Akatsuki Venus Climate Orbiter Options

[pandaneko]

Page-19

Test observation result (1) by LIR（mid infra red camera）

(graphics here)

・ Functions confirmed normal. Currently conducting continuous near normal observation

・ Observed cloud top temps in line with past average temperatures

・ Arc structures were found in the early evening side sitting astride southern and northern hemispheres

immediately after orbit insertion on 7 December 2015. These continued to exist for the next four days.

Phenomenon of this kind had been unknown.

・ Highest temperatures were found in the southern polar region, judged from the images thus far obtained

・ Filament like low temp regions exist north-south in lower lattitude zone

Image processing by courtesy of National Institute of Advanced Industrial Science and Technology

Page-20


Test observation result (2) by LIR （mid infra red camera)

(graphics here)

Continous images taken by LIR from 31 January to 2 February 2016 as Akatsuki passed the nearest Venus point (※)

Akatsuki obtained 4 to 5 images every 2 hours everyday. During this period the characteristic temp structure seen

over 7 to 11 December was not identified.

※ Note tht images of 1 and 2 February are enlarged twice that of 31 January

Image processing by courtesy of National Institute of Advanced Industrial Science and Technology

Page-21

Test observation result (1) by UVI (ultra violet imager)

(upper right, above the graph)

Observed frequency ranges

(inside the graph, lower bttom)

Venus reflectance

(vertical scale, Y-axis)

Reflectance

(horizontal scale, X-axis)

Frequency (μm)

・ UVI takes images of solar ultra violet lgiht reflected from cloud tops. Brightness level changes

according to the amount of absobing materials and the observed patterns move in unison with the clouds,

enabling cloud velocity calculation.

・ Akatsuki's UVI makes use of frequencies used by other past probes and also the absorption frequency

of SO2, whic is the main component of the clounds. Origins of these clouds will also be investigated

P

[pandaneko]

Page-22

Test observation result (2) by UVI (Ultra violet imager)

3 successive images of clouds taken by UVI every 2 hours (14:10UT、16:10UT、18:10UT）, 2 days after insertion on 9 December 2015

Resolution: approx. 70km/pixel

Page-23

LAC (1) (Lightening and atmospheric camera)

Are there lightenings on Venus?

️ This is the subject of arguments for more than 30 years by now including papers in Nature and Science

️ Lack of decisive observtion by dedicated instruments

️ If detected this time it may lead to clarification of the mechanism by which vertical atmospheric movement takes place

Everybody is waiting for decisive evidence from LAC

Roughly 50:50 about the existence, judged from past publications

(Inside the square, there are two sets of chracter srtings, left and right)

(Set of left, top-bottom)

Optical observation

Venera 9/10 P
Pioneer Venus N
Vega baloon N
Galilleo N
U. Arizona ground observation P

Radio wave observation

Venera 11/12 landers P
Pioneer Venus P & N
Galilleo P
Cassini N
Venus Express P

P: positive, N:negative

P

[pandaneko]

Page-24

LAC （Lightening and atmospheric camera） （2）

Unique instrument dedicated to planetary lightening observtion

Current status and prospect

・ Function confirmed by starting up the high tention current on 20 January 2016

・ Voltage to be increased in steps to the level required for regular observatin

・ Full scale observation is expected to start in June 2016. Operation is only possible for one hour every 10 days

as it needs to be done in darkness

(below left graphic)

Recording is made approx. 30,000 times per second to seperate out lightenings from noise

(inside graphic, clockwise)

avalanche photo diode array
band pulse filter array
lens
Solar light shutter filter

P

[JRehling]

Thanks for all that you're doing, pandaneko! It's really wonderful to know that Akatsuki is delivering such fantastic science after its long odyssey in interplanetary space.

I'd like to understand the ways in which Akatsuki is providing data that Venus Express did not, and the ways in which their observations overlap. I may try to list that (or find someone else's list). It seems like Akatsuki is going to give us an excellent account of the motions in Venus' atmosphere – better than we have for any world besides Earth.

[pandaneko]

Page-25

Test observation result (1) by Radio wave occultation (RS)

• Radio waves reaching earth ground stations will slightly change in signal strength and frequencies if they go through

Venus atsmosphere when Akatsuki hides behind Venus and when it reappears from behind.

We can then find something about the structure in vertical direction of Venus atmosphere, thereby augumenting

observations made by other cameras in understnding the horizontal structure of Venetian atmosphere.

• Carrying on board USO（Ultra-Stable Oscillator）, as the very stable radio wave source

• Initial observation was made on 4 and 25 March 2016

(characters on the graphics are not translated)

P

[pandaneko]

Page-26

Test observation result (2) by Radio wave occultation (RS)

(graphics upper left)

Akatsuki's motion on 4 March as seen from earth

(graphics lower left)

Temporal variation in frequency

Frequency shift (Herz): (vertical axis)
Time lapse in second from observation start: (horizontal axis)

Black line: predicted value in absence of atmosphere
Red line: actual observation

(grapics right)

Temp. variation with height

Height (km): vertical axis
Temp (K: absolute) : horizontal axis

(below grapicd right)

Complex layer structure can be seen.
How it is related to atmospheric motion will be examined
as more data comes in from other cameras

P

[pandaneko]

I am now in the Philippines since yesterday, finding it difficult time for translation.
I will keep trying, but full scale translation may be delayed into next month.
Also, unsure about internet stability in some places to come.

P

[JRehling]

I was curious about the comparative abilities of Venus Express and Akatsuki. This is not easy to capture with just one number or a couple of numbers: The instruments and orbits vary in several ways, and the details of Venus itself contain unknowns (which is why we explore it!). However, one fact that emphasizes the value of Akatsuki begins with the failure of Venus Express's PFS instrument. Though Venus Express was a great success, the loss of that instrument left the mission blind to a certain range of long-IR wavelengths. As a result, VEx imaged Venus at wavelengths up to 5 µm, but no longer. PFS would have taken that all the way up to 45 µm, but that did not take place.

Akatsuki images Venus at wavelengths up to 10 µm… so this is part of the mission's distinctive value: the range from 5-10 µm. This means that Akatsuki can directly measure temperature variation in and above the clouds of Venus.

I was curious about this, because Venus Express led to the discovery of a "cold collar" quite high above the cloud layer. But upon reading that work, I see that it was very clever analysis, but was done by calculating the temperature from other measured qualities, and not directly.

So, it may be difficult to contrast the capabilities of the two missions in a completely straightforward manner, but the ability to remotely measure temperatures at the cloud layer is what makes Akatsuki distinctive. This will presumably result in higher spatial/temporal detail than the work done with VEx observations. So one thing to look for is an improved understanding up upper atmosphere circulation patterns. Probably, the data already collected is sufficient for revolutionary advances in this understanding.

I look forward to seeing the work that all of Akatsuki's observations will lead to!

[pandaneko]

Page-27

3. Science made possible by data obtained

Page-28

Example 1: Research into upper most structure of the clouds (IR1+IR2+LIR+UVI)

(Here, there are 3 boxes with character sets in red. Between the 1st and 2nd set there is a small blue box. Translations are from
upper left to the right hand most with a dip pointing upward. That is to say 4 boxes in a gentle stream, irrespective of size and colour,
generally from left to right)

Box 1:

IR2 daylight observation can look at the uneveness of the cloud tops without being affected by temperatures.

It is estimated that because the lightness above 50 °in lattitude is roughly one third of that in lower lattitude areas
cloud tops are lower by 4km.

Box 2:

IR2 dalight observation

Box 3:

LIR observation can look at the temp. distribution of cloud tops.

We know cloud tops are lower above 50 °(IR2) and yet temperatures are not much different. It seems to suggest there are differences

in atmospheric temp. structure.

Therefore, we would like to investigate, using the large scale circulation model, downward stream mechanism in higher lattitude region.
IR2
Box 4:

Minute uneveness at cloud tops (IR2), cloud top temp. (LIR), SO2 distribution and ultra violet light absorbing materials (UVI),

subtle contrast patterns by IR1

We would like to investigate how these are related to one another. In so doing we would like to understand how upper atompsphere's

thermal balancing affects circulation dynamics.

(Hereafter, there are two entries that need translation, one graph on left and one graphics on right)

Re graph on left :

the vertical axis is reflection rate, and horizontal axis is distance from Venus centre, with the centre at origin



With the graphic on right there are character sets in three columns, left (C-1), middle (C-2), and right (C-3).

C-1: There are (meaningwise, not apperancewise) 9 character sets from top to bottom. These are simply numbered as follows.

1. Altitude difference in Tempt. and sulfulic acid vapour distribution (radio wave occultation)

2. Atmospheric lights (lightening and atmospheric camera)

(These two charcter sets appear white in colour, whereas followings appear black)

3. Sulfur dioxide (ultra violet imager)

4. Cloud temps (mid infra red camera)

5. Lower clouds (1 and 2 micron cameras)

6. Wind velocity vector (as seen from clouds motion)

7. Carbon monoxide (2 micron camera)

8. Lightenings (lightening and atmospheric camera)

9. Water vapour (1 micron camera)

C-2:

Volcanoes and ground materials properties

C-3:

1. Stratsphere
2. Clouds
3. convection zone (there may be a special term for this, P)
4. ground surface

P

[pandaneko]

Page-28 omission

(small box on lower left bottom graph)

1:3 contrast corresponds to 4km difference in cloud top height

Page-29

Example 2: Formation and maintenance mechanism of cloud layers (IR1+IR2+RS)

(layout of this page is complicated. Apart from the tilte on top there are 4 boxes with outward pointers. 3 of these have character sets
red in colour. The left most box characters are all black in colour.

(In the following notation Box-1 is the top right box with red characters. Box-2 is the left hand box with characters all in black.
Box-3 is the vertically oblong box with red characters. Box-4 is the horizontally oblong box with red characters in it.)

Box-1:

Remove clouds on IR1 night image by referring to IR2 image. We will be looking at chemical reactions and physical properties of
ground materials by gaining a precision map of ground temperatures and radiation rates.
IR1夜面
Box-2:

We will be doing cloud tracing and minute (or subtle) modelling of clouds in order to understand how the huge north-south structure
is formed.

Box-3:

Look at the cloud particle size by IR2's 1.735 and 2.26 mm observation. By drawing brightnesses in two different wavelengths
on a (spread?) graph we can group them into different sizes.

Box-4:

Capture the position of RS radio wave passage almost simultaneously by IR2.

In so doing we wish to clarify the formation/maintenace mechanism by comparing cloud structure and gradation
with temp. structure/sufulic acid vapour density.

(in addition to above 4 boxes there are 3 smaller blue boxes with white characters. They are, from left to right)

Box-1: IR2 night surface
Box-2: IR1 night surface
Box-3: Radio wave occultation observation

(Inside the box with yellow lines) :

Vertical characters on right : convection zone
Horizontal characters at bottom: ground surface
(Here, background graphic is the same as that on page 28)

(at lower left bottom there are two smaller night side Venusian images. The characters on these are from left to right)

1.74 miron and 2.3 micron captured by Galileo NIMS

(with the small graph at very bottom in the middle) vertical axis is the brightness at 1.74 micron, horizontal at 2.3 micron)

(finally, with the graph on lower bottom right)
vertical axis is height (km) and horizontal temp. in (K absolute), and the character on the graph itself means clouds.

P

[elakdawalla]

I just want to chime in a note of thanks to you for your work in translating these documents, pandaneko.

[pandaneko]

Page-30

Example 3: Clarifyinng mechanism for complex patterns (UVI+LIR)

(1st character set after above in yellow box):

In particular, complex abosrption patterns in dark area

(2nd character set):

Are solar light absorbing materials lifted from lower height?
Are they newly chemically produced at cloud tops?
Are they moved horizontally?
What kind of convection, pulsage, random flow currents are involved?

(3rd character set in yellow box):

Very clear boundary between dark and light regions

(4th character set):

In particular, complex absorption patterns in dark area
Is there a barrier of horizontal mixture of absorbing material and haze (translation unsure, P)?
Is new aerosol produced in a particular area?

(5th character set):

Clarify air mass transport and change (?) process at cloud top from observing distribution of absorption materials and haze (UVI),
cloud temp. variation with height (LIR), wind velocity disribution form cloud tracing

P

[pandaneko]

I have this nagging thought. In fact, I have had it for long time by now.

If Akatsuki was able to enter a kind of orbit around Venus with its smaller
engines, then why did they bother with the larger engine that failed?

They could have designed a craft with a few more of these smaller engines and
made Akatsuki go around in a proper circle? Tha wouod have been a lot cheaper?

P

[Hungry4info]

I can't say for certain that this is the case, but the most obvious reason to me would be the approach velocity and how much Delta-v was needed to reach orbit. Akatsuki approaching Venus direct from Earth required a much bigger VOI burn than the lower-velocity approach late last year.

[pandaneko]

Page-31

Example 4: Clarifying transport mechanism of materials for sulfuric acid clouds (UVI+RS+IR2)

(left hand graphic title):

Image of north to south-height cross section

(numbers extreme left are height in km)

(on the lefthand grapic there 8 boxes and they are numbered anti-clockwise such as GB1, GB2)
(character at lower left bottom on graphic is equator)
(character at lower right bottom on graphic is poles)

GB1: Generation of H2SO4 from SO2, H2O
GB2: Upward transport of SO2, H2O？
GB3: Condensation in upward flow of H2SO4？
GB4: Circulation of SO2, H2O, CO？
GB5: Decomposition of H2SO4 and generation of SO2, H2O
GB6: Evaporation of H2SO4？
GB7: Unknown circulation
GB8: Transport of cloud seeds and CO

(directly below left hand graphic):

Clarify the mechanism in which sulfuric acid clouds are formed by the circulation that penetrates cloud layers
from observation of SO2 (UVI), H2SO4 by radio wave occultation, cloud amout data (IR2)

(There are ２ images and 1 graphic on right hand side)

(2 character sets above images are, from left to right):

Lighter = small amount of SO2
Darker = large amounnt of SO2

(character set below left hand image):

Reflection rate map derived from UVI images. We can see distribution of SO2

(character set below right hand image):

Image taken by UVI at 283nm（absorption of SO2）

(with the graphic at lower bottm right the only character set to be translated is):

Measure H2SO4 vapour by radio wave occultation

P