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IKAROS Deployment in Translation

For those of you interested in the key IKAROS post describing the final deployment of the sail, Lionel Ward has been so kind as to translate it in context. I’m leaving out the actual photographs, which you can see via the links posted in my previous IKAROS coverage — and also here in context — but here is the text from JAXA:



A world first! Solar Powered Electrical Sail deployment and power generation is successful!


On June 8th the finalization of the primary deployment was executed, and on June 9th the secondary deployment was executed.


IKAROS’ state at the end of the primary is detailed over on the Ikaros blog.


Upon sending the command to initiate secondary deployment, a state of nervousness persisted in the command center during the 46 second propagation delay (the separation from earth is 7.4 million km!) until the initial data could be seen.

That deployment had occurred normally was first able to be seen from from the spin rate data and the positioning data. Continuing, although only a part of the monitoring camera’s images were being down-linked, we were able to confirm the deployment from the images. During June 10th the sail spread out beautifully, images of the ‘stretched state’ were acquired, and the post-secondary deployment confirmation efforts ended with the sail confirmed as successfully deployed.

 二次展開開始のコマンドを送ってから,伝播遅延のため最初のデータが見えるまで46秒 (地球からの距離,約740万km!)もかかるため,運用室では緊張した状態がしばらく続きました.
 まず,最初にきたスピンレートやIKAROSの姿勢データから正常に展開しているということが分かりました.続いて,モニタカメラで撮像した画像の一部 データをダウンリンクしたのですが,画像からもセイルが展開していることが確認できました.  6月10日にはセイルの綺麗に展開している,「展張状態」の画像を取得し,二次展開後の確認作業を終えセイルの展開成功を確認しました.

The simultaneously deployed thin film solar batteries’ power generation is confirmed – minimum success targets have been accomplished!! This realisation of solar sail deployment and power generation becomes a world first!


Post-secondary deployment images taken by monitoring cameras showing the stretched sail state are below.



These images are taken by IKAROS in space!


Comments on this entry are closed.

  • Istvan June 11, 2010, 18:25

    Great news!

  • James M. Essig June 11, 2010, 22:55

    Hi All;

    As my buddy Jason would say, “Cool Beans!”

    Tomorrow I am going to run some numbers after I catch some sleep to see what we can do with a sun diver space craft that would approach the Sun at a distance of about 0.03 AU, 0.06 AU, and 0.09 AU. I am going to assume sufficiently refractive sail materials that are monolithic such as a perhaps metalized Boron Nitride Nanotube based knit or weave membranes and a sail thickness of 10 nanometers and 100 nanometers and a reflectance of a reasonable 80 to 90 percent which seems doable. A relatively recent news report indicated that Boron Nitride fibers where found to be producable by a relatively simple industrial process and these fibers have a maximum theoretical strength on the order of carbon nanotubes which is about 60 times that of Kevlar.

    Carbon Graphene is stronger yet, but so far can only be made in very small quantities.

    The point of the above digression is that we are now entering a stage in our technological abilities where fast interplanetary and slow generation or multi-generation space arks to nearby stars is going be become possible that are powered by ambient sunlight alone, such as by dive and fry manuevers.

    The success of JAXA has greatly renewed my wonderlust of deep space solar sailing and in beam sailing in general.

    Powered by light pressure alone! If the concept was not so simple in theory, I”d be tempted to view it with the same mystique frame of mind as notions of gravity wave propulsion or anti-gravatic propulsion.

    Projects like the Project Icarus, the IKAROS mission, and the like, make the motto of Ad Astra Incrementis, all the more encouraging.

    Quite frankly, I was feeling a little down after the Constellation Project was terminated as I had high hopes for the Nastalgia of mankind returning to the Moon by 2020 or even by 2018, but I think the success of IKAROS will result in a bold new direction for advanced manned space craft propulsion and the prospects of going further, faster.

    IKAROS is just way too cool! or should I say hot.

  • James M. Essig June 12, 2010, 10:03

    Hi Folks,

    Here are the calculations I mentioned above.

    Assuming fraction f of the starlight is reflected straight back and the sail moves radially outward, the equation of motion is,
    B[(1 + (B EXP 2)]dB/[(1 − B)EXP 2] {[1 − (B EXP2)] EXP 3/2} = p [(R0/x) EXP 2](dx/Ro), where B = v/c, v is the speed of the sail, x is the distance from the star, R0 is the initial distance from the star, P = 2fA(u0)R0/[M0(C EXP 2)] and where; A is the area of the sail, M0 is its rest mass, and u0 is the energy density of starlight at x = R0; thus, u(x) = (u0)[(R0/x) EXP 2].

    Adopting f = 0.8, a value of M0/A = [2 x (10 EXP − 5)] kg/(meter EXP 2) = the effective mass specific reflecting area of the sail craft, and u0 ~ L/[4(pi)(Ro EXP 2)C] with L the Sun’s luminosity at [4 x (10 EXP 26)] watts and R0 = 0.03AU = [4.5 x (10 EXP 9)] meters , I find p = [2 .09586 x (10 EXP −5)].

    Note also that the equation of motion can be integrated analytically to find the terminal speed. Just integrate B from zero to its terminal value and x from R0 to infinity. This yields for the terminal velocity: {[(1 − (B EXP 2)] EXP (1/2)} [7 − 14B + 11 (B EXP 2) + 2(B EXP 3)]/[(1 − B ) EXP3](1 + B) = 7 + 15p. With p = [2 .09586 x (10 EXP −5)], the terminal velocity = 0.00641 C = 1,923 km/second.

    Using the same formula with M0/A = [2 x (10 EXP – 4)] kg/(meter EXP 2), we find that v = 0.00205 C = 615 km/second.

    Now if we chose a closest solar approach of 0.06 AU = [9 x (10 EXP 9)] km, then the velocities for M0/A = [2 x (10 EXP – 5)] kg/(meter EXP 2), and M0/A = [2 x (10 EXP – 4)] kg/(meter EXP 2), are v = 0.0045 C = 1,350 km/second and v = 0.00145 C = 435 km/second respectively.

    Choosing an closest approach of 0.09 AU = [13.5 x (10 EXP 9)] meters will yield v = 0.0038 C = 1,140 km/second and v = 0.0012 C = 360 km/second respectively for M0/A = [2 x (10 EXP – 5)] kg/(meter EXP 2), and M0/A = [2 x (10 EXP – 4)] kg/(meter EXP 2).

    Choosing a closest approach of 0.03 AU = [4.5 x (10 EXP 9)] meters will yield v = 0.0203 C = 6,090 km/second and v = 0.062 C = 18,600 km/second respectively for M0/A = [2 x (10 EXP – 6)] kg/(meter EXP 2), and M0/A = [2 x (10 EXP – 7)] kg/(meter EXP 2). This could get us to Alpha Centauri in 64.5 years or to Barnard’s Star in about 90 years.

    Adopting f = 0.8 and an extreme value of M0/A = [0.8 x (10 EXP −8)] kg/(meter EXP 2) = the effective mass specific reflecting area of the sail craft, and u0 ~ L/[4(pi)(Ro EXP 2)C] with L the Sun’s luminosity and R0 = 0.03AU, I find p ~ [5 × (10 EXP −2)].

    With p = 5 × (10 EXP −2), the terminal velocity = 0.251 C. This could get us to Alpha Centauri in 16 years and to Barnard’s Star in about 24 years. We could send humans out to every one of the 33 stars within a 12.5 light year radius of Earth in under 60 years transit time

    An M0/A = [2 x (10 EXP – 5)] kg/(meter EXP 2) could conceivably be achieved for monolithic sails made of 10 nanometer thick metalized Boron Nitride Nanotube material or Carbon Nanotube materials in the form of a weave or a knit with ion beam deposition, or chemical vapor deposition of highly refractive elements. An M0/A = [2 x (10 EXP – 4)] kg/(meter EXP 2) could conceivably be achieved by similar means except now the sheet would be 100 nanometers thick. Here, we assume that the effective volumetric density of the sail is roughly twice that of water at STP.

    An M0/A = [2 x (10 EXP – 6)] kg/(meter EXP 2) might be achieved for a sail composed of a cross weave of 10 nanometer wide Boron Nitride Nanotubes or Carbon Nanotubes that are metalized and where parallel fibers are separated by 200 nanometers.

    An M0/A = [2 x (10 EXP – 7)] kg/(meter EXP 2) might be achieved for a sail composed of a metalized sheet of graphene which is a one atom thick membrane made of carbon atoms.

    An M0/A = [0.8 x (10 EXP – 8)] kg/(meter EXP 2) might be achievable by a cross weave of 8 nanometer wide metalized graphene strips, where parallel strips are separated by 160 nanometers.

    I thought the Tau Zero readership would find the above somewhat idealized numbers intriging.

  • webjones June 14, 2010, 11:34

    Outstanding! This is truly exciting to watch. Thanks for keeping us up to date, Paul and thanks, Lionel for the translations.