Orbit Determination of Interplanetary Kite-craft Accelerated by Radiation of the Sun (IKAROS)
By Sho TANIGUCHI1) , Takafumi OHNISHI1), Osamu MORI2) , Hideki KATO2), Yuya MIMASU2), Naoko OGAWA2), Atsushi TOMIKI2), Hiroshi TAKEUCHI2), Tsutomu ICHIKAWA2), Makoto YOSHIKAWA2) and Shota KIKUCHI3)
1) Science Solutions Division, Fujitsu limited, Tokyo, Japan 2)The Institute of Space and Astronautical Science, JAXA, Sagamihara, Japan 3)Department of Aeronautics and Astronautics, The University of Tokyo, Tokyo, Japan Abstract
The IKAROS (Interplanetary Kite-craft Accelerated by Radiation Of the Sun) was launched along with the Venus Climate Orbiter Akatsuki in May 2010. IKAROS was successful missions that have been planned for first half year. This phase has been able to operate a stable orbit determination. And we acquired the skills to consider polarization bias and to eliminate spin modulation. Those were required for orbit determination of the spin solar sail. After the Venus flyby in Dec 2010, it was carried out an extended mission. IKAROS has achieved a variety of results in the extended mission. In orbit determination in low spin rate it was necessary to correspond to changes in spin rate in orbit determination arc. IKAROS was performed a reverse spin operation in order to solve the problem of spin rate uncontrolled by the fuel depletion in Oct 2011. After this operation IKAROS began to repeat the hibernation of the 10-month period by substantially fixed attitude in inertial coordinate while maintaining the spin rate between 5rpm and 6rpm without fuel. After wake up from hibernation, it is necessary to difficult orbit determination for 10 months or more the long-term trajectory prediction. In order to perform the orbit determination of long-term arc to construct an optical model of the solar sail back surface. And we study to estimate the uncertainty orbit determination error. In this paper, we present orbit determination in each phase of the IKAROS.
Key Words: IKAROS, orbit determination, predict, Solar Sail.
1. Introduction the power generation period and hibernation period cycle for 10 months. Even though we cannot be obtained enough observation The world’s first solar sail IKAROS was launched along data, it has been determined orbit with a long-term propagation with the Venus Climate Orbiter Akatsuki. The dual launch to over several years for the search operation after the woke up deep space was first experience in JAXA (Japan Aerospace from hibernation. Exploration Agency). The sub spacecraft and piggyback spacecraft have restriction of antenna station resources. 2. Overview of IKAROS Resources of antennas for deep space are not enough for initial orbit determination more than one spacecraft in parallel. IKAROS is constructed to maintain the shape of a huge 14 Therefore IKAROS’s antennas predictions are using an m x 14m square by spinning, and the square of the Akatsuki’s orbit determination result which was made by quadrilateral have a mass attached. Spin rate and attitude are sufficient tracking station resources1). controlled through the tether by thruster of the main body in IKAROS achieved various success of experiment in the the center. An outline of IKAROS is shown in Fig 2.1. nominal operation phases as shown in Figure 3.1. In this phase, the spin rate of IKAROS was maintained between 1.2 rpm to 2.5 rpm using spin up thruster. In this stage, we were able to The world's深宇宙初のソーラ・セイル宇宙機 first solar sail spacecraft in the deep space. make a stable orbit determination. ☆展開した衛星の断面積は In the extension phase, IKAROS implemented low spin rate ☆The cross-sectional area of 183.93mexpanded 2spacecraft約14m× is14m operation, large angle attitude control, and reverse spin の183.93m正方形2 operation. In low spin rate operation, it was maintained from The shape is square about 14m ×14m 0.2 rpm to 0.5 rpm. In this phase, the spin rate significantly ☆衛星本体は直径☆Cylindrical spacecraft1.6m× 高 さbody0.8m isの円筒形、全部の重さ diameter 1.6m × decreased in an orbit determination arc and the orbit height 0.8m,the total weight は310kg determination was more difficult than in the previous phase. is about 310kg After reverse spin operation, rotational torque around the spin axis due to solar radiation pressure increases the spin rate, the attitude motion shifts from sun orientation to inertia orientation, and eventually it went into hibernation in January Fig 2.1 IKAROS’s Overview. 2012. We are still maintaining operation of IKAROS repeating
1
Reverse spin operation
Inertial motion
st Hibernation mode 1 Hibernation Fitr （2012/9/6） flyby Venus (2010/12/8) 2nd Hibernation Fitr （2013/6/20） Extra success (after flyby) 3rd Hibernation Fitr （2014/5/22） 4th Hibernation Fitr Full success （2015/4/16） (in six months) Demonstration of th 5 Hibernation Fiter guidance,navigation and （2016/1～2 plan） control by solar sail. Minimum success 6th Hibernation Fiter (in several weeks) Earth Flyby Demonstration of photon propulsion by （2016/11～12 plan） solar sail.
Power generation by thin film solar cells
Launch (2010/5/21) Membrane deployment
Fig 3.1 Mission sequence.
As a characteristic of IKAROS, rotational torque called the 3. Orbit determination for nominal phase. wind turbine effect occurred due to unbalance of solar radiation pressure caused by unevenness of the large film. In the nominal phase, it was necessary to remove the spin Since this torque worked in the direction of gradually rate modulation and perform orbit determination. There was a decreasing the spin, regular operation period from launch to polarization bias due to the spin rate and it was necessary to Venus swing-by had to spin up by thruster periodically. consider it in the orbit determination. It was possible to maintain spin rate without consuming fuel The equation of Doppler bias due to polarization is shown due to changing direction of spin rate and rotational torque by in (1). solar radiation pressure after reverse spin operation carried 1 1 out. 푓푏푖푎푠 = 퐶 ( + ) 휔 (1) 푓푇 푓푅 The acceleration due to solar radiation pressure is about 100 m / sec in a half year. In search operation after wake up from hibernation, it was necessary that a long-term prediction orbital trajectory more than 10 months which considering the Table 3.1 shows the definition of variables. solar radiation pressure. For that purpose, we are constructing an attitude dynamics model 3) to predict attitude in the future, Table 3.1 Doppler bias due to polarization making it possible to create a future trajectory over several C: Speed of light(m/sec) years. fT: transmit frequency(Hz)
fR: Receive frequency(Hz) ω: Spin rate(round/sec) Sun fbias: Doppler bias due to polarization(m/sec) Γ Spin axis Unit Vector Ｄ θ The solar radiation pressure model used is shown in Table A（absorption） Unbalanced component of radiation 3.2. A huge thin film of solar sail is thought to emit absorbed Back side A×（Back F-Face F） sunlight with almost no time delay. Therefore, a model Face side （２Γ COS(θ ）＋２／３ D）×COS(θ ） considering the thermal radiation was needed. Fig 3.2 shows a
（２Γ COS(θ ）＋２／３ D）×SIN(θ ） １－Γ －Ｔ＝Ａ＋Ｄ conceptual view of the model considering the thermal Adsorption of diffusion Adsorption of absorption radiation. 2/3 A（F2-F1)×SIN(θ ） Unbalanced component of radiation The solar radiation pressure acceleration for a plane ２Γ COS(θ ）＋２／３ D Specular reflection and diffuse reflection perpendicular to the spin axis Zs is given as follows (2).
2 S0R0 S 1 2 2 2 r r 1 cos 2cos D A(F F )cos srp c m r 2 s s 3 3 2 1 s r Fig3.1 Conceptual diagram of solar radiation pressure model s of IKAROS 2 2 r r 2coss D AF2 F1 coss zs 3 3 r r (2)
2
The definition of the solar radiation pressure model is shown In the first recapture, the radiation pressure parameter 2) on in Table 3.2. the back side was also studied, and the orbital error was propagated after considering the thermal radiation model from Table 3.2 IKAROS solar radiation presser model. the large film. The area of error by the orbit determination was estimated to be about 2 to 3 times (3σ) of the half beam-width 3 2 S0: Solar constant (= 1.35 × 10 [W/m ]) 8 of USUDA deep space station, but it took several months to R0: 1A.U.(=1.4959787×10 [km]) receive signal from IKAROS. This is due to the uncertainty of c: Speed of light the orbit determination error as well as the uncertainty of the ms: S / C mass S: Area of the plane attitude transition when the sunlight shining the back side Γ: Reflection coefficient while long-term prediction. As a result, we succeeded in D: Diffusion coefficient receiving signal from IKAROS, searching using an attitude T: Transmittance dynamics model that maintains the inertia attitude even if r: S / C position vector of the sun center sunlight shining the back side. The search area of the forecast zs: Unit vector in the inertial space of the S / C spin axis value including the uncertainty of the attitude transition model θ s Solar orientation angle (cos θ s = (- r / r) ・ Z s) was about 10 times the Usuda antenna half width of capture A Absorption rate A =1 - D - Γ - T: T = 0 range. After in the first search operation, we were obtain one The emissivity ratio of the surface F1 nominal Doppler data and three Doppler data created by post F2 Emissivity ratio on the back side processing of data acquired from Open Loop receiver. Totally
four Doppler data and AZ EL data when it was successfully The estimated value of the solar radiation model was received signals were newly added for observation data. gradually changing in nominal phase. Since this AZ and EL data were obtained by performing
offset operation while observing the sensitivity by human eyes 4. Orbit determination for extended phase. in program tracking. It is guaranteed that the actual IKAROS
trajectory is an error on the order of half beam-width of Usuda, In extended operation, we mainly operated with low spin but actual observation does not guarantee passing through the rate. We conducted a number of experiments, such as middle of the data. For this reason, it is difficult to evaluate operation and guidance control where the attitude of the spin because even if the O-C residual becomes flat, the result is not axis was largely changed. In anticipation of depletion of fuel, necessarily correct. reverse spin operation was carried out to stabilize the spin rate without fuel. As a result, the spin rate gradually increased 5.2 Second search operation. without fuel and the moment of inertia increased gradually, so In the second search operation, we had predicted that the the attitude changed from solar tracking to inertial fixation. In search area due to propagation 3 sigma errors were about 10 the end, IKAROS could not maintain the power and times the half beam-width of Usuda, but it was able to be hibernated. found in the initial search operation. In addition to being able In this phase, the spin rate/rate in the trajectory determination to search about 2 to 3 times the half beam-width at maximum arc became large and spin modulation could not be removed by the time offset if it is an error in the direction of spacecraft with fixed parameters. In addition, the quality of tracking data progression. In addition to the fact that the motion model itself worsened as the distance to the earth gradually increased. The of the attitude was unclear in the first search operation. It can uncertainty of attitude by low spin rate has also appeared. The be said that narrowing of the comprehensive search area accuracy of orbit determination worsened than the previous became a factor in the initial success because it was able to phase. predict the parameter of attitude dynamics model using Therefore we have constructed a system that simultaneously observation data of solar angle and spin rate earth angle in the performs attitude motion and orbit determination. We were first search operation. In this operation, 7 Doppler data created able to achieve highly accurate orbit determination. by post processing from Open Loop receiver and AZ EL data
when it was receiving signals were added as observation data. 5. Orbit determination for Long-term prediction and
search operation. 5.3 Third search operation.
In the third search operation, the first search was conducted IKAROS hibernated because the spin rate increased and the on April 22, 2014 and succeeded in the third search. We inertial directivity increased. After that, the search operation succeeded in searching using forecast values improved on the became necessary. back and surface optical parameters by observation data The problem of this phase was the long-term orbit prediction, acquired in 2012 and 2013. In the search operation of 2014, highly reliable trajectory determination and prediction of the assumption of the search area spreads to about 30 times attitude motion model was necessary. The initial attitude (3σ) of Usuda's half beam width, as compared with the search motion model was roughly classified into three models3). As a operation in the last time in 2013. Fig 5.1 shows the transition result, it was discovered using a model with strong inertial of the assumed error ellipse 3σ of the search operation from orientation. the first search operation to the third. Although the axes are
Right Accession (RA) and Declination (DEC), the scale in the 5.1 First search operation. Dec direction is enlarged twice the RA direction.
3
In addition, in the third search operation after hibernation, not only the conventional time offset search but also the offset Error ellipse from Earth Center 3σ search in the RA DEC direction converting to the AZ EL 1st Hibernation Fiter 3σ 2nd Hibernation Fiter 3σ 3th Hibernation Fiter 3σ offset using the instantaneous azimuth / latitude gradient by 0.15 the predicted value was also performed.
5.4 Fourth search operation. The fourth search operation started searching on March 5, 0
2015 and spent a period of one and a half months until Dec(deg) discovery. We have succeeded in searching by applying a new search method 4) such as post-processing analysis using 1-way -0.15 data with open loop receiver. The ID’s 0100 to 0130 shown in -0.60 -0.45 -0.30 -0.15 0.00 0.15 0.30 0.45 0.60 Fig. 5.2 are the ID’s of the antenna predict values actually Ra(deg) used in operation. It is possible to conduct 2 to 3 search areas with about 6 hours of operation. Perform time offsets of Fig 5.1 1st～3rd Error Ellipse from Earth Center several cases per one search area. The offset value add to the nominal antenna prediction is Instead of the offset search for the time, the offsets of RA expressed as an error ellipse in Fig 5.1. The inclination of the and DEC were used as the search area. We searched for RA principal axis of the error ellipse changes because the speed DEC offset search area by converting it into AZ EL offset direction at that time was tilted with respect to the equatorial search area for antenna prediction. We went searching while plane. The error ellipse is enlarging. In the fourth search updating candidates of forecast values to nominal 0100 at 3/5, operation, the distribution of search area in each orbit 0110 at 3/19, 0120 at 4/2, 0130 at 4/16. determination case and the variance of the error ellipse due to On 9th and 16th April, we changed to 1Way data extensive the error covariance did not coincide. In the fourth search search method and searched RA offset values from -0.180 deg. operation, the distribution of the search area in each orbit to 0.06 deg. and DEC offset values from -0.006 deg. to 0.165 determination case and the variance of the error ellipse due to deg. at 0.03 deg. step. This rhombus shape area roughly the error covariance did not coincide. For orbit propagation including all forecast values by orbit determination. On from November 2011 to June 2014 in order to prepare forecast April 23, we were exploring the area where IKAROS values, some new attempts such as shifting the initial value to subcarriers could be confirmed from the result of 1 Way 2012 and binding the initial covariance were carried out. searching on 9th and 16th April, and successfully confirmed
03-04b 03-04c Distribution of Antenna prediction in each orbit determination results 03-04d 03-04e at 2015/4/9 00:00:00 for IKAROS 03-04f 03-04g 03-05h 03-05i 03-12a 03-12b 03-12c 03-12d 16.80 03-12e 03-12f Ellipse radius is 0.02deg IKAROS LONG TERM 03-17-5 DP2 O-C(km/sec) 1.20E-02 IKAROS USUDA XX DP2( KM/S) 1.00E-02 03-12g 03-12h 8.00E-03 IKAROS LONG TERM 04-02-10 DP2 O-C(km/sec) 03-12i 03-17-1 7.00E-04 6.00E-03 IKAROS USUDA XX( HZ)
6.00E-04 4.00E-03 C(km/sec)
- 03-17-2 03-17-3 5.00E-04 O 2.00E-03 03-17-5 4.00E-04 0.00E+00 03-17-4 03-17-5 3.00E-04
2.00E-04 -2.00E-03 C(km/sec) - 03-17-6 03-17-7 IKAROS LONG TERM 03-03d DP2 O-C(km/sec) O 1.00E-04 -4.00E-03 7.00E-04 0 1,000 2,000 3,000 4,000 5,000 6,000 IKAROS USUDA XX DP2( KM/S) Time 0.00E+00 6.00E-04 03-17-8 03-17-9 -1.00E-04 5.00E-04 -2.00E-04 4.00E-04 03-17-10 03-17-11 -3.00E-04 3.00E-04 0 1000 2000 3000 4000 5000 6000 Time 03-17-11
2.00E-04 03-17-12 03-04aL1
C(km/sec) -
O 1.00E-04 EL(deg) 0.00E+00 IKAROS LONG TERM 03-17-11 DP2 O-C(km/sec) 03-04dL1 03-17-2L1 5.00E-03 -1.00E-04 4.00E-03 -2.00E-04 4/4 ID 0100 04-02-1 04-02-2 3.00E-03 IKAROS USUDA XX DP2( KM/S) -3.00E-04 4/16 ID 0130 0 1000 2000 3000 4000 5000 6000 16.60 Time 2.00E-03 04-02-3 04-02-4 03-04a 1.00E-03
04-27f C(km/sec) 0.00E+00 - 04-02-10 O 04-02-5 04-02-6 4/4 ID 0110 04-27e -1.00E-03 04-02-1 04-02-8 -2.00E-03 04-02-7 04-02-8 03-04dL1 03-17-3 -3.00E-03 -4.00E-03 04-02-9 04-02-10 03-04d 0 1,000 2,000 3,000 4,000 5,000 6,000 04-21i add DP2 Time
IKAROS LONG TERM 03-17-8 DP2 O-C(km/sec) 04-02-11 04-02-12 2.50E-03 03-17-2 IKAROS USUDA XX DP2( KM/S) 04-15-4 04-15-5 2.00E-03 03-12g 03-17-7 IKAROS LONG TERM 03-04a DP2 O-C(km/sec) 1.50E-03 7.00E-04 04-02-6 04-15-7 6.00E-04 IKAROS USUDA XX DP2( KM/S) 1.00E-03 5.00E-04
C(km/sec) 4/4 ID 0120 -
O 04-15-8 04-15-9 4.00E-04 5.00E-04 IKAROS LONG TERM 03-17-2 DP2 O-C(km/sec) 3.00E-03 3.00E-04 IKAROS USUDA XX DP2( KM/S)
0.00E+00 2.50E-03 2.00E-04 04-21i add DP2 04-27a C(km/sec)
3/18 ID 0110 - 2.00E-03 O 1.00E-04 -5.00E-04 1.50E-03 0 1000 2000 3000 4000 5000 6000 0.00E+00 04-27c 04-27e Time 1.00E-03 -1.00E-04 5.00E-04 -2.00E-04 0.00E+00
C(km/sec) 04-27f 05-01a -
O -3.00E-04 -5.00E-04 0 1000 2000 3000 4000 5000 6000 Time 03-17-8 -1.00E-03 03-04a 16.40 -1.50E-03 -2.00E-03 -2.50E-03 0 1000 2000 3000 4000 5000 6000 71.78 71.98 Time 72.18 72.38 AZ(ｄｅｇ)
Fig 5.2 Distribution of antenna predictions in each orbit determination results.
4 the 2Way carrier lock on the signal form a spacecraft. The 5.6 Sixth search operation. carrier position found by 1 Way wide area search was found at In the sixth search operation, the range data was created the position offset to RA - 0.015 deg. DEC - 0.022 deg. with pseudo by using at the timing when the frequency sweep respect to nominal ID 0130 (04-02-10). ended. It was possible to create one point pseudo range data From the third search to the fourth search, it is difficult to for each period at 2013 and 2015. It was formulating spin match the dynamic model to the whole of orbit determination modulation and statistically processing, we were able to arc by long-term propagation, and it became not possible to reduce the error of each data to 8000 km and 1000 km determine the best orbit determination result from the O-C's respectively. As a result of orbital determination while residual shape. And, the tendency of the error ellipse by the assigning parameters using these data, the search area could covariance analysis was not appropriate. Therefore, the be reduced as shown in Fig 5.3. In January 2016, the search dispersion of search area was calculated by assigning the area when sweep timing pseudo range data is used is indicated estimated parameters using ordinary orbit determination by red solid line. The search area when sweep timing pseudo knowledge. range data is not used is indicated by a pink dashed line. Fig. 5.2 shows the distribution of forecast values at 00:00:00 Azimuth and elevation by predicted trajectory of each orbit determination on April 9, corresponding to each orbit determination case. result at 2016/1/24 01:00:23 (distance form Earth 70,000,000km) 16 The O-C graph in Fig. 5.2 is the residual of Doppler in 2012 - - Search range not using sweep range data and 2013, which is a representative case O-C arranged in data 15.8 ━ Search range using sweep range data order instead of time. It can be understood that the case of 15.6 Search range reduction efect by sweep timeing 3-17-5, 03-17-11, 03-17-8 where the RMS of the O - C range data 15.4 extends to several m/sec are out of the distribution of the u64.IKAROS.160122d_new_RA2_rev16 15.2 whole. Even if the O - C residual is several m / sec, there are EL(deg) cases like case 03-17-02 which is almost in the center of 15 01-24 CASE11 u64.IKAROS_2016_CASE14 distribution. The case of 03-07-02 seems to be consistent 14.8 u64.IKAROS_2016_CASE18 u64.IKAROS_2016_CASE17 azimuth direction because there is flat in Doppler residual an 01-24 CASE12 14.6 arc in a day. But a predict position of orbit determination case u64.IKAROS_2016_CASE19 14.4 which has a large residual of Doppler is largely moving from 106 106.2 106.4 106.6 106.8 107 107.2 the relative predicts position of the whole when the evaluation AZ(deg) time changes. Fig 5.4 Search area for IKAROS in 2016/1/24
5.5 Fifth search operation. In the sixth search, it can be considered that the transmitting / In the 5th search operation, a program was created so that a receiving antenna is facing the earth, so it is an assumption search in a wide range can be automatically carried out by that stronger radio waves can be received than the fifth search. adding an offset of the search area planned in advance to the For this reason, it is possible to search an area wider than the antenna prediction value. It is possible to detect weak received 5th search area. Fig. 5.5 shows the search area up to the data by FFT analyzing the received frequency data at offline. present. I expect it to analyze offline, but it has not been The 5th search is very close in terms of distance but discovered as of December 2016. It seems that the spin torque IKAROS's transmitting and receiving antennas are facing the force is reversed from the observed spin rate data. Therefore, back side and could not be found. Perhaps it seems that radio we plan to restructure the spin torque motion model. waves were weaker than assumed, or it was hibernating rather than being as expected. The search area is shown in Figure 5.3. It was searched that about 1.5 deg. x 0.5 deg. range. RA DEC offset search area by Orbit Determination results in 2016/11/03 20:00:30 u64.IKAROS.160122d_new_RA2_rev10 0.6 u64.IKAROS.160122d_new_RA2_rev11 u64.IKAROS.160122d_new_RA2_rev12 u64.IKAROS.160122d_new_RA2_rev13 0.4 u64.IKAROS.160122d_new_RA2_rev14 u64.IKAROS.160122d_new_RA2_rev15 u64.IKAROS.160122d_new_RA2_rev16 RA,DEC Offset Search Range For Auto Search u64.IKAROS.160122d_new_RA2_rev17 0.2 u64.IKAROS.160122d_new_RA2_rev18 u64.IKAROS.160122d_new_RA2_rev40 CASE 160122d Ra Dec Offset(dec) u64.IKAROS.160122d_new_RA2_rev19 u64.IKAROS.160122d_new_RA2_rev20 0.60 0.0 u64.IKAROS.160122d_new_RA2_rev39 u64.IKAROS.160122d_new_RA2_rev21 01-24 CASE7 u64.IKAROS.160122d_new_RA2_rev22 0.50 01-24 CASE8 u64.IKAROS.160122d_new_RA2_rev23 01-24 CASE9 u64.IKAROS.160122d_new_RA2_rev24 -0.2 u64.IKAROS.160122d_new_RA2_rev25 0.40 01-24 CASE10 01-24 CASE11 u64.IKAROS.160122d_new_RA2_rev26 u64.IKAROS.160122d_new_RA2_rev27
01-24 CASE12 DEC(deg) 0.30 -0.4 u64.IKAROS.160122d_new_RA2_rev28 01-24 CASE7 RER u64.IKAROS.160122d_new_RA2_rev29 01-24 CASE RER BIAS u64.IKAROS.160122d_new_RA2_rev30 0.20 01-24 CASE13 -0.6 u64.IKAROS.160122d_new_RA2_rev31 01-24 CASE160122b u64.IKAROS.160122d_new_RA2_rev32 u64.IKAROS.160122d_new_RA2_rev33 0.10 01-24 CASE13 RER u64.IKAROS.160122d_new_RA2_rev34 01-24 CASE13 BIAS -0.8 u64.IKAROS.160122d_new_RA2_rev35 0.00 01-24 CASE160122c u64.IKAROS.160122d_new_RA2_rev36 01-24 CASE160122d u64.IKAROS.160122d_new_RA2_rev37 u64.IKAROS.160122d_new_RA2_rev38 Dec(dec) -0.10 01-24 CASE160122e -1.0 u64.IKAROS.160122d_new_RA2_rev39 01-24 CASE160122f u64.IKAROS.160122d_new_RA2_rev40 -0.20 01-24 CASE 160122g 11/7（UT）Search Area 01-24 CASE12 RA -1.2 11/3（UT）Search Area -0.30 01-24 CASE160122h -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 11/4（UT）Search Area Search at 1/24 RA(deg) -0.40 Search at 1/25 Search at 1/26 Search at 1/27 -0.50 Fig.5.5 Search area by Usuda deep space station for 3 days 2/4- 2/5- -0.60 Remark point -1.0 -0.9 -0.8 -0.7 -0.6 -0.5 -0.4 -0.3 -0.2 -0.1 0.0 0.1 0.2 0.3 0.4 0.5 Ra(dec) 6. Summary. Fig. 5.3 RA DEC Offset Search Area Search operation of IKAROS due to hibernation has been successful as a result of trial and error in the past 4 times. In
5 the fifth time, there was a possibility of receiving signal but we could not catch the signal from the IKAROS's antenna. 7. Conclusion In the sixth search operation, automatic offset program makes search area larger, offline FFT analysis made it IKAROS's orbit determination requires technical elements possible to pick up weak signal. Pseudo-created range greatly that are not ordinary operation such as construction of attitude reduced search area. As these results, the search area is motion model and long - term prediction due to hibernation. considered to be no problem. We think that it is necessary to These technical elements to be useful in next solar power sail extend the attitude motion model. It is the spin motion model spacecraft. changes possible to deal with all direction from handling the angle around the sun orientation. As a result, it will be possible to predict a more precise period of wake up from hibernation. References
1) Sho Taniguchi, Takafumi Ohnishi, Hiroshi Takeuchi, Yuichi Tsuda, Tsutomu Ichikawa, Takaji Kato, Hiroshi Takeuchi, Makoto Yoshikawa, Application to Hayabusa2 initial acquisition of IKAROS initial acquisition results, JAXA Astrodynamics and Flight Mechanics,( 2014). 2) Sho Taniguchi, Takafumi Ohnishi, Yuya Mimasu, Yuji Shirasawa, Katsuhide Yonekura, Mori Osamu, Hiroshi Takeuchi, Tsutomu Ichikawa, and Makoto Yoshikawa, Orbit Determination and Evaluation of Prediction Error to Acquire IKAROS, 57th Space Science and Technology Conference. (2013). 3) Yuya Mimasu, Sho Taniguchi, Hiroshi Takeuchi, Yuji Shirasawa, Katsuhide Yonekura, Osamu Mori, Ryu Funase, Yuichi Tsuda, Attitude and Orbit Prediction of Solar Power Sail Demonstrator IKAROS, 30th Induction Control Symposium Presentation Papers, (2013) 4) Shota Kikuchi, Hiroshi Takeuchi, Osamu Mori, Yuya Mimasu, Yoji Shirasawa, Hideki Kato, Naoko Ogawa and Sho taniguchi, Progress of Search Operation for IKAROS by means of Open-loop Tracking Data, 30th International Symposium on Space Technology and Science, (2015).
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