IKAROS JAXA Solar Sail mission Options

[punkboi]

IKAROS sounds really cool, is there any website to find more info on it?

Project Page: http://www.jaxa.jp/projects/sat/ikaros/index_e.html

Photos: http://jda.jaxa.jp/jda/p3_e.php?mode=level...mp;mission=9095

Description Page: http://www.jspec.jaxa.jp/e/activity/ikaros.html

[pandaneko]

Here is a movie about the Ikaros. It is a bit long, but it should give you some idea.

http://www.youtube.com/watch?v=7_6HOqBkP2o

Pandaneko

[punkboi]

Akatsuki and IKAROS about to be transported to the VAB for mating to H-2A rocket

http://twitter.com/ikaroskun/status/13593614219

And here are photos showing the aluminum plates containing 63,248 names and a Planetary Society-provided DVD containing 89,000 names (that were submitted online between December of last year and March 22) being installed onto IKAROS

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[JTN]

(We don't seem to have a dedicated IKAROS thread, so...)

Here is a movie about the Ikaros. It is a bit long, but it should give you some idea.
http://www.youtube.com/watch?v=7_6HOqBkP2o

In Japanese (which I can't understand), but that implies that a free-flying craft will be deployed from IKAROS just to take photos of the deployed sail. (Around 9:30.) K3wl.

Anyone know of an English-language (or translatable) resource that describes in detail what instruments/equipment (e.g., cameras, radios) are on board IKAROS? The press kit just mentioned is the best I've seen so far, but there's hints of stuff in the video that's not mentioned there (such as the aforementioned free-flyer).

I'm impressed how much functionality they've crammed onto the sail itself -- it's not just a passive sail, it has solar cells, a dust counter, "liquid crystal device that controls attitude by changing light reflection characteristics", etc. Hope it all works.

[Juramike]

JAXA set to launch a solar sail technology demonstration mission:
space.com article: http://www.space.com/businesstechnology/ja...ion-100516.html

[Paolo]

IKAROS has been spun up to 25 rpm in preparation for sail deployment within the next few days.
The counterweights that will draw out the sail masts have been deployed (see pictures in http://www.jspec.jaxa.jp/ikaros_channel/bn004.html

[akibow]

Now(6/5 0:54 JST) IKAROS is drawing out the sail by the centrifugal force.
The sail is still bundled.
Please refer to the animation below URL.
The bundled sail has been extended to the opening drawing out passing about 10m.
It is a state of about 35 seconds of this animation now.
http://www.youtube.com/watch?v=7Mb47w0vB04...feature=related

[akibow]

http://www.isas.jaxa.jp/home/IKAROS-blog/?itemid=549
----from IKAROS blog (japanese) , translated by akibow-----
Japan Aerospace Exploration Agency (JAXA) operated IKAROS (launched from Tanegashima Space Center on May 21, 2010(JST) until last night, and normally ended the second day of first-step of sale development.

However, there were some differences between the flight result and the simulation about development.
For more careful second development, we decided to examine the numerical value closely.

Therefore, the third day of first development and the second development is scheduled after Tuesday, June 8(JST).
We will announce schedule of the third day of first development and the second development as soon as we decides it.

The state of the explorer is excellent.

http://twitter.com/ikaroskun
----from IKAROS twitter (japanese) , translated by akibow-----
I'm telling many information to USUDA antenna.
They say that my movement is different from the simuration in pre-launch.
I am safe and energetic though movement seems to be different.

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[nprev]

Argh. Thanks very much, Akibow.

The IKAROS team is going about the deployment slowly & cautiously, and that's eminently sensible. It's gonna be done right!

[akibow]

related article.
http://www.planetary.org/blog/article/00002527/

[akibow]

http://www.isas.jaxa.jp/home/IKAROS-blog/?itemid=550

---translated by akibow---
TODAY'S IKAROS (6th,June)

IKAROS stands by with maintaing first development, length=5m or more.
Under this condition, the spin rate is increasing very slowly.
This is anxious for the developer of IKAROS , though is not an amount that becomes a problem.
it is the one about which it is anxious in a small symptom though it is not an amount that actually becomes a problem on because it is very slow.
The cause is not specified yet.
Many reasons are thought.
For instance, it is accelerated the rotation by the sunlight pressure like the pinwheel,
or an influence of the out gas or might be the one more by another factor.

We obsere this phenomenon by using this standby time. (Y)

6/6 IKAROS
Distance of the sun:1.04AU
Distance of the earth: 6,342,032km and right ascension =- 157.8° and celestial declinations =- 23.0°
Distance of Venus: 1.25AU
Posture: 7.4 rpm and spin rate = sun corner 15.0deg

[Paolo]

my impression is that IKAROS, in its current semi-deployed status is just spinning up like a propeller due to solar radiation pressure, which in itself would be proof that the sail is working

[akibow]

http://www.isas.jaxa.jp/home/IKAROS-blog/?itemid=551
---- summary ---
Japan Aerospace Exploration Agency (JAXA) will execute the third day of first developnent and the second development.

June 8th evening-midnight (JST) : 3rd day of 1st development + 2nd development
June 9th evening-midnight (JST) : confirm development

second development is full expansion of sail.
http://www.youtube.com/watch?v=7Mb47w0vB04...feature=related

[punkboi]

Sail Deployment Schedule for IKAROS

(SUCCESSFUL) June 2 (Wednesday) evening - midnight: pre-deployment check sail (motor and commissioning)

(SUCCESSFUL) June 3 (Thursday) evening - the night: the early development of first stage sail deployment

(SUCCESSFUL) June 4 (Friday) evening - midnight: Day 2 Official first stage sail deployment

June 08 (Tuesday) evening - midnight: Day 3 Official second (and final) stage sail deployment

Tuesday, June 09 (Wednesday) evening - midnight: Review of second stage sail deployment

http://www.isas.jaxa.jp/home/IKAROS-blog/

[BrianJ]

Another fascinating mission from JAXA :-) Hope it all goes well.

Can anyone tell me if it is planned to put IKAROS into orbit around Venus? Is it possible?
Or will there be a flyby?

Is there any information available about how much force/acceleration the sail experiences due to solar wind and radiation pressure?

Thanks and regards,
Brian

[ngunn]

See here for an interesting idea
http://www.unmannedspaceflight.com/index.p...st&p=160641

[Norm Hartnett]

Another fascinating mission from JAXA :-) Hope it all goes well.

Can anyone tell me if it is planned to put IKAROS into orbit around Venus? Is it possible?
Or will there be a flyby?

Is there any information available about how much force/acceleration the sail experiences due to solar wind and radiation pressure?

Thanks and regards,
Brian

Brian, the only info I've found is from http://en.wikipedia.org/wiki/IKAROS which states "IKAROS will unfurl its sail several weeks after launch, then will spend six months traveling to Venus, and then will begin a three-year journey to the far side of the Sun." Their source was an article in the The Guardian Weekly http://www.guardian.co.uk/world/2010/may/1...ros-japan-venus.

The Guardian article contains several errors so I'm not sure of its validity.

[punkboi]

Believe it or not, the Guardian is correct.

IKAROS will deploy a small free-floating camera once its solar sail completely deploys (which hopefully already happened) to photograph the spacecraft in all her diamond-shaped (or square-shaped, depending on your POV) beauty... I gotta check online to see if it has a second camera onboard that it could deploy once it reaches Venus.

To have a wide shot of IKAROS in deep space, with Venus in the background would be one of the coolest space images, ever.

[elakdawalla]

Lou said in an update from Japan that IKAROS does have two deployable cameras. I assumed both would be used right away to observe the sail after deployment. How close will IKAROS actually get to Venus? Any camera with a wide enough FOV to take in the deployed sail would probably only see Venus as a pretty small (and unbearably bright) light source, right?

[ugordan]

Yup, particularly the unbearably bright part. Remember the automatic exposure control on LCROSS' live camera and the Moon isn't even that bright.

[Norm Hartnett]

Lou said in an update from Japan that IKAROS does have two deployable cameras. I assumed both would be used right away to observe the sail after deployment. How close will IKAROS actually get to Venus? <snip>

I suspect that it will depend on how steerable the craft turns out to be. It is an incredibly sexy space craft, using the solar sail for both power generation via the integrated thin film solar cells and for steering via integrated LCD panels to produce variable light pressure.

Edit; that's right, I saw the comment about IKAEOS' future in Lou's post and couldn't remember the link.

[Hungry4info]

Not sure how to interpret it, but at the IKAROS twitter (translated with Google translator), IKAROS reports having been too tired to concentrate, and will try again tomorrow.

[elakdawalla]

I saw that, but thought it just meant that it was the end of a long day of work. IKAROS only communicates through Usuda, so there's a window of time very late in the day Japan time when they do all their work. I interpreted that just as IKAROS signing off for the night.

That being said, I spoke with Lou Friedman on the phone a couple of hours ago and he said he wasn't sure they really commanded the final stage of deployment last night. I won't be really confident it happened until I see pictures.

[punkboi]

Second stage sail deployment is scheduled to take place tomorrow...while IKAROS completed the full first stage deployment today

http://www.isas.jaxa.jp/home/IKAROS-blog/

[gilster]

Second stage sail deployment is scheduled to take place tomorrow...while IKAROS completed the full first stage deployment today

http://www.isas.jaxa.jp/home/IKAROS-blog/

It looks like full deployment of the boom structure was completed (i.e., first stage deployment), but from what I'm seeing on the IKAROS blog, the secondary deployment (the sail itself) should be ongoing. The most recent photo on the blog appears to show sail material.

[Norm Hartnett]

Hum, the latest (6/9 @ 17:33) post on the blog indicates a fouled tether. (I think)

[gilster]

Hum, the latest (6/9 @ 17:33) post on the blog indicates a fouled tether. (I think)

I hope you're wrong, but that photo looks troubling to me, too.

[marsbug]

The planetary society blog has a nicer (and I hope correct) interpretation.

[Norm Hartnett]

The planetary society blog has a nicer (and I hope correct) interpretation.

Much nicer, my Google translation came out;

2. Camera images after the expansion of primary
The image was deployed after the primary operation was conducted yesterday.
Strong sunlight, it looks a tether connecting the two overlap and sail body, the body close to the incident light in the shadows for the weak, the tether can see that reflected in the surface membrane and harness .

Hopefully elakdawalla's interpretation is correct.

[Hungry4info]

A google translation of the most recent IKAROS blog post.

The operation ended today as planned. We will report tomorrow to get further data, I would like once again after 11 days.
However, it is usual state of good IKAROS

[elakdawalla]

Here's a much better translation of that photo caption, provided by Lionel Ward:

These are photographs taken after yesterday's completion of primary deployment. Due to intense sunlight, in the photograph there is the appearance that the two tethers connecting the sails to the probe's body are piled on top of each other. However, since the side of the sail close to the probe's body is in shadow, and the incident light there is weaker, we can confirm that the tether and membrane harness are photographed.

[Hungry4info]

From the IKAROS blog via Google translator.

IKAROS planned today and confirmed that the state of posture data, images etc. to get done. IKAROS state is found to be made good.
For more data, so once the report tomorrow, please wait a moment.

[Hungry4info]

Success.

From the IKAROS blog.

Japan Aerospace Exploration Agency (JAXA) is May 21, 2010 (Japan Standard Time, as follows:
Like) was launched from Tanegashima in the application of the IKAROS, June 3
Began to hoist the sail, the distance from the Earth about 770 million on October 6 km at the Sail
Stretched, and was confirmed by photovoltaic power generation.
Continue to measure the status of PV power generation patents or photon acceleration using a pressure
We demonstrate Bisoreniyoru orbit control, navigation through the acquisition of solar sail technology

It ended with a final check image expansion operation yesterday, will announce the successful deployment of state to sail solar power. Also check the power of thin film solar cells on the surface of sail that followed, IKAROS minimum mission success achieved!
For images, etc. We will also open more channels of specialized pursuit.

Images.
http://www.jaxa.jp/press/2010/06/20100611_ikaros_j.html#pict
http://www.jspec.jaxa.jp/ikaros_channel/bn005.html

While the sail doesn't really look deployed from this awkward angle, remember these cameras are near edge-on with the sail and there is a large gap between IKAROS and its sail.

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[nprev]

Emily reports that the sail is fully deployed & IKAROS is power-positive; congratulations to the project and to JAXA!!!

This is truly historic; a pioneering first by any standard. Can hardly wait to hear how he (is IKAROS a he?) performs during his shakedown cruise!

[punkboi]

All that needs to be done now is for IKAROS to deploy those two free-floating cameras and photograph the sail in all its beauty

[Astro0]

Can't wait for the images from the free floating cameras.
Looking at that diagram above, it looks like the deployment-view cameras overlap, but it's a bit hard to find anything to match up in each image.
Rather than fudge it, here's a foreshortened polar view created from the four sail-deploy images with no overlap attempted.

[punkboi]

I hope they deploy that free-floating camera soon. Totally looking forward to seeing IKAROS in all its kite-shaped beauty

http://www.isas.jaxa.jp/home/IKAROS-blog/i....php?itemid=595

[Hungry4info]

Anyone notice the IKAROS twitter profile pic keeps getting sadder and sadder? It's practically crying a flood now. Hilarously cute.

[nprev]

Why would it be getting sadder? Is something not going well???

[punkboi]

Maybe it's getting sadder 'cause it knows that brother Hayabusa most likely doesn't have any samples inside its capsule. I kid.

[nprev]

Mmm...close! According to my wife, the latest tweets are an imaginary conversation between IKAROS & Hayabusa (messages of encouragement for the latter.) Guess the tears are for Hayabusa-san's impending EOM.

[punkboi]

IKAROS has stopped crying...while Akatsuki has been smiling the whole time. Must have had a beef with his older brother.

[punkboi]

Looks like the first of two free-floating cameras (DCAM 2) will be deployed from IKAROS today

http://www.isas.jaxa.jp/home/IKAROS-blog/?itemid=629

And the IKAROS Twitter avatar is happy again.

[Spin0]

Seems free-floating DCAM2 has been released and the camera twitters here: http://twitter.com/DCAM2


Heh, Ikaros and DCAM2 are twittering about imaging.

[punkboi]

Darn it. For some odd reason my Google toolbar won't automatically translate the DCAM2 Twitter page

[Tom Tamlyn]

Great picture of the fully deployed sail here (in case there's anyone at umsf.com who doesn't check Emily's blog several times a day.)

Are there any specs on how long the camera is expected to remain within wireless range? And what's the plan for the second camera? I like punkboi's suggestion of "a wide shot of IKAROS in deep space, with Venus in the background."

TTT

[nprev]

I've been wondering how long they'll stay near IKAROS as well. Also, do those things have some sort of attitude control? Can't figure out how they made sure that IKAROS stayed in the camera's FOV unless it was very precisely ejected.

[punkboi]

Naw, the cameras don't have attitude control... They're gonna drift off into deep space after being released from IKAROS. Check out the Youtube link below... The DCAM floats off in a spiral fashion after it is ejected from IKAROS...which would explain why the spacecraft is off-center in the image (which I'll provide below...despite Tom helpfully providing a link to the TPS blog )

http://www.youtube.com/watch?v=7_6HOqBkP2o...player_embedded

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[nprev]

Oh, okay, I get it now: The camera's actually spin-stabilized upon ejection. Thanks, PB!

[tolis]

Hi Brian,

I am not involved with the project myself, so someone should confirm the following:

If IKAROS is following (more or less) the same trajectory as Akatsuki, then it is not possible to insert in orbit around Venus.
The problem is that, although solar sails can in principle affect "large" changes in their speed (DV), they cannot do so quickly.
They are a bit like ion drives in that respect: they thrust gradually but continuously. To go into orbit around a planet,
you would need to gradually modify the sail's orbit around the sun using the solar radiation pressure force (SRPF)
until it is essentially identical to the planet's. I would imagine that, SRPF being quite flimsy a force, that process will take many years.

By the same token, however, the sail should flyby Venus at around the same time as Akatsuki enters orbit, probably at a distance
of several hundred thousand km or more. It could also be maneuvered to encounter near-Earth objects (asteroids or comets)
although I imagine that, for now, the technology demonstration objectives take priority over any other activity.

Regards,

Tolis.

[Norm Hartnett]

Hopefully some kind person here will be willing and able to explain how IKAROS is going to be able to maneuver using its LCD panels. I understand that by darkening and lightening the panels IKAROS can increase or decrease the light pressure (terminology?) thus increasing or decreasing its ‘thrust’ in relation to the sun. I also understand that, depending on its angle in relation to the sun, it can either slow or accelerate in relation to its orbit. What I have a great deal of difficulty envisioning is how it can change its attitude, pitch and yaw if you will. Given that the satellite has to rotate to maintain rigidity how can the LCDs modify its angle to the sun? Can they modify its rotation rate?

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[fredk]

This is just a complete guess, but I would think that they could control the LCD panels on different sides of the sail independently. Darkening/lightening the panels on one side would provide a torque that presumably would change the orientation of the sail to the Sun.

[ugordan]

What I have a great deal of difficulty envisioning is how it can change its attitude, pitch and yaw if you will. Given that the satellite has to rotate to maintain rigidity how can the LCDs modify its angle to the sun?

Perhaps they plan to alternate the LCDs to on/off and time it depending on rotational rate so that always the same "side" of the spacecraft relative to the sun is dark. This would over time slowly nudge the rotational axis in one direction.

EDIT: fredk beat me to it!

[Schillrich]

Hello,

I once found one abstract on the project page telling that it is indeed possible to change the rotation rate via the solar pressure on areas of the sail, or better that it will be part of the experiment to verify this technique. The idea behind that it not "simply" brightening and darkening of areas, but to switch between diffuse and specular reflection.

I also have one question (because the google translation of Japanese leaves me quite clueless):
Is there a difference between the 2 DCAMs (something about 'separate antennas' and 'only one has a receiver' comes out of google's translation attempts)? Has only one been deployed so far?

source: http://www.jspec.jaxa.jp/ikaros_channel/bn006.html

[Paolo]

I also have one question (because the google translation of Japanese leaves me quite clueless):
Is there a difference between the 2 DCAMs (something about 'separate antennas' and 'only one has a receiver' comes out of google's translation attempts)?

I think I understand that only DCAM1 has a receiving antenna on its housing on IKARUS, and DCAM2 uses that of DCAM1

[Schillrich]

I also came to that conclusion. But would that mean both have been deployed?

[punkboi]

What I have a great deal of difficulty envisioning is how it can change its attitude, pitch and yaw if you will. Given that the satellite has to rotate to maintain rigidity how can the LCDs modify its angle to the sun? Can they modify its rotation rate?

IKAROS uses its thrusters to position the main spacecraft bus in a certain attitude...which in turn tugs on the tethers attached to the sail membrane and causes the membrane to be pulled and positioned into different angles. There's a computer animation of this towards the latter part of the video below

http://www.youtube.com/watch?v=7_6HOqBkP2o...player_embedded

[Norm Hartnett]

Thanks punkboi, Schillrich, ugordan, and fredk, it becomes clearer to me now. IKAROS is a remarkably dynamic craft and I hope we get some detail on how its trip goes.

[punkboi]

IKAROS' spin rate has decreased from 2.5 rpm to 1.1 rpm to allow better stability of the sail membrane as it gets tested for attitude control

http://www.isas.jaxa.jp/home/IKAROS-blog/

[Schillrich]

Actually I understand it that way that it was decreased in order to allow attitude control experiments by reducing the angular momentum of the spinning craft.

[punkboi]

Heh, that's what I meant. I worded it wrong

[punkboi]

Hm. I thought DCAM1 was already jettisoned... I guess not

http://www.isas.jaxa.jp/home/IKAROS-blog/?itemid=646

Since IKAROS is spinning at only 1.1 rpm, I would assume the deployment of DCAM1 will be much more stable than that of DCAM2...and that IKAROS will be better framed (much more centered) in the DCAM1 images this time around

[BrianJ]

Thanks ngunn, norm and Tolis (and everyone else) for the great info. Sending IKAROS to Apophis (via one or more flybys) is an interesting idea. I have a hunch that it could be possible for an IKAROS type spacecraft to be captured by Venus or maybe Mercury (solar sails work better closer to the sun - not so good for outer solar system). Someone must have studied this possibility, I'll see what I can google. It would also be interesting to get some idea of the numbers involved regarding possible acceleration, dV, etc.

The complexities involved with attitude control of a (slowly) spin-stabilized flexible sail attached to a rigid "hub", using two different methods (hub thrusters / sail variable reflectivity), are fairly mind boggling. I can imagine the whole thing starting to "ripple" like a flag in the wind, or even just wrap itself up into a ball, if you don't do it right!

Amazing stuff.

Thanks and regards,
Brian

[Paolo]

From what I understand of the Google translation of the IKAROS blog http://www.isas.jaxa.jp/home/IKAROS-blog/i....php?itemid=647 it appears that the second camera pod is released today. It is to be jettisoned at a slower relative speed (details of the separation system and separation speeds anyone?) to conduct a longer imaging session from a closer distance.
Anybody knows also how long are the DCAM batteries supposed to last?

[djellison]

I would imagine the batteries last far longer than the RF link budget between DCAM and IKAROS can last.

[punkboi]

A previous IKAROS blog stated that the DCAM batteries...at least the one for DCAM2...is designed to last 15 minutes

[brellis]

15 minutes of fame

[Paolo]

First picture from DCAM1 released! http://www.jspec.jaxa.jp/ikaros_channel/bn007.html
from much closer to IKAROS than DCAM2

[Norm Hartnett]

According to today's blog post (6/22) they are adjusting the spin rate to "The spin rate will be selected to operate at optimum balance with light pressure" and they are seeking the optimum spin rate (now at 1.4 rpm). Also the GAP experiment is being activated under the charge of Kanazawa University.

[punkboi]

DCAM1 images finally released

http://www.jspec.jaxa.jp/ikaros_channel/bn009.html

[pandaneko]

Great picture of the fully deployed sail here (in case there's anyone at umsf.com who doesn't check Emily's blog several times a day.)

TTT

I am not very surprised about this. About 15,16 years ago I was chatting to a prof at ISAS about the anntena opeinng of Halca space intereferometry satellite and asked him about the possibility. He simply flatly said that he would be extremely surprised if it did open up.

Apparently, he had seen it fully opended up at Mitsubishi's kamakura factory and never believed it will open up in space, but it did...

Second generation is going up in 2012, and what follows is some info on that.

http://www.jaxa.jp/pr/brochure/pdf/04/sat24.pdf

Of course, opening mechanisms must be different, I think. Halca anntena was built of very fine metal mesh, as I remember. Ikaros anntena must have been a lot easier to open up, I think. After all, it is a membrane, not a metal mesh.

Pandaneko

[JimOberg]

To continue this line of thought:

What is the possible ultimate fate of Ikaros? Is there a maximum communications range?

Can the inspection camera be also used to image asteroids or comets during a fly-by five or ten years from now, or are they only in the jettisoned pods?? We can still do radio occultation science.

Can it achieve solar system escape velocity?

[gwiz]

To continue this line of thought:

What is the possible ultimate fate of Ikaros? Is there a maximum communications range?

Can the inspection camera be also used to image asteroids or comets during a fly-by five or ten years from now, or are they only in the jettisoned pods?? We can still do radio occultation science.

Can it achieve solar system escape velocity?

From the images I've seen, the on-board cameras are wide-angle, not suitable for distant objects.

[punkboi]

http://www.jaxa.jp/index_e.html

July 9, 2010 Updated
IKAROS: Acceleration by solar sail confirmed

The small solar power sail demonstrator "IKAROS," which successfully deployed its solar sail, was confirmed to accelerate by solar sail receiving solar pressure.

This proved that the IKAROS has generated the biggest acceleration through photon during interplanetary flight in history.

[elakdawalla]

There's much more info in the Japanese version (Google translate link)

[Paolo]

At last a release in English: http://www.jaxa.jp/press/2010/07/20100709_ikaros_e.html

[Paolo]

Meanwhile, IKAROS is also doing some science. There is a release today (in Japanese) about the first gamma-ray burst detection

[Norm Hartnett]

Some gems about the possible future of IKAROS from The Mainichi Daily News http://mdn.mainichi.jp/mdnnews/news/201007...0na012000c.html

The cellophane-like film of the sail is made of the same materials used for the electronic substrate of mobile phones, and it boasts an expected operational life of over 10 years even as it is exposed to strong radiation in space.

By the time IKAROS has approached Venus in six months, all the necessary experiments will have been completed, and the spacecraft will start orbiting between Earth and Venus without need for refueling.

[Paolo]

Apparently the solar radiation pressure attitude control experiment was successful! we have a true solar sail out there!
release (in Japanese only at the moment): http://www.jaxa.jp/press/2010/07/20100723_ikaros_j.html

[Norm Hartnett]

Solar Distance : 1.05AU
Earth Distance : 26105537km, ascension =- 141.2 °, declination =- 26.2 °
Venus Distance : 0.75AU
Attitude : spin rate = 1.5rpm, sun angle 22.4deg

For the last few days IKAROS was spun back down and the solar angle increased as JAXA continues to investigate sail trimming. Experiments in ranging are on going and increased emphisis is being given to acceleration. Since the 24th of July all attitude control is being handled by the RCD (LCD panels), a truely stunning breakthrough in propellantless deep space navigation.

[punkboi]

According to this animated image, IKAROS will arrive at Venus on December 18 (Japan time)...11 days after Akatsuki does

http://twitpic.com/2g57yr/full

[Norm Hartnett]

8 / 26 IKAROS
Solar Distance : 1.00AU
Earth Distance : 31401035km, ascension =- 130.8 °, declination =- 28.0 °
Venus Distance : 0.48AU
Attitude : spin rate = 1.3rpm, sun angle = 26.0deg

IKAROS has crossed Earth's orbit and is headed Sunward. The last few weeks have seen experiments with rotation rates going up to 2.0rpm and back down and sun angles reaching as high as 32.2 degrees.

From punkboi's post above it appears that IKAROS will be passing Venus on the "outside" as would be expected since it has been increasing its orbital speed since deployment.

[Norm Hartnett]

Soon , no communication zone . Set IKAROS autonomous operation is almost complete .
IKAROS to the upper surface of the earth is soon found success with . (Y)

9 / 9 IKAROS
Solar Distance : 0.96AU
Earth Distance : 32181854km, ascension =- 126.3 °, declination =- 28.5 °
Venus Distance : 0.35AU
Attitude : spin rate = 1.4rpm, sun angle = 29.9deg

I think this means that due to the angle of IKAROS vs location of the Earth IKAROS is losing com. Also they seem to be having troubles at their ground stations. I have seen no comments on when they expect to regain communications.

Does anyone (Emily?) have any further information?

[elakdawalla]

I actually just sent an email to a Japanese contact about this today. I can't quite figure out what these updates mean. I'll post a blog entry if I learn anything.

[elakdawalla]

Aha, it's not as bad as it seems. The problem is that Earth is passing through the sail plane, which is apparently a blind horizon for radio comms. Once Earth has gone through the sail plane to the other side, comms should resume. Today, Earth is within 13 degrees of the sail plane. IKAROS is being configured for autonomous operation during the communications blackout.

[Norm Hartnett]

Thanks Ms. E.

I was pretty sure that things weren't as bad as my worry wart self thought but my confident self just could not sort out the good data from the noise.

(Nice rant today BTW)

[Norm Hartnett]

In today's operation , IKAROS able to successfully communicate with !

While the folks running IKAROS were acting fairly confident about the four day communications blackout, their relief and joy as IKAROS reestablished com was evident in the 9-18 Blog entry. http://www.isas.jaxa.jp/home/IKAROS-blog/?blogid=12



9 / 18 IKAROS
Solar Distance : 0.94AU
Earth Distance : 31844918km, ascension =- 124.5 °, declination =- 28.5 °
Venus Distance : 0.34AU
Attitude : spin rate = 1.3rpm, sun angle = 29.0deg

[Paolo]

The October issue of the French magazine "l'Astronomie" (http://www.saf-lastronomie.com/revue/index.html) has a very interesting article on a French radio-ham who managed to receive the signal from Ikaros during June using a 3.5 m parabola.
unfortunately I don't have a scanner at hand...

[djellison]

Good old Amatuer DSN guys. There's a ham radio group in Germany with a dish that would rival the smaller dishes of the DSN itself.

[Paolo]

A report by the French radio ham is available here

[Norm Hartnett]

IKAROS has spin up today. This is a very long time 2rpm.
A high spin rate, increasing the spin stiffness (as a frame) in space
Try to maintain a constant attitude.
Conversely a low spin rate will be strongly influenced by movements of the solar light pressure.
Adjusting the spin rate means that a balance of both to take advantage of this
I can do to change the direction of the desired position.

The IKAROS 10/18
Solar Distance: 0.84AU
Earth Distance: 28891627km, RA =- 132.6 °, declination =- 23.5 °
Venus Distance: 0.11AU
Attitude: spin rate = 2.1rpm, sun angle = 4.3deg

(Earth Distance 0.19AU)

Sun angle has been decreasing for several weeks now I wonder if they are "coming about" and reversing the "thrust" vector? One of the animations I saw seemed to indicate that might happen as they approached Venus.

[Norm Hartnett]

The IKAROS 11/05
Sun Distance: 0.77AU
Earth Distance: 33318160km (0.22AU), RA=-146.5deg, Dec=-15.3deg
Venus Distance: 0.06AU (8975880km)
Attitude: Spin Rate=1.7rpm, Sun Angle=16.4deg

Blog entries are becoming sparser and apparently there are fewer communications periods as JAXA increasingly focuses on the Akatsuki Venus mission.

[Paolo]

while Akatsuki was being recovered, IKAROS also flew by Venus last 8 December, some 80,000 km away
http://www.isas.jaxa.jp/home/IKAROS-blog/i....php?itemid=786

[punkboi]

Interesting... I thought IKAROS wasn't suppose to pass by Venus till December 18

[pandaneko]

I am posing a very stupid question, I think...

Akatsuki has sped by Venus, right?, and IKAROS has done that, too? That means they are going in the same general direction. My question is this. Can they not direct IKAROS to Akatsuki and take a look at Akatsuki's nozzle skirt? After all, we have another 5 to 6 years.

As I am not sure as to what IKAROS's ultimate goal, I just thought that it can get closer and closer to Akatsuki. Does it have a telephoto lens, bet not...

With future missions we do need engineering cameras!!!

Pandaneko

[gwiz]

They passed Venus at very different distances, which means that IKAROS (80000 km) would have been less deflected by the gravity of Venus during the fly-by than Akatsuki (600 km). Add to that that Akatsuki also performed the incomplete injection burn as it passed the planet. As a result, the two would have been on rapidly diverging trajectories after the Venus encounters.

[Gsnorgathon]

In addition, Ikaros has only engineering cameras designed to monitor sail deployment. They're pretty low-res, and have a very wide field of view that would make getting a good view of Akatsuki very difficult. The danger of a collision between the two spacecraft would be too high.

OTOH, the thought of Akatsuki taking a self-portrait as reflected in Ikaros's sails is truly delightful! But will have to stay just a thought, alas.

[Hungry4info]

Akatsuki should cast a shadow, having IKAROS close by would allow something for that shadow to fall on. You could just image that shadow. I would figure it could be done at a greater separation than would allow for Akatsuki to image its reflection.

[djellison]

You can't be serious H4I, Ikaros and Akatsuki are going to be thousands, probably millions of miles apart.

[Hungry4info]

Oh I know. I thought it was understood we were just throwing ideas out there in a hypothetical situation.

...But will have to stay just a thought, alas.