Jeffrey Antol

Commercially hosted government payloads: Lessons from recent programs

In a commercially hosted operational mode, a scientific instrument or operational device is attached to a spacecraft but operates independently from the spacecrafts primary mission. Despite the expected benefits of this arrangement, there are few examples of hosted payload programs actually being executed by government organizations. The lack of hosted payload programs is largely driven by programmatic challenges, both real and perceived, rather than by technical challenges. Partly for these reasons, NASA has not sponsored a hosted payload program, in spite of the benefits and visible community interest in doing so. In the interest of increasing the use of hosted payloads across the space community, this paper seeks to alleviate concerns about hosted payloads by identifying these programmatic challenges and presenting ways in which they can be avoided or mitigated.

Exploring Mars Using a Group of Tumbleweed Rovers

Current Mars exploration and science is limited to orbiters and areas close to original rover landing sites. Most of the places of geological interest lay many kilometers outside of suitable landing sites. In-situ resources such as wind can enable rovers to travel great distances on Mars while using little internal power. In this paper, a dynamic model of an individual wind driven rover is used to enhance a stochastic simulation of multiple rovers traversing the Martian environment. The results from this simulation support the claim that a group of rovers equipped with minimal control mechanisms or internal energy sources can autonomously disperse and explore Mars.

The potential for hosted payloads at NASA

The 2010 National Space Policy encourages federal agencies to “actively explore the use of inventive, nontraditional arrangements for acquiring commercial space goods and services to meet United States Government requirements, including...hosting government capabilities on commercial spacecraft”. NASAs Science Mission Directorate has taken an important step towards this goal by adding an option for hosted payload responses to its recent Announcement of Opportunity (AO) for Earth Venture-2 missions. Since NASA selects a significant portion of its science missions through a competitive process, it is useful to understand the implications that this process has on the feasibility of successfully proposing a commercially hosted payload mission. This paper describes some of the impediments associated with proposing a hosted payload mission to NASA, and offers suggestions on how these impediments might be addressed. Commercially hosted payloads provide a novel way to serve the needs of the science and technology demonstration communities at a fraction of the cost of a traditional Geostationary Earth Orbit (GEO) mission. The commercial communications industry launches over 20 satellites to GEO each year. By exercising this repeatable commercial paradigm of privately financed access to space with proven vendors, NASA can achieve science goals at a significantly lower cost than the current dedicated spacecraft and launch vehicle approach affords. Commercial hosting could open up a new realm of opportunities for NASA science missions to make measurements from GEO. This paper also briefly describes two GEO missions recommended by the National Academies of Science Earth Science Decadal Survey, the Geostationary Coastal and Air Pollution Events (GEO-CAPE) mission and the Precipitation and All-weather Temperature and Humidity (PATH) mission. Hosted payload missions recently selected for implementation by the Office of the Chief Technologist are also discussed. Finally, there are technical differences specific to hosted payloads and the GEO environment that must be considered when planning and developing a hosted payload mission. This paper addresses some of payload accommodation differences from the typical NASA LEO mission, including spacecraft interfaces, attitude control and knowledge, communications, data handling, mission operations, ground systems, and the thermal, radiation, and electromagnetic environment. The paper also discusses technical and programmatic differences such as limits to NASAs involvement with commercial quality assurance processes to conform to the commercial schedule and minimizing the price that makes hosted payloads an attractive option.

Design, Analysis and Testing of Mars Tumbleweed Rover Concepts

A Mars Tumbleweed rover is a spherical, wind-driven, planetary rover. Compared with conventional rovers, a tumbleweed rover can travel farther faster and gain access to areas such as valleys and chasms that previously were inaccessible. This paper presents design, mathematical modeling, computer simulation, and testing of various tumbleweed rover concepts. In particular, we present wind-tunnel data indicating that a box-kite configuration represents a promising tumbleweed rover design, we show that a working box-kite–type tumbleweed can be constructed, and we show that center of mass variation shows promise as the basis of a tumbleweed rover navigation system.

The NASA Langley Mars Tumbleweed Rover Prototype

The Mars Tumbleweed is a concept for an autonomous rover that would achieve mobility through use of the natural winds on Mars. The wind-blown nature of this vehicle make it an ideal platform for conducting random surveys of the surface, scouting for signs of past or present life as well as examining the potential habitability of sites for future human exploration. NASA Langley Research Center (LaRC) has been studying the dynamics, aerodynamics, and mission concepts of Tumbleweed rovers and has recently developed a prototype Mars Tumbleweed Rover for demonstrating mission concepts and science measurement techniques. This paper will provide an overview of the prototype design, instrumentation to be accommodated, preliminary test results, and plans for future development and testing of the vehicle.

Wind Tunnel Tests of Evolved Mars Tumbleweed Concepts

*† ‡ § The Mars Tumbleweed rover is a concept for an exploration vehicle that would derive mobility through use of the winds on Mars. The Tumbleweed would conduct random sampling of the surface and atmosphere, traveling long distances over broad regions of the Martian surface. NASA Langley Research Center (LaRC) has developed notional concepts of Tumbleweed rovers and has been studying the aerodynamics of these concepts through wind tunnel testing and computational fluid dynamics analysis. This paper will provide an overview of the latest wind tunnel tests, which were conducted in the fall of 2004 in the LaRC Basic Aerodynamic Research Tunnel (BART). Various configurations of three Tumbleweed concepts, evolved from similar concepts tested in the BART during the previous year, were tested to determine and assess their drag characteristics. Descriptions of the models are provided as well as an overview of the BART facility and the strain gage balance used in the test. A description of the test methodology and the resulting data is presented followed by conclusions drawn from the results.

Tumbleweed: A New Paradigm for Surveying the Surface of Mars for In-Situ Resources

Mars missions to date have interrogated the planet at very large scales using orbital platforms or at very small scales intensively studying relatively small patches of terrain. In order to facilitate discovery and eventual utilization of Martian resources for future missions, a strategy that will bridge these scales and allow assessment of large areas of Mars in pursuit of a resource base will be essential. Long-range surveys of in-situ resources on the surface of Mars could be readily accomplished with a fleet of Tumbleweeds - vehicles capable of using the readily available Martian wind to traverse the surface of Mars with minimal power, while optimizing their capabilities to perform a variety of measurements over relatively large swaths of terrain. These low-cost vehicles fill the niche between orbital reconnaissance and landed rovers, which are capable of much more localized study. Fleets of Tumbleweed vehicles could be used to conduct long-range, randomized surveys with simple, low-cost instrumentation functionally equivalent to conventional coordinate grid sampling. Gradients of many potential volatile resources (e.g. H2O, CH4, etc.) will also tend to follow wind-borne trajectories thus making the mobility mode of the vehicles well matched to the possible target resources. These vehicles can be suitably instrumented for surface and near-surface interrogation and released to roam for the duration of a season or longer, possibly on the residual ice cap or anywhere orbital surveillance indicates that usable resources may exist. Specific instrument selections can service the exact exploration goals of particular survey missions. Many of the desired instruments for resource discovery are currently under development for in-situ applications, but have not yet been miniaturized to the point where they can be integrated into Tumbleweeds. It is anticipated that within a few years, instruments such as gas chromatograph mass spectrometers (GC-MS) and ground-penetrating radar (GPR) will be deployable on Tumbleweed vehicles. The wind-driven strategy conforms to potential natural gradients of moisture and potentially relevant resource gases that also respond to wind vectors. This approach is also useful for characterizing other resources and performing a variety of basic science missions. Inflatable and deployable structure Tumbleweeds are wind-propelled long-range vehicles based on well-developed and field tested technology (Antol et al., 2005; Behar et al., 2004; Carsey et al., 2004; Jones and Yavrouian, 1997; Wilson et al., 2008). Different Tumbleweed configurations can provide the capability to operate in varying terrains and accommodate a wide range of instrument packages making them suitable for autonomous surveys for in-situ natural resources. Tumbleweeds are lightweight and relatively inexpensive, making them very attractive for multiple deployments or piggybacking on larger missions.

Lunar Lander Structural Design Studies at NASA Langley

The National Aeronautics and Space Administration is currently developing mission architectures, vehicle concepts and flight hardware to support the planned human return to the Moon. During Phase II of the 2006 Lunar Lander Preparatory Study, a team from the Langley Research Center was tasked with developing and refining two proposed Lander concepts. The Descent-Assisted, Split Habitat Lander concept uses a disposable braking stage to perform the lunar orbit insertion maneuver and most of the descent from lunar orbit to the surface. The second concept, the Cargo Star Horizontal Lander, carries ascent loads along its longitudinal axis, and is then rotated in flight so that its main engines (mounted perpendicular to the vehicle longitudinal axis) are correctly oriented for lunar orbit insertion and a horizontal landing. Both Landers have separate crew transport volumes and habitats for surface operations, and allow placement of large cargo elements very close to the lunar surface. As part of this study, lightweight, efficient structural configurations for these spacecraft were proposed and evaluated. Vehicle structural configurations were first developed, and preliminary structural sizing was then performed using finite element-based methods. Results of selected structural design and trade studies performed during this activity are presented and discussed.

Comet/Asteroid Protection System (CAPS): A Space-Based System Concept for Revolutionizing Earth Protection and Utilization of Near-Earth Objects

Abstract There exists an infrequent, but significant hazard to life and property due to impacting asteroids and comets. There is currently no specific search for long-period comets, smaller near-Earth asteroids, or smaller short-period comets. These objects represent a threat with potentially little or no warning time using conventional ground-based telescopes. These planetary bodies also represent a significant resource for commercial exploitation, long-term sustained space exploration, and scientific research. The Comet/Asteroid Protection System (CAPS) would expand the current detection effort to include long-period comets, as well as small asteroids and short-period comets capable of regional destruction. A space-based detection system, despite being more costly and complex than Earth-based initiatives, is the most promising way of expanding the range of detectable objects, and surveying the entire celestial sky on a regular basis. CAPS is a future space-based system concept that provides permanent, continuous asteroid and comet monitoring, and rapid, controlled modification of the orbital trajectories of selected bodies. CAPS would provide an orbit modification system capable of diverting kilometer class objects, and modifying the orbits of smaller asteroids for impact defense and resource utilization. This paper provides a summary of CAPS and discusses several key areas and technologies that are being investigated.

Multigenerational Independent Colony for Extraterrestrial Habitation, Autonomy, and Behavior Health (MICEHAB): An Investigation of a Long Duration, Partial Gravity, Autonomous Rodent Colony

The path from Earth to Mars requires exploration missions to be increasingly Earth-independent as the foundation is laid for a sustained human presence in the following decades. NASA pioneering of Mars will expand the boundaries of human exploration, as a sustainable presence on the surface requires humans to successfully reproduce in a partial gravity environment independent from Earth intervention. Before significant investment is made in capabilities leading to such pioneering efforts, the challenges of multigenerational mammalian reproduction in a partial gravity environment need be investigated. The Multi-generational Independent Colony for Extraterrestrial Habitation, Autonomy, and Behavior health is designed to study these challenges. The proposed concept is a conceptual, long duration, autonomous habitat designed to house rodents in a partial gravity environment with the goal of understanding the effects of partial gravity on mammalian reproduction over multiple generations and how to effectively design such a facility to operate autonomously while keeping the rodents healthy in order to achieve multiple generations. All systems are designed to feed forward directly to full-scale human missions to Mars. This paper presents the baseline design concept formulated after considering challenges in the mission and vehicle architectures such as: vehicle automation, automated crew health management/medical care, unique automated waste disposal and hygiene, handling of deceased crew members, reliable long-duration crew support systems, and radiation protection. This concept was selected from an architectural trade space considering the balance between mission science return and robotic and autonomy capabilities. The baseline design is described in detail including: transportation and facility operation constraints, artificial gravity system design, habitat design, and a full-scale mock-up demonstration of autonomous rodent care facilities. The proposed concept has the potential to integrate into existing mission architectures in order to achieve exploration objectives, and to demonstrate and mature common capabilities that enable a range of destinations and missions.