Jaime Esper

NASA-GSFC nano-satellite technology for Earth science missions

Abstract The NASA-GSFC Nano-satellite Technology Program is currently formulating solutions for 21st century Earth Science requirements. We anticipate that nano-satellite (~ 10 kg) and micro-satellite (10 to 100 kg) constellations will have important applications in both Earth and Space science. Such constellations, acting in unison and with a large degree of autonomy, could form “virtual platforms” of detailed remotely sensed measurements providing orders of magnitude more information than todays thinly-populated networks of LEO and GEO satellites. If the constellations include a variety of basic, versatile instruments, for example UV, VIS and IR hyperspectral spectrometers, then virtual platforms for different applications can be formed in space, on the fly, and “disassembled” later for other uses or to test other scientific hypotheses. Example applications include weather prediction, radiative/reflected energy measurements for global change studies, hazard warning and monitoring systems (fires, volcanoes, hurricanes, etc.), and in-situ measurements of Earths magnetic field. For a wide range of applications, nano- and micro-satellite technology is likely to further the way NASA explores not only the Earth, but the solar system and beyond. Identifying the strategies and technologies that provide strong benefit to both the Earth and Space science programs will provide the best return on NASAs technology investment. This paper will highlight some possible Earth Science applications for nano- and micro-satellite constellations as well as the current status of planned NASA-GSFC nano/micro-satellite technology development.

Nano/Micro Satellite Constellations for Earth and Space Science

Spacecraft constellations are becoming a reality for NASA’s Earth and Space science, with the first steps already under way in building the infrastructure and knowledge base required for their implementation. In this paper we provide updated information on nano/micro satellite constellation missions either within NASA’s strategic plan or in the proposal stages. We will also present two examples of New Millennium Program technology missions that are today finding the solutions required to enable the constellations of the near and far-term future. Finally we will show what is being done in the area of Guidance, Navigation, and Control to facilitate the interconnectivity of constellations to act as single systems.

Trends and Visions for Small Satellite Missions

Small satellite missions can be achieved by using different approaches and methods. One possible approach takes full advantage of ongoing technology development efforts leading to miniaturization of engineering components, development of micro-technologies for sensors and instruments, and others which allow the design of dedicated, well-focused Earth observation missions. Application Specific Integrated Micro-instruments (ASIM) are enabled by Micro-Electro-Mechanical Systems (MEMS) using microelectronics for data processing, signal conditioning, power conditioning, and communications. These micro- and nano-technologies have led to the concepts of nano- and pico-satellites, constructed by stacking wafer-scale ASIMs together with solar cells and antennas on the exterior surface. Space sensor webs are one outcrop of this technology. Further milestones in the cost-effective Earth observation mission developments are the availability and improvement of small launchers, the development of small ground station networks connected with rapid and cost-effective data distribution methods, and cost-effective management and quality assurance procedures. The paper is based on the outcomes of the study “Cost.Effective Earth Observation Missons” by an international team of experts in the framework of the International Academy of Astronautics cite ch03:bib01. It deals with general trends in the field of small satellite missions for Earth observation as well as trends specific for the segments of a misson: space segment, launch segment, ground segment. Visions are given for their further developments in the direction of improvement of cost-effectiveness of Earth observation missions.

VOLCAN: a mission to explore Jupiter's volcanic moon Io

Abstract This paper presents a near-term implementation solution to the exploration of Jupiters volcanic moon Io. We first start by providing the scientific rationale for a mission to Io, and its alignment within NASAs strategic plan. The instruments selected represent a careful balance between focused scientific goals, and programmatic restrictions imposed by a Discovery-class mission. We discuss the difficulties inherent in visiting distant Io, including those to be expected from its extreme radiation environment. The mission design incorporates a trajectory in line with overall cost constraints, including launch vehicle limitations. Finally, the spacecraft design incorporates the use of solar arrays and chemical propulsion as a demonstration of the feasibility of executing an outer planet mission with state-of-the-art technology. In summary, we present the scientific rationale and demonstrate both the feasibility and limitations of a Discovery-class mission to Io, relying exclusively on existing or near-term developing technologies.

Low-cost, compact, and robust gas abundance sensor package

Gas Abundance Sensor Package (GASP) is a stand-alone scientific instrument that has the capability to measure the concentration of target gases based on a non-dispersive infrared sensor system along with atmospheric reference parameters. The main objective of this work is to develop a GASP system which takes advantage of available technologies and off-the-shelf components to provide a cost-effective solution for localized sampling of gas concentrations. GASP will enable scientists to study the atmosphere and will identify the conditions of the target’s planetary local environment. Moreover, due to a recent trend of miniaturization of electronic components and thermopiles detectors, a small size and robust instrument with a reduction in power consumption is developed in this work. This allows GASP to be easily integrated into a variety of small space vehicles such as CubeSats or small satellite system, especially the Micro-Reentry Capsule (MIRCA) prototype vehicle. This prototype is one of the most advanced concepts of small satellites that has the capability to survive the rapid dive into the atmosphere of a planet. In this paper, a fully-operational instrument system will be developed and tested in the laboratory environment as well as flight preparation for a field test of the instrument suite will be described.

Aerocapture design study for a Titan polar orbiter

In 2014 a team at NASA Goddard Space Flight Center (GSFC) studied the feasibility of using active aerocapture to reduce the chemical ΔV requirements for inserting a small scientific satellite into Titan polar orbit. The scientific goals of the mission would be multi-spectral imaging and active radar mapping of Titans surface and subsurface. The study objectives were to: (i) identify and select from launch window opportunities and refine the trajectory to Titan; (ii) study the aerocapture flight path and refine the entry corridor; (iii) design a carrier spacecraft and systems architecture; (iv) develop a scientific and engineering plan for the orbital portion of the mission. Study results include: (i) a launch in October 2021 on an Atlas V vehicle, using gravity assists from Earth and Venus to arrive at Titan in January 2031; (ii) initial aerocapture via an 8-km wide entry corridor to reach an initial 350×6000 km orbit, followed by aerobraking to reach a 350×1500 km orbit, and a periapse raise maneuver to reach a final 1500 km circular orbit; (iii) a three-part spacecraft system consisting of a cruise stage, radiator module, and orbiter inside a heat shield; (iv) a 22-month mission including station keeping to prevent orbital decay due to Saturn perturbations, with 240 Gb of compressed data returned. High-level issues identified include: (i) downlink capability - realistic downlink rates preclude the desired multi-spectral, global coverage of Titans surface; (ii) power - demise of the NASA ASRG (Advanced Stirling Radioisotope Generator) program, and limited availability at present of MMRTGs (Multi-Mission Radioisotope Generators) needed for competed outer planet missions; (iii) thermal - external radiators must be carried to remove 4 kW of waste heat from MMRTGs inside the aeroshell, requiring heat pipes that pass through the aeroshell lid, compromising shielding ability; (iv) optical navigation to reach the entry corridor; (v) the NASA requirement of continuous critical event coverage for the orbiter, especially during the peak heating of the aerocapture when the radio link will be broken. In conclusion, although Titan aerocapture allows for considerable savings in propellant mass, this comes at a cost of increased mission complexity. Further architecture study and refinement is required to reduce high-level mission risks and to elucidate the optimum architecture.

Overcoming design challenges for a radiation-tolerant, radiation-hardened Fast Ethernet interface

10 Mbps Ethernet communication has been available for Space applications for several years, however this has not been the case for Fast Ethernet (i.e. 100basetx) operating at 100 Mbps. A 100basetx interface has been developed using radiation tolerant components that can be replaced with radiation hardened components. This implementation can operate at the input baud rate allowing for a wider component selection.