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Thread: Questions from Mensa

  1. #1
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    I'm told this month's Mensa publication contains these hoax-related questions allegedly asked by Mensans.

    From one person:

    1. The tremendous height of the Saturn V launch vehicle was attributed to the amount of fuel needed to escape Earth's gravity. Given the fact that the moon's gravity is 1/6th that of the Earth, you'd need something 1/6th the height of the Saturn V to blast off from the moon. So how did the Eagle lift off?

    2. Once achieving escape velocity when leaving the Earth, the Apollo would need to lose 5/6th of its velocity in order to be captured by the moon's gravity and swing into orbit. The spacecraft is moving at a velocity that prevents the Earth's gravity from pulling it back down - so unless they "put on the brakes" they certainly aren't going to be captured by the moon's gravity. However, all three stages of the Saturn V had been dropped - only the LEM remained.

    3. How do humans survive at the top of a rocket? The space shuttle is fairly well isolated from the heat of its boosters, but no so with Saturn and its command module. At launch they had to spray lots of water on the launch pad to keep the concrete from cracking. Metal is a great conductor of heat. What kept the astronauts cool? Did they have a zillion air conditioners in the command module?

    And from a different person:

    4. Since studies estimate that the walls of the Apollo craft would have to be between six to eight inches thick with lead, how did we manage to send our astronauts through the Van Allen radiation belts without them receiving lethal doses of radiation? The Apollo craft walls were merely millimeters thick.

  2. #2
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    Isn't Mensa supposed to be an organization for smart people?

  3. #3
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    I.Q. is like the numbers on a measuring cup. The numbers show only the capacity. Also, quality is at least as important as quantity. A bucket full of mud is still full of mud.

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    I'm sure I'm preaching to the choir here, but I have got to respond to some of this nonsense.

    On 2001-11-15 10:07, JayUtah wrote:
    I'm told this month's Mensa publication contains these hoax-related questions allegedly asked by Mensans.

    From one person:

    1. The tremendous height of the Saturn V launch vehicle was attributed to the amount of fuel needed to escape Earth's gravity. Given the fact that the moon's gravity is 1/6th that of the Earth, you'd need something 1/6th the height of the Saturn V to blast off from the moon. So how did the Eagle lift off?
    This is a total non sequitur. The Saturn V is so big because it needs to send a huge amount of payload (its third stage and the command and lunar modules) to the moon. Even a rocket as small as a Delta is capable of giving its payload escape velocity.

    The lunar module, on the other hand, only needs to deal with its upper stage and only needs to get that into lunar orbit, not out of lunar orbit.

  5. #5
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    On 2001-11-15 10:07, JayUtah wrote:

    2. Once achieving escape velocity when leaving the Earth, the Apollo would need to lose 5/6th of its velocity in order to be captured by the moon's gravity and swing into orbit. The spacecraft is moving at a velocity that prevents the Earth's gravity from pulling it back down - so unless they "put on the brakes" they certainly aren't going to be captured by the moon's gravity. However, all three stages of the Saturn V had been dropped - only the LEM remained.
    First off, it's not true that only the LM (the correct acronym) remained: the command and service modules were along, too. Second, the spacecraft was significantly slowed down by earth's gravity since the force that sent it outward was only slightly more than the minimum needed to get it to the moon. Thus, the service module engine was quite capable of "putting on the brakes."

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    On 2001-11-15 10:07, JayUtah wrote:

    3. How do humans survive at the top of a rocket? The space shuttle is fairly well isolated from the heat of its boosters, but no so with Saturn and its command module. At launch they had to spray lots of water on the launch pad to keep the concrete from cracking. Metal is a great conductor of heat. What kept the astronauts cool? Did they have a zillion air conditioners in the command module?
    By the same reasoning, a guy operating a blowtorch or a flamethrower has serious problems. Simply, the heat is being thrown out away from the spacecraft, not towards it.

    I won't even bother to mention the millions of pounds of cryogenic liquids between the first stage engines and the spacecraft - I think the greater issue would be how to keep the astronauts warm under the circumstances, not cold.

  7. #7
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    My membership in Mensa lasted less than one year, precisely because of the climate at the meetings. After a while it became apparent to me that these were people so stuck on their self-perception of intelligence in some areas that they were blinded to their ignorance in others. They'd go around confidently expounding utter nonsense just because they didn't want to admit ignorance of a pertinent fact.

    What's the line from The Englishman Who Went Up A Hill And Came Down A Mountain? "We may be twp (i.e., stupid), but we're not so twp that we don't know we're twp."

    Some of these people are precisely the type who can talk for three hours about hyperspatial manifolds and Grand Unification, and then go out and put oil in their car radiators.

  8. #8
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    Wasn't it an episode of Frasier where he took a date to a plane'arium*, but there was a group from Mensa there who kept asking the presenter questions to which the answer was "Uranus," ("Are any other planets similar in size and composition to Neptune?" "Yes, Neptune is similar in size and composition to Uranus.") and giggling like little kids?

    *That's a planetarium, for those of you who don't watch South Park. Ever since seeing that particular episode, I simply cannot pronounce the "t" in that word!


  9. #9
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    On 2001-11-15 12:30, SeanF wrote:
    Wasn't it an episode of Frasier where he took a date to a plane'arium*, but there was a group from Mensa there who kept asking the presenter questions to which the answer was "Uranus," ("Are any other planets similar in size and composition to Neptune?" "Yes, Neptune is similar in size and composition to Uranus.") and giggling like little kids?
    My wife was a Mensa member for a little while and took me to meetings, and that's about the sense of humor I remember encountering, except their favorite phrase was "joint meeting," which they accompanied with puffing on an imaginary, um, cigarette.

  10. #10
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    Okay, I'll just take this apart piece by piece and sell it on as the scrap it is.
    (here's guessing this board supports UBB code)
    1. The tremendous height of the Saturn V launch vehicle was attributed to the amount of fuel needed to escape Earth's gravity. Given the fact that the moon's gravity is 1/6th that of the Earth, you'd need something 1/6th the height of the Saturn V to blast off from the moon. So how did the Eagle lift off?
    Bear in mind that one extra pound of weight means 40lb of fuel. More fuel is more weight.
    Earth is bigger than the moon. Eagle had to reach Lunar Orbit. SaturnV had to reach Earth orbit (and cope with atmospheric drag) and also then ESCAPE from Earth orbit. Eagle did not.
    2. Once achieving escape velocity when leaving the Earth, the Apollo would need to lose 5/6th of its velocity in order to be captured by the moon's gravity and swing into orbit. The spacecraft is moving at a velocity that prevents the Earth's gravity from pulling it back down - so unless they "put on the brakes" they certainly aren't going to be captured by the moon's gravity. However, all three stages of the Saturn V had been dropped - only the LEM remained.
    LEM + Command Module + Service Module.
    Recap basic Newtonian physics. You're making these up and claiming false authority.
    3. How do humans survive at the top of a rocket? The space shuttle is fairly well isolated from the heat of its boosters, but no so with Saturn and its command module. At launch they had to spray lots of water on the launch pad to keep the concrete from cracking. Metal is a great conductor of heat. What kept the astronauts cool? Did they have a zillion air conditioners in the command module?
    What metal? The half a foot of metal that wasn't even solid? And pray explain how the ceramic engine nozzles were going to conduct heat to the metal?

    And from a different person:
    4. Since studies estimate that the walls of the Apollo craft would have to be between six to eight inches thick with lead, how did we manage to send our astronauts through the Van Allen radiation belts without them receiving lethal doses of radiation? The Apollo craft walls were merely millimeters thick.
    No studies indicated that. That's a lie. Like I said, this is all made up. The Van Allen belts are thickest at the poles. Apollo escaped pretty close to the equator for this reason. At the poles, they are also more energetic. At the equator, they're mainly beta particles and alpha particles. An inch of aluminium will stop all beta particles. A sheet of paper does the same to alpha particles. Apollo had not millimeters (how can a few mm of metal support it's own weight?) but inches. Like I say, this is all made up.


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    On 2001-11-15 14:40, Hat Monster wrote:
    Bear in mind that one extra pound of weight means 40lb of fuel. More fuel is more weight.
    Earth is bigger than the moon. Eagle had to reach Lunar Orbit. SaturnV had to reach Earth orbit (and cope with atmospheric drag) and also then ESCAPE from Earth orbit. Eagle did not.
    I think the air resistance must be huge. A cyclist going 20 mph expends 90% of his or her energy overcoming are resistance. Of course cyclists don't have to overcome gravity (I refuse to cycle uphill) but I'd still wager that air resistance will be significant.

  12. #12
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    My wife was a Mensa member for a little while and took me to meetings, and that's about the sense of humor I remember encountering, except their favorite phrase was "joint meeting," which they accompanied with puffing on an imaginary, um, cigarette.
    A cigarette with certain select herbs inside, for flavour of course.

    Oh my, I didn't know Mensa was so low-brow. This is even worse than those South Park Mensa-Uranus jokes.

    I guess it's as someone said it's quantity not quality, to them a tanker of sewers liquid and that slime that drips below dumps is better than a glass of water. Their choice, I know which one I'd choose though.

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    This list of question confirms my rather low opinion of Mensa. My one brush with them came when I lived in Chicago. The guy in the apartment across from mine was a member. When he found my IQ to be above their threshold he invited me to a meeting. My observation was, most of them would have had to get smarter to be blathering morons. About half were 10 pound of ego in a 5 pound bag and spent the evening trying to intelectually humilliate everyone else.

    But other than that, I had a great time! I Didn't join.

  14. #14
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    As I've mentioned elsewhere on this forum, Ralph Rene was a Mensan, before they kicked him out. Rene is one of the moon hoax "experts", having written a book where he smugly points out all the allegedly fatal flaws in the Apollo program. Mensa disowned him after he wrote a book in which he claimed, despite any relevant education on his part, that both Einstein and Newton were charlatan physicists.

    Question 4 applies to Rene's major thesis, which is that the radiation in the Van Allen belts and beyond would have cooked the astronauts instantly.

    Who was it who said, "I would never belong to an organization that would have me as a member"?

    My favorite quote relating to Mensa comes from Will Rogers: "We're all ignorant. We're just ignorant about different things."

  15. #15
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    On 2001-11-15 17:26, JayUtah wrote:

    Who was it who said, "I would never belong to an organization that would have me as a member"?
    Groucho Marx. But it was probably originated by one of his writers.

    In the interest of completeness, the entire line (as given by a couple of Groucho Web Sites) was, "I sent the club a wire stating, 'Please accept my resignation.' I don't want to belong to any club that will accept me as a member."



    <font size=-1>[ This Message was edited by: The Bad Astronomer on 2001-11-15 21:43 ]</font>

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    David-- I edited the post a bit; it got bollixed up. I hope that's okay.

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    Mensa continues to prove Bailey's Second Law; There is no relationship between the three virtues of intelligence, education, and wisdom.

    I have taken Mensa's tests and passed with flying colours, but see no reason to join. I've met Mensa members who couldn't change a fuse if their life depended on it.

    Oh, by the way, my first law is;

    Necessity may be the mother of invention, but laziness is usually the father.

    Dave Bailey, aka The Rat

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    The Van Allen belts are thickest at the poles. Apollo escaped pretty close to the equator for this reason. At the poles, they are also more energetic. At the equator, they're mainly beta particles and alpha particles.
    Thickest at the poles? Are you sure? I don't know a whole lot about it, but all of the pictures I've seen of the Van Allen belts are, well, belts. As in, around the equator. And since they're held there and energized by the Earth's magnetic field, I would think that at the poles any energetic particles would spiral down and cause aurorae, though I'm not an expert on that either.

    I think the air resistance must be huge. A cyclist going 20 mph expends 90% of his or her energy overcoming are resistance. Of course cyclists don't have to overcome gravity (I refuse to cycle uphill) but I'd still wager that air resistance will be significant.
    I think a conical rocket made out of smooth metal is a bit more aerodynamic than a cyclist. And it would also get above most of the atmosphere pretty quickly, as in before the first stage seperated. So air resistance is still a factor, but it hardly uses up 90% of the energy.

  19. #19
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    On 2001-11-15 22:19, The Rat wrote:

    Oh, by the way, my first law is;

    Necessity may be the mother of invention, but laziness is usually the father.

    -The Rat
    That's good, Rat. [img]/phpBB/images/smiles/icon_smile.gif[/img] Mind if I take it? [img]/phpBB/images/smiles/icon_confused.gif[/img]

  20. #20
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    On 2001-11-16 06:30, James wrote:
    On 2001-11-15 22:19, The Rat wrote:

    Oh, by the way, my first law is;

    Necessity may be the mother of invention, but laziness is usually the father.

    -The Rat
    That's good, Rat. [img]/phpBB/images/smiles/icon_smile.gif[/img] Mind if I take it? [img]/phpBB/images/smiles/icon_confused.gif[/img]
    Go ahead. Just call it 'Bailey's first law'

  21. #21
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    On 2001-11-15 15:10, Wiley wrote:

    I think the air resistance must be huge. A cyclist going 20 mph expends 90% of his or her energy overcoming are resistance. Of course cyclists don't have to overcome gravity (I refuse to cycle uphill) but I'd still wager that air resistance will be significant.
    Actually, in the space systems class I'm taking now, the section on calculating velocity after launch doesn't even consider the effects of aerodynamic drag. All it says is that for most launches the attempt is to get above most of the atmosphere before doing most of the acceleration.

  22. #22
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    On 2001-11-16 09:57, ToSeek wrote:
    On 2001-11-15 15:10, Wiley wrote:

    I think the air resistance must be huge. A cyclist going 20 mph expends 90% of his or her energy overcoming are resistance. Of course cyclists don't have to overcome gravity (I refuse to cycle uphill) but I'd still wager that air resistance will be significant.
    Actually, in the space systems class I'm taking now, the section on calculating velocity after launch doesn't even consider the effects of aerodynamic drag. All it says is that for most launches the attempt is to get above most of the atmosphere before doing most of the acceleration.
    While in the atmosphere, what is the speed? If I recall correctly, aerodynamic drag is proportional to velocity cubed.

    Also what level (sophmore, junior, grad) is the class? Air resistance is very hard to quantify, so in lower level classes, it's ignored.

    Thanks,

  23. #23
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    1. The tremendous height of the Saturn V launch vehicle was attributed to the amount of fuel needed to escape Earth's gravity. Given the fact that the moon's gravity is 1/6th that of the Earth, you'd need something 1/6th the height of the Saturn V to blast off from the moon. So how did the Eagle lift off?
    I'm willing to bet everything I own that the LMs are quite a bit less massive than 1/6th their fully fuel-loaded Saturn rockets, thus it takes less force to propel them into orbit, and thus less fuel. If the lander was 100 times less massive it would only take 1/100th as much fuel, and be approximately 1/100th in size just to leave Earth. (That is, were its engines powerful enough to do so.) One would think that it would require even less to liftoff from the Moon.


    2. Once achieving escape velocity when leaving the Earth, the Apollo would need to lose 5/6th of its velocity in order to be captured by the moon's gravity and swing into orbit. The spacecraft is moving at a velocity that prevents the Earth's gravity from pulling it back down - so unless they "put on the brakes" they certainly aren't going to be captured by the moon's gravity. However, all three stages of the Saturn V had been dropped - only the LEM remained.
    When you throw a baseball up, does it keep going? No, it SLOWS and falls back down. As the LM gets farther from Earth it slows down becuase gravity is trying to pull it back. A baseball has no brakes to make it fall back down and neither did the LM/Command/Service Module. It may have been going too fast to fall all the way back down anytime soon, but certainly enough to be slowed over such a great distance as that between the Earth and Moon. NASA simply calculkated what the correct deorbiting speed would need ot be to avoid shooting past the moon, not so difficult to put Sir Issac Newton in the drivers seat. (If you think about it this means the spacecrafts were at thier lowest velocity at the Lagrange point, and then sped up as the moons gravity pulled them more strongly than the Earth's. Thus the speed was not constant throughout the journey, and Mensa incorrectly assumes it is. Shame on them.)

  24. #24
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    On 2001-11-15 18:19, David Simmons wrote:
    On 2001-11-15 17:26, JayUtah wrote:

    Who was it who said, "I would never belong to an organization that would have me as a member"?
    Groucho Marx. But it was probably originated by one of his writers.

    In the interest of completeness, the entire line (as given by a couple of Groucho Web Sites) was, "I sent the club a wire stating, 'Please accept my resignation.' I don't want to belong to any club that will accept me as a member."
    <font size=-1>[ This Message was edited by: The Bad Astronomer on 2001-11-15 21:43 ]</font>
    I was a member for a while too. Still am I guess. (Haven't gone to the meetings recently.) Not all "Mensans" are naive, but some will do until a naive person comes along.
    BTW - the reason the Astronauts did not get overheated in the Apollo Command Module was because it wasn't hot in there, being positioned above the rocket engine rather than beneath it.

    Thanks for quoting my favorite quote!
    Chip [img]/phpBB/images/smiles/icon_smile.gif[/img]



  25. #25
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    On 2001-11-16 11:58, Wiley wrote:

    Also what level (sophmore, junior, grad) is the class? Air resistance is very hard to quantify, so in lower level classes, it's ignored.

    Thanks,
    It's theoretically a graduate-level class, though with the Johns Hopkins engineering night school, the levels are sometimes kind of bogus. Also, it's just an overview course, so we don't go into a whole lot of depth. (In this semester alone, we're discussing system engineering, astrodynamics, propulsion, space environment, launch systems, attitude determination and control, and space power systems.)

  26. #26
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    > 2. Once achieving escape velocity when leaving the Earth, the Apollo would need to lose 5/6th of its velocity in order to be captured by the moon's gravity and swing into orbit. The spacecraft is moving at a velocity that prevents the Earth's gravity from pulling it back down - so unless they "put on the brakes" they certainly aren't going to be captured by the moon's gravity. However, all three stages of the Saturn V had been dropped - only the LEM remained.


    J-Man says:
    Actually, I believe, the CSM/LM were put into a free-return trajectory during the translunar burn. That means if they never fired the SM rocket they would return to earth. (Basically a figure 8 around the moon and earth. Good thing for 13.) They never actually reached earth escape velocity. They had to slow down (speed up? depends what direction you're talking about...) only to establish a near-circular lunar orbit. The earth was slowing them down before they even took off... and continued "pulling" them back the whole time.

    That was my nitpick for the day... you guys are doing alright with the rest of it...

  27. #27
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    On 2001-11-16 14:02, ToSeek wrote:
    On 2001-11-16 11:58, Wiley wrote:

    Also what level (sophmore, junior, grad) is the class? Air resistance is very hard to quantify, so in lower level classes, it's ignored.

    Thanks,
    It's theoretically a graduate-level class, though with the Johns Hopkins engineering night school, the levels are sometimes kind of bogus. Also, it's just an overview course, so we don't go into a whole lot of depth. (In this semester alone, we're discussing system engineering, astrodynamics, propulsion, space environment, launch systems, attitude determination and control, and space power systems.)
    If aerodynamic drag is important, I would've thought they would mention it in grad survey class. Mayhap it's not too important.

  28. #28
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    On 2001-11-16 17:27, J-Man wrote:

    Actually, I believe, the CSM/LM were put into a free-return trajectory during the translunar burn. That means if they never fired the SM rocket they would return to earth. (Basically a figure 8 around the moon and earth. Good thing for 13.)
    Ironically, Apollo 13 was the first moon shot in which the spacecraft was not on a free-return trajectory. This was true at the time of the accident, and once they had things somewhat stabilized, they used the descent stage engine to put the ship back on a free-return track.

    The reason they were not on free return had to do with their targeted landing site. If they'd been on free return they couldn't have achieved the correct lunar orbit to put them on line for the Fra Mauro site.

  29. #29
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    Aerodynamic forces should be close to negligible. As the rocket gets higher, it gets faster since it's always under acceleration. As the rocket gets higher, air gets thinner.
    So when the craft is in the thick tropospheric air, it's velocity is quite low. It's only ten miles to travel up and a rocket does that in less than a minute. It's once they get in the stratosphere and beyond that the real speeds start to be reached. Up there, there's precious little air to do any resisting.

    The main reason for the vast size of the rocket is that as you add more weight to be lifted, you need more fuel. More fuel means bigger fuel tanks. Bigger fuel tanks mean more weight. More weight means more fuel. More fuel means bigger fuel tanks. Bigger fuel tanks mean more weight. More weight means more fuel. More fuel means bigger fuel tanks. Bigger fuel tanks mean more weight. More weight means more fuel, ad nauseatum.

    Eventually, it levels off so that once you have a craft capable of reaching LEO then the payload needs 40x it's own weight in fuel and other weight extra on to the launch weight. That's on top of the fuel and engine power needed to get the craft itself into orbit, neglecting the payload.

    SaturnV was capable of launching the Apollo Service Module, Command Module and LEM completely clear of Earth. That means that the rocket could lift the combined weight of those three modules, no mean feat, and drop them off anywhere in the solar system. We used it to take us to the moon. The SaturnV would have done for Mars, but technology of the day couldn't have kept the astronauts alive that long.

    The LEM on the other hand, didn't even have to escape the moon. It just had to reach a low lunar orbit, which isn't a difficult thing to do in the 1/6th gravity and the designed low mass of the LEM. Many cheap enthusiast rockets could get themselves into lunar orbit from the lunar surface quite easily.

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    [quote]
    On 2001-11-15 14:40, Hat Monster wrote:
    Bear in mind that one extra pound of weight means 40lb of fuel. More fuel is more weight.
    Earth is bigger than the moon. Eagle had to reach Lunar Orbit. SaturnV had to reach Earth orbit (and cope with atmospheric drag) and also then ESCAPE from Earth orbit. Eagle did not.
    [quote]

    Is it really accurate to say that the Apollo spacecrafts "escaped" from Earth's orbit? Isn't it true that they were simply placed into a highly eliptical Earth orbit that in fact brought it within the affects of Moon's gravity, at which time it slowed down enough to be captured in a lunar orbit? Point is, it never really "escapes" Earth's orbit, right? The fact that they remain in Earth orbit (albeit, a highly eliptical one)explains why they experience weightlessness during the whole journey. Am I correct here?

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