Development of a Modular Propulsion System for Use in a Deep Space Hybrid Architecture

With recent and upcoming initiatives to revisit the moon and to begin planning for sending humans to Mars, the role of small spacecraft to facilitate and compliment these types of missions continues to grow. However, unlike low-Earth orbit (LEO), where small satellites have historically found their highest utilization, venturing further away from Earth and the more benign space environment it provides can prove to be a challenge for spacecraft designers. Factors can become difficult to design for, such as expected temperature ranges, power generation and radiation effects. At the same time, the objectives that small spacecraft are attempting to accomplish are becoming more and more complex as the capabilities of these spacecraft continues to grow. One example of this increasing complexity can be found in Rendezvous and Proximity Operations (RPO) missions, where spacecraft attempt to perform tasks involving on-orbit servicing, docking, active debris removal, formation flying, inspection, or any other function that involves one or more satellites (natural or otherwise) matching their orbital plane, altitude and phasing while also performing maneuvers to approach at a close distance1. As the number of small satellite missions operating beyond LEO grow, so too will the need for spacecraft that are capable of performing complex RPO. One key technology that is needed to facilitate these types of missions is a means of propulsion that is capable, reliable, and safe to use and handle. Benchmark Space Systems is poised to provide the mobility solutions that will enable these deep space missions to traverse the vast distances as well as help carry out the precise maneuvers necessary for these types of endeavors. One such example is the RPO Kit that Benchmark Space has recently developed for a commercial customer, whose mission objectives will take their spacecraft to Cislunar orbit

Adaptable, Multi-Mission Design of CanX Nanosatellites

Through the development of a low-cost, 5 kg multi-mission nanosatellite bus at the University of Toronto Institute for Aerospace Studies’ Space Flight Laboratory, a number of new and interesting applications are now possible on a nanosatellite platform. Two ventures currently underway that adopt the multi-mission nanosatellite bus are an astronomy mission, CanX-3 (also known as the BRight Target Explorer - BRITE), and a dual-satellite formation flight mission, CanX-4/5. CanX-3 is a space telescope that will monitor long-term light fluctuations from the brightest stars in our galaxy to study stellar structure and galactic evolution. CanX-4/5 will demonstrate precise formation flight by controlling position to the 1 m level, and by providing determination with an order of magnitude better accuracy, all via a commercial GPS receiver and a custom propulsion system. The driving force behind the multi-mission concept is the objective of reducing non-recurring engineering design costs. While this approach violates microspace philosophy by not tailoring to each specific mission, this paper argues that consideration and combination of the mission requirement sets allow a limited generic approach that holds to the basic tenets of the philosophy, allowing substantial cost savings to be realized, over and above the case of tailoring to specific mission interests

The Design and Test of a Compact Propulsion System for CanX Nanosatellite Formation Flying

The NANOsatellite Propulsion System (NANOPS) is part of the CanX-2 (Canadian Advanced Nanospace eXperiement 2) mission to demonstrate enabling component technologies in support of future formation flying missions. Flight test results in 2006 from NANOPS on board CanX-2 will augment ground test results with the goal of refining the design to support the CanX-4 / CanX-5 formation flying mission in 2008. The CanX-2 NANOPS uses liquefied sulfur hexaflouride (SF6) as a propellant because of its high storage density. The target performance goals are 50 mN of thrust, a specific impulse of 45s. and a minimum impulse bit of 0.0005Ns. The CanX-2 experiement will mainly involve attitude control maneuvers in order to evaluate the performance of the propulsion system through on-board attitude sensors. NANOPS is novel not only because it is the first of its kind in microsatellites based on commercial off-the-shelf components. This paper describes the development metholdology as well as the ground-based and space-based testing involved during the development of NANOPS, and its suitability for future missions

The MOMENT Magnetic Mapping Mission Martian Science on a Nanosatellite Platform

MOMENT (Magnetic Observations of Mars Enabled by Nanosatellite Technology) will obtain high-resolution maps of remnant-magnetic fields over Mars’ southern highlands. A sub-nanotesla magnetometer employed in a highly-elliptical and low-nightside-periapsis (100 km) orbit will provide greater spatial resolution and anomaly delineation than is available from Mars Global Surveyor. During the aerobraking phase of that mission, low-altitude measurements were corrupted by solar wind because they were acquired in sunlight, where solar winds interacted with the crustal-magnetic field. During the mapping phase, spatial resolution was limited to about 400 km. Improving upon these limitations, MOMENT’s mapping strategy will allow detailed studies of regional tectonics and core-dynamo history. MOMENT’s design is based on the Space Flight Laboratory’s Generic Nanosatellite Bus. Developed for the BRITE and CanX-4&5 missions, MOMENT re-uses this technology to provide a rapid and cost-effective mission. Implementation of the mission requires payload space on a larger carrier spacecraft and use of Martian communication relays to transfer information to and from Earth; MOMENT is otherwise fully autonomous. This paper describes the conceptual MOMENT mission (funded by the Canadian Space Agency) and illustrates that nanosatellite technology is a relatively-simple and cost-effective means to enhance solar system exploration

Guidelines for the use and interpretation of assays for monitoring autophagy (4th edition)

In 2008, we published the first set of guidelines for standardizing research in autophagy. Since then, this topic has received increasing attention, and many scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Thus, it is important to formulate on a regular basis updated guidelines for monitoring autophagy in different organisms. Despite numerous reviews, there continues to be confusion regarding acceptable methods to evaluate autophagy, especially in multicellular eukaryotes. Here, we present a set of guidelines for investigators to select and interpret methods to examine autophagy and related processes, and for reviewers to provide realistic and reasonable critiques of reports that are focused on these processes. These guidelines are not meant to be a dogmatic set of rules, because the appropriateness of any assay largely depends on the question being asked and the system being used. Moreover, no individual assay is perfect for every situation, calling for the use of multiple techniques to properly monitor autophagy in each experimental setting. Finally, several core components of the autophagy machinery have been implicated in distinct autophagic processes (canonical and noncanonical autophagy), implying that genetic approaches to block autophagy should rely on targeting two or more autophagy-related genes that ideally participate in distinct steps of the pathway. Along similar lines, because multiple proteins involved in autophagy also regulate other cellular pathways including apoptosis, not all of them can be used as a specific marker for bona fide autophagic responses. Here, we critically discuss current methods of assessing autophagy and the information they can, or cannot, provide. Our ultimate goal is to encourage intellectual and technical innovation in the field