The extreme environmental challenges of deep space exploration force unique solutions to small satellite design in order to enable their use as scientifically viable spacecraft. The challenges of implementing small satellites within limited resources can be daunting when faced with radiation effects on delicate electronics that require shielding or unique adaptations for protection, or mass, power" and volume limitations due to constraints placed by the carrier spacecraft, or even Planetary Protection compliant design techniques that drive assembly and testing. This paper will explore two concept studies where the environmental constraints and/or planetary protection mitigations drove the design of the Flight System. The paper will describe the key technical drivers on the Sylph mission concept to explore a plume at Europa as a secondary free-flyer as a part of the planned Europa Mission. Sylph is a radiation-hardened smallsat concept that would utilize terrain relative navigation to fly at low altitudes through a plume, if found, and relay the mass spectra data back through the flyby spacecraft during its 24-h mission. The second topic to be discussed will be the mission design constraints of the Near Earth Asteroid (NEA) Scout concept. NEAScout is a 6U cubesat that would utilize an 86 sq. m solar sail as propulsion to execute a" flyby with a near-Earth asteroid and help retire Strategic Knowledge Gaps for future human exploration. NEAScout would cruise for 24 months to reach and characterize one Near-Earth asteroid that is representative of Human Exploration targets and telemeter that data directly back to Earth at the end of its roughly 2.5 year mission.

NASA first published a roadmap for the Astronomical Search for Origins in 1997. Now, six years and 3 roadmaps later, some lessons have been learned, results have been accomplished, some approaches have been modified, but the vision remains. In 2003, the roadmap has simplified and refined its objectives, and added alternate routes and off-ramps to enhance the manageability of one of NASA's most ambitious science themes.

In 2009, NASA's Origins Program will launch the Space Interferometry Mission (SIM), a 10-meter-baseline optical interferometry instrument, into an Earth-trailing solar orbit. This instrument will be comprised of four parallel optical interferometers whose prime mission objective is to perform astrometric measurements at unprecedented accuracy. Launched by the Space Shuttle and boosted into its final trajectory by an integral propulsion system, SIM will collect data for more than five years in the search for extra-solar system planets. NASA has assembled an integrated Jet Propulsion Laboratory (JPL)/Industry team comprised of TRW, Lockheed Martin, and Caltech to formulate a reference design to meet the SIM science objectives. Addressing unique technical challenges has proven to be a formidable task in numerous aspects of the system definition, from component development to system-level integration and test. Parallel activities to develop and test the necessary enabling technologies for SIM are coupled with the ongoing flight system design. The flight system design poses unique challenges in many areas, including geometric aspects of the layout, stability of the precision structure, thermal control, active vibration suppression, picometer-level laser metrology, etc. System-level trade studies that balance the requirements of the optics and metrology layouts and develop clean interfaces are presented herein. This paper also addresses the issues of the System Engineering processes and validation of performance specifications. Finally, this paper describes the current status of the SIM Reference System design.

In 2006, NASA's Origins Program will launch the Space Interferometry Mission (SIM), a 10 meter baseline optical interferometry instrument, into an earth trailing orbit. This instrument will be comprised of three collinear optical interferometers whose prime mission objective is to perform astrometric measurements of unparalleled accuracy. NASA has assembled an integrated Jet Propulsion Laboratory (JPL)/Industry team to formulate a reference design to meet the SIM Science objectives. Unique technical challenges have proved to be a formidable task in numerous aspects of the system definition, from component development to system-level integration and test. Parallel activities to develop and test the necessary enabling technologies for SIM are coupled with the ongoing Flight design. The SIM Project has taken a multi faceted approach to dealing with its numerous technical challenges. Key working groups are addressing specific, integrated areas such as thermal design, dynamics and control, and operations. In addition, detailed integrated models of optical systems, structural dynamics and thermal control systems are being implemented in a large integrated modeling effort in order to validate the system level performance requirements. The implementation of enabling technologies from picometer and nanometer technology testbed programs are crucial to developing a detailed design and mitigating or retiring risk early in the Project development cycle. This paper describes the current SIM Reference System Design, the key required technologies, the requirements development process and the approach to an integrated systems development

In 2005, NASA's Origins Program will launch the Space Interferometry Mission (SIM), a 10 meter optical interferometer instrument, into a circular 900 km Earth orbit. This instrument will be comprised of three collinear optical interferometers whose prime mission objectives are to perform astrometric measurements of unparalleled accuracy and to perform rotational synthesis imaging of stellar debris disks. To deal with the huge technical challenges of developing this instrument, innovative approaches to system engineering are being tested and applied in order to achieve the target performance objectives. Defining requirements flow down from the highest system level to the detailed equipment specifications demanding a tracing capability that has not been previously available or maintainable on past projects. The SIM System Engineering activity has been chosen to utilize a requirements tracing tool to help it track changes and, hopefully, limit volumes of documentation that have become burdens in the past, Additionally, cross-cutting system models will be applied using new processes and infrastructure being instituted at JPL. Detailed models of optical systems, structural dynamics and thermal control systems are being implemented in an integrated fashion. The fidelity of these models will be verified in a series of evolving hardware and software testbeds that will culminate in a functioning ground version of the flight system. This testbed, supported by a separate technology program, will validate the system level requirements on astrometric performance, visibility and throughput. SIM will be one of the first missions to apply all of these techniques to enhance design detail and mitigate or retire risk early in it's development cycle.