Geoffrey A. Landis

National Aeronautics and Space Administration · Photovoltaics and Power Technologies

The thermoradiative cell is a solid-state device for conversion of heat energy to electrical power. The maximum power point bias for a thermoradiative cell is derived from detailed balance considerations, and the effects of parasitic thermal emissivity on the conversion efficiency is considered.

View Video Presentation: https://doi.org/10.2514/6.2022-1570.vid An analysis of the use of in-situ volatile propellants for a sample return mission from Titan shows that this mission should be feasible. Such a mission would be invaluable for its science return, and its contribution to our understanding the origins of organic compounds in the solar...

View Video Presentation: https://doi.org/10.2514/6.2021-3244.vid The radioisotope heat exchanger rocket is a new vehicle concept, designed to use heated gas as a means of propellant. The vehicle collects gas from the surface of a body, stores it in a heated tank, and passes it through a heat exchanger. This process significantly increases the tempe...

This article describes the idea of using satellites that receive solar energy for use on Earth. Solar irradiation is collected and converted by solar cells to electrical energy which is subsequently transferred using microwaves to large earth-based antennae.

Although the surface of Venus is an extremely hostile environment, at about 50 kilometers above the surface the atmosphere of Venus is the most earthlike environment (other than Earth itself) in the solar system, and the atmospheric pressure is similar to the Earth surface atmospheric pressure of 1 Bar, there is abundant solar energy, and the tempe...

The Mars ISPP Precursor, “MIP”, was a flight experiment on the 2001 Mars Surveyor Lander that was designed to demonstrate In-situ Propellant Production-- ISPP-- for the first time on Mars. The experiment was designed to show that it was possible to produce oxygen from the carbon dioxide atmosphere, and to demonstrate the individual technology compo...

Conceptual designs for a submersible vehicle for exploration of the hydrocarbon seas of Saturn’s moon Titan were done by the NASA Glenn COMPASS systems engineering team, as part of the NASA’s Innovative Advanced Concepts (NIAC) program. The efforts investigated what approaches and technologies would allow exploration below the surface of the low te...

Future missions to Venus will require electrical power, but providing power systems that work in the high temperature environment of the surface of Venus is difficult. Power system choices include solar power from photovoltaic arrays, batteries, radioisotope power systems, and wind. The current state of power technology for operation on the Venus s...

A candidate technology for the launch of a probe to a nearby star is propulsion of a spacecraft by accelerating of a sail to near relativistic speeds by a laser array. This would require miniaturization of the spacecraft by many orders of magnitude compared to existing spacecraft, and one difficulty for such a concept is reducing the mass of the po...

Advances in laser technology now makes it reasonable to use a laser to beam power directly from a power source at the illuminated rim of the crater to a photovoltaic laser receiver on a rover exploring inside the permanently shadowed region. To move this technology from the conceptual design to a system that can be implemented for exploration, it w...

NASA is currently designing a conceptual vehicle to explore the surface and atmosphere of Triton, Neptune’s captured Kuiper Belt Object, under a NASA Innovative Advanced Concepts (NIAC) Phase 2 study. This tholin-rich moon is dynamic, with an atmosphere, active geysers, and a unique “cantaloupe” terrain. Based on observations from Voyager-2, the su...

The Triton Hopper is a concept for a spacecraft that will explore the unique surface of Neptune's moon Triton through a series of 300-second hops. The Triton Hopper was conceptualized and evaluated by the COMPASS Engineering Team at NASA Glenn Research Center. This hopper design has a significant advantage over a rover, since this hopper is able to...

Neptune’s moon Triton is a fascinating object, a dynamic moon with an atmosphere, and geysers. Given the availability of volatiles (primarily nitrogen ice) on the surface a concept study was performed to see how these ices could be used as propellant to hop across the surface and explore the many different terrains of the moon. Termed Triton Hopper...

The gravitational field of the sun will focus light from a distant source to a focal point at a minimal distance of 550 Astronomical Units from the sun. A proposed mission to this gravitational focus could use the sun as a very large lens, allowing (in principle) a large amplification of signal from the target, and a very high magnification. This a...

A Space Power Satellite capable of providing solar electric power economically for 24 hours per day has been a dream for decades. Herein, an alternative will be described. Mirrors deflecting sunbeams down to earth is a much simpler concept. While this idea is very intriguing, the magnitude of its implementation is daunting. Nevertheless, the idea i...

The gravitational field of the sun will focus light from a distant source to a focal point at a minimal distance of 550 Astronomical Units from the sun. A proposed mission to this gravitational focus could use the sun as a very large lens, allowing (in principle) a large amplification of signal from the target, and a very high magnification. This a...

To explore the depths of the hydrocarbon rich seas on the Saturn moon Titan, a conceptual design of an unmanned submarine concept was recently developed for a Phase I NASA Innovative Advanced Concept (NIAC) study. Data from Cassini Huygens indicates that the Titan polar environment sustains stable seas of variable concentrations of ethane, methane,...

The atmospheric composition and geologic structure of Venus have been identified by the US National Research Council's Decadal Survey for Planetary Science as priority targets for scientific exploration, however the high temperature and pressure at the surface, along with the highly corrosive chemistry of the Venus atmosphere, present significant o...

A conceptual design was performed for a 6-U cubesat for a technology demonstration to be launched on the NASA Space Launch System (SLS) test launch EM-1, to be launched into a free-return translunar trajectory. The mission purpose was to demonstrate use of electric propulsion systems on a small satellite platform. The candidate objective chosen was...

As humanity begins to reach out into the solar system, it has become apparent that supporting a human or robotic presence in transit and/or on station requires significant expendable resources including consumables (to support people), fuel, and convenient reliable power. Transporting all necessary expendables is inefficient, inconvenient, costly,...

The Planetary Science Decadal Survey of 2013-2022 stated that the exploration of Venus is of significant interest. Studying the seismic activity of the planet is of particular importance because the findings can be compared to the seismic activity of Earth. Further, the geological and atmospheric properties of Venus will shed light into the past an...

From the intersection of computational science and technological speculation, with boundaries limited only by our ability to imagine what could be. Autonomous or not, design is destiny.<!-- END_PAGE_1 --

The ExoMars programme, which is carried out by European Space Agency (ESA) in cooperation with the Russian federal Space Agency (Roscosmos), foresees a two-steps mission to Mars. The first mission consists of an orbiter and an Entry Descent and Landing Demonstrator Module (EDM) to be launched in January 2016 and is scheduled to land on the planet d...

Satellite on-orbit failures are rare, but costly. Understanding causes of failures has benefits to commercial, government, and military satellite customers. In order to understand the causes of power-system related failures, publicly-available data sources were analyzed to catalog anomalies and failures of spacecraft in orbit due to power-system re...

A simplified model of solar power in the Venus environment is developed, in which the solar intensity, solar spectrum, and temperature as a function of altitude is applied to a model of photovoltaic performance, incorporating the temperature and intensity dependence of the open-circuit voltage and the temperature dependence of the bandgap and spect...

Large terrestrial solar electric power fields are being built around the world. However, sunlight is only available during normal daylight hours but not in the evenings. If lightweight mirrors can be deployed in space in a sun-synchronous dawn/dusk orbit, these mirrors can reflect sunlight down to these terrestrial solar farms to provide solar elec...

Venus, with a surface temperature of 450°C and an atmospheric pressure 90 times higher than that of the Earth, is a difficult target for exploration. However, high-temperature electronics and power systems now being developed make it possible that future missions may be able to operate in the Venus environment. Powering such a rover within the scop...

This paper presents an exploration strategy for human missions beyond Low Earth Orbit (LEO) and the Moon that combines the best features of human and robotic spaceflight. This “Human Exploration using Real-time Robotic Operations” (HERRO) strategy refrains from placing humans on the surfaces of the Moon and Mars in the near-term. Rather, it focuses...

From the intersection of computational science and technological speculation, with boundaries limited only by our ability to imagine what could be. How to colonize the galaxy, one electron spin state at a time.

The Mars Geyser Hopper is a design concept for a Discovery-class spacecraft using Advanced Stirling Radioisotope Generator (ASRG) power source, with the capability to make a rocket-powered "hop" to investigate regions of scientific interest.

NASA has missions planned to targets in the solar system ranging from the permanently shadowed craters of Mercury to the icy reaches of the Kuiper belt and beyond. In 2011, the NASA Office of the Chief Technologist (OCT) requested the NASA Ames and Glenn Research Centers to assess the potential of small power supplies based on direct conversion of...

Future exploration of Saturn's moon Titan can be carried out by airships. Several lighterthan- atmosphere gas airships and passive drifting heated-atmosphere balloon designs have been studied, but a heated-atmosphere airship could combine the best characteristics of both. This work analyses the thermal design of such a heated-atmosphere vehicle, an...

This paper presents concepts for human missions to the orbits of Mars and Venus that feature direct robotic exploration of the planets' surfaces via teleoperation from orbit. These missions are good examples of Human Exploration using Real-time Robotic Operations (HERRO), an exploration strategy that refrains from sending humans to the surfaces of...

A Mars rocket-propelled hopper concept was evaluated for feasibility through analysis and experiments. The approach set forth in this paper is to combine the use of in-situ resources in a new Mars mobility concept that will greatly enhance the science return while providing the first opportunity towards reducing the risk of incorporating ISRU into...

The Mars Geyser Hopper is a design reference missions (DRMs) for a Discovery-class spacecraft using Advanced Stirling Radioisotope Generator (ASRG) power source. The Geyser Hopper is a mission concept that will investigate the springtime carbon-dioxide geysers found in regions around the south pole of Mars. The Geyser Hopper design uses Phoenix her...

The surface of Venus is a location that is of great interest for future scientific exploration, but designing a rover that can move and conduct science operations on Venus is a difficult task. Electronic and materials technologies are available that could survive the furnace of Venus, but such a rover represents a challenging design problem. One ap...

The Mars Exploration Rovers Spirit and Opportunity observed changes in the surface soils and dusts as a result of local wind activity. The dustier Spirit landing site documented a series of dust deposition and cleaning events on the rover and surrounding terrain, redistribution of fines excavated by the rover wheels, small ripple migrations, disapp...

Combined observations from the MER rovers on the surface and the MRO HiRISE camera in orbit show that Martian winds actively alter the planet's surface on seasonal and geological time scales.

The surface of Venus is a hostile environment, with a surface temperature averaging 452°C, and atmospheric pressure of 92 bars of carbon dioxide. Nevertheless, exploration of the surface of Venus is of scientific interest. Technologies currently being developed at NASA bring the operation of robots on Venus into the range of feasibility. These incl...

This paper presents a concept for a human mission to Mars orbit that features direct robotic exploration of the planet's surface via teleoperation from orbit. This mission is a good example of Human Exploration using Real-time Robotic Operations (HERRO), an exploration strategy that refrains from sending humans to the surfaces of planets with large...

Use of solar electric propulsion can result in mass and propellant savings for future NASA missions to explore the solar system, enabling lightweight probes to targets in the solar system that have previously been out of reach. However, such electric-propulsion missions require large amounts of power, and require extremely lightweight solar arrays....

The Solar Probe Plus (SPP) is an upcoming mission in NASA's "Living with a Star Program" to be built by the Johns Hopkins University Applied Physics Laboratory. The spacecraft will orbit the sun for a primary mission duration of seven years, making a closest approach to the sun at a distance of 0.0442 AU. Instrumentation on SPP will focus on two pr...

Measurements of multijunction space solar cells were taken as a function of temperature for low intensity operation (down to 0.02 suns), and also at high intensities (up to 60 suns). Cells from two vendors were tested. The effect of intensity on the measured temperature coefficient was analyzed. The temperature coefficient of the short circuit curr...

The Photovoltaic EngineeringTestbed (PET) is a facility to fly on the International Space Station to test advanced solar cell types in the space environment. The purpose is to reduce the cost of validating new technologies and bringing them to spaceflight readiness by measuring them in the in-space environment. The facility is scheduled to be launc...

Spirit began operations in Gusev Crater in January 2004 and has returned data on three seasons of dust devil (DD) activity. Total DDs observed were 533 in season one, 101 in season two, and 127 in season three. Their general characteristics are the same within factors of 2 among the seasons, with median diameters of 19 m in season one, 24 m in seas...

The surface of Venus is one of the most challenging environments for the operation of spacecraft. With a surface temperature of around 460 degrees C and a surface atmospheric pressure of 92 bar of carbon dioxide, conventional power technologies are not usable. A number of battery technologies can be adapted to the high-temperature environment. A ne...

Future NASA missions into regions close to the sun will require power systems to operate in high temperature, high light-intensity environments. Some of the missions are: *Solar Probe Plus *Mercury probes *Venus probes Approaches to solar array design include developing improved high-temperature solar cells, reducing incident intensity to limit tem...

In 2009, the U.S. President convened a special committee to recommend directions for the U.S. human spaceflight program. One preferred option - the “Flexible Path” strategy - differs markedly from the Moon and Mars-oriented paradigm that has driven U.S. planning in the past. Specifically, it refrains from placing humans on the surfaces of these pla...

This paper presents an exploration strategy for human missions beyond Low Earth Orbit (LEO) and the Moon that combines the best features of human and robotic spaceflight. This "Human Exploration using Real-time Robotic Operations" (HERRO) strategy refrains from placing humans on the surfaces of the Moon and Mars in the near-term. Rather, it focuses...

The planet Venus represents an exciting target for future exploration by spacecraft. One target of scientific interest is the lower atmosphere, which represents an environment of high temperature and moderate to high atmospheric pressure. This represents a considerable challenge to the technical art of ballooning, but one which may be amenable to s...

The Spirit rover completed a 2.5 km traverse across gently sloping plains on the floor of Gusev crater from its location on the outer rim of Bonneville crater to the lower slopes of the Columbia Hills, Mars. Using the Athena suite of instruments in a transect approach, a systematic series of overlapping panoramic mosaics, remote sensing observation...

This work describes dust deposits on the Spirit Rover over 2000 sols through examination of Pancam and Microscopic Imager observations of specific locations on the rover body, including portions of the solar array, Pancam and Mini-TES calibration targets, and the magnets. This data set reveals the three "cleaning events" experienced by Spirit to da...

In 2009, the U.S. President convened a special committee to recommend directions for the U.S. human spaceflight program. One preferred option - the "Flexible Path" strategy - differs markedly from the Moon and Mars-oriented paradigm that has driven U.S. planning in the past. Specifically, it refrains from placing humans on the surfaces of these pla...

In 2009, the U.S. President convened a special committee to recommend directions for the U.S. human spaceflight program. One preferred option - the "Flexible Path" strategy - differs markedly from the Moon and Mars-oriented paradigm that has driven U.S. planning in the past. Specifically, it refrains from placing humans on the surfaces of these pla...