Title: LMPC CubeSat Status
Presenting Author: Renny Fields
Organization:The Aerospace Corporation

Abstract:
The Aerospace Corporation has been awarded a 3year funded flight 3U cubesat mission by ESTO as part of the INVEST program. The effort commenced on August 1, 2013 and is entitled Linear Mode Photon Counter (LMPC) Cubesat. The mission is quickly approaching CDR and many of the critical components and designs have been developed with all long lead elements currently on contract. We will demonstrate in space a new and highly sensitive 2x8 HgCdTe electron Avalanche Photo Diode (e-APD) array developed by DRS-RSTA that operates at 77 K, has high quantum efficiency and single photon level response at IR wavelengths from 0.7 to 4 microns. In addition this mission will integrate a micro-lens array produced by JenOptik to optimize fill factor for the specific DRS pixel layout. We are moderately modifying a standard DRS tactical integrated detector cooler assembly which includes a cryostat/Dewar connected to a linear sterling cooler so it can fit and optimally operate in a new Aerospace 3U cubesat that will be capable of open loop pointing to angles of 1.5 mrad. The electrical interface to the array will support 3 orbital mission modes. Mode 1 is a long term dark current measurement which monitors all 16 channels with 16 bit counters. Mode 2 is designed to support incident radiation centroiding and time of flight by supporting 20 Msample/sec on all 16 channels at 12 bits. This mode will also be capable of on-board processing before storage so only relevant data will be recorded for ultimate down-linking. Finally, Mode 3 will support a full waveform capture at 500 MSamples/sec and 8 bits on a single pixel over a full ground station pass from Low Earth Orbit. The LMPC optical design is F7 with a 6mm entrance diameter. Custom Materion cold filters will be installed in the Dewar to support photon counting tests at 1.06, 1.57 and 2.06 microns and minimize background detections from 0.7-1.06 and 2.07-4 microns where the array also responds. The LMPC test modes are designed to support future NASA missions such as ICESat, ASCENDS, LIST and others that require photon-sensitive IR detector arrays. The overall mission will characterize the detector response to 1-2 micron sources and measure its dark current as a function of time, ideally 1 year on orbit in the integrated space radiation environment. We are on the NASA cubesat mission manifest and are planning to launch in August 2016 which coincides with the satellite completion date and an orbit with suitable radiation exposure.