Mission: Hayabusa 2 Options

[pandaneko]

the collision will result in huge fragmentation, generating a kind of cloud of material, which will collide each other and dissipate the energy, to the point their relative speed is reduced and accretion starts again.

movies illustrating the various mechanisms here : simulations of asteroid collisions

OrbitrapInSpace , thank you for this. My thinking was too simplistic. I would have thought that all bits and pieces on the asteroid surface
will move in the same way upon impact, each with enough escape velocity. Mutual collisions in confusion after impact leading to energy
dissipation, no, never thought about it that way.

My guess is that they will then fall into an equilibrium state for some time, just like gas molecules in a container, forming, presumably
clouds around the asteroid, then eventually falling back down to its surface, making up regolith and boulders as we see now.

Yes, it makes sense.

P

[Guest_mcmcmc_*]

Highly detailed paper on interior mechanisms of 4th rover, MASCOT:
https://elib.dlr.de/104842/1/Bachelor%20The...%20Hass_red.pdf

[Guest_mcmcmc_*]

Hayabusa 3d/HD realtime simulator soon available? (maybe)
https://www.nhk.or.jp/corporateinfo/english...df/20180906.pdf


Next operations in schedule:
MASCOT operation: October 2 ~ 4 (MASCOT separation October 3)
Touchdown 1 rehearsal 2: mid-October
Touchdown 1: late-October

Press briefings:
Sept. 27, Thursday 15:30-16:30 JST (06:30-07:30 GMT)
Oct. 11, Thursday 15:30-16:30 (TBD)

http://global.jaxa.jp/projects/sat/hayabus...hayabusa2_e.pdf

[Guest_mcmcmc_*]

3D Web Visualization Tool to support HAHAYBUSA2-MASCOT Landing Site Selection Process
Imagine if it was made available to the public! :-)

[Guest_mcmcmc_*]

It is possible to calculate H2 altitude in real time from value ONC_A contained in this file (used by http://haya2now.jp/):

Altitude (km) = 354 / sqrt(ONC_A)


It's a pity there is not such a page for rovers!

[pandaneko]

Here, I am not talking about gaseous planets and icy comets.

Having seen NASA photos of Mars over the years and those from Itokawa, and this time from Ryugu it makes me think that the materials
we see on these cellestrial bodies remarkably look like the soil on which, for instance my house stands. When Bennu photos reach us
showing another soild surface like earth soil that will be enough to convince me that our solar systmes is made up of common soils,
common to everybody.

Am I right in thinking that way. That is to say that our earth soil is not unique. My previous thinking was that soils were produced by
rivers.

P

[kenny]

Soils on Earth have a high biological content and well as water, rock fragments, minerals etc. The biological element makes them very different from the soils on all other bodies, as far as we know.
I believe the soils (more accurately regolith) of the Moon, asteroids, comets, Venus, Mars etc are made up solely of rock. Ice fragments are also in the mix in the case of Martian poles and comets, and possibly lunar and Mercury polar areas. The rock fragments are produced by collision -- meteoroids hitting the surface of the Moon or an asteroid, breaking up larger rocks and splattering melt around, which hardens into lumps. On planets with atmospheres and water there is also wind and water erosion creating sands and gravel, frost-shattering, and perhaps rocks ejected from volcanoes. So it is all quite complex and varied.

[nprev]

Remember that appearance does not equate to composition. Relatively fine-grained material of all types on any body will look quite similar, but it originated via a variety of processes. For example, the 'sand dunes' of Titan would quickly melt or sublimate under terrestrial conditions.

[pandaneko]

Does the Sun spin?

P

[pandaneko]

I am trying to build up of an image of our solar system formation in my own small way.

P

[nogal]

Does the Sun spin?

It does, and does rotate faster near the equator than at the poles. Speed can be estimated from sun spot motion. See, for instance this wikipedia article on "Solar rotation"
Thank you for all your contributions to this forum.
Fernando

[neo56]

Just for fun... what if Ryugu was on Paris

[Floyd]

This really helps get scale. The little rock on the surface are not very little.

[Guest_mcmcmc_*]

Useful for upcoming MASCOT delivery: you can know in realtime Hayabusa 2 altitude by reading this file:
http://haya2now.jp/data/data.json

I reverese-engineered the source, and after several calculations it appears that H2 altitude in km is given by this formula:

A = 354 / sqrt(ONC_A)

File is updated in realtime during operations, and ONC_A value is used to set the size of the disk which represents Ryugu in Hayabusa2 simulator.

ONC_A represents the area of the disk.

You can then use this page to figure out how big the rovers would appear:
http://win98.altervista.org/telescopio.html

(MINERVA-II rovers have a 0.00018 km diameter and 0.00007 km height.)
(MASCOT is around 40x30x20cm, hence maximum dimension is 0.00040 km)

I'm trying to setup a page which automatically determines pixel size of the rovers depending on altitude, but I am encountering difficulties with cross-site data access.

[pandaneko]

Here is my simplistic view of the formation of our solar system.

Big bang, then elementary particles collied with one another, producing light atoms. Light atoms in turn collied amongst themselves and
accretion started all over the univere.

Here, I turn my attetion to our own. Sun was being formed, but smaller accretions were also taking place all over in our solar system.

There must have been porous asteroids, already hardened, rock solid asteroids, and those somewhere between. They kept colliding over
astronomical time scale.

If, as I have been reminded, there had been post collisional accretions then most of healthy (not bombarded by other asteroids) and
unhealthy (affected but still kept accretion) asteroids must be like Ryugu, with an equatorial vulge.

I bet Bennu will be looking like Ryugu and perhaps, Ikokawa was one of the odd asteroids?

P