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Off Topic => Other Conspiracy Theories => Topic started by: Rob260259 on August 05, 2013, 03:43:47 PM

Title: Curiosity fake...?
Post by: Rob260259 on August 05, 2013, 03:43:47 PM
From a moon hoax conspiracy theorist:

"A parachute will NOT work in a vacuum or a very thin ,light atmosphere.The lander ,according to my calculations, would have hit the martian surface at over 30,000 miles per hour,instantly desintegrating. For there to be enough accumulated drag from any latent´╗┐ noble gases around the martian surface -even a thinner atmosphere - I estimate the chute would have had to have been a minimum of 15-18 miles in diameter, to have had any significant effect on the descent rate in these conditions.The air density of Mars is indeed considerably thinner than that of Earth,´╗┐ however the atmospheric density on Earth varies with altitude. As you rise higher into Earth's atmosphere so the density drops, and it eventually falls off to near zero as you start to escape the Earths Atmosphere.

Mars has an average (depending on the hight) atmospheric density of 0.087 Psi here on earth you got a sea level pressure of 14.7 psi you notice a difference ? You need a certain atmosperhic densitiy to enflate the parachute and to gain a velocity reduction. But that is impossible with that thin atmospere."


Anyone able to refute this with a simple equation, as I am not an expert in this field.



Title: Re: Curiosity fake...?
Post by: Chew on August 05, 2013, 04:29:50 PM
First, it is a known fact that almost all conspiracy theorists are barely capable of adding, let alone multiplying and working with squares. Ask to see his math. I would bet anything he will balk and try to bluff his way through.

Second, tell him atmospheric density is measured in kg per cubic meter, or pounds per cubic foot, and not PSI. Drag formulae use density, not pressure.

Third, parachutes don't need a "certain" density to inflate; they need a gas blowing into it to inflate.

Here's the real math:

Mars' atmospheric density  (http://nssdc.gsfc.nasa.gov/planetary/factsheet/marsfact.html)at the surface is about .02 kg/m3. The density scale height is 11.1 km. At 100 km the density is about 2.4461e-6 kg/m3.

So at 100 km,
30,000 mph (13,411 m/s),
a parachute coefficient of drag of 1,
a parachute diameter of 10 m (I don't know what it was. 10 meters seems reasonable for demonstration purposes),
and a spacecraft mass of 3893 kg,

would generate 4.4 m/s2 of deceleration. That's about half a g.

To rub more salt into his wound, tell him meteors burn up at an altitude of around 80 kilometer in the Earth's atmosphere. The density at that altitude is equal to the density of the Martin atmosphere at an altitude of 71 kilometers.
Title: Re: Curiosity fake...?
Post by: Rob260259 on August 05, 2013, 05:30:36 PM
Wow. Thanks. I'm going to get my Japanese friend out of the cabin first and try to catch up a little.
Title: Re: Curiosity fake...?
Post by: smartcooky on August 05, 2013, 07:15:47 PM
First, it is a known fact that almost all conspiracy theorists are barely capable of adding, let alone multiplying and working with squares.

You have given them far too much credit.
Title: Re: Curiosity fake...?
Post by: ka9q on August 05, 2013, 08:26:58 PM
Mars' low atmospheric surface pressure does make it difficult to land with a parachute; you just can't get a survivable terminal velocity from any practical parachute.

That's why every successful lander has used rockets at some point in its terminal descent.  But at the much higher velocities found earlier in the descent, a parachute (and before that, a blunt heat shield) provide plenty of deceleration.
Title: Re: Curiosity fake...?
Post by: ka9q on August 05, 2013, 08:34:58 PM
It's interesting to note that the average scale height of the earth's atmosphere is only 7.64 km, so the Martian atmosphere, while thin, doesn't fall off with altitude as rapidly as the earth's.

I looked this up. For constant temperature (which is not the case), the scale height is kT/Mg, where k = Boltzmann constant, T = temperature, M = molecular mass and g = gravity. The lower temperature and higher molecular mass of the Martian atmosphere would make the scale height lower than earth except for Mars' much lower gravity of about 1/3 g.
Title: Re: Curiosity fake...?
Post by: Nowhere Man on August 05, 2013, 08:45:59 PM
So, does he also believe that the successful landings of Mars 3, Viking 1 & 2,  Mars Pathfinder, Spirit and Opportunity, and Phoenix were also faked?

Fred
Title: Re: Curiosity fake...?
Post by: smartcooky on August 05, 2013, 08:52:50 PM
So, does he also believe that the successful landings of Mars 3, Viking 1 & 2,  Mars Pathfinder, Spirit and Opportunity, and Phoenix were also faked?

Fred

Probably.

Some of these numbskulls actually believe that ALL space-flight is faked because (apparently, according to those very same numbskulls) rockets don't work in a vacuum as they have no air to push against.
Title: Re: Curiosity fake...?
Post by: Chew on August 05, 2013, 09:59:31 PM
It's interesting to note that the average scale height of the earth's atmosphere is only 7.64 km, so the Martian atmosphere, while thin, doesn't fall off with altitude as rapidly as the earth's.

It never occurred to me to think about it that way until I had the insight of comparing the different altitudes meteors would burn up.

With lower surface density but larger scale height, there is an altitude where the density would be the same. For Earth and Mars it's 101 km.
Title: Re: Curiosity fake...?
Post by: Chew on August 05, 2013, 10:12:29 PM
The OP got it from here: http://www.burlingtonnews.net/spiritmars6.html

Apparently, the same guy believes the atmosphere comes from a reservoir somewhere on the equator that gets sucked up as the Earth spins, centripetal force is linearly proportional to speed, the laws of buoyancy don't exist, our sky is blue because of all the chlorophyll, the inverse square law works by first squaring the ratio then taking the square root, and cameras cannot be made to control the amount of light they receive.
Title: Re: Curiosity fake...?
Post by: gillianren on August 05, 2013, 10:30:59 PM
Oddly, the one of those that confuses me most is the one about chlorophyll.
Title: Re: Curiosity fake...?
Post by: Rob260259 on August 06, 2013, 01:55:04 AM
So, does he also believe that the successful landings of Mars 3, Viking 1 & 2,  Mars Pathfinder, Spirit and Opportunity, and Phoenix were also faked?

Fred

I already asked him several days ago. I guess he's still hurting his brains on this. As he's also very busy with the 'no crater' issue. I told him about the force impacting the surface of the moon being approx. 20 g/cm^2. And he did not knew about the LM having a throttle to handle that thrust (facepalm ::)
Title: Re: Curiosity fake...?
Post by: BazBear on August 06, 2013, 02:50:07 AM
The OP got it from here: http://www.burlingtonnews.net/spiritmars6.html

Apparently, the same guy believes the atmosphere comes from a reservoir somewhere on the equator that gets sucked up as the Earth spins, centripetal force is linearly proportional to speed, the laws of buoyancy don't exist, our sky is blue because of all the chlorophyll, the inverse square law works by first squaring the ratio then taking the square root, and cameras cannot be made to control the amount of light they receive.
Actually it's a woman named Mary Sutherland, (http://www.burlingtonnews.net/press-ms.html) "Now Available for Television, Radio, and Lectures"  ;D
Title: Re: Curiosity fake...?
Post by: darren r on August 06, 2013, 03:50:03 AM

Actually it's a woman named Mary Sutherland, (http://www.burlingtonnews.net/press-ms.html) "Now Available for Television, Radio, and Lectures"  ;D

Hoo boy.

It's odd, but I always get the word 'shaman' confused with the word 'charlatan' (I also sometimes say 'fridge' instead of 'lift' but that's another story).
Title: Re: Curiosity fake...?
Post by: Echnaton on August 06, 2013, 08:28:08 AM
A candidate for the new queen of woo.  Sharing "valuable 'inside' information of which the public and even most researchers are
not familiar with."
Title: Re: Curiosity fake...?
Post by: Peter B on August 06, 2013, 09:55:03 AM
A candidate for the new queen of woo.  Sharing "valuable 'inside' information of which the public and even most researchers are
not familiar with."
I see from her website that she's associated with a group called BUFO. It occurs to me, probably completely unfairly, that bufo is Latin for "toad".
Title: Re: Curiosity fake...?
Post by: ka9q on August 06, 2013, 10:21:35 AM
With lower surface density but larger scale height, there is an altitude where the density would be the same. For Earth and Mars it's 101 km.
Good point! So the Karman line is more general than we realized...

I help mentor a high school group that flies balloons. We typically make it to 30 km or so (about 100,000') before the balloon bursts. I like to tell them that at that altitude earth's atmospheric pressure and temperature (if not composition) are roughly the same as on the surface of Mars. So in that sense they're building a payload to go to Mars.
Title: Re: Curiosity fake...?
Post by: Chew on August 06, 2013, 11:53:31 AM
Mary didn't write the OP quote. "Shadow" did.
Title: Re: Curiosity fake...?
Post by: Chew on August 06, 2013, 12:41:55 PM
Good point! So the Karman line is more general than we realized...

Actually, the Karman line on Mars is at 71 km. Remember you have to account for gravity vs lift and compare lift to orbital speed.
Title: Re: Curiosity fake...?
Post by: ka9q on August 06, 2013, 02:17:00 PM
Oh, right...it's not just atmospheric density, but the altitude at which the lift of an aircraft wing at orbital velocity would be insufficient.

Title: Re: Curiosity fake...?
Post by: ka9q on August 06, 2013, 07:43:41 PM
It would be interesting to work out the Karman line for all the planets with atmospheres (and Titan).
Title: Re: Curiosity fake...?
Post by: Chew on August 06, 2013, 08:59:50 PM
It would be interesting to work out the Karman line for all the planets with atmospheres (and Titan).

Venus   266 km
Mars       71 km
Jupiter   415 km
Saturn   810 km
                         Titan 152 km
Uranus   366 km
Neptune 270 km

 ;)

Couldn't find the atmo info I needed for Titan.
Title: Re: Curiosity fake...?
Post by: ka9q on August 06, 2013, 09:24:03 PM
Titan's atmosphere is nearly all N2, with a surface pressure of 1.5 bar (146.7 kPa), surface gravity of 1.352 N/kg (less than our moon), and surface temperature of 93.7 K.
Title: Re: Curiosity fake...?
Post by: Chew on August 06, 2013, 10:23:19 PM
Titan 152 km
Title: Re: Curiosity fake...?
Post by: ka9q on August 07, 2013, 08:00:43 AM
What are the reference altitudes for the gas planets? I think the usual convention for their "surfaces" is the 1-bar (100 kPa) pressure level.
Title: Re: Curiosity fake...?
Post by: ka9q on August 07, 2013, 08:06:09 AM
Interesting that they're all higher (in some cases much higher) than Earth with the sole exception of Mars. OTOH, the planets and moons with surface-bounded exospheres have Karman lines at 0 km.

Speaking of planetary comparisons, I've always found it interesting that their surface gravities tend to fall into just a few bins. Mars and Mercury are about 1/3 g. Venus, Earth, Saturn, Uranus and Neptune are all around 1 g. Jupiter, at about 2.5 g, is in a class by itself.
Title: Re: Curiosity fake...?
Post by: Chew on August 07, 2013, 11:47:52 AM
What are the reference altitudes for the gas planets? I think the usual convention for their "surfaces" is the 1-bar (100 kPa) pressure level.

Yeah, 1 bar.
Title: Re: Curiosity fake...?
Post by: Captain Swoop on August 19, 2013, 06:49:17 AM
Why are these web sites always so terrible to look at?
Title: Re: Curiosity fake...?
Post by: cjameshuff on September 01, 2013, 08:09:46 PM
Titan 152 km

You sure about that? Orbital velocity at that altitude would be ~1800 m/s, and Titan's atmosphere at that altitude ought to be about equivalent to Earth's at 10 km...about 4x as dense at the surface and in 1/7.25 as strong a gravity field.
Title: Re: Curiosity fake...?
Post by: Chew on September 02, 2013, 12:19:55 PM
What scale height did you use? I calculated a scale height of 20.58 km.
Title: Re: Curiosity fake...?
Post by: cjameshuff on September 02, 2013, 02:04:24 PM
What scale height did you use? I calculated a scale height of 20.58 km.

I got 20.65 km, so that's about right. So with the same surface density, 152 km on Titan would be equivalent to 56 km on Earth. Redoing my calculations, I get 152 km on Titan being equivalent to 45 km on Earth...looks like I did something wrong previously, but it's still far too low. Balloons would still work at that altitude.
Title: Re: Curiosity fake...?
Post by: Noldi400 on September 26, 2013, 09:15:45 PM

Some of these numbskulls actually believe that ALL space-flight is faked because (apparently, according to those very same numbskulls) rockets don't work in a vacuum as they have no air to push against.

There's at least one guy (I know ka9q has gone a round or two with him) who insists that rockets cannot possibly work in space, based on his interpretation of Boyle's Law - the "infinite vacuum" of space would cause the propellants to expand out of the combustion chamber before they could ignite.

A new queen of Woo, huh? I guess Judy Wood finally has some competition.