June 8, 2010
Hayabusa project team successfully completed the most critical maneuver TCM-3 from June 3rd to 5th. It made the trajectory flying by the Earth rim to the Woomera Prohibited Area, a designated landing area. Attached is the relevant information regarding the approach geometry. It also presents the reentry objects light trace seen from Glendambo city, South Australia. On June 9th, the final TCM-4 will be conducted to precisely target the landing point near the recovery team already deployed.
May 31, 2010
Hayabusa started its TCM-2 operation from May 24th and completed it on
May 27th. TCM-2 is the largest orbit correction among a series of TCMs.
The operation was performed almost as planned and the ion engine aboard
worked in order.
Currently the rigorous orbit estimation is under way, but the project thinks the TCM-2 successfully guided the spacecraft well within the intended zone for the TCM-3.
May 10, 2010
It was the Hayabusa's 7 years old birthday yesterday.
TCM-1 was successfully performed between May 1st and May 4th, last week. The distance to the Earth seems to have been reduced not so much. This is true. The purpose of TCM-1 was to control the instance of flying by Australia. With the combination with TCM-2, the vectorized and synthesized delta-V constitute the aimed delta-V toward the Sun. There is a strict attitude constraint imposed on the spacecraft. The attached figures comprehensively provide the essence of this operation.
This week, Hayabusa will reduce the wheel speed that has accumulated the solar radiation disturbance. And the precise orbit determination will be performed for TCM-2 after that.
April 30, 2010
Hayabusa successfully terminated its first correction maneuver (TCM-0) from April 4th to April 6th. According to the latest information, the correction was confirmed well accurately performed. Until the end of this month, further fine orbit estimation continues. (Attached orbital sequence may vary dependent on the subsequent status.)
The spacecraft condition remains unchanged as before. As the distance to the Sun decreases, the solar radiation effects increases and it has made the reaction wheel rotation speed higher. The project team, in the middle of this month, performed the desaturation maneuver for three days. The project team is going to perform the next TCM-1 during next week.
Now the spacecraft is approaching very near to the Earth surface. At the end of this month, the spacecraft enters inside the Earth distance (1 AU from the Sun), and will approach from inside to the Earth this June.
April 12, 2010
The project team schedules five TCMs until the reentry in June.Impact parameter distance is gradually reduced as the attached figures indicate. The impact parameter means the distance from the center of Earth that the spacecraft passes over, in case no Earth gravity acts on it.
From this time on, the trajectory information update is presented in different formats from before, where impact parameter and inclination of incoming orbit are plotted along with the TCMs.
During every TCM, NASA Deep Space Network (DSN) provides around the clock tracking, telemetry and commanding supports, and the Jet Propulsion Laboratory of the California Institute of Technology provides the velocity variation information all the time during each TCM.
Hayabusa, if seen, will be a little east of Pollux in Gemini this April and May. Hayabusa approaches Earth right along on the line of the sight.
April 1, 2010
Hayabusa terminated its long term propulsion on March 27th. According to the orbit estimated on March 31st, it was confirmed that the resulted trajectory will pass through the target point as planned. In the BR-BT plane, the final spot in the figure clearly shows the guidance and navigation made the intended point precisely reached. However, according to the trajectory predict in the inertial frame, the trajectory shows a more sharp bend motion after it passes the Earth. It is due to the guidance error that still remains with respect to the target. The project team has introduced an alterative ion engine operation configuration from last November. The configuration conceals us from looking into an important information that affects the ion engine thrust magnitude, and this leads to the unexpected trajectory control error. As this loci indicate, swingby schemes are very sensitive to the guidance error generally, while the method is a mighty power to greatly amend the trajectory and useful. This thing is what we frequently face, when we adopt the swingby, in other word, the gravity assist operation.
From now on until June, Hayabusa is guided through several times of ion engine burns to accurately target the landing area. Being assisted by the NASA Deep Space Network, by being monitored all the time via the ground stations in real time, the subsequent corrections will be rigorously performed with this error excluded thoroughly.