telescope gets hit once every few thousand years, mostly by small objects that would just punch a hole in the primary dish. A catastrophic hit during the telescope lifetime is really unlikely.
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  39. It won't be rebuilt.
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  40. NASA remains a civilian agency, entirely separate from US military activity in space.
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  41. According to the accident investigation, the Arecibo structure failed because the cable ends were terminated incorrectly. They were embedded in zinc, and over time the cable strands pulled out of that zinc jacket.
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  42. "But concerning that day and hour no one knows, not even the angels of heaven, nor the Son, but the Father only."
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  43. They won't need to.
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  44.  @zJKjanozyH1  You overestimate how many meteoroids hit the moon. An area of 1 km2 gets hit once every 10,000 years, and most hits are tiny. So a. the impact frequency is low enough not to matter, and b. if a small meteoroid hits the antenna, it just punches a small hole in the antenna surface, reducing the effective surface a tiny bit.
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  45.  @zJKjanozyH1  Again, there is a big difference between 'how many meteoroids hit the moon' and 'how many meteoroids hit 1 km2 of the lunar surface'. The moon gets hit 33000 times per year, divided over a surface area of 37 million km2. That's one hit per km2 per 1000 years.
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  46. The 'money we throw at space' is 1. a tiny fraction of the total amount we spend, and 2. has an excellent return on investment. Fundamental research in general is essential for our progress as a species. Spaceflight has been a key enabler in learning more about our planet.
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