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Mission: Hayabusa 2
Daniele_bianchin...
post Oct 8 2018, 02:36 PM
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I do not know if this question has already been done. I can not understand the temperature in Ryugu's color scale. What does 4000/-2000 mean? these are not C. F. K.?
The site is unclear simply writes:" High temperatures on the asteroid reach 100C, while the coldest regions sit at about room temperature. Temperatures also change depending on the solar distance of the asteroid".
http://www.hayabusa2.jaxa.jp/en/topics/20180907e/
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fredk
post Oct 8 2018, 02:52 PM
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The caption reads "The scale bar shows relative temperature (the values have no meaning)." So it sounds like this is some temperature-dependent signal (intensity at some wavelength?) that hasn't yet been (or won't or can't be) converted to temperature. You can perhaps very crudely estimate temperatures based on that stated range (ie, deepest red ~ 100 C, deepest blue ~ 20 C), but there's no guarantee that is accurate or that the colour scale is linearly proportional to temperature in between those limits.
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Guest_mcmcmc_*
post Oct 10 2018, 07:28 AM
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Guests






Unfortunately thermal cameras have no an absolute scale: they draw in blu the coldest thing they see and in white or red the hottest thing... but right in that moment! When the subject changes or move... blu is still the coldest point and whitethe hottest, but they can mean different absolute temperatures.
So in one image you could have blue=0C and red/white=+100C, but in another image you could have blue=-100C and white=-50C (different extreme values and different range).

I don't know how you can calibrate them, especially if you have no references with known temperatures in the image.
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Gerald
post Oct 10 2018, 11:17 PM
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Here is the most accurate description I found about the thermal infrared imager (TIR). See subsection 5.4 for the temperature accuracy.
The instrument is built on the basis of an uncooled NEC 320A bolometer.

Be aware, that these instruments usually measure brightness temperatures.
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Hungry4info
post Oct 11 2018, 02:59 AM
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Press Conference in 2.5 hours (as of the time of this post).
https://www.youtube.com/watch?v=zXXepYfsiQc


--------------------
-- Hungry4info (Sirius_Alpha)
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Marcin600
post Oct 11 2018, 06:53 AM
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QUOTE (Hungry4info @ Oct 11 2018, 04:59 AM) *
Press Conference in 2.5 hours (as of the time of this post).
https://www.youtube.com/watch?v=zXXepYfsiQc


today's press conference pdf in japanese http://fanfun.jaxa.jp/jaxatv/files/20181011_hayabusa2.pdf.
There are no new pictures
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abalone
post Oct 11 2018, 08:48 PM
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Japan delays touchdown of Hayabusa2 probe on asteroid: official
http://www.spacedaily.com/m/reports/Japan_...ficial_999.html

JAXA project manager Yuichi Tsuda said they needed more time to prepare the landing as the latest data showed the asteroid surface was more rugged than expected.
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mcaplinger
post Oct 11 2018, 09:41 PM
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QUOTE (mcmcmc @ Oct 9 2018, 11:28 PM) *
I don't know how you can calibrate them...

Pretty much the same way you calibrate anything, you use calibrated blackbody sources of known temperatures and then you assume the camera stays stable over operating conditions, or you calibrate it over those conditions in ground testing.


--------------------
Disclaimer: This post is based on public information only. Any opinions are my own.
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pandaneko
post Oct 12 2018, 04:56 AM
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I could not upload my translation all last two days. Screen just kept jittering. Anyway, some of the new things in the press briefing are
as follows:

p6

We were engaged in MASCOT seperation from 30 September to 4 October and MASCOT was successfully seperated on 3 October and
it landed on the asteroid and functioned for about 17 hours.

Rehearsal (again) for the 1st touch down (TD1-R1-A) will be conducted from 14 to 15 October.

p7 Operation outline

On 28 September we receivded in writing, from Dr Tra-MiHo, project manager of MASCOT, her order to seperate MASCOT from
the mothership.


As a result, on 2 Octber at 11:50 (JST) a command was sent to Hayabusa 2 to start descending and at 10:57:20 on 3 October
MASCOT was seperated at a height of 51m. We received from Dr Tra-MiHo at 04:30 on 4 October her declaration of the completion of
this mission.

MASCOT functined for about 17 hours and all instruments on board obtained data. The data was then sent to the team in Germany.
It has been confirmed that MASCOT did one hopping.

MASCOT operation was entirely conducted at the German end and about 40 people were involved at DLR and 5 people at CNES
supported this operation.

US support with DSN came at level 2 (redundant antenna plus maximum manpower support)

Received data will be used for touch down operation as well

p15

6 descending operations have been conducted by now. As a direct result of these operations following schedule has been agreed on.


TD1-R1-A(2nd TD rehearsal) on 14-15 October.
TD1-R3(3rd TD rehearsal) on 24-25 October.

Late November to December overall operation.

1st touch down after January 2019.


p17

TD1-R1 was made to equatorial zone, MINERVA-II northern hemisphere, and MASCOT middle lattitude area of southern
hemisphere. From these operations it is now known that H2 can be guided to +/-30 degrees from the equator and with an accuracy of
+/-10m down to the height of about 50m.

P18

From observations we find that TD candidate areas (L08,L07,M04)are densely covered by boulders( larger than 50cm). Their
distribution has been obtained. TD areas are found to be very difficult to land with so many boulders.

P19

From the photos that have been taken by MINERVA and MASCOT Ryugu's surface is not that of a few boulders sitting here and there on
sandy ground, but it is rather that the ground itself is made up of boulders.

Some more to follow. P
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pandaneko
post Oct 12 2018, 05:55 AM
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Press briefing findings

p20

Touch down rehearsal and policy

Things that need confirmation

1. confirm that we can combat an extremely rough terrain.

2. confirm spacecraft behaviour at an extremely low altitude below 50m.

3. Confirm navigation precision below 50m via TD1-R1-A

4. cinfirm LRF properties via TD1-R1-A

5. Target markers tracking properties, if possible via TD1-R3 operation

※TM
in our earlier project plan target marker tracking was not part of it, but it was decided to add this operation in our new plan.

In addition we may also consider pin point touch down.

NB: Target marker tracking(TMT)

Markers are identified within photos and positions are reflected into orbt controling.

What is wanted in TD1-R1-A :

Confirmation of control precision.

LRF properties.

NB: with LRF only measurments will be taken and they are not immediately used for actual controling.

What is wanted in TD-R3:

Confirmation of control precision

Incorporate LRF measurments into control programme

If possible release target markers ™

P21

Rehearsals

14-15 October: TD1-R1-A (2nd touch down rehearsal)

24-25 October: TD1-R3 (3rd touch down rehearsal)

Press briefings

16:00 23 October
11:00 8 November

End of this briefing

P









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Guest_mcmcmc_*
post Oct 12 2018, 07:40 AM
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Guests






Just in time for next mission, here it is a fully functional simulator:
https://programmi.000webhostapp.com/hayabus...simulator3.html


Changes:
Added speed to realtime data
Added speed to history chart
Moved/resized ryugu/H2 schematic
Added decimals to rovers images sizes in ONC
(Invisible: added speed data to history log)


Plans for the future:
Add a box with a zoom of the chart on last 72 hours.
Add a box with a zoom of the chart between 0 and 500 meters (or configurable).
Add the schedule for next missions.
Add playback function for previous missions; in the meantime you can use separate pages to perform a replay of MINERVA release mission and MASCOT release mission. Players are still in beta so pay attention not to move mouse over images until they are fully loaded or they will stop loading.



Next missions:
14-15 October: TD1-R1-A (2nd touch down rehearsal)
24-25 October: TD1-R3 (3rd touch down rehearsal)

Next press conferences:
23 October-16:00 JST (07:00GMT)
8 November - 11:00 JST (02:00 GMT)
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pandaneko
post Oct 13 2018, 01:34 PM
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I was watching the last and latest press briefing once again and I noticed that my earlier translation needs improvements.

TD1-R1-A: This is exactly the same operation as the very first rehearsal, which was aborted due to LIDAR not feeling very well.They are
will be trying to repeat the same operation.

TD1-R3 : This is a new rehearsal based on the findings of TD1-R1A (JAXA said that this operation could be named as TD-R2).

During Late November to December H2 will be hidden behind the Sun, so other operations will be running.

And, by far the most important is that the first touch down operation will be delayed into the latter half of January 2019, simply
because the surface is so violently rocky.

P
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Therion
post Oct 14 2018, 07:08 AM
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There is new press release by DLR with some new images and details about MASCOT landing:

Numerous boulders, many rocks, no dust: MASCOT's zigzag course across the asteroid Ryugu


mcmcmc: That is very nice simulator! Thank you for that : )
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yoichi
post Oct 15 2018, 04:59 AM
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https://twitter.com/haya2e_jaxa/status/1051693960429633537
HAYABUSA2@JAXA‏ @haya2e_jaxa
The material from the press briefing that was held on October 11 is now available on the project website. Content includes:
(1) Report on the separation of MASCOT,
(2) Touchdown rehearsals and plans.
http://www.hayabusa2.jaxa.jp/en/enjoy/mate...1011_ver7en.pdf
13:39 - 2018年10月15日
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Guest_mcmcmc_*
post Oct 15 2018, 06:40 AM
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Guests






Theorical MASCOT size in ONC-T camera crossed 1 pixel, so it could be visible from now on, at least as a bright dot where no bright dots were visible before.
MINERVA rovers still around 0.6 pixel.
But please note that most of the released images are form ONC-W, which has 1/10 resolution of ONC-T.
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