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Curiosity Mars Lander… she’s off… ETA August 2012: soft landing on Mars
Posted: 28 November 2011 04:27 PM   [ Ignore ]   [ # 16 ]
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traveler - 28 November 2011 04:09 PM
dougsmith - 28 November 2011 04:00 PM

Not sure how you contaminate a lifeless planet, so long as the lander is sterile.

Our definition of life is very limited. There is a very small chance that there is some sort of life on Mars that we are contaminating (irradiating). It’s a risk NASA believes is acceptable.

Fair enough, but the lander is tiny compared with the size of Mars. Unless the lander happens to crash and explode on the last vestige of life there, it seems to me a non-issue.

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Posted: 28 November 2011 04:40 PM   [ Ignore ]   [ # 17 ]
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dougsmith - 28 November 2011 04:27 PM
traveler - 28 November 2011 04:09 PM
dougsmith - 28 November 2011 04:00 PM

Not sure how you contaminate a lifeless planet, so long as the lander is sterile.

Our definition of life is very limited. There is a very small chance that there is some sort of life on Mars that we are contaminating (irradiating). It’s a risk NASA believes is acceptable.

Fair enough, but the lander is tiny compared with the size of Mars. Unless the lander happens to crash and explode on the last vestige of life there, it seems to me a non-issue.

Agreed. That’s the acceptable risk.

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Posted: 28 November 2011 05:31 PM   [ Ignore ]   [ # 18 ]
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Here’s something interesting i just learned. I was curious about the RTG’s ( radioisotope thermoelectric generators) used on curiosity so I looked into it and had forgotten that the Viking landers had similar power units aboard when they landed on Mars back in the 70’s. Of course all the long range probes ( Pioneers 10,11, Voyagers 1and 2, Casini, Galileo and New Horizons) have used these devices but i was surprised to learn that many other US and USSR probes have used them. Several Apollo missions even carried them for use in science experiments to be left behind on the moon. In fact the RTG for the Apollo 13 mission which had to abort its moon landing ended up at the bottom of the ocean when the craft returned home and jettisoned that portion of the ship prior to reentry.

Whats even more surprising is that many of these devices have been put to much more mundane use here on Earth in places too remote to power in any other fashion. The USSR used them to power lighthouses.

It seems that any risk of contaminating Mars is a small worry compared to how much we have contaminated our own highly populated planet with RTG’s.

Here’s the wikipedia link for anyone whos interested: http://en.wikipedia.org/wiki/Radioisotope_thermoelectric_generator

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Posted: 28 November 2011 09:55 PM   [ Ignore ]   [ # 19 ]
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macgyver - 28 November 2011 06:33 AM

I am not 100% certain but I’m pretty sure that curiosity will not be going into orbit prior to landing. No component of the craft remains in orbit so there is no need to establish orbit first. Going into orbit would require carrying a large engine and would consume a lot of fuel especially with a craft this large since the ship has to be slowed down from a speed that is far above orbital velocity to one that can achieve a stable orbit. Both of those things would add weight which would mean you need a larger rocket to launch the craft or you would have to launch a proportionately smaller probe.

If you’re goal is to land on the planet it makes much more sense to plunge straight down to the surface from interplanetary space and let the atmosphere slow the craft down like the Apollo crew capsules did when they returned from the moon. I’m pretty certain that’s what they will be doing here. The controllers of course have the entire cruise period from earth to check out the craft prior to the final landing sequence so going into orbit really wouldn’t make the whole process any safer and would just add complexity. What if the rocket used to put the craft in orbit doesn’t fire as has happened to some probes in the past ( like the recent Japanese Akatsuki probe to Venus).

From what I understand, Mars’ atmosphere is too thin to provide enough braking, unlike on Earth. Thus, being in orbit for a revolution or two may make sense if doing so will enable atmospheric entry at a slower speed.

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Posted: 29 November 2011 05:43 AM   [ Ignore ]   [ # 20 ]
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macgyver - 28 November 2011 05:31 PM

Here’s something interesting i just learned. I was curious about the RTG’s ( radioisotope thermoelectric generators) used on curiosity so I looked into it and had forgotten that the Viking landers had similar power units aboard when they landed on Mars back in the 70’s. Of course all the long range probes ( Pioneers 10,11, Voyagers 1and 2, Casini, Galileo and New Horizons) have used these devices but i was surprised to learn that many other US and USSR probes have used them. Several Apollo missions even carried them for use in science experiments to be left behind on the moon. In fact the RTG for the Apollo 13 mission which had to abort its moon landing ended up at the bottom of the ocean when the craft returned home and jettisoned that portion of the ship prior to reentry.

Whats even more surprising is that many of these devices have been put to much more mundane use here on Earth in places too remote to power in any other fashion. The USSR used them to power lighthouses.

It seems that any risk of contaminating Mars is a small worry compared to how much we have contaminated our own highly populated planet with RTG’s.

Here’s the wikipedia link for anyone whos interested: http://en.wikipedia.org/wiki/Radioisotope_thermoelectric_generator

Batteries with a half-life of about 88 years ain’t too shabby. I agree that the risk of contaminating Mars is small when compared to what we have done here, but of course that’s a lame excuse for any extraterrestrial contamination. We are an arrogant species and often do too little to pick up after ourselves.

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Posted: 29 November 2011 05:49 AM   [ Ignore ]   [ # 21 ]
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TromboneAndrew - 28 November 2011 09:55 PM

From what I understand, Mars’ atmosphere is too thin to provide enough braking, unlike on Earth. Thus, being in orbit for a revolution or two may make sense if doing so will enable atmospheric entry at a slower speed.

Mars atmosphere is about 1% the density of earths but when you are traveling at nearly 20,000 kph that can still provide significant breaking ability. If you click on the link to the mission profile in my previous post and also check THIS LINK youo will find no mention of the craft going into Mars orbit. I’ve searched NASA and JPL’s web sites and have been unable to find anything that mentions insertion into MArs orbit.  If you look at the design of the ship in cruise phase it also becomes somewhat obvious that it will not be going into orbit. As the MSL approaches Mars it is encased in an aeroshell. There are maneuvering rockets on the aeroshell but no large engine that could slow the ship. Finally, I realize wikipedia is not always a great source of info but for what its worth, here is a QUOTE:

“Guided entry: The rover is folded up within an aeroshell which protects it during the travel through space and during the atmospheric entry at Mars. Atmospheric entry is accomplished using a Phenolic Impregnated Carbon Ablator (PICA) heat shield. The 4.5 m (15 ft) diameter heat shield, which will be the largest heat shield ever flown in space,[95] reduces the velocity of the spacecraft by ablation against the Martian atmosphere, from the interplanetary transit velocity of 5.3 to 6 km/s (3.3 to 3.7 mi/s) down to approximately Mach-2, where parachute deployment is possible. “

Dont mean to beat a dead horse. I just find this stuff interesting. Becoming a doctor was always plan B for me. Working for NASA was Plan A but didnt work out

[ Edited: 29 November 2011 05:52 AM by macgyver ]
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Posted: 29 November 2011 06:25 AM   [ Ignore ]   [ # 22 ]
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macgyver - 29 November 2011 05:49 AM

Dont mean to beat a dead horse. I just find this stuff interesting. Becoming a doctor was always plan B for me. Working for NASA was Plan A but didnt work out

I don’t think this horse is dead. I love to read about all of this stuff and I hope you keep sharing it. Engineering was plan C for me. I wanted to be an astronaut or airline pilot. My ex told me that if I took either of those paths, then she and my son would not be joining me (although I have all the ratings and flight time required). Biatch!

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Posted: 29 November 2011 07:37 AM   [ Ignore ]   [ # 23 ]
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To add to macgyver’s info on Curiosity…

After the parachute is deployed and the craft reaches an altitude of 1.6km, a “specially designed descent stage bearing the rover will drop away from this vehicle. The descent stage has eight rocket motors on its corners. These will slow its fall to a relatively sedate 0.75 m/s. When it is about 20m above the surface, the rover will be lowered from it on wires and deposited gently onto the Martian landscape. The cables will then be cut with explosives, the descent stage will fly off and crash land elsewhere…” (The Economist, Nov 26)

That will be an amazing feat of engineering if it works.

Edit to add: The video provided in the OP is an excellent animation, but what is not clear is how they ensure that the cables do not get tangled up on the rover. In the animation sequence, the cables just disappear. I hope they accounted for that potential problem (of course they have, right?)  tongue rolleye

[ Edited: 29 November 2011 07:55 AM by traveler ]
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Posted: 29 November 2011 08:14 AM   [ Ignore ]   [ # 24 ]
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I just hope Howard Wolowitz isn’t driving the rover.

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Posted: 29 November 2011 08:25 AM   [ Ignore ]   [ # 25 ]
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FreeInKy - 29 November 2011 08:14 AM

I just hope Howard Wolowitz isn’t driving the rover.

lol -  I think his drivers license might have been revoked after Sheldon spilled the beans to the FBI agent.

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Posted: 29 November 2011 09:09 AM   [ Ignore ]   [ # 26 ]
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Nice to see I’m not the only one addicted to that show.  LOL

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Posted: 29 November 2011 09:34 AM   [ Ignore ]   [ # 27 ]
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traveler - 29 November 2011 09:09 AM

Nice to see I’m not the only one addicted to that show.  LOL

BAZINGA!!!  LOL

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Posted: 29 November 2011 11:18 AM   [ Ignore ]   [ # 28 ]
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Let me know when the Martians attack for dropping junk on their planet.

psik

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Posted: 29 November 2011 11:57 AM   [ Ignore ]   [ # 29 ]
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psikeyhackr - 29 November 2011 11:18 AM

Let me know when the Martians attack for dropping junk on their planet.

psik

Meaning???

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Posted: 29 November 2011 03:34 PM   [ Ignore ]   [ # 30 ]
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traveler - 29 November 2011 11:57 AM
psikeyhackr - 29 November 2011 11:18 AM

Let me know when the Martians attack for dropping junk on their planet.

psik

Meaning???

It’s a joke dude.

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