Rosetta & Philae
 

I am surprised that no one has started something on this achievement so here goes.
I think that this is one of the most important achievements of recent history. Humans have landed a spacecraft on a foreign body traveling through the solar system at astonishing speed and with such a small gravitational field it produced the kind of problems we find every year in our games.
Reading this morning, the gravitational field of a 4 kM object makes the lander's 200 lb weight equivalent to about 1/30 of an ounce. This required the lander to screw itself into the surface of the comet to hold on. The comet is currently traveling about 23 miles/sec and is 315 million miles from earth. Imagine that! A ship traveling for more than ten years, catches up with an object traveling at 88,00 miles per hour, over 300 milllion miles from Earth and then was able to land on that moving object. Add to that, an unknown surface, temperatures of -70 on the surface and gas escaping constantly in the solar wind.
I can't think of anything but "cool"!

Re: Rosetta & Philae
 

It's truly inspiring. Also, NASA's first Orion test flight is within a couple weeks! If this flight also goes well, they will use this crew module in future flights to land more people on the moon, asteroids, and even mars.

We're living in a freaking awesome time.

Re: Rosetta & Philae
 

You can relive the excitement here (through Randal's eyes)

Disclaimer: Expect to lose an hour of your life to this.

Re: Rosetta & Philae
 

Not to diminish the magnitude of the accomplishment in any way, but Mars is traveling through the solar system far faster than that comet¹.

The accomplish is novel and impressive because of a host of other factors, including but not limited to its size, gravity, terrain, rotation period, and orbit.



¹at the time of landing

Re: Rosetta & Philae
 

Not to mention the chained gravity assists!

Earth to solar orbit, earth assist, mars assist, earth assist, asteroid flyby earth assist again, another asteroid flyby, then rendezvous with the comet. Planning a trajectory with 4 assists, 2 flybys, and final orbit in mind over a 12 year period is a very easy thing to screw up

Re: Rosetta & Philae
 

They had this thing sit silent for 10 years! Then they used gravity to sling them around, then they did some zig zags to slow down, then they landed a little pod on the comet and drilled into it!

I don't even know I am going to eat later on today and these guys planned most of this 10 years ago!

Re: Rosetta & Philae
 

Except unfortunately it didn't. From what I've heard, the 'harpoons' failed to fire and anchor Philae into the ground, causing it to bounce back up into space twice, at one point an entire kilometer above the surface of the comet, which took two hours. Luckily, 67P's gravity pulled it back down, but the new landing site was hundreds of meters away from the planned site. Scientists still haven't located its final resting position, but based on photos from the probe, they believe it ended up landing next to a cliff, and leaning askew on a rock. This caused its solar panels to get much less solar power than planned, and as a result the battery died, bringing the probe into sleep mode.

However, this is still a huge accomplishment, and according to BBC, "the probe managed to complete more than 80% of its planned primary science campaign on the surface", including drilling into the comet's surface, and was able to send its data back to Earth before losing contact. Scientists are hoping that as the comet approaches the sun (which sounds like next August), Philae will get enough light to reboot and charge its battery again.

Re: Rosetta & Philae
 

https://www.youtube.com/watch?v=H08tGjXNHO4

I saw the above a few days before the landing. Well worth the watch. (As a mentor, there are days I feel like the Male character)

And Philae may reawaken. We'll have to wait til next August but if it does, be curious to see what happens then. Maybe it'll get enough sunlight to keep it charged for a more prolonged period of observation.

Re: Rosetta & Philae
 

Dave Lavery keeps tweeting some really interesting things about the mission.

Re: Rosetta & Philae
 

Philae is currently in a coma.

Maybe it will wake up by the time Chury-Gera gets a coma of its own.

Re: Rosetta & Philae
 

+2 and FTW.

Re: Rosetta & Philae
 

I'm just concerned as to what the ejected gases will do to the lander once it reaches that stage...

Re: Rosetta & Philae
 

Voyager 1, Galileo, MESSENGER, and Cassini all used multiple gravity assists.

Re: Rosetta & Philae
 

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.

On the plus side, useful science data was acquired from Philae and this will give us new insight into comets.

Oh yes, and ESA gets the award for the coolest video associated with the Rosetta mission.

Re: Rosetta & Philae
 

I actually think it's pretty amazing we don't screw it up more often. How often do we lose a space probe because we commanded it into the wrong orbit? It seems like if we can get 'em into space successfully they usually make it to their final destination. The interplanetary FedEx drivers of the world do a great job getting their packages to the intended destination.

We looked this up at work because we were curious what the most ridiculous trajectory is, and it looks like MESSENGER wins.

How do we know we live in the future? Two people looked at each other and seriously asked, "Did our robot just bounce off that comet?" Maybe one day bounced comet landings will be as routine as bounced airplane landings.

One space robot taking pictures of another space robot

Re: Rosetta & Philae
 

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.

Re: Rosetta & Philae
 

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.

Re: Rosetta & Philae
 

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!"

Re: Rosetta & Philae
 

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).

Re: Rosetta & Philae
 

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.

Re: Rosetta & Philae
 

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

Re: Rosetta & Philae
 

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.

Re: Rosetta & Philae
 

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.

Re: Rosetta & Philae
 

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.

Re: Rosetta & Philae
 

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.

Re: Rosetta & Philae
 

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

Re: Rosetta & Philae
 

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

Re: Rosetta & Philae
 

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.

Re: Rosetta & Philae
 

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

Re: Rosetta & Philae
 

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.

Re: Rosetta & Philae
 

I'm not going to start a philosophical argument, but we must realize these are different measures of success and it's irrelevant to say one is more successful than the other.

We landed on the moon. We brought the astronauts back safely. We landed on a comet. We got meaningful scientific data.

Both were successful in their mission.

Re: Rosetta & Philae
 

Actually what was most inspirational to me in a lot ways was Apollo 13. Not successful on the top level since they just did a drive by on the moon. But the way the system was able to shift gears & get the astronauts home with a very broken space ship.

Re: Rosetta & Philae
 

When Apollo 11 happened, everybody knew about it and celebrated it. Kids, parents, grandparents - in America, at least, it was completely pervasive.

Last week, I asked my grandparents what they thought about Rosetta and Philae. They had no clue what I was talking about.

For capturing the world's collective imagination and pride, Apollo 11 was much much bigger.

Sadly, I cannot recall a single positive world-unifying event since the fall of the Berlin Wall. The Olympic Games, maybe. Certainly not a STEM achievement. (I suppose Curiosity-SkyCrane came close, but it's still not the same)