IPB

Welcome Guest ( Log In | Register )

58 Pages V  « < 56 57 58  
Reply to this topicStart new topic
Mission: Hayabusa 2
Marcin600
post Nov 13 2020, 03:09 AM
Post #856


Member
***

Group: Members
Posts: 205
Joined: 14-December 15
Member No.: 7860



JAXA has released a new Hayabusa2 extended mission video (English version): here and here (540 MB)
Go to the top of the page
 
+Quote Post
Explorer1
post Nov 13 2020, 03:08 PM
Post #857


Senior Member
****

Group: Members
Posts: 1764
Joined: 13-February 10
From: Ontario
Member No.: 5221



Thanks for the link, I completely forgot that they still have one target marker and one "bullet" they can fire from the sample collector! If there is an extended period near the asteroid, there might even be a chance to test the gravity tractor theory of asteroid deflection. Could the mass of something so small, with virtually non-existent gravity, even be measured to any degree?
Go to the top of the page
 
+Quote Post
Marcin600
post Nov 19 2020, 06:16 PM
Post #858


Member
***

Group: Members
Posts: 205
Joined: 14-December 15
Member No.: 7860



QUOTE (Explorer1 @ Nov 13 2020, 04:08 PM) *
Thanks for the link, I completely forgot that they still have one target marker and one "bullet" they can fire from the sample collector! If there is an extended period near the asteroid, there might even be a chance to test the gravity tractor theory of asteroid deflection. Could the mass of something so small, with virtually non-existent gravity, even be measured to any degree?

I feel (but not sure) that Hayabusa2, due to its design for a completely different purpose, is not a suitable spacecraft for the "gravity tractor" experiment.
1. For example, it does not have sufficiently sensitive instruments (?).
2. The target asteroid (1998 KY26) is so small and distant that it is a great challenge to measure from Earth the possible extremely small effect of changing its orbit.
3. In addition, this experiment requires a really long operation of the ship's engines in the gravitational field of the asteroid. I don't know how much fuel (ionic and conventional) will remain in the Hayabusa2 tanks after many years of flight, correction maneuvers and the asteroid's "orbit insertion". But I'm afraid there will be too little for this experiment...

But seeing this strange object up close will be very interesting. If this is a "standard rubble pile", why has it not broken up into a cloud of debris by extremely fast rotation (and therefore strong centrifugal force) with minimal gravity? It must be something very interesting and different from the conventional models of internal structure of asteroids. Maybe it's just a huge boulder in space?!

As a curiosity, it can be added that if 1998 KY26 were a sphere, then for an astronaut with a height of 1.8 m, the horizon line would be at a distance of less than 7.5 m!
(according to the formula: horizon distance = square root of the sphere diameter times the height of the observer (all in meters); √D x h (in meters), where: D - sphere diameter in meters, h - observer's height in meters)

For Curiosity rover's Mastcam on the surface of 1998 KY26 the horizon would be only approx. 8 m from the rover! Pretty limited field of view
Go to the top of the page
 
+Quote Post
Explorer1
post Nov 20 2020, 04:31 AM
Post #859


Senior Member
****

Group: Members
Posts: 1764
Joined: 13-February 10
From: Ontario
Member No.: 5221



Yes, the tractor is probably implausible. I do wonder how 'station-keeping' works at something so small. Solar pressure is undoubtedly a major factor when compared with the asteroid's own gravity.
Go to the top of the page
 
+Quote Post
Marcin600
post Nov 21 2020, 12:22 AM
Post #860


Member
***

Group: Members
Posts: 205
Joined: 14-December 15
Member No.: 7860



It will be more like the parallel flight of two spaceships than orbiting.

And the solar radiation pressure should be quite disturbing to the orbit of such a small asteroid itself (over a long period of time).

[With a diameter of 30 m, the mass of 1998 KY26 (depending on density: from 0.5 to 5 g/cm3) should be between 7,000 and 70,000 t (metric ton). That is between 17 and 170 times more than ISS and between 14,000 and 140,000 times more than Hayabusa2 (approximately, if I did not make a calculation error smile.gif]
Go to the top of the page
 
+Quote Post
Marcin600
post Nov 21 2020, 07:18 PM
Post #861


Member
***

Group: Members
Posts: 205
Joined: 14-December 15
Member No.: 7860



"Information on observing the re-entry capsule" on the JAXA website (in English, pdf with the application)
Go to the top of the page
 
+Quote Post

58 Pages V  « < 56 57 58
Reply to this topicStart new topic

 



RSS Lo-Fi Version Time is now: 24th November 2020 - 11:55 AM
RULES AND GUIDELINES
Please read the Forum Rules and Guidelines before posting.

IMAGE COPYRIGHT
Images posted on UnmannedSpaceflight.com may be copyrighted. Do not reproduce without permission. Read here for further information on space images and copyright.

OPINIONS AND MODERATION
Opinions expressed on UnmannedSpaceflight.com are those of the individual posters and do not necessarily reflect the opinions of UnmannedSpaceflight.com or The Planetary Society. The all-volunteer UnmannedSpaceflight.com moderation team is wholly independent of The Planetary Society. The Planetary Society has no influence over decisions made by the UnmannedSpaceflight.com moderators.
SUPPORT THE FORUM
Unmannedspaceflight.com is a project of the Planetary Society and is funded by donations from visitors and members. Help keep this forum up and running by contributing here.