Starship Asterisk*

To be continued... A nice place to visit but would you want to live there? At least you would swing back by but how would you ever get the smell out.

Chris Peterson wrote:

JaxJoe wrote:
I am assuming that given that velocity at impact, it is totally destroyed (like Brad).

As noted above, the damage was likely very minimal.

JaxJoe wrote:I am assuming that given that velocity at impact, it is totally destroyed (like Brad).

As noted above, the damage was likely very minimal.

Jim Leff wrote:I'd imagine that our descendants will be extraordinarily interested in salvaging and examining this next time it circles back. Even wrecked, it will be a far better preserved example of 21st century tech than anything on earth. Imagine if the ancient Egyptians had crashed a spacecraft on a comet soon to circle back; we'd be extraordinarily excited to take a look!

So two questions:

1. When's the next approach to the inner solar system?

2. How badly did we crash it? I'm assuming, given weak gravity, that it wasn't totaled.

I am assuming that given that velocity at impact, it is totally destroyed (like Brad). I forgot to pay that extra premium to cover "full replacement" costs... Does that mean that I don't get a new car? Just three-wheels instead of four...one-third of a car....That is, all I paid for. Why should I get the whole car?

Looks are deceiving peering at the surface of 67P. This 4.6 billion year old relic appears a combination of hard and soft surfaces although it was described as "very, very fluffy". With much learned from this rendezvous and landing what would ESA do different next time so a lander wouldn't "skip" off like water off a duck's back?

Just watched the "Sky at Night"'s Farewell to Rosetta, on BBC TV. If you get a chance, do watch it. It gave the Mission Scientists the opportunity to explain the reasons WHY they have crashed the spacecraft, mainly that it is aging - it's been in space since 2004, was losing power and was about to go into conjunction with the Sun so that we would lose contact anyway - and that this strategy would get data that could not be collected any other way, not only pictures but on gases near to the comet and on it's gravity.

But despite that, scientists are human, and several looked ready for a good cry when the signal was lost.
JOhn

PS Here's ESA's own version: http://www.skyatnightmagazine.com/news/farewell-rosetta

PPS Jim Armstrong, NASA has done much, but this achievement is by ESA, the European Space Agency.

It has been a fascinating mission . In the words of the 1971 Alan Price and Georgie Fame 'Rosetta' lyrics "Rosetta are you better, are you well, well, well" she sadly is not well anymore.

If the bright spots are not photo artifacts, I suppose they could be areas where out-gassing water vapor is condensing into ice (frost). Most of the spots are near crevasses or shadowed areas (colder areas where out-gassing is more likely), so that seems to support the idea. And maybe the two spots in the sky are chunks of ice that have been 'blasted' upward by the vapor pressure.

nebosite wrote:

Tekija wrote:What are those many white spots?

Ditto! What are those super bright spots? Are the similar the the bright material on Ceres?

I'm no expert, but some of them could be caused by charged particles from the sun, and/or bad pixels in the sensor. Note that there is one in the 'sky' to the far left, and another one just above the edge of the comet, left of center. Or they could be space puffins.

Tekija wrote:What are those many white spots?

Ditto! What are those super bright spots? Are the similar the the bright material on Ceres?

Many above have repeated my request for a discussion on how the process outlined by neifer leads to strata and the other planetary formations. Anyone?
John

Rob, That tree is an imager artifact. I was fooled by it a while back in similar images.

Jim Armstrong wrote:I have to say that I am astounded by, and proud of, the ongoing results of America's investment in NASA. And not in the DoD.

ESA. This was not an American project. Still something to be proud of as a fellow human being.

ta152h0 wrote:
I have often wondered, while sitting on a stool having a beer and observing the oter half of humanity, what is the actual interaction between the atoms in my seat and the actual atoms of the stool. I am sure one atom has a repelling force on the other, and yet they stick together to make " wood " and " flesh " and the aggregate force probably equals my weight.

Your seat and the stool induce mutual electric dipoles which produce a van der Waals attractive force that goes as the inverse of the distance to the seventh power.

However, after 'contact' the quantum mechanically identical electrons in your seat and in the stool generate a much stronger repulsive force to counteract both gravity & the van der Waals attraction.

Craggy bit o' rubble...

:---[===] *

Seedsof Earth wrote:There is one object on the comet in this image that is unusual in that it almost looks artificial (but I'm sure it is not). It is located in the upper left corner of the lower right quadrant of the image, and appears to be a pointed stake poking up from the ice, and is casting a shadow to the left. ...

I think what we're seeing is a V-shaped shadow of a rock which is covered in the same material that covers the plain. See this pic...
The object you're asking about is in my top-right red circle. Compare it to an obvious rock which is in my bottom-left red circle. If that latter object had the same fine material covering it, all we'd see would be its V-shaped shadow line, similar to what we see (I think) around your object.

Rob

There is one object on the comet in this image that is unusual in that it almost looks artificial (but I'm sure it is not). It is located in the upper left corner of the lower right quadrant of the image, and appears to be a pointed stake poking up from the ice, and is casting a shadow to the left. Just to the left of the "stake" are two large, flat boulders (for reference). Do scientists have any idea what it might be?

Further, concerning the crag at the top of the image, I would assume that contrary to what many might imagine, one could not leap off the top of the crag and expect to land somewhere down along the "talus" slope. Since gravity "flows" to the greatest mass, it would not pull one down to the talus slope, but rather to the wall of the crag where the gravimetrics are theoretically stronger. In fact, there is probably stronger gravitational pull toward the two lobes of the comet rather than toward the center, or "neck" of the comet. With this in mind, I am assuming that the talus is not talus at all, but rather loosely packed rubble, while the rubble that forms the cragg is more tightly packed, and less "loose" looking due to the stronger gravity within the structure of the cragg. Would you agree with this? If not, please enlighten me.

I was also struck by how "planetary" the terrain in the photograph appears.
I expected a 67P article, but immediately assumed the subject was Martian when it came up.
Or maybe the box canyon in the Mojave where we used to shoot our .22's 60 years ago.
I have to say that I am astounded by, and proud of, the ongoing results of America's investment in NASA. And not in the DoD.

I have often wondered, while sitting on a stool having a beer and observing the oter half of humanity, what is the actual interaction between the atoms in my seat and the actual atoms of the stool. I am sure one atom has arepelling force on te other, and yet they stick together to make " wood " and " flesh " and the aggregate force probably equals my weight.( I like your real time spell checker )

I have a couple of questions :

Was it was not possible to let Rosetta sleep for some years until the comet returns ?
Would it stay in orbit around the comet all this time ?
Would the battery or some other component be damaged by the cold at Jupiter's distance from the sun ?
So would it be a dead spacecraft when the comet returns ?

ta152h0 wrote:
How much mass does a body of rubble have to have before gravity becomes detectable ?

In so far as having gravity become the dominant factor in planetesimal growth

• —about 1 km in diameter:

https://en.wikipedia.org/wiki/Nebular_hypothesis#Rocky_planets wrote:
<<After small planetesimals—about 1 km in diameter—have formed by one way or another, runaway accretion begins. It is called runaway because the mass growth rate is proportional to R⁴~M^4/3, where R and M are the radius and mass of the growing body, respectively. It is obvious that the specific (divided by mass) growth accelerates as the mass increases. This leads to the preferential growth of larger bodies at the expense of smaller ones. The runaway accretion lasts between 10,000 and 100,000 years and ends when the largest bodies exceed approximately 1,000 km in diameter. Slowing of the accretion is caused by gravitational perturbations by large bodies on the remaining planetesimals. In addition, the influence of larger bodies stops further growth of smaller bodies.>>

How much mass does a body of rubble have to have before gravity becomes detectable ?

Wonder if CERES looks like that up close ?

PeterL wrote:Is there gravity on this comet? The pebbles and rocks look very stationary on the surface rather than floating off into space.

The comet has mass, and therefore it has gravity. Indeed, it is gravity that holds it together. The surface gravity is around a ten-thousandth that of Earth, which means the comet has an escape velocity of about a meter per second. That's low enough that escaping gases can blow material away when the comet is near the Sun, but otherwise, what's laying there will keep laying there.