Author Topic: Alos (Daichi) Suffered from Power Generation Anomaly  (Read 5774 times)

Offline osiossim

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http://www.jaxa.jp/press/2011/04/20110422_daichi_e.html

The Japan Aerospace Exploration Agency (JAXA) has been operating the Advanced Land Observing Satellite "DAICHI" (ALOS) exceeding its design life of three years, and even after its target life of five years. However, at around 7:30 a.m. on April 22 (JST), we found that the satellite shifted its operation mode to the low load mode (*1), and all the onboard observation devices were turned off due to power generation precipitation. The anomaly was detected through relayed data via the Data Relay Test Satellite "KODAMA."
Since then, the power generation has been rapidly deteriorating, and we currently cannot confirm power generation.
The DAICHI was launched on January 24, 2006.

JAXA is investigating the cause of this phenomenon while taking necessary measures.

*1: Low generation mode: the mode to save power consumption to maintain the minimum function of the satellite.

Offline osiossim

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Re: Alos (Daichi) Suffered from Power Generation Anomaly
« Reply #1 on: 04/22/2011 11:38 AM »
Here is the news (machine translation) from 2008, the link is no longer active.

http://www.yomiuri.co.jp/dy/national/20080110TDY02309.htm

Images obtained by a land-observation satellite developed by the Japan Aerospace Exploration Agency are of lower quality than expected due to errors and image noise, meaning the image data cannot be used to create maps, which was the primary purpose of the satellite, The Yomiuri Shimbun has learned.

The Geographical Survey Institute planned to use the image data from the 55 billion yen satellite Daichi to create updated, more accurate maps of the country at 1-25,000 scale. However, due to the inaccurate data from the satellite, the institute will have to carry out additional ground surveys. As a result, only 52 of about 4,300 basic maps have been appropriately updated. Until now, these maps have been made using images from aerial photographs taken from an altitude of 6,000 meters. The maps contain updated geographical changes such as newly constructed roads.

For the updates, the institute planned to use data obtained through Daichi, which has been operational since October 2006, to revise about 700 maps a year. Because the use of aircraft is not constantly needed, obtaining geographical data through the satellite was projected to cost less than 1 percent to 10 percent of obtaining data through aerial photographs. The margin of error required in geographical data for making the basic maps is five meters. However, Daichi's data of altitude to plot contours have been found to have a margin of error of about six meters.

Before Daichi's launch, JAXA estimated the margin of error would be within the acceptable range. However, due to a failure to appropriately control the satellite's attitude, only insufficient altitude data could be obtained through the satellite. In addition, image information has been discovered to contain "noise," which causes speckling. Images taken by the satellite are compressed for transmission. However, received images varied in quality more than expected, making it impossible for the institute to reproduce the original images.

"We carried out transmission experiments on the ground before the launch, but we failed to find the problem," a JAXA spokesman said. The central government spent about 55 billion yen to develop the satellite. Daichi's attitude can be modified from the ground, but the image noise is said to be impossible to fix.


Daichi aldready had some problems...

Offline tul

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Re: Alos (Daichi) Suffered from Power Generation Anomaly
« Reply #2 on: 04/22/2011 04:05 PM »
Daichi aldready had some problems...

Not that much. According to some old JAXA reply the Yomiuri article was  exaggerated. I am trying to find the answer.

Offline osiossim

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Offline Fuji

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Re: Alos (Daichi) Suffered from Power Generation Anomaly
« Reply #4 on: 05/12/2011 02:27 AM »
ALOS was not recovery and abandand today.

JAXA press release. (Japanese)
http://www.jaxa.jp/press/2011/05/20110512_daichi_j.html

Offline bolun

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Re: Alos (Daichi) Suffered from Power Generation Anomaly
« Reply #5 on: 05/12/2011 08:47 PM »
ALOS was not recovery and abandand today.

JAXA press release. (Japanese)
http://www.jaxa.jp/press/2011/05/20110512_daichi_j.html

JAXA press release. (English)

http://www.jaxa.jp/press/2011/05/20110512_daichi_e.html

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