Vegetation Canopy  Lidar (VCL)

VCL is scheduled for launch in 2003 on board an Athena launch vehicle. The VCL mission will be conducted by means of a small satellite carrying the MBLA instrument in a 400 km orbit of 67° inclination with a two-year nominal lifetime. This will provide sufficient coverage of the Earth to characterize the vegetation canopy structure on a global basis during two growing seasons and produce a global reference grid of land topography. Because of increased atmospheric drag caused by the solar maximum during the mission, monthly reboosts are required to maintain nominal orbital altitude. Command and control of the spacecraft during operation, as well as data processing will take place at the University of Maryland. Distribution and archiving of VCL data products will be performed by the EROS Data Center. Table 1 lists VCL data characteristics and quality.

VCL visits, on average, the same 1 cell at the equator every two weeks, with more frequent revisits away from the equator. The exact ground track through any cell is essentially random, being a function of orbital drag and the monthly reboost required to keep the satellite at altitude. The number of visits to a 4 km cell, globally averaged over all cells, is approximately 10 during the two-year mission (with more frequent visits away from the equator, and less frequent visits at the equator).
 
 

Table 1. VCL Data Characteristics and Quality
Swath width	8 km
Number of beam tracks	3
Footprint (at 400 km)	25 m (60 @ mu @rad)
Footprint spacing	contiguous over land (approx)
Track spacing	4 km
Pulses per second	290 over land (approx.)
Wavelength	1064 nanometer
Coverage	between 67 ° N and S
Elevation accuracy	< 1 m in low slope terrain
Waveform digitization	250 Megasamples/sec
Samples per waveform	10-200, average=50
Sample precision	10 bits
Pulse detection dynamic range	100:1