Mission: Hayabusa 2 |
Mission: Hayabusa 2 |
May 14 2018, 12:14 AM
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#211
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Member Group: Members Posts: 817 Joined: 17-April 10 From: Kamakura, Japan Member No.: 5323 |
It means the time it takes for electromagnetic waves to make the round trip from Earth to Hayabusa 2 and back. Thank you Charborob. I thought that it might be somehow related to the flight time. It is some time sice I last looked at the relative velocity. A few weeks ago it was 100m/s and now it is now down to 60m/s. That must mean that the ion engines are pointing to Ryugu. It makes me uneasy because by the look of the diagram both telephoto (once used to catch a glimpse of the asteroid, about 5,6 weeks ago?) and the wide angle cameras are pointing perpendicular to the flight direction. Haya2 web page shows that it is now the wide angle camera in use, but it is not looking forward, yet, I think. Display window is totally dark. I was hoping that Haya 2's display window will show us continous image of approaching Ryugu, but it seems very unliklely, unless they use chemical thrusters on and off for us. How soon will we be seeing anything at all? P |
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May 14 2018, 01:19 AM
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#212
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Senior Member Group: Members Posts: 2082 Joined: 13-February 10 From: Ontario Member No.: 5221 |
They already confirmed where Ryugu was back in February, they would have to stop firing the engines to turn the craft and take pictures. They will wait to be close enough to resolve it, presumably.
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May 14 2018, 08:04 AM
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#213
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Member Group: Members Posts: 817 Joined: 17-April 10 From: Kamakura, Japan Member No.: 5323 |
I have had a look at a radar image of the target asteroid for OSIRIS-REX. The image looked a bit wobbly, but it looked just like those
comments made about it, its shape in particular. And, presumably, by triangulation and experience with mereorites they can estimate its mass. I have seen comments that not much is known about Ryugu. How then did they estimate the escape velocity for MASCOT? My guess is that the design velocity is far below the thinkable upper limit, so that MASCOT is not lost into space after its first hop? My general cuoriosity is simply, how do they know anything at all about these asteroids from such a distant place like earth. P |
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May 16 2018, 08:48 AM
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#214
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Member Group: Members Posts: 817 Joined: 17-April 10 From: Kamakura, Japan Member No.: 5323 |
There is a consolation, after all, except that we do not know when it will be.
Haya2's pop-up for the display window translates as follows: "Asteroid position and size. In the final stage of approach to Ryugu Hayabusa 2 will be showing approaching Ryugu in the display window." Very irritating. They could tell us roughly when it will be. Very bad PR activity, I think. Anyway, the relative velocity is now down to 50m/s. P |
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May 16 2018, 10:43 AM
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#215
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Senior Member Group: Members Posts: 1419 Joined: 26-July 08 Member No.: 4270 |
15 May 2018. Star-tracker has detected Ryugu.
http://www.hayabusa2.jaxa.jp/topics/20180515_e2/ QUOTE Hayabusa2 is currently operating its ion engines as the spacecraft approaches asteroid Ryugu. But on May 11, the ion engines were temporarily stopped so that the onboard Star Tracker (see note 1) could take a photograph of Ryugu. This observation of the direction of Ryugu from the spacecraft will be used for optical navigation (see note 2).
-------------------- -- Hungry4info (Sirius_Alpha)
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May 18 2018, 12:43 AM
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#216
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Member Group: Members Posts: 817 Joined: 17-April 10 From: Kamakura, Japan Member No.: 5323 |
There is a short article about Hayabusa 2 on today's local newspaper here. JAXA told the municipality of Sagamihara where
ISAS (part of JAXA) is located. Students in ISAS control room are operating Hayabusa 2. It confirms that the arrival of Hayabusa 2 (apparently to the altitude of 20km) is 21 June (as opposed to a longer window starting from 21 June). P |
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May 20 2018, 07:18 AM
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#217
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Member Group: Members Posts: 817 Joined: 17-April 10 From: Kamakura, Japan Member No.: 5323 |
Below really is for myself.
As of 20 May the relative velocity is 180km/h, already slower than shinkansen trains. The distance to be closed is 38,000km, about two round trips bet. Tokyo and London. If this speed is maintained Hayabusa will reach Ryugu in 8.8 days, i.e. before the end of this month. How soon it is to slow down further remains to be seen. P |
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May 23 2018, 11:20 PM
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#218
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Solar System Cartographer Group: Members Posts: 10151 Joined: 5-April 05 From: Canada Member No.: 227 |
Less than 24000 km to go! But who's counting? (hint: me!)
Another new world about to be revealed. This is going to be a very cool mission. Phil -------------------- ... because the Solar System ain't gonna map itself.
Also to be found posting similar content on https://mastodon.social/@PhilStooke Maps for download (free PD: https://upload.wikimedia.org/wikipedia/comm...Cartography.pdf NOTE: everything created by me which I post on UMSF is considered to be in the public domain (NOT CC, public domain) |
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May 24 2018, 06:41 AM
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#219
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Member Group: Members Posts: 817 Joined: 17-April 10 From: Kamakura, Japan Member No.: 5323 |
24 May (144km/h): 16/11/18/10/15/13/19/8/9/9/7/8
I want to continue , for some time to come, with this above to see if it is useful. This is the speed of Hayabusa 2 with chemical thrusters cumulative burn time (numbers are rounded). Neither Hayabusa 2 nor Haya2 web page indicates significant changes in the flight in an easy to understand manner, so I decided to monitor what chemical thrusters are doing. It may be that only ion engines are used until Hayabusa 2 comes to a halt and in that case no significant changes will have been made to above matrix of numbers (right now only one row). This matrix will continue to build up unil it is 7 rows. If nothing has happned by that time a new matrix will appear wih its first row being the latest input into Hayabusa 2 web page. That way, we may be able to know when the landing gear is out. P |
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May 25 2018, 02:37 AM
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#220
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Member Group: Members Posts: 817 Joined: 17-April 10 From: Kamakura, Japan Member No.: 5323 |
24 May (144km/h): 16/11/18/10/15/13/19/8/9/9/7/8
25 May (144km/h): 16/11/18/10/15/13/19/8/9/9/7/8 No change, yet... P |
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May 25 2018, 03:34 AM
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#221
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Merciless Robot Group: Admin Posts: 8783 Joined: 8-December 05 From: Los Angeles Member No.: 602 |
Is the landing gear supposed to deploy THIS early? Thought it was going to spend some time in orbit surveying the asteroid before attempting to touch down.
-------------------- A few will take this knowledge and use this power of a dream realized as a force for change, an impetus for further discovery to make less ancient dreams real.
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May 25 2018, 03:54 AM
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#222
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Solar System Cartographer Group: Members Posts: 10151 Joined: 5-April 05 From: Canada Member No.: 227 |
just an analogy? Does it even have landing gear? I think the drogue chute might be enough.
Phil -------------------- ... because the Solar System ain't gonna map itself.
Also to be found posting similar content on https://mastodon.social/@PhilStooke Maps for download (free PD: https://upload.wikimedia.org/wikipedia/comm...Cartography.pdf NOTE: everything created by me which I post on UMSF is considered to be in the public domain (NOT CC, public domain) |
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May 25 2018, 05:35 AM
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#223
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Merciless Robot Group: Admin Posts: 8783 Joined: 8-December 05 From: Los Angeles Member No.: 602 |
The landing gear would be for touchdown on the asteroid, I think. Return capsule should indeed be just the aeroshell & chute, no legs.
-------------------- A few will take this knowledge and use this power of a dream realized as a force for change, an impetus for further discovery to make less ancient dreams real.
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May 25 2018, 09:38 AM
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#224
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Member Group: Members Posts: 817 Joined: 17-April 10 From: Kamakura, Japan Member No.: 5323 |
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May 26 2018, 02:10 AM
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#225
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Member Group: Members Posts: 817 Joined: 17-April 10 From: Kamakura, Japan Member No.: 5323 |
just an analogy? Does it even have landing gear? I think the drogue chute might be enough. Phil I have been using "landing gear being out" to mean a significant reduction in speed. My matrix was a means to feel the onset of slowing down, but overnight from yesterday to this morning Hayabusa2's speed went down from 144km/h to 108km/h, and it is pretty clear, I think, that the breaking power of ion engines alone is good enough to make Hayabusa2 to come to a halt without relying on chemical thrusters. I am excited to see this asteroid!!! 加油!!! P |
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