Toshifumi Yanagisawa

Optical Tracking and Spectroscopic Measurement of Hayabusa Capsule Reentry Fireball

The asteroid explorer HAYABUSA finally returned to the earth on June 13rd 2010 and the sample return capsule experienced a super-orbital atmospheric reentry. To recover the sample return capsule and to conduct optical measurements, the Japan Aerospace Exploration Agency organized a ground observation team and conducted optical tracking of the sample return capsule, spectroscopy of the fireball as well as the fireball trail, and measurement of infrasounds and shock waves generated by the fireball. In this article, an overview of the ground observation is presented, and the preliminary results derived from observations are reported.

Effective Search Strategy Applicable for Breakup Fragments in the Geostationary Region

This paper proposes to apply the space debris modeling techniques to devise an effective search strategy applicable for breakup fragments in the geostationary region. The space debris modeling techniques describe debris generation and orbit propagation to effectively conduct predictive analyses of space objects that include characterizing, tracking, and predicting the behavior of individual and groups of space objects. Therefore, the techniques can predict population of debris from a specific breakup event. The population prediction specifies effectively when, where, and how optical measurements using ground-based telescopes should be conducted. The space debris modeling techniques can also predict motion of debris in successive images taken with ground-based telescopes. The motion prediction specifies effectively and precisely how successive images of objects in the geostationary region should be processed. This paper also validates the proposed search strategy through actual observations, targeting the ...

Detection of LEO Objects Using CMOS Sensor

We succeeded in detecting 10 cm LEO objects at 1000 km altitude with a CMOS sensor installed to the 18cm telescope by using fast frame rate of the CMOS sensor and FPGA-based image-processing technique. The LEO survey system using numerous sets of the CMOS sensor will contribute the monitoring LEO environments which is currently done with the space surveillance network of the United States and solving the space debris problem in the future.

Research and Development on Space Debris Observation Technologies in Japan Aerospace Exploration Agency

JAXA is developing optical observation technologies for space debris. For GEO debris, the stacking method, which uses numerous CCD frames to detect objects under background noise level, is developed and shown to work well, so far. However, the method has the disadvantage that is time-consuming to detect objects whose movements are unpredictable. In order to overcome this, a new algorithm which uses binarization of CCD images and calculates sum values instead of median, is developed. Moreover, the algorithm is applied to the FPGA board system. These reduce analysis time to about one thousandth which enables us to analyze one night data till next night observation. For LEO debris, a ground-based optical observation system for monitoring LEO objects ,which uses a lot of optical sensors to cover the vast region of the sky, is being proposed. Detection abilities and orbital determination possibilities of the system were examined. About 30cm LEO objects at 1000km altitude are detectable using a 18cm telescope, a CCD camera and the developed analysis software. Simulations and a test observation showed that two longitudinally separate observation sites with arrays of optical sensors can identify same objects from a lot of data set and determine their orbits precisely. The proposed system may complement or replace the current radar observation system for monitoring LEO objects like space situation awareness in the near future.

ELECTRODYNAMIC TETHER CURRENT CONTROL USING SINGLE GPS RECEIVER MEASUREMENTS

2) the Aerospace Research and Development Directorate, JAXA The quantity of space debris has been increasing lately, and it must be removed as soon as possible. JAXA is investigating a debris removal system, and electrodynamic tethers (EDT) are promising technology for its orbital transfer system since they can generate sufficient thrust without requiring propellant. However, an EDT may start librating and tumbling when it is used for a long period of time. The tether can be stabilized by current control if the in-plane libration inclination of the tether is known, and for this a practical measurement device is required. Since a mother satellite is assumed to be the debris object, measurement using a single GPS receiver on an end-mass is studied. In this paper, precise numerical simulations are performed to estimate the orbit and in-plane inclination of the tether using GPS measurements. It is shown that orbit and in-plane inclination of the EDT can be estimated by Powell’s method.

THE STACKING METHOD: THE TECHNIQUE TO DETECT SMALL SIZE OF GEO DEBRIS

We propose a new method that we call “the stacking method” to detect unknown small size of GEO debris. A middle size of telescope and a normal CCD camera are enough to realize a fine result of the method. Many CCD images are used to detect GEO debris. With this method, streaks of stars except debris are disappeared completely and the sky background fluctuation decreases extremely. This means very dark debris, which is not visible on a single image, is detectable. We evaluated this method using actual observation images taken by a 35cm telescope of Mt.Nyukasa Astronomical Observatory and a 2K2K back-illuminated CCD camera. The observation was carried out on 2003 Feb 6th. The total sky coverage of the image area of the CCD camera is about 1.69 square degrees. 150 images with a 10-second exposure time were taken for one geostationary region. Some GEO debris candidates were detected by analyzing the images with the stacking method. Most of the candidates were too dark to be visible on a single CCD image. With this method, by means of observations using a 1m telescope and a back-illuminated CCD camera, we may be expected to detect GEO debris of about 30cm.