Szatkowski J.,Unite Launch Alliance |
Czajkowski D.R.,Space Micro
AIAA SPACE 2013 Conference and Exposition | Year: 2013
United Launch Alliance (ULA) EELV launch vehicles have a long history of providing high-value payload accommodations for a variety of customer spacecraft and missions, including planetary missions. Rideshare - the approach of sharing available performance margin with a primary spacecraft, provides satellite developers the opportunity to get their spacecraft to orbit and beyond in a cost effective and reliable manner. Hosted experiments provide another opportunity to fly nonseparating systems on the upper stage through disposal/reentry that may take up to 5 years to complete. This opportunity of hosted experiments allows for data gathering in the space environment and/or for raising technology readiness levels. This paper will give a brief overview of the rideshare capabilities that are available with current status. This includes the results from the NROL-36 launch of 8 PPODs in Sep of 2012. This presentation will focus on Rideshare delivery options for CubeSats/SmallSats and Hosted Experiments, with emphasis on support for command/ control, sequencing, data collection, and data transport to ground stations for experiment data products.
Barnaby H.J.,Arizona State University |
Vermeire B.,Space Micro |
IEEE Transactions on Nuclear Science | Year: 2015
Current gain degradation in irradiated bipolar junction transistors is primarily due to excess base current caused by enhanced carrier recombination in the emitter-base space-charge region (SCR). Radiation-induced traps at the interface between silicon and the bipolar base oxide facilitate the recombination process primarily above the sensitive emitter-base junction. This leads to an increase in surface recombination current in the SCR, which is a non-ideal component of the BJT's base current characteristic under active bias conditions. In this paper, we derive a precise analytical model for surface recombination current that captures bias dependencies typically omitted from traditional models. This improved model is validated by comparisons to these traditional approaches. © 1963-2012 IEEE.
Agency: National Aeronautics and Space Administration | Branch: | Program: SBIR | Phase: Phase I | Award Amount: 100.00K | Year: 2010
Micro-Space proposes to develop a low mass, automated form of the classic navigator's bubble sextant, with no moving parts, for rapid localization and reliable navigation on the Moon and Mars. Day, night, near side and far side lunar operations will all be handled. Exploration of the Moon (or Mars) without navigation aids comparable to those now common on Earth is a daunting, and generally unacceptable concept. Since neither body has a significant magnetic field, even a compass is useless. Creating and sustaining a GPS type satellite constellation will not occur soon. But the self contained, automated system Micro-Space proposes is an excellent substitute. It can be installed on top of an astronaut's helmet, or atop a vehicle, in extended EVA. With exploration extended into terrain where a vehicle is likely to become immobilized, but access by a walking human is practical, vast areas of currently unknown territory can be examined at very close range. But an hour's trek into convoluted terrain can leave the trekker seriously disoriented, and subject to human course decisions which could prove fatal. The helmet mount system will provide continuous EVA crew localization for emergency walk back to a safe haven, even if that path crosses unexplored territory. Fixed asset or notable planetary feature localization will also be straightforward at any point in the EVA. The proposed optical navigation system uses production, solid state camera modules for Solar, Earth Shine, and Celestial sight readings, all with an accurate artificial horizon. But the accuracy required is produced by Micro-Space proprietary "Sub Pixel" processing techniques. Lunar localization accuracy will exceed ¼ mile. With the excellent directional reference also produced, this information will make visual identification of relevant terrain features easy.
Lam Q.M.,LexerdTek Corporation |
Jacox M.,Space Micro
AIAA Guidance, Navigation, and Control (GNC) Conference | Year: 2013
It is well known to the estimation community that the values of the process noise covariance matrix, Q (as a function of gyros' noise parameters and filter update cycle time), and measurement noise covariance matrix, R (e.g., star tracker accuracy), primarily dictate the performance of the Extended Kalman Filter (EKF). The theoretical formulations of these two matrices are mathematically straightforward. Nevertheless, getting them to be tuned at the right values to reflect optimal or suboptimal performance for a certain operating condition is a completely different story. As a matter of fact, many of designers tend to consider this particular tuning is really a matter of art rather than science. In reality, selecting proper values for Q and R has been traditionally done in an ad-hoc manner. This paper provides a new look into the roles of the process noise and measurement noise matrices for the spacecraft attitude estimation problem as the design benchmark. This includes an interesting situation where the theoretical values of Q and R, derived as a function of gyro and star tracker noise parameters, are exactly matched with the noise characteristics employed on the sensor model side. However, the filter still exhibits poor attitude estimation performance, as measured against an attitude knowledge requirement, while subject to a high rate slew profile. A simulation based tuning methodology is developed to optimize the filter performance and bring the attitude estimation back to within the required attitude knowledge requirement bound. Lessons learned from this tuning strategy are drawn to derive guidelines and rules of thumbs for accuracy enhancement optimization.
Agency: Department of Defense | Branch: Air Force | Program: SBIR | Phase: Phase II | Award Amount: 1.25M | Year: 2003
Innovative satellite computer architecture that combines power savings techniques, high throughput microprocessors and new single event upset mitigation techniques. By combining low power, state-of-the-art Very Long Instruction Word (VLIW) microprocessorswith a novel form of triple modular redundancy on a single processor, Space Micro is able to achieve >1,200 MIPS performance at