IKAROS JAXA Solar Sail mission Options

[Vultur]

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

[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

[elakdawalla]

Mine was taken from the press kit too -- I think yours has more pixels but is just upsampled. Which is not to say that upsampling to make the image occupy more space on the screen doesn't help in interpreting the image; I just don't think it actually contains any more data.

[pandaneko]

Page 20:

4: Supplementary information

Significance of solar power sailing:

This is expected to lead to flexible operation of probes.

It is also expected to provide enough electrical power in the vicinity of Jupitor and beyond.

P

[pandaneko]

Page 21:

There are graphs and other structures with this page, but they are self-explanetary. So, my translation is only about IKAROS specs, as follows.

Main body size: 1.6 m in diam. and height 0.8 m

Membrane size:s 20m by 20 m, and membrane thickess of 7.5μm

Mass: 308kg, of this 16kg is the membrane mass

Orbit: direct flight to Venus

Orbit determination: range fidings and Doppler measurements

Attitude control: by spin

Propulsion: vapour and liquid equilibrium thruster and gas jet thrusters

Mission duration: longer than 6 months

Comms: 2 LGAs and 1 MGA

P

[pandaneko]

I will skip pages 22 and 23 as they are too obvious.

Page 24: Supplementary info on GAP

1. Small table header from left to right:

GRB name, trigger time, distance, alpha, beta, angle of entering, simultaneous observation

2. With the 3 graphs here vertical axis is intensity, horizonrtal time in seconds

Main text (jist of it) as follows:

GAP is a ganma ray burst polariser detector. It also achives simultaneous Compton scattering counting.

Power was switched one month after launch. Data is stored in memory and sent back to earth. No mulfunction to date. GAP detects polarisation of megnetic field.

P

[pandaneko]

Page 25:

4: Supplementary info on GAP

(Here, I am only translating gists of what this page says, P)

Primary objective of GAP is to measure polarisation of ganma ray bursts and try to understand the mechanism. However, it is only 4 months in operation and we have not yet meaure enough of these bursts.

Following report (what follows?, P) is based on the collaborative work with all those GRB satellites around the world with a view to determining the directions of these bursts.

Earlier page's list has data from Russian Konus satellie (K), US Fermi satellite (F), and US-Italy Swift satellite (S). For example, the burst, GRB 100826A (detected on 26 August 2010) was determined to be within the region surrounded by the blue frame with the graph here. Due to polarisation measurements IKAROS is providing additional accuracy.

P

[pandaneko]

Page 26:

4: Supplementary info on VLBI (multi tone transmitter)

Result of of experiments:

Succeeded in obtaining about 20 times more accuracy of orbit determination compared with earlier JAXA measurements (Hayabusa and AKATSUKI), with the thermal noise level of 50 pico seconds.

Objectives of the experiments:

This is a mission devoted to try out DDOR(Delta differential one-way range) techniques. Basically, very far radio emitting stars are used and the very long baseline interferrometry and triangulation is involved. Participants are as follows:

University of Tasmania: Hobart26m
DSN: DSS34 34m,DSS45 34m, DSS43 70m
ESA: Cebreros 35m New Norcia 35m
ATNF: Mopra 22m, ATCA 22m
Shanghai Observatory: Urmuchi 25m, Shanghai 25m, Konmei 40m
Japan, 32m, 34m, 34m and 64 m)

NASA JPL is quite active in this technology, and for instance, NASA DSN were deeply involved, when required, with DDOR determination of Akatsuki, almost everyday. Collaboration has been done before, but we lacked this essential element, multi tone transmitter, and this time we developped a dedicated transmitter and used it with 8 organisations' 15 antennas with 24 pases.


Comparison (orbit information) between Akatsuki and IKAROS data is as follows:

Akatsuki:

precision : (thermal noise) 700 pico seconds
accuracy : 1 to 2 nano seconds

IKAROS:

precision: (thermal noise) 50 pico seconds
accuracy: 50 to 150 pico seconds

This comparison was made around August 2010

P

[pandaneko]

What follows from page 27 on, I find it very difficult to translate (technical terms, mainly), but I will give it a try in the belief that even if my translation is not good some people with background knowledge may find them useful.

Page 27:

4: Supplementary info on VLBI multitone transmitter

We developped a DDOR digital base band converter (64 Msps/16 ch/4 bit, 4096 Gbps). 2 graphs here, one on left is the result obtained by this digital wideband system, and one on right is the data recorded by conventional analogue/narrowband system.

With conventional recording system you need to combine a couple of 8 MHz bandwidth analogue signals. The right graph indicates that the gain and the phase within the band are not flat enough.

With this new system it becomes possible to use weak qasor signals as calibrators and that will be useful with future wideband DDOR systems using Ka band.

Page 28:

4: Supplementary info on VLBI multitone transmitter

There is one graph on this page, which came from the observation made on 29 July 2010, using Usuda-Canbera baseline for VLBI observation.

Vertical axis is the delay residual (whatever it means, P) in nano seconds. Horizontal axis is the time ellapse from the start of observation in seconds.

Upperleft character string says "Lizzard constellation's star BL's delay residual"

Character string down right says "delay residual of quasor J1425-2513"

Character string to the left os it in blue says "delta DOR observed quantity"

The bottommost character string says "IKAROS delay residual"

There are 2 texts here on this page, the first one being explanation of the chart itself, and the second one is on future operations from now on. And, I am now going to paste those text down here for further translation. If it does not go well, then I will send this up anyway and try to upload another post.

On the graph, 6 groups of dots (I find only 5, P) relate to IKAROS' VLBI delay residual and those 3 upper left and another 3 upper right exists in the vicinity of IKAROS on the "star sphere surface" (I do not know the word for this, P)

These two are the delay residuals of the astronomical bodies whose positions are accurately known. IKAROS' plot is based on range/Doppler measurements and if its orbit determination is correct IKAROS' delay residual should be on the same line as these of two astronomical bodies'.

However, these are not in line, clearly suggesting a bias coming from orbit determination error not accurately estimated by range/Doppler measuments.


ΔDOR observation quantity: (-7.83 ns±50ps)

With these two astronomical bodies we see that , despite weak signals from quasor producing a lot of noise, delay residuals are on the same line, suggesting that bias due to the presence of atmosphere etc has been successfully removed.

Operations from now on:

Compared with bus system antennas VLBI transmitter has a narrower bandwidth and future observation oppotunities are limited and measurment accuracy is not large. However, we will continue to operate the system because we expect to be using this system with our future missions a lot regularly and we need to improve on the system such as pipelining and semi-automatic operation.

Observation so far has given us a lot of quality data for orbit determination and we should be able to come up with detrmination accuracy of a few centimeters, compared with a few meters accuracy required for deep space orbit determination.

We will also be making use of near Earth satellites for further improvements on accurate orbit determination.

P