Hayabusa-2’s highest resolution image so far
The Hayabusa-2 science team has released the highest resolution image taken by the spacecraft so far. The image on the right, reduced to post here, is that image. Click on it to see the full resolution version.
The image resolution is about 4.6mm/pixel. This is the highest resolution image that Hayabusa2 has taken so far and even small rocks with a diameter of 2 – 3cm are clearly visible. The maximum resolution of AMICA –the camera at the time of the first Hayabusa mission— was 6 mm/pixel, so even its resolution has now been exceeded. As the image captured of the asteroid surface from the spacecraft, it will be one of the highest resolution to be taken of Ryugu (MINERVA-II1 and MASCOT which landed on the surface, have captured even higher resolution images).
A feature from the image is the lack of regolith (sandy substance). This was suspected to be true from the images obtained so far, but it is more clearly seen in this high resolution photograph. There is also a collection of pebbles with different colors, which may be evidence that the surface material of Ryugu is mixed.
This was taken during the second landing rehearsal about two weeks ago. The image clearly shows the rubble pile that is Ryugu, lacking anything but cemented rocks. It also illustrates the landing problem faced by Hayabusa-2’s engineers. They need a flat smooth area to land, and they have not really found one that fits their needs.
On Christmas Eve 1968 three Americans became the first humans to visit another world. What they did to celebrate was unexpected and profound, and will be remembered throughout all human history. Genesis: the Story of Apollo 8, Robert Zimmerman's classic history of humanity's first journey to another world, tells that story, and it is now available as both an ebook and an audiobook, both with a foreword by Valerie Anders and a new introduction by Robert Zimmerman.
The ebook is available everywhere for $5.99 (before discount) at amazon, or direct from my ebook publisher, ebookit. If you buy it from ebookit you don't support the big tech companies and the author gets a bigger cut much sooner.
The audiobook is also available at all these vendors, and is also free with a 30-day trial membership to Audible.
"Not simply about one mission, [Genesis] is also the history of America's quest for the moon... Zimmerman has done a masterful job of tying disparate events together into a solid account of one of America's greatest human triumphs."--San Antonio Express-News
The Hayabusa-2 science team has released the highest resolution image taken by the spacecraft so far. The image on the right, reduced to post here, is that image. Click on it to see the full resolution version.
The image resolution is about 4.6mm/pixel. This is the highest resolution image that Hayabusa2 has taken so far and even small rocks with a diameter of 2 – 3cm are clearly visible. The maximum resolution of AMICA –the camera at the time of the first Hayabusa mission— was 6 mm/pixel, so even its resolution has now been exceeded. As the image captured of the asteroid surface from the spacecraft, it will be one of the highest resolution to be taken of Ryugu (MINERVA-II1 and MASCOT which landed on the surface, have captured even higher resolution images).
A feature from the image is the lack of regolith (sandy substance). This was suspected to be true from the images obtained so far, but it is more clearly seen in this high resolution photograph. There is also a collection of pebbles with different colors, which may be evidence that the surface material of Ryugu is mixed.
This was taken during the second landing rehearsal about two weeks ago. The image clearly shows the rubble pile that is Ryugu, lacking anything but cemented rocks. It also illustrates the landing problem faced by Hayabusa-2’s engineers. They need a flat smooth area to land, and they have not really found one that fits their needs.
On Christmas Eve 1968 three Americans became the first humans to visit another world. What they did to celebrate was unexpected and profound, and will be remembered throughout all human history. Genesis: the Story of Apollo 8, Robert Zimmerman's classic history of humanity's first journey to another world, tells that story, and it is now available as both an ebook and an audiobook, both with a foreword by Valerie Anders and a new introduction by Robert Zimmerman.
The ebook is available everywhere for $5.99 (before discount) at amazon, or direct from my ebook publisher, ebookit. If you buy it from ebookit you don't support the big tech companies and the author gets a bigger cut much sooner.
The audiobook is also available at all these vendors, and is also free with a 30-day trial membership to Audible.
"Not simply about one mission, [Genesis] is also the history of America's quest for the moon... Zimmerman has done a masterful job of tying disparate events together into a solid account of one of America's greatest human triumphs."--San Antonio Express-News
Looking at the image it raises the question as to how the asteroid formed. It seems so loose…is there a large boulder at the center which acts as a gravitational magnet? Are the rocks ejecta from the Earth and Mars? Remnants of Alderaan? Hopefully they can land and bring back a sample
born01930-
…just an amateur; I might be mangling this-
For math, you treat gravity as a point-source, but in actuality gravity is a result of all the bits-n-piece’s acting as a whole.
(there is a mathematical “gravitational center” for irregular body’s, but that’s way out of my bailiwick.)
Think of it along these lines–in space, a ‘pile’ of sand has the same gravitational force as a ‘pile’ of boulders, if the mass is equal. “Stuff” tends to “stick” together in Space.
If this is typical of most asteroids, mining them will be an even bigger challenge.
Digging into them would likely cause them to fall to pieces rather easily.
Gravity field of Vesta
JPL 2012
https://youtu.be/Q3qrGPFmG38
1:21
Gravity Slope On Asteroid Eros
-Views of the asteroid Eros generated by data from the laser rangefinder on the NEAR spacecraft.
https://youtu.be/XV-ds0pbsts
(0:28)
wayne wrote: “For math, you treat gravity as a point-source, but in actuality gravity is a result of all the bits-n-piece’s acting as a whole.”
Largely correct, especially for high school and undergraduate orbit calculations around a star or a hypothetical spherical uniformly-dense planet. The bits-n-pieces will eventually add up for a planet with mountains, craters, oceans, and differences in density or for an asteroid or comet with a non-spherical shape, such as cube-shaped Ryugu or duck-shaped comet 67P.
For a planet that has a mountain jutting up, an orbiting satellite passing by that mountain, with the mountain on its left, will be pulled a little extra to the left, turning slightly left, and the orbital plane will precess. In a similar way, an ocean on the satellite’s right will have a similar effect due to the reduced density and reduced gravitational pull, also turning slightly left.
For those who are serious about tracking and predicting orbits, the math gets far more detailed than just using a point source. Perturbations occur from not only atmospheric drag but from the gravitational differences due to shape and density of the planet. These gravitational differences are accounted for in much more complicated versions of orbital equations. Sun synchronous orbits are possible due to these perturbations, specifically due to the bulge of the Earth’s equator. Stated simply:
https://en.wikipedia.org/wiki/Orbital_mechanics#Perturbations
A sun synchronous orbit is roughly polar and elliptical, so as the satellite passes the equator, the Earth’s bulge pulls less while the satellite is farther from the Earth, more as the satellite is closer to the Earth in the elliptical orbit. The net result is a slight change in the orbital plane that keeps the plane’s relationship with the sun the same all year as the Earth revolves around the sun. This allows a satellite to remain in sunshine all the time (fewer batteries needed) or to take photos of the Earth around the same time of day each orbit (shadows are always similar).
The math gets complicated:
https://en.wikipedia.org/wiki/Orbital_perturbation_analysis#The_effect_of_the_Earth_flattening
The math can also go farther into more detailed differences by adding J3, J4, J5, et cetera factors to account for features that are smaller than the equatorial bulge.
These J factors were one of the outputs of the Grail mission’s lunar gravity map. Remember the lunar satellites Ebb and Flow?
https://www.nasa.gov/mission_pages/grail/news/grail20121205.html