Onboard calibration of the ASTER instrument over twelve years
Onboard calibration of the ASTER instrument over twelve years
复制标题
十二年来 ASTER 仪器的机载校准
作者：
F. Sakuma;M. Kikuchi;H. Inada;S. Akagi;H. Ono
ASTER是1999年12月发射的Terra卫星上用于观测地球的高分辨率光学传感器。ASTER由三个辐射计组成。VNIR在可见光和近红外区有三个波段，SWIR在短波红外区有六个波段，TIR在热红外区有五个波段。VNIR和SWIR的机载校准设备是卤素灯和光电二极管监视器。在轨道上，VNIR的三个波段显示输出信号迅速下降。波段1是最短的波长，在12年中下降最多，达到70%。在用于偏移和增益校准的长期校准中，TIR的板载黑体的温度在270 K至340 K之间变化。TIR的长期校准显示发射后响应下降。下降最明显的是在波段12下降到60%，在11年。TIR的降解光谱表明，降解的可能原因可能是有机硅和肼。ASTER机载校准通常每49天进行一次，但在倾斜调整机动（IAM）之前和之后增加了额外的机载校准，以检查对RCC的影响。在2011财政年度，对每个独立行政管理机制进行了三次实验。结果表明，无论是VNIR还是TIR，RCC的变化都很小。
The ASTER is a high-resolution optical sensor for observing the Earth on the Terra satellite launched in December1999. The ASTER consists of three radiometers. The VNIR has three bands in the visible and near-infrared region, the SWIR has six bands in the shortwave infrared region, and the TIR has five bands in the thermal infrared region. The onboard calibration devices of the VNIR and SWIR were halogen lamps and photodiode monitors. In orbit three bands of the VNIR showed a rapid decrease in the output signal. The band 1, the shortest wavelength, decreased most to 70% in twelve years. The temperature of the onboard blackbody of the TIR is varied from 270 K to 340 K in the long term calibration for the offset and gain calibration. The long term calibration of the TIR showed a decrease in response after launch. The decrease was most remarkable at band 12 decreasing to 60% in eleven years. The degradation spectra of the TIR shows that the possible causes of the degradation might be silicone and hydrazine. ASTER onboard calibration is normally carried out once in 49 days but additional onboard calibrations were added just before and after the inclination adjustment maneuver (IAM) to check the effect on the RCC. This experiment was carried out three times for each IAM in the fiscal year 2011. The result showed that the change in the RCC was small for both VNIR and TIR.