Small Satellites: A Revolution in Space Science

This report describes the results of a study program sponsored by the Keck Institute for Space Studies (KISS) at the California Institute of Technology to explore how small satellite systems can uniquely enable new discoveries in space science. The disciplines studied span astrophysics, heliophysics, and planetary science (including NEOs, and other small bodies) based on remote and in-situ observations. The two workshops and study period that comprised this program brought together space scientists, engineers, technologists, mission designers, and program managers over 9 months. This invitation-only study program included plenary and subject matter working groups, as well as short courses and lectures for the public. Our goal was to conceive novel scientific observations, while identifying technical roadblocks, with the vision of advancing a new era of unique explorations in space science achievable using small satellite platforms from 200 kg down to the sub-kg level. The study program participants focused on the role of small satellites to advance space science at all levels from observational techniques through mission concept design. Although the primary goal was to conceive mission concepts that may require significant technology advances, a number of concepts realizable in the near-term were also identified. In this way, one unexpected outcome of the study program established the groundwork for the next revolution in space science, driven by small satellites platforms, with a near-term and far-term focus. There were a total of 35 KISS study participants across both workshops (July 16-20, 2012 and October 29-31, 2012) from 15 institutions including JPL, Caltech, JA / PocketSpacecraft.com, MIT, UCLA, U. Texas at Austin, U. Michigan, USC, The Planetary Society, Space Telescope Science Institute, Cornell, Cal Poly SLO, Johns Hopkins University, NRL, and Tyvak LLC. The first workshop focused on identifying new mission concepts while the second workshop explored the technology and engineering challenges identified via a facilitated mission concept concurrent design exercise. The Keck Institute limits the number of participants per workshop to at most 30 to encourage close interaction where roughly 20% involved in this study were students. This report is organized to communicate the outcome of the study program. It is also meant to serve as a public document to inform the larger community of the role small satellites can have to initiate a new program of exploration and discovery in space science. As such, it includes recommendations that could inform programmatic 1-5 decision making within space exploration agencies, both in the USA and internationally, on the promise of low-cost, focused, and high impact science should a strategic plan for small satellite space science be pursued. As such, the study program organizers and all participants are available to respond to any aspect of this report

A Fractionated Space Weather Base at L_5 using CubeSats and Solar Sails

The Sun–Earth L_5 Lagrange point is an ideal location for an operational space weather forecasting mission to provide early warning of Earth-directed solar storms (coronal mass ejections, shocks and associated solar energetic particles). Such storms can cause damage to power grids, spacecraft, communications systems and astronauts, but these effects can be mitigated if early warning is received. Space weather missions at L5 have been proposed using conventional spacecraft and chemical propulsion at costs of hundreds of millions of dollars. Here we describe a mission concept that could accomplish many of the goals at a much lower cost by dividing the payload among a cluster of interplanetary CubeSats that reach orbits around L5 using solar sails

The Habitable Exoplanet Observatory (HabEx) Mission Concept Study Final Report

The Habitable Exoplanet Observatory, or HabEx, has been designed to be the Great Observatory of the 2030s. For the first time in human history, technologies have matured sufficiently to enable an affordable space-based telescope mission capable of discovering and characterizing Earthlike planets orbiting nearby bright sunlike stars in order to search for signs of habitability and biosignatures. Such a mission can also be equipped with instrumentation that will enable broad and exciting general astrophysics and planetary science not possible from current or planned facilities. HabEx is a space telescope with unique imaging and multi-object spectroscopic capabilities at wavelengths ranging from ultraviolet (UV) to near-IR. These capabilities allow for a broad suite of compelling science that cuts across the entire NASA astrophysics portfolio. HabEx has three primary science goals: (1) Seek out nearby worlds and explore their habitability; (2) Map out nearby planetary systems and understand the diversity of the worlds they contain; (3) Enable new explorations of astrophysical systems from our own solar system to external galaxies by extending our reach in the UV through near-IR. This Great Observatory science will be selected through a competed GO program, and will account for about 50% of the HabEx primary mission. The preferred HabEx architecture is a 4m, monolithic, off-axis telescope that is diffraction-limited at 0.4 microns and is in an L2 orbit. HabEx employs two starlight suppression systems: a coronagraph and a starshade, each with their own dedicated instrument

The Habitable Exoplanet Observatory (HabEx) Mission Concept Study Final Report

The Habitable Exoplanet Observatory, or HabEx, has been designed to be the Great Observatory of the 2030s. For the first time in human history, technologies have matured sufficiently to enable an affordable space-based telescope mission capable of discovering and characterizing Earthlike planets orbiting nearby bright sunlike stars in order to search for signs of habitability and biosignatures. Such a mission can also be equipped with instrumentation that will enable broad and exciting general astrophysics and planetary science not possible from current or planned facilities. HabEx is a space telescope with unique imaging and multi-object spectroscopic capabilities at wavelengths ranging from ultraviolet (UV) to near-IR. These capabilities allow for a broad suite of compelling science that cuts across the entire NASA astrophysics portfolio. HabEx has three primary science goals: (1) Seek out nearby worlds and explore their habitability; (2) Map out nearby planetary systems and understand the diversity of the worlds they contain; (3) Enable new explorations of astrophysical systems from our own solar system to external galaxies by extending our reach in the UV through near-IR. This Great Observatory science will be selected through a competed GO program, and will account for about 50% of the HabEx primary mission. The preferred HabEx architecture is a 4m, monolithic, off-axis telescope that is diffraction-limited at 0.4 microns and is in an L2 orbit. HabEx employs two starlight suppression systems: a coronagraph and a starshade, each with their own dedicated instrument.Comment: Full report: 498 pages. Executive Summary: 14 pages. More information about HabEx can be found here: https://www.jpl.nasa.gov/habex

Packaging and Deployment of Large Planar Spacecraft Structures

This thesis presents a set of novel methods to biaxially package planar structures by folding and wrapping. The structure is divided into strips connected by folds that can slip during wrapping to accommodate material thickness. These packaging schemes are highly efficient, with theoretical packaging efficiencies approaching 100%. Packaging tests on meter-scale physical models have demonstrated packaging efficiencies of up to 83%. These methods avoid permanent deformation of the structure, allowing an initially flat structure to be deployed to a flat state. Also presented are structural architectures and deployment schemes that are compatible with these packaging methods. These structural architectures use either in-plane pretension -- suitable for membrane structures -- or out-of-plane bending stiffness to resist loading. Physical models are constructed to realize these structural architectures. The deployment of these types of structures is shown to be controllable and repeatable by conducting experiments on lab-scale models. These packaging methods, structural architectures, and deployment schemes are applicable to a variety of spacecraft structures such as solar power arrays, solar sails, antenna arrays, and drag sails; they have the potential to enable larger variants of these structures while reducing the packaging volume required. In this thesis, these methods are applied to the preliminary structural design of a space solar power satellite. This deployable spacecraft, measuring 60 m x 60 m, can be packaged into a cylinder measuring 1.5 m in height and 1 m in diameter. It can be deployed to a flat configuration, where it acts as a stiff lightweight support framework for multifunctional tiles that collect sunlight, generate electric power, and transmit it to a ground station on Earth.</p

Deployment mechanics of highly compacted thin membrane structures

We studied the effects of membrane thickness and crease density on the forces required to unfold creased membrane structures. 26 cm-diameter models were made using two different thicknesses (7.5 μm and 25 μm) of polyimide film, and wrapped around a 4 cm-diameter hub using two different crease densities. They were deployed quasi-statically, and the deployment forces were measured. Two regimes were observed: an initial phase (up to about 85% deployed) of low and variable stiffness, and a second phase (above 85% deployed) of high stiffness. The thinner membrane models required higher deployment forces than the thicker membrane models during the initial phase

Deployment mechanics of highly compacted thin membrane structures

We studied the effects of membrane thickness and crease density on the forces required to unfold creased membrane structures. 26 cm-diameter models were made using two different thicknesses (7.5 μm and 25 μm) of polyimide film, and wrapped around a 4 cm-diameter hub using two different crease densities. They were deployed quasi-statically, and the deployment forces were measured. Two regimes were observed: an initial phase (up to about 85% deployed) of low and variable stiffness, and a second phase (above 85% deployed) of high stiffness. The thinner membrane models required higher deployment forces than the thicker membrane models during the initial phase

Wrapping Thick Membranes with Slipping Folds

A novel method of packaging finite-thickness membranes tightly and with high packaging efficiency is presented. This method allows the membrane to be packaged without extension and without plastic creasing. As such, initially flat membranes can be deployed to a flat state. Membrane thickness is accommodated by removing material along fold lines and exploiting the slipping deformation mechanism thus created. Also presented are methods for prestressing and deploying membranes packaged according to this technique. Initial tests demonstrate packaging efficiencies of 73% without plastic deformation. Experimental deployment tests of a meter-scale model showed controlled deployment with unfolding forces of less than 0.6 N

Wrapping Thick Membranes with Slipping Folds

A novel method of packaging finite-thickness membranes tightly and with high packaging efficiency is presented. This method allows the membrane to be packaged without extension and without plastic creasing. As such, initially flat membranes can be deployed to a flat state. Membrane thickness is accommodated by removing material along fold lines and exploiting the slipping deformation mechanism thus created. Also presented are methods for prestressing and deploying membranes packaged according to this technique. Initial tests demonstrate packaging efficiencies of 73% without plastic deformation. Experimental deployment tests of a meter-scale model showed controlled deployment with unfolding forces of less than 0.6 N