Quinn Young

Modular Thermal Control Architecture for Modular Spacecraft

Development of modular spacecraft requires modularization of interfaces between modules as well as the functions of the modules themselves. Although many of the functions and interfaces of a spacecraft are already well adapted to modularization, the traditional thermal control architecture is not. The thermal control system is the most significant hurdle to modularization yet to be overcome. This paper provides an overview of the issues related to creating a modular thermal control subsystem and how this last major hurdle can be overcome. Principles of product architecture and modularity are used to define the functional elements, interfaces, and physical components and develop a modular thermal control architecture. A means of decoupling the thermal control subsystem, perhaps the most difficult characteristic necessary to implement, is presented. The process of developing the architecture is summarized with illustrations.

SOFIE instrument overview

Space Dynamics Laboratory (SDL) recently designed, built, and delivered the Solar Occultation for Ice Experiment (SOFIE) instrument as the primary sensor in the NASA Aeronomy of Ice in the Mesosphere (AIM) instrument suite. AIMs mission is to study polar mesospheric clouds (PMCs). SOFIE will make measurements in 16 separate spectral bands, arranged in eight pairs between 0.29 and 5.3 μm. Each band pair will provide differential absorption limb-path transmission profiles for an atmospheric component of interest, by observing the sun through the limb of the atmsophere during solar occulation as AIM orbits Earth. A pointing mirror and imaging sun sensor coaligned with the detectors are used to track the sun during occulation events and maintain stable alignment of the sun on the detectors. This paper outlines the mission requirements and goals, gives an overview of the instrument design, fabrication, testing and calibration results, and discusses lessons learned in the process.

Standard Network Adapter for Payloads (SNAP)

Given todays challenging budget environment for the Department of Defense, the National Security Space Enterprise is seeking unique and affordable ways to gain access to space. An emerging solution is aimed at addressing the fiscal challenges using commercially hosted payloads for military missions. With the success of Commercially Hosted Infrared Payload (CHIRP) in 2011, the United States Air Force is continuing to pursue new and innovative concepts and technologies to ensure hosted payloads remain an affordable avenue for resilient future space architectures. A specific enabling concept is a Modular, Open Networked Architecture (MONA) which is an outgrowth of two Department of Defense policy documents: the DODI 5000.02 and DoDD 8320.02. An emerging technology demonstration of MONA for the Hosted Payload Office is the Standard Network Adapter for Payloads (SNAP). In conjunction with the Space Dynamics Laboratory at Utah State University, the Space & Missiles Systems Centers Development Planning Directorate has demonstrated adapter between diverse hosted payloads and a spacecraft The demonstration was successfully conducted on November 2013 utilizing the ORS MSV testbed located at Northrop Grumman Corporation in Redondo Beach, California. The SNAP ground demonstration showcased ability to interface multiple payload types with multiple spacecraft vehicles. A specific outcome of the ground demonstration is a flight-ready version of SNAP software that can be utilized for follow-on on-orbit demonstration. The SNAP software supports both Linux and VxWorks Operating Systems. demonstration entailed three different simulated hosted payloads and quantified the integration time for each payload. The SNAP unit demonstrated that a payload with a Mil-Std-1553, RS-422, or SpaceWire connection can successfully, rapidly interface with a spacecraft that provides one of these connections. One critical component for the hosting of future military missions is resolving the information assurance aspect. For purposes of SNAP demonstration, the security layer was incorporated into the project but must be addressed operational viability in future hosted DoD missions. Demonstration of the SNAP capability has validated potential utility of adopting a MONA approach for a hosted payload adapter, and supports the notion that broader adoption of MONA for space systems development could significant benefits.

Thermal control subsystem requirements and challenges for a responsive satellite bus

The traditional approach to satellite design is a customized and highly optimized satellite bus. The primary design driver is to minimize mass but often at the expense of schedule and non-recurring engineering costs. The result after years of development is a high performance system with minimal flexibility. Consequently, there is a need for responsive, small satellites that are able to accommodate different missions, changing threats, and emerging technologies for which the traditional development approach is unable to satisfy. Instead, systems must be modular and/or robust. One of the subsystems that will be challenging for the development of modular and/or robust architectures is the thermal control subsystem (TCS). To design a traditional TCS, virtually every aspect of the mission, the satellite, and the components must be known before an intense design program can be completed. However, the mission, payload, components, and requirements are largely unknown before mission initiation. To provide a baseline for the TCS design and to help bound the problem for the development of robust thermal systems, the range of external and internal heat loads for small satellites were evaluated. From this analysis, the realistic worst design cases were identified along with other requirements for robust thermal control systems. Finally, the paper will discuss the merits of various thermal architectures and the challenges associated with achieving the requirements for robust thermal control for responsive satellite buses.

SOFIE Instrument Model and Performance Comparison

Space Dynamics Laboratory (SDL), in partnership with GATS, Inc., designed, built, and calibrated an instrument to conduct the Solar Occultation for Ice Experiment (SOFIE). SOFIE is the primary infrared sensor in the NASA Aeronomy of Ice in the Mesosphere (AIM) instrument suite. AIMs mission is to study polar mesospheric clouds (PMCs). SOFIE will make measurements in 16 separate spectral bands, arranged in 8 pairs between 0.29 and 5.3 μm. Each band pair will provide differential absorption limb-path transmission profiles for an atmospheric component of interest, by observing the sun through the limb of the atmosphere during solar occultation as AIM orbits Earth. A fast steering mirror and imaging sun sensor coaligned with the detectors will track the sun during occultation events and maintain stable alignment of the Sun on the detectors. This paper outlines the instrument specifications and resulting design. The success of the design process followed at SDL is illustrated by comparison of instrument model calculations to calibration results, and lessons learned during the SOFIE program are discussed. Relative spectral response predictions based on component measurements are compared to end-to-end spectral response measurements. Field-of-view measurements are compared to design expectations, and radiometric predictions are compared to results from blackbody and solar measurements. Measurements of SOFIE detector response non-linearity are presented, and compared to expectations based on simple detector models.

Challenges in the application of modular open system architecture to weapons

The overarching objective for Flexible Weapons is to replace current inventory weapons that will not fully utilize the increased capabilities of 6th generation platforms, with a single weapons kit made up of flexible, open architecture components. Flexible Weapon will develop a common architecture to enable modular subsystems to achieve flexible weapons capability while allowing technology refresh at the pace of technology discovery in an affordable and sustainable design. The various combinations of weapons to address multiple missions must be 100% compatible with 6th generation delivery platforms (fighters, bombers, RPAs) and backwards compatible with 4th and 5th generation platforms.

Open architecture applied to next-generation weapons

The Air Force Research Laboratory (AFRL) has postulated a new weapons concept known as Flexible Weapons to define and develop technologies addressing a number of challenges. Initial studies on capability attributes of this concept have been conducted and AFRL plans to continue systems engineering studies to quantify metrics against which the value of capabilities can be assessed. An important aspect of Flexible Weapons is having a modular “plug-n-play” hardware and software solution, supported by an Open Architecture and Universal Armament Interface (UAI) common interfaces. The modular aspect of Flexible Weapons is a means to successfully achieving interoperability and composability at the weapon level. Interoperability allows for vendor competition, timely technology refresh, and avoids costs by ensuring standard interfaces widely supported in industry, rather than an interface unique to a particular vendor. Composability provides for the means to arrange an open end set of useful weapon systems configurations. The openness of Flexible Weapons is important because it broadens the set of computing technologies, software updates, and other technologies to be introduced into the weapon system, providing the warfighter with new capabilities at lower costs across the life cycle. One of the most critical steps in establishing a Modular, Open Systems Architecture (MOSA) for weapons is the validation of compliance with the standard.