Rosetta & Philae

[DonRotolo]

Originally Posted by stinglikeabee

Hopefully, the solar panels will be able to get sunlight before the electronics freeze. Once that happens, it's likely game over. I don't know the battery life in sleep mode, nor what temperature minimum the electronics can withstand. Has anyone found this information? I know without heaters, current flight hardware lasts only minutes.

I can't verify that is true. It has been in a pretty cold part of the solar system (i.e., not on a planet) for a decade or more. The folks at ESA didn't seem concerned about the freeze - they assume it will wake up when it get some sunlight.

Dave might know better though.

[protoserge]

Originally Posted by DonRotolo

I can't verify that is true. It has been in a pretty cold part of the solar system (i.e., not on a planet) for a decade or more. The folks at ESA didn't seem concerned about the freeze - they assume it will wake up when it get some sunlight.

Dave might know better though.

The electronics (including battery) should have been heated during that time. I found out the battery needs to be at 0 degrees C to charge, but haven't found out anything more.

[EricH]

Question for anybody that doesn't mind dating themselves:

Was Philae's landing/surface operations more exciting than Apollo 11? How about inspirational?



I was tracking progress on that mission thinking "This is pretty cool!"

[g_sawchuk]

Well, Apollo 11 was a complete success. Philae however, was not. As stated above, Philae bounced upon landing, (not surprised based off of the speed of the comet) making it land in a place without sunlight, and therefore it has lost power. If the Philae was to somehow make a miracle and complete the goal of the mission, and find the answers of our orgin, then I would classify it as more amazing then Apollo 11. However, if that does not happen, then Apollo 11 was better. After all, Apollo 11 directly involved humans going into space and physically landing on something (the moon).

[Al Skierkiewicz]

Eric,
I am old and don't mind. Apollo 11 was spectacular on many levels. It was, in my opinion, the single greatest technological advancement up to that point during peacetime. Not only had we gone from blowing up rockets on the launch pad to putting three men in multiday missions in less than a decade. Additionally, this was a test that America could "commit itself to achieving the goal, before this decade is out, of landing a man on the moon and returning him safely to the earth." It was a time when we as high school seniors whispered the names of our heroes, Chris Craft, Gene Kranz, Neil Armstrong, Buzz Aldrin and Michael Collins. Yes Gene was and is still a big hero for me. Check out his book "Failure Is Not An Option".
Yes this latest achievement is still a big deal for me. I didn't tear up like I did that July night in 1969 but I was very excited. As FRC builders we should remember that the achievement of getting to a moving object in space after a ten year journey is a test that was passed with flying colors. Additionally, landing on that object that has nearly no gravitational field and still hanging on is a spectacular achievement. Think about it, 1/30 of an ounce is all that the lander had as an equivalent weight. So it bounced, it finally was able to hang on. Remember also that the solar wind is pulling debris off that rock and, as it is likely to be composed of mostly ice, so it is melting as it nears the sun. As that cold rock continues to tumble through our neighborhood, I am betting it will turn towards the sun. It is constantly changing it's COG and I only hope that once the lander gets sunlight it doesn't get blown off in the "wind". I think it's finest hour is yet to come.
And just because I am old doesn't mean that every time a crew member is lost, that I don't think to myself, I still would like to go. I want to be a part of this new frontier even if it means sitting at home and praying that they get there and get home. I am still a part of it and so are you.

[Ether]

Originally Posted by GrifBot

Philae bounced upon landing, (not surprised based off of the speed of the comet)

Please explain why you think the comet's speed was a factor in the bouncing.

[FrankJ]

For Apollo 11, I was at summer camp. The whole camp was allowed to stay up late & watch the landing on what was large at the time color TV. The information that was available "real time" was certainly a lot less. Being in 4th grade at the time, I did not realize the magnitude of the feat. Since the moon race was a much bigger program, I don't think it totally fair to compare them. The concept of systems engineering was largely developed to send people to the moon.

While we were not in a shooting war, the whole moon race thing was driven by the cold war.

[g_sawchuk]

Originally Posted by Ether

Please explain why you think the comet's speed was a factor in the bouncing.

Well, I'm not extremely educated in the means of how no gravity would effect this, but logically speaking, it would typically bounce or not smoothly land. Imagine a treadmill going on full speed. Imagine jumping on it. You will most likely fall and slide off. The higher you come from, you will also fall harder. Although the no gravity environment would change the Philae landing, I'm imagining that it would have some factor.

[JesseK]

Originally Posted by GrifBot

Well, I'm not extremely educated in the means of how no gravity would effect this, but logically speaking, it would typically bounce or not smoothly land. Imagine a treadmill going on full speed. Imagine jumping on it. You will most likely fall and slide off. The higher you come from, you will also fall harder. Although the no gravity environment would change the Philae landing, I'm imagining that it would have some factor.

There's a fairly good explanation and "simulation" here https://www.youtube.com/watch?v=GlMR...=TLU-o4vCFhIP0 for how Rosetta got into orbit and also learn some fun history.

The fact that the parent craft is in an orbit around the comet means that Philae was only moving at an orbital velocity relative to the comet. Since 67P's gravity is so low, we can deduce that the velocity required to orbit the comet is also quite low (relative to the comet, of course). Forget that they're moving umpteen thousand km/s around the sun - that's irrelevant for a landing from orbit.

To change your analogy, it's like you increased the speed of a neighboring treadmill that you're jumping from to match the speed of the treadmill you're jumping to prior to jumping. Getting into orbit around the comet is like running next to a moving train prior to jumping on it.

[protoserge]

Is it time to break out the orbital mechanics book?

http://en.wikipedia.org/wiki/67P/Chu...%93Gerasimenko
http://en.wikipedia.org/wiki/Rosetta_(spacecraft)


The term "no gravity" is a bit of a misnomer. Gravity is always present. Weightlessness is an effect of being in orbit. If the craft were to slow down, the object would de-orbit and be pulled toward the celestial body via gravity.

[Monochron]

Originally Posted by stinglikeabee

Is it time to break out the orbital mechanics book?

Probably just time to go play some Kerbal Space Program...

[Electronica1]

Originally Posted by Monochron

Probably just time to go play some Kerbal Space Program...

Yea, that game got me through AP physics (only person in my class to get a 5 on the exam).

[Alan Anderson]

After being "dropped" by Rosetta, Philae reached the surface of the comet traveling at about one meter per second. The 1 km bounce says a lot about the unexpectedly hard surface, but absolutely nothing about the orbital speed of the comet.

[gblake]

Originally Posted by GrifBot

Well, Apollo 11 was a complete success. Philae however, was not.

Back that horse up cowboy.
If Philae managed to use the last bit of its battery power to pick up and examine a sample of the comet material, it DID achieve all of its primary mission objectives, according to an ESA rep I heard on the radio (during the last few hours of the battery's life(lives)).

And, Apollo 11 had a few glitches ...

Originally Posted by EricH

Was Philae's landing/surface operations more exciting than Apollo 11?

I was bit too young (11?) to fully appreciate the size and complexity of the NASA programs that culminated in the Apollo missions. I do remember *expecting* those programs to be successful, because good people were carrying them out (I was too young to fully appreciate when earlier unmanned and manned missions failed).

Similarly, for whatever reasons, I usually expect our unmanned Mars missions to be (generally) successful.

OBTW - I don't remember hearing anything at the time of Apollo 11 about the nearly simultaneous Soviet unmanned mission to the moon. A mission that attempted to use a robot to retrieve soil samples ... The lack of coverage of and/or enthusiasm for that mission was a sign of the times.

For whatever reason, right now I think I'm more excited about the Philae mission than I was about the moon landings. Maybe it's because I think that comets and asteroids can be occupied, moved, and mined? The moon can be occupied and mined, but my wild guess is that comets and asteroids are going to turn a profit, or otherwise be significantly useful, first.

OBTW - In the foreseeable future, I have a hunch that comets and asteroids are going to be way more terrifying and obtainable than any nuclear device ever was. Discuss ...

When you ask which event was more exciting, I gather that you are asking about which event excited/inspired a 3rd-party observer more. However, my first reaction to your question was to put myself into the shoes of the Apollo 11 astronauts, and to then assume that having to fly the lander to a new (fewer boulders) landing spot while your onboard computer continuously crashed, was probably pretty exciting, even for a well-trained, cool-as-a-cucumber test pilot / astronaut. Philae's landing didn't involve an excitable pilot in the same sense. It was, and is, cool and interesting, but not "exciting" in the same way.

Bottom Line: I sent a big +1 to all of my European WhatsApp buddies when Philae landed, and I remain amazed at the past and present technical prowess of the NASA team (and their commercial/military/overseas partners).

Blake

[g_sawchuk]

Originally Posted by gblake

Back that horse up cowboy.
If Philae managed to use the last bit of its battery power to pick up and examine a sample of the comet material, it DID achieve all of its primary mission objectives, according to an ESA rep I heard on the radio (during the last few hours of the battery's life(lives)).

And, Apollo 11 had a few glitches ...

I was bit too young (11?) to fully appreciate the size and complexity of the NASA programs that culminated in the Apollo missions. I do remember *expecting* those programs to be successful, because good people were carrying them out (I was too young to fully appreciate when earlier unmanned and manned missions failed).

Similarly, for whatever reasons, I usually expect our unmanned Mars missions to be (generally) successful.

OBTW - I don't remember hearing anything at the time of Apollo 11 about the nearly simultaneous Soviet unmanned mission to the moon. A mission that attempted to use a robot to retrieve soil samples ... The lack of coverage of and/or enthusiasm for that mission was a sign of the times.

For whatever reason, right now I think I'm more excited about the Philae mission than I was about the moon landings. Maybe it's because I think that comets and asteroids can be occupied, moved, and mined? The moon can be occupied and mined, but my wild guess is that comets and asteroids are going to turn a profit, or otherwise be significantly useful, first.

OBTW - In the foreseeable future, I have a hunch that comets and asteroids are going to be way more terrifying and obtainable than any nuclear device ever was. Discuss ...

When you ask which event was more exciting, I gather that you are asking about which event excited/inspired a 3rd-party observer more. However, my first reaction to your question was to put myself into the shoes of the Apollo 11 astronauts, and to then assume that having to fly the lander to a new (fewer boulders) landing spot while your onboard computer continuously crashed, was probably pretty exciting, even for a well-trained, cool-as-a-cucumber test pilot / astronaut. Philae's landing didn't involve an excitable pilot in the same sense. It was, and is, cool and interesting, but not "exciting" in the same way.

Bottom Line: I sent a big +1 to all of my European WhatsApp buddies when Philae landed, and I remain amazed at the past and present technical prowess of the NASA team (and their commercial/military/overseas partners).

Blake

As I stated, if Philae does get useful information that could explain a lot more about our world, it would be a better mission. However, at this point, it appears that Apollo was more successful.