What follows is what was left of page 5, the graphic image in the middle

3-D observation of thick atmosphere (is the title of this graphic)

There are 9 lines all pointing to the image in the middle. Numbering corresponds to
those lines from top to bottom.

1. Temperature/sulfuric acid vapour altitude (radio waves protected (unsure about this
translation, perhaps something like radio waves unable to penetrate?)

2. Atmospheric lights (Lightening and atmospheric camera)

3. Sulfur dioxide (Ultra violet image)

4. Cloud altitude (Mid infra red camera)

5. Lower altitude clouds (1&2 micrometer camera)

6. Wind velocity spectrum (as judged by cloud movement)

7. Carbon monoxide (2 micrometer camera)

8. Lightening discharge (Ligthening and atmospheric light camera)

9. Water vapour (1 micrometer camera)

Character sets on the right hand side (Top to bottom)

1. Stratosphere
2. Sulfuric acid clouds
3. Troposphere

Page 6

Predicting success criteria achievement

Notation belows is as follows.
Circle : Success or good or done as intended
Cross: Not success or bad or not done as planned
Triangle: Between circle and triangle

R1-C4: All instruments normal

R1-C5: ＊ Some instruments deteriorated (currently checking)

R2-C1: Minimum success

R2-C2/3: Capture overall cloud structure by obtaining successive (every few hours) pictures by any one of the cameras
while in orbit over one week period in which clouds move around the planet in east-west direction

R2-C4: ○

R2-C5: ○

R3/5-C1: Full success

R3/5-C2: Carry out all the observations indicated on the right over the 2 year period which is the time scale of
atmospheric changes of the cloud region

R3-C3: 1μm camera (IR1), 2μm camera (IR2), and Ultra violet imager (UVI) are used to clarify 3-D structurse of
atmospheric movements by obtaining successive (every few hours) Venetian images by mid-range infra red camera (LIR)

R3-C4: ○

R3-C4: spatial resolution 1/5, however

R3-C5: △

R4-C3: Conduct obervations by Lightening/Atmospheric light camera (LAC) in order to determine if there are
lightening discharges on Venus

R4-C4: ○

R4-C4: observation frequency 1/10, however

R4-C5: ×

R5-C3: Observe temperature structure of Venetian atmosphere by radio wave science

R5-C4: ○

R5-C4: observation frequency 1/10, however

R5-C5: ×

R6/8-C1: Extra success

R6/8-C2: Achieve one of those mentioned on the right

R6-C3: Conduct Venus observation over a period longer than 4 earth years in order to capture atmospheric strutural changes
due to changes in solar activity

R6-C4: ○

R6-C5: △

R7-C3: Obtain data relating to volcanic or physical structure of of Venus using IR1

R7-C4: ○

R8-C4: ×

R8-C3: Observe zodiacal light distribution inside the earth orbit by IR2

R7-C5: ×

R8-C5: ×

P

Page-7

Observation scheme

(Loooking at 6 square character sets placed anti-clockwise against the black background)

1. Observation scheme

2. Imaging whole planet:

Visualise, as a 3-Ｄ continous movie, changes in the amount of trace gases and the clouds movement pushed along
by high speed air stream

3. Looking at cloud layer structure from its side

4. To ground stations

5. Radio wave occultation:

Clarify layer structure by receiving the radio signals horizontally penetrating through Venetian atmosphere on the gournd stations

6. Close-up imaging:

Micro structure monitoring
3-D visualisation of cloud structure
Detecting thunder lightening on the night side

PS: "radio wave protected" on page 5 now should be read as "radio wave occultation" and also my apologies for not
saying earlier that tables are regarded as matrices and usual notation is used for components.

P

Page-8

Preperation status (1) for transition to normal mode of observation

• Orbit correction on 20 December 2015

- insertion into an orbit with a period 10.5 days with farthest distance of 360,000 km and
nearest distance of 1,000-10,000 km from Venus

• Preperation status

– Confirmed full functioning of high gain antenna (HGA)

– Cofirmed that flying in the dark side does not cause power or temperature problems with Akatsuki

– Confirmed that solar lighting from different directions will not cause teperatrue problems with Akatsuki

P

Page-9

Preperation status (2) for transition to normal mode of observation

• Starting up of instruments one by one -> generally smoothe

– mid infra red camera (LIR), 1mm camera (IR1), and ultra violet imager (UVI) up and running immediately
after insertion into circular orbit

– 2mm camera (IR2) on 11 December 2015, and ultra stable osciilater on 1 February 2016 up and running

• Thunder and atmospheric lighting camera (LAC)

– only chance of observation is when Akatsuki is in the dark side, every 10 days

– slowly proceeding by reducing the applied voltage in steps

– expected to move into normal mode of operation over the next 2 months or so

• operation status of individual instrument will be explained on later pages

P

Page-10

Preperation status (3) for transition to regular mode of observtion

• Communication was interrupted for a while on 20 February during the test observation phase, but it returned to normal.
The causes were examined and neccesary measures were taken.

• Newly arrived images were checked and instrument setup is being optimised.

• Transition to normal mode of observation will be starting in mid April.

P

Page-11

Results of test observation (Summary)

• 1μm camera （IR1）：Functioning properly.

The image taken immediately after insertion into circular orbit （VOI） was a cloud picture on the daylight side, but night side ground
images were also obtained later.

• 2μm camera（IR2）： Successfully captured the cloud picture on the daylight side immediately after insertion into circular orbit.

Clyogenics is being optimised for optical and sensing elements. Consequently, success rate in capturing night side images is steadily
increasing.

• Mid infra red camera（LIR）： Functioning properly.

Already near normal, successive image capturing has been conducted and exceptionally interesting hitherto unreported phenomena
were discovered.

• Ultra violet imager（UVI）： Functioning properly.

It has been rarely used since VOI 、because Akatsuki has been largely flying in the night side until now . This camera is meant for
day side observation only.

It will be used for continous observation from April when the day side comes into view.

• Lightening and atmospheric light camera（LAC）： The voltage applied for the detector has been slowly increased, but observion has
not yet started.

• Radio wave occultation observation（RS）： It has been confirmed that the frequency stability of the ultra stable oscillator （USO） has
not deteriorated.

The first radio wave occultation observation was conducted on 4 March using the USO.

P

Page-12

Observation range of individual instrument

(There are 9 lines on the lefthand side of this graphics page, all pointing to the image in the middle. Numbering corresponds to
those lines from top to bottom)

1. Temperature/sulfuric acid vapour altitude (radio wave occultation)
2. Atmospheric lights (Lightening and atmospheric camera)
3. Sulfur dioxide (Ultra violet image)
4. Cloud altitude (Mid infra red camera)
5. Lower altitude clouds (1&2 micrometer camera)
6. Wind velocity spectrum (as judged by cloud movement)
7. Carbon monoxide (2 micrometer camera)
8. Lightening discharge (Ligthening and atmospheric light camera)
9. Water vapour (1 micrometer camera)

(and at the very bottom, from left to right)

Ground surface material/active volcanos (1 micrometer camera)

Ground surface

(Character sets on the right hand side (Top to bottom))

3-D observation of thick atmosphere

1. Stratosphere
2. Sulfuric acid clouds
3. Troposphere

P

That is tantalizing. Thanks for all this hard work, P.

Page-13

2. Prepertion status of individual instrument on board Akatsuki

Page-14

(Left hand side, from top to bottom)

Observation result by IR1（1mm camera）

Unevenness is emphasized on the image

(Here is the left hand side image)

Wind velocities are estimated from cloud movement

・ possible to map wind distrbution at 60km altitude
・ possible to map wind distrbution at different altitudes using different wave lenghts
・ It is expected that we will be able to see where the super rotation is started

(Below the image on the right)

Day side raw image at 0.9mm
at around 13:50 on 7 December 2015
Distance to Venus: 68,000km

Page-15

Observstion result by IR1（1mm camera） (2)

(comments on the left hand side image)

Night side raw image (right) at 1.01 mm
44,000km on 21 December 2016
Right underneath Akatsuki at +30 lattitude and +670 longtitude

・ Terrain is mainly visible
・ It is hope that we will be able to find mineral composition at ground surface
・ Continous observation is hoped to lead to information on the interiod of Venus

(comments inside the left hand side image)

Pioneer Venus Altimeter data
Aphrodite
lattitude

(comments below the right hand side image)

Dark spot lower left is the Aphrodite continent
It is dark because this spot is 4km higher than surrounding areas and colder by 30K, resulting in smaller thermal radiation

P

Thank you so much pandaneko

Been waiting for your translation of Page-15.
Beautiful image.

What a wonderful mission.

Page-16

Result of observation (3) by IR1（1mm　camera）

(Caption on the left empty space)

0.90mm night side raw image
31 January 2016
Dark spot near equator is the Aphrodite continent

(title on the left)

11:36UT 91,000km
Right below Akatsuki
Latitude:+1° Longtitude:102°


(title on the right)

13:36UT 76,000km
Right below Akatsuki
Latitude:+1° Longtitude96°

(inside image on the riｇht)

2 hours later

P

Page-17

Observstion result (1) by IR 2 （2mm camera）

(2 captions on the left)

Electricity read out boundary within the detector element

Night side-Day side boundary

(on the border between two images)

Night side observation

Left) Night side image taken of Venus at 2.26mm on 13 March 2016

Page-18

Observstion result (2) by IR 2 （2mm camera）

(2 captions on the left, top to bottom)

Cloud top height is responsible for streaky pattern

Cloud tops are lower above 50° latitude

(between two images)

Day side observation

Day side images taken of Venus at 2.02mm on 14 March 2016 (above)

and 11 December 2015 (left)

(at very bottom)

Cloud tops are brighter if higher and darker if lower, through CO2 absorption

P

I now have located a copy of another, earlier JAXA report put up by Explorer in November last year.

I have started translating it and I will put up my translations immediately
after the current series.

I view it as making good reading for undergraduates, possibly also for MSc
students interested in this subject.

P

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

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

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

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.

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

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

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

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!

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

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

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

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

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.

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

the orbit that Akatsuki has entered is not optimal and a few of the scientific objectives have been compromised

Thank you for this. Thank you.

P

No spacecraft has ever entered a close-in circular orbit around another planet without aerobraking. Orbits like that have only been achieved at Venus (Magellan being the only case) and Mars (several cases, but much less planetary mass).

An elliptical orbit with a low periapsis is pretty good for many scientific purposes. Akatsuki, like Venus Express, Mars Express, and all pre-Nineties Mars/Venus orbiters are/were able to get periodic close-ups along with regular global monitoring. Given that Venus doesn't have seasons, it seems like a pretty good option to have a Venus atmosphere observer in an orbit like Akatsuki's, to collect both close-up and global monitoring, although an orbit like that would have drastically compromised the goals of surface-mapping missions like Magellan or Mars Reconnaissance Orbiter.

Page-31

Example 5:

(title):

Clarifying atmospheric motions by cloud chasing (UVI+IR1+IR1 (must be 2?, P)+ LIR)

(just below mini image of Venus, above earlier graphic):

Obtained wind velocity distrbution by analysing 3 images (at 365mm and every 2 hours) taken by UVI

(just above wind vector diagram):

Wind velocity distribution in equator region (S Latitude 25 ° -　N Latitude 25 °）

(immediately below wind vector diagram):

Atmospere flows by super rotation, but motion's spatial pattern changes constantly. By analysing, at a number of
different altitudes, we aim to find out what kind of fluid waves exist and how they are related to super rotation, and
how they are responsible for vertical circulation of Venusian atmosphere.

P

Thank you for this. "periapsis" and a counterpart to it are the words I should have been using
in some places of my translation. Instead, I always use "nearest Sun"etc etc because I can never
distinguish them and remember which is which.

It took me 15 to 20 years to learn the difference between latitude and longtitude, after all.
So, my excuses...

P

Page number of the last translated page shoud be 32, instead of 31.

Page-33

Observation results (summary)

Same as page-10

(After this page there are some more on instruments, mainly. I think I will do them, if not all,
as students may not be that familiar with them)

P

Page-36

IR1: 1mm camera

By using 1 mm wave length which enables the camera to see below Venusian clouds down to ground level we aim to:

cloud movements in lower atmosphere, water vapour distribution, mineral composition of ground surface, existence of
active volcanoes etc.

1mm camera IR1

Mass: approx. 6.7kg ※
Field of view: 12°
Detector: Si-CSD/CCD (1024 pixels×1024 pixels)

Observed wave lengths (targets)

1.01 mm （night： ground surface, clouds）
0.97 mm （night: water vapour）
0.90 mm （night: ground surface, clouds）
0.90 mm （day time: clouds）

※ including circuits (approx. 3.9 kg) shared with IR2

P

Page-37

IR2: 2mm camera

1. By using wave lengths near 2mm which alow us to penetrate Venusian clouds we aim to obtain basic data for
lower atmospheric circulation and cloud physics via cloud density, cloud nucleus size, and carbon monoxide distribution.

2. By observing, before reaching Venus, zodiacal lights we aim to clarify the behaviour of interplanetary dusts.

2mm camera: IR2

Mass: approx. 18kg ※
Field of view: 12°
Detector: PtSi-CSD/CCD (1024×1024)
Wave length (observation target）

1.735mm （night: clouds and nucleus size distribution）
2.26 mm （night: clouds and nucleus size distribution）
2.32 mm （night: carbon monoxide）
2.02 mm （day time: cloud top altitude）
1.65 mm （Zodiacal lights）

※ including cryos and circuits commmon to IR1 (approx. 3.9kg)

P

Page-38

LIR: Mid infra red camera

This camera is meant to capture cloud temperatures using 10mm wave length, thereby clarifying wave motions
at top cloud layers, convection activities, and wind velocity distribution at the night side cloud top altitude.

Mid infra red camera: LIR

Mass: approx. 3.3kg
Field of view: 12.4×16.4°
Detector: unclooled borometer (248×328)
Observed wavelength (target): 10 mm （Day time/night time： cloud top temp.）

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UVI: Ultra violet imager

By imaging the distribution of sulfur dioxide responsible for cloud formation and unkown chemical substance
which absorbs ultra violet light and their variations we aim to obtain wind velocity distribution at cloud top levels.

Ultra violet imager: UVI

Mass: approx. 4.1kg
Field of view: 12°
Detector: Si-CCD (1024×1024)
Observed wavelength (target):

283 nm: （daytime： sulfur dioxide at cloud top level）

365 nm: (night time: unknown absorbing substance）

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LAC: Lightening and atmospheric light camera

1. By imaging the pale light emitted by oxygen molecules in the upper layer of Venusian atmosphere at around 100km
we aim to visualise the variations in daytime/nightitme circulation and atmospheric wave motion.

2. By high speed exposure of 30,000 times/second (temporal resolution of 32msec) we aim to put a final end end to
ongoing argument about the existence or otherwise of Venusian lightenings.

Lightening/atmospheric light camera: LAC

Mass: approx. 2.3kg
Field of view: 16°
Detector: 8×8 APD matrix array
Observed wavelength (target):

777.4nm: （night： lightenings）
480-650nm: （night： oxygen molecules atmospheric light）
557.7 nm: （night： oxygen atoms atmospheric light）
545 nm （for comparison purposes）

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USO: Ultra stable oscillator

This is used for radio wave occultation.

We can gain information about vertically propagating wave motion and thermal structure of Venusian atmosphere
and its temperature variation with altitude by monitoring changes in strength and frequency of the radio waves reaching earth
through Venusian atmosphere.

Ultra stable oscillator: USO

Mass: approx. 2kg
Wavelength :

USO frequency: 38MHz
Transmission frequency: 8.4GHz

Target: Temp., sulfuric acid vapour, electron density

[graphic image: radio wave occultation]

USO is fixed inside the satellite

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In the immediate wake of this year's report I am now on to JAXA's November 2015 report.

There will be some overlapps with this year's and they will be omitted.

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Circular orbit insertion (plan) and observation scheme of Akatsuki

9 November 2015
JAXA
ISAS project team for Akatsuki


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Outline

・　Re-insertion of Akatsuki will be attempted on 7 December 2015 (JST).

・　We tried to insert Akatsuki into a circular orbit around Venus on December 2010. That attemt failed due to mul-functioning
of the main engine. Akatsuki is currently flying in an orbit around the sun.

・　The renewed attmpt this time will insert Akatsuki into an elliptical orbit with a higher furthest point from Venus using 4 attitude control
engines without relying on the failed main engine.

・　Mission objective is to continously observe atmospheric motion of Venus and ellucidate on the mechanisms of
its atmospheric circulation.

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Mission Objectives

1. Earth and Venus are similar in size and solar radiation inputs are also similar.

2. However, climates are very different. For instance, the high velocity wind (approx. 100m/sec) at the upper layer of
Venusian atmosphere, called "Super rotation", is noticeable.

It is a high velocity wind which goes around Venus in 4 earth days. Venus has a rotation period of approx. 243 days.

3. Why these differences? We want to know.

(On the diagram left globe is earth. Right globe is Venus)

(around earth peripheral):
Character set at 10:00 is Hudley circulation, at 11:00 Ferrell circulation, and at 11:50 Polar circulation.

Character set in upper hemisphere of earth is Westerly, and that near the equator is the trade wind.

Character set in the middle of Venus is Super Circulation, and at the bottom is the Meridian plane circulation.

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Mission objective

(above two graphical images)

By examining, 3-dimentionally, the motion of thick Venus atmosphere we wish to clarify the mechanisms controlling the climate
on Venus and compare them with those on the earth.

(graphical images here)
(Satellite graphic not translated)

(There are 9 lines on the lefthand side of this graphics page, all pointing to the image in the middle. Numbering corresponds
to those lines from top to bottom)

1. Temperature/sulfuric acid vapour altitude (radio wave occultation)
2. Atmospheric lights (Lightening and atmospheric camera)
3. Sulfur dioxide (Ultra violet image)
4. Cloud altitude (Mid infra red camera)
5. Lower altitude clouds (1&2 micrometer camera)
6. Wind velocity spectrum (as judged by cloud movement)
7. Carbon monoxide (2 micrometer camera)
8. Lightening discharge (Ligthening and atmospheric light camera)
9. Water vapour (1 micrometer camera)

(and at the very bottom, from left to right)

Ground surface material/active volcanos (1 micrometer camera)
Ground surface

(Character sets on the right hand side (Top to bottom))

3-D observation of thick atmosphere

1. Stratosphere
2. Sulfuric acid clouds
3. Troposphere

(below these two graphical images)

・　Why does the super rotation occur?
・　How does the Meridian rotation affect Venetian climate?
・　How are clouds produced that cover the entire surface of Venus?
・　Can lightenings occur in the atmosphere in which there are no ice crystals?
・　Are there active volcanoes?

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Hello-

You can get into orbit with big engines or with small engines. But if you
plan to use a big engine, and then only have small engines, things
get difficult.

Look at the Dawn mission at Ceres. They have an ion engine, which has very
small thrust. But the engine is designed to operate for a very long time.
This was in the design, and the approach to Ceres was designed for the
amount of thrust available.

The main Akatsuki engine seems to have burned for about 3 minutes out of
the planned 12 minutes. So the spacecraft did slow down significantly, but
not nearly enough. So it went past Venus pretty fast. Later, some burns
were performed, but I assume that the spacecraft was still moving fast
when it returned to Venus.

All they had available were the attitude thrusters. I do not now know anything
about the Akatsuki attitude thrusters, but in general they are quite small
compared to a main engine, say 1 to 5% as big. And they are not designed to
fire continuously for long periods of time. Attitude thrusters are designed
to give very short bursts that are very accurate. Akatsuki now had to use
thrusters designed for short bursts, for a very long continuous burn. I
suspect that the thrusters were never designed, let alone even tested, for
such a long continuous burn. If I had been the propulsion engineer on
Akatsuki, I would have been very afraid of a failure of one or more of
the thrusters.

So, the answer to your question is: you can use small engines or big engines.
But if your mission is designed for one or the other, it is very very
difficult to change the mission design because your hardware may not work.

I hope this may have been helpful. Sorry if it is not.

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Main events up to now
(right hand side strings, top to bottom)

・ Akatsuki was launched on 21 May 2010.

・ Insertion into Venus circular orbit was attempted on 7 December 2010. However, due to main engine failure firing was stopped
after 2 minutes and 38 seconds (planned firing was for 12 minutes) and Akatsuki is currentlyflying in an orbit around the sun.

・ With a view to the reunion with Venus in winter of 2015 three orbit corrections were made during November 2011. (DV1, DV2, DV3)

・ Further orbit corrections were made during July 2015. (DV4-1, DV4-2, DV4-3)

・ Akatsuki passed the last nearest Sun point in August 2015 (9th approach). Akatsuki is currently seen to be healthy
except for the main engine.

・ Re-insertion attempt is planned for 7 December 2015. (VOI-R1)

(left hand table, top to bottom)

21 May 2010 Launch by H2-A #17)

7 Dec 2015 VOI-1
1 Nov 2011 DV1
10 Nov 2011 DV2
21 Nov 2011 DV3
17 July 2015 DV4-1
24 July 2015 DV4-2
31 July 2015 DV4-3
30 Aug 2015 Nearest Sun (last and 9th)
Sept-Dec 2015 additionl corrections
6 Dec 2015 attitude change
7 Dec 2015 Re-insertion attempt VOI-R1

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cndwrid

Gracias y mucho obligado. Le entiendo muy bien.

Thaks.

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You can get the same velocity change out of your propellant load using a long burn with a small engine or a short burn with a large engine. However, for orbital insertion it is much better to have the burn near the peri-apsis as a given velocity change there brings the apo-apsis altitude down fastest. A short burn is thus better, as a long burn is spread over a large altitude range and so ends up giving a higher apo-apsis.

Like in Akatsuki, sometimes the rockets for the attitude thrusters and the main thrusters use the same fuel system, with the attitude thrusters using the fuel as a monopropellant (one-part) (like in the Martian, where Watney drips the fuel on a catalyst) but the main thrusters using the fuel together with an oxidizer as a bipropellant (two-part), typically hypergolic (self-igniting when mixed). When used as a bipropellant, the reaction is much more energetic, and provides greater thrust. When used as a monopropellant, the reaction is less energetic, but only requires pumping one liquid. The simplicity of only having to pump one fluid matters when you have multiple attitude thrusters around a probe. The thrust bipropellant provides is worth the additional weight and complexity if the delta-V required is high enough, like orbit insertion.