Planetary Science Vision 2050 Workshop, Feb 1, 2017
Extra-terrestrial space elevators are technically feasible with current materials and can be part... more Extra-terrestrial space elevators are technically feasible with current materials and can be part of a transportation network to fulfill NASA's strategic exploration goals for the next three decades.
The Lunar Plasma Environment: Real time navigation and communication will be especially difficult... more The Lunar Plasma Environment: Real time navigation and communication will be especially difficult in the lunar polar regions, with heavily shadowing, at best oblique sunlight and frequent lack of line of sight to the Earth or any high-altitude communications relay. Unlike the Apollo surface Extra-Vehicular Activities (EVAs), where direct line of site was maintained between astronauts and either a lander or rover in direct communication with Earth, future astronauts on polar surface EVAs will need means to communicate and perform local positioning beyond the local lines of sight to radio relays. Here we describe how these problems can be addressed through the use of low frequency radio (in this context, any usage with a radio frequency, f, with 1 Hz . f . 100 MHz). It is important to realize that at the lunar polar regions astronauts will be entering a novel and relatively poorly explored plasma and radio frequency (RF) environment, quite different from the direct sunlight and solar ...
Introduction: The Deep Space Gateway (DSG) proposed for cis-lunar space offers an opportunity to ... more Introduction: The Deep Space Gateway (DSG) proposed for cis-lunar space offers an opportunity to both improve tests of fundamental physics and to develop chronometric navigation techniques for the human exploration of Mars and beyond. Here we outline how the DSG, equipped with highly accurate optical atomic clocks and optical phase coherent links with the Earth and other spacecraft, can used to develop and apply the science of chronometric geodesy and navigation, where the clock-spacecraft system is used to both position the spacecraft and measure adjacent gravitational fields. It appears likely that the DSG will be placed in a lunar Near Rectilinear Halo Orbit (NRHO), which offers many advantages for access to the lunar surface and the Earth, while minimizing or even eliminating both solar eclipses and terrestrial communications blackouts [1, 2, 3]. For definitiveness, we assume a 4:1 synodic resonant Halo orbit with a perilune radius of 5600 km and an apolune radius of ∼75,000 km.
The Plasma Environment at the Lunar Poles: At the lunar polar regions astronauts will be entering... more The Plasma Environment at the Lunar Poles: At the lunar polar regions astronauts will be entering a novel and relatively poorly explored plasma and radio frequency (RF) environment, quite different from the direct sunlight and solar wind encountered in Apollo EVAs. We are developing a unified “LunaCell” system with very small SDR modules for deployment onto the lunar surface, with low frequency radio capabilities both to enable communications beyond the line-of-sight, and as a tool for exploring the lunar RF environment [1]. Table 1 briefly describes the complicated and timevariable plasma environment near the lunar surface. The Moon is in the complicated plasma dynamics of the Earth’s magnetotail roughly 25% of the time, and the remainder of the time will be in the supersonic solar wind [2]. In the lunar wake the e− density is substantially decreased, and the plasma can become non-neutral as the thermal velocities of the solar wind electrons are higher than the bulk wind velocity, ...
It has been proposed to use microwaves to beam down power to Earth from space based solar power s... more It has been proposed to use microwaves to beam down power to Earth from space based solar power stations in Geosynchronous Orbit. However the Rayleigh diffraction limited optics requires enormous antennas, typically a few kilometers in diameter, and huge power levels, of 5GW to 10GW. A much lower cost of entry investment (100x lower) is afforded by use of optical or infrared lasers with much shorter wavelength, hence much smaller system size, e.g. 10MW, with one meter size collimator mirror diameter. Since there is no "grid power" in space, most spacecraft today use solar power sources, mostly photovoltaic solar cells. Powering lasers requires high levels of power. PV solar cells are usually less than 25% efficient. This multiplied by a typical 20% “wall plug” efficiency of lasers results in overall a mere 5% efficiency (95% waste heat!). This strongly motivates interest in solar pumping of lasers to greatly increase overall efficiency; theoretical efficiency of about 38% ...
Introduction: A Schumann Resonance is an electromagnetic oscillation excited in a closed waveguid... more Introduction: A Schumann Resonance is an electromagnetic oscillation excited in a closed waveguide formed by multiple reflecting layers at or near the surface or interior of a planetary body. The waveguide, for spherical bodies with uniform reflecting layers, is a resonant cavity with a fundamental wavelength ∼ the circumference of the body. The terrestrial Schumann Resonance, predicted by W.O. Schumann in 1952 [1], is formed by the cavity between the ionosphere and the surface of the Earth, with a fundamental frequency ∼7 Hz and the resonance primarily being excited by lightning. A Schumann Resonance was detected on Titan at ∼36 Hz by the Huygens probe [2], with the resonant cavity being formed by Titan’s and subsurface ocean and the excitation thought to result from currents in the ionosphere induced by the advected Saturnian magnetic field [3]. The same mechanisms should apply to Europa, leading to a prediction of a Schumann resonance between near-surface charged particles and th...
Introduction: Small lunar penetrators are poised to become a valuable new tool for lunar science ... more Introduction: Small lunar penetrators are poised to become a valuable new tool for lunar science and exploration during the next decade. These low-cost ballistic probes can be deployed from orbit, or from descending robotic or crewed vehicles in large numbers to explore and characterize the diversity of extreme lunar shallow subsurface environments. In this white paper, we describe the science opportunities for these penetrators, their general characteristics, as well as two mission concepts that employ them to enable groundbreaking lunar science. Lunar Science in the Next Decade: Lunar exploration during the next decade will see many opportunities for human and robotic missions. Some key next-decade mission goals currently under consideration include sample return, lunar network science, and exploring extreme environments (LEAG, 2016). The Moon's extreme environments that have thus far been identified through analysis of orbital data include: Permanently shadowed regions at the lunar poles; Steep topographic slopes; Extreme rocky regions; Lunar caves and pits, and the Lunar swirls. These extreme environments present significant challenges for accessibility, as well as potentially significant rewards for science. Small penetrators hold great potential for precursor and survey missions for the exploration of extreme lunar environments, producing early science data and geotechnic information crucial to science goals and later mission planning. One of the biggest remaining mysteries about the Moon are its polar volatile deposits. We have several lines of evidence that a range of volatiles are present in the Moon's permanently shadowed regions (
With current technology prediction errors in Low Earth Orbit (LEO) are frequently greater than th... more With current technology prediction errors in Low Earth Orbit (LEO) are frequently greater than the estimated separation distance between objects undergoing conjunction. Current predictions are thus frequently false alarms, and real collisions have been missed resulting in expensive losses. The February 2009 collision between the active Iridium 33 and the inert Kosmos-2251 was predicted to have a miss distance of 584 metres, but this was less than the error, and so the prediction was ignored, and the actual collision and destruction of Iridium-33 came as a complete surprise.
The concept of a space elevator dates back to Tsilokovsky, but they are not commonly considered i... more The concept of a space elevator dates back to Tsilokovsky, but they are not commonly considered in near-term plans for space exploration, perhaps because a terrestrial elevator would not be possible without considerable improvements in tether material. A Lunar Space Elevator (LSE), however, can be built with current technology using commercially available tether polymers. This paper considers missions leading to infrastructure capable of shortening the time, lowering the cost and enhancing the capabilities of robotic and human explorers. These missions use planetary scale tethers, strings many thousands of kilometers long stabilized either by rotation or by gravitational gradients. These systems promise major reduction in transport costs versus chemical rockets, in a rapid timeframe, for a modest investment. Science will thus benefit as well as commercial activities.
Space-beamed solar power (SSP) is a concept based on a solar power satellite, that is, a solar pa... more Space-beamed solar power (SSP) is a concept based on a solar power satellite, that is, a solar panel…
Instrumentation located on the Earth for monitoring, tracking, and communicating with satellites,... more Instrumentation located on the Earth for monitoring, tracking, and communicating with satellites, sp…
Introduction: With the recent expansion of plans for lunar exploration there has been increased i... more Introduction: With the recent expansion of plans for lunar exploration there has been increased interest in support of operations at and near the Moon (i.e., in Cislunar Space), including robotic and crewed missions to the lunar polar regions. Real time navigation and communication will be especially difficult on the heavily shadowed lunar polar regions, given the bad lighting, the frequent lack of line of sight to the Earth, the extreme Geometrical Dilution of Precision (GDOP) for any use of terrestrial GPS and the lack, at least in the near term, of continual overhead satellite coverage. Unlike the Apollo surface Extra-Vehicular Activities (EVAs), future astronauts on polar surface EVAs will need local relays to communicate with the home base, and to perform local navigation, and communication beyond the local line of sight to a central lander.
A Lunar Space Elevator [LSE] can be built today from existing commercial polymers; manufactured, ... more A Lunar Space Elevator [LSE] can be built today from existing commercial polymers; manufactured, launched and deployed for less than $2B. A prototype weighing 48 tons with 100 kg payload can be launched by 3 Falcon-Heavy's, and will pay for itself in 53 sample return cycles within one month. It reduces the cost of soft landing on the Moon at least threefold, and sample return cost at least ninefold. Many benefits would arise. A near side LSE can enable valuable science mission, as well as mine valuable resources and ship to market in cislunar space, LEO and Earth's surface. A far-side LSE can facilitate construction and operation of a super sensitive radio astronomy facility shielded from terrestrial interference by the Moon. The LSE would facilitate substantial acceleration of human expansion beyond LEO.
The Lunar Space Elevator, a Near Term Means to Reduce Cost of Lunar Access
Read More: https://a... more The Lunar Space Elevator, a Near Term Means to Reduce Cost of Lunar Access
Planetary Science Vision 2050 Workshop, Feb 1, 2017
Extra-terrestrial space elevators are technically feasible with current materials and can be part... more Extra-terrestrial space elevators are technically feasible with current materials and can be part of a transportation network to fulfill NASA's strategic exploration goals for the next three decades.
The Lunar Plasma Environment: Real time navigation and communication will be especially difficult... more The Lunar Plasma Environment: Real time navigation and communication will be especially difficult in the lunar polar regions, with heavily shadowing, at best oblique sunlight and frequent lack of line of sight to the Earth or any high-altitude communications relay. Unlike the Apollo surface Extra-Vehicular Activities (EVAs), where direct line of site was maintained between astronauts and either a lander or rover in direct communication with Earth, future astronauts on polar surface EVAs will need means to communicate and perform local positioning beyond the local lines of sight to radio relays. Here we describe how these problems can be addressed through the use of low frequency radio (in this context, any usage with a radio frequency, f, with 1 Hz . f . 100 MHz). It is important to realize that at the lunar polar regions astronauts will be entering a novel and relatively poorly explored plasma and radio frequency (RF) environment, quite different from the direct sunlight and solar ...
Introduction: The Deep Space Gateway (DSG) proposed for cis-lunar space offers an opportunity to ... more Introduction: The Deep Space Gateway (DSG) proposed for cis-lunar space offers an opportunity to both improve tests of fundamental physics and to develop chronometric navigation techniques for the human exploration of Mars and beyond. Here we outline how the DSG, equipped with highly accurate optical atomic clocks and optical phase coherent links with the Earth and other spacecraft, can used to develop and apply the science of chronometric geodesy and navigation, where the clock-spacecraft system is used to both position the spacecraft and measure adjacent gravitational fields. It appears likely that the DSG will be placed in a lunar Near Rectilinear Halo Orbit (NRHO), which offers many advantages for access to the lunar surface and the Earth, while minimizing or even eliminating both solar eclipses and terrestrial communications blackouts [1, 2, 3]. For definitiveness, we assume a 4:1 synodic resonant Halo orbit with a perilune radius of 5600 km and an apolune radius of ∼75,000 km.
The Plasma Environment at the Lunar Poles: At the lunar polar regions astronauts will be entering... more The Plasma Environment at the Lunar Poles: At the lunar polar regions astronauts will be entering a novel and relatively poorly explored plasma and radio frequency (RF) environment, quite different from the direct sunlight and solar wind encountered in Apollo EVAs. We are developing a unified “LunaCell” system with very small SDR modules for deployment onto the lunar surface, with low frequency radio capabilities both to enable communications beyond the line-of-sight, and as a tool for exploring the lunar RF environment [1]. Table 1 briefly describes the complicated and timevariable plasma environment near the lunar surface. The Moon is in the complicated plasma dynamics of the Earth’s magnetotail roughly 25% of the time, and the remainder of the time will be in the supersonic solar wind [2]. In the lunar wake the e− density is substantially decreased, and the plasma can become non-neutral as the thermal velocities of the solar wind electrons are higher than the bulk wind velocity, ...
It has been proposed to use microwaves to beam down power to Earth from space based solar power s... more It has been proposed to use microwaves to beam down power to Earth from space based solar power stations in Geosynchronous Orbit. However the Rayleigh diffraction limited optics requires enormous antennas, typically a few kilometers in diameter, and huge power levels, of 5GW to 10GW. A much lower cost of entry investment (100x lower) is afforded by use of optical or infrared lasers with much shorter wavelength, hence much smaller system size, e.g. 10MW, with one meter size collimator mirror diameter. Since there is no "grid power" in space, most spacecraft today use solar power sources, mostly photovoltaic solar cells. Powering lasers requires high levels of power. PV solar cells are usually less than 25% efficient. This multiplied by a typical 20% “wall plug” efficiency of lasers results in overall a mere 5% efficiency (95% waste heat!). This strongly motivates interest in solar pumping of lasers to greatly increase overall efficiency; theoretical efficiency of about 38% ...
Introduction: A Schumann Resonance is an electromagnetic oscillation excited in a closed waveguid... more Introduction: A Schumann Resonance is an electromagnetic oscillation excited in a closed waveguide formed by multiple reflecting layers at or near the surface or interior of a planetary body. The waveguide, for spherical bodies with uniform reflecting layers, is a resonant cavity with a fundamental wavelength ∼ the circumference of the body. The terrestrial Schumann Resonance, predicted by W.O. Schumann in 1952 [1], is formed by the cavity between the ionosphere and the surface of the Earth, with a fundamental frequency ∼7 Hz and the resonance primarily being excited by lightning. A Schumann Resonance was detected on Titan at ∼36 Hz by the Huygens probe [2], with the resonant cavity being formed by Titan’s and subsurface ocean and the excitation thought to result from currents in the ionosphere induced by the advected Saturnian magnetic field [3]. The same mechanisms should apply to Europa, leading to a prediction of a Schumann resonance between near-surface charged particles and th...
Introduction: Small lunar penetrators are poised to become a valuable new tool for lunar science ... more Introduction: Small lunar penetrators are poised to become a valuable new tool for lunar science and exploration during the next decade. These low-cost ballistic probes can be deployed from orbit, or from descending robotic or crewed vehicles in large numbers to explore and characterize the diversity of extreme lunar shallow subsurface environments. In this white paper, we describe the science opportunities for these penetrators, their general characteristics, as well as two mission concepts that employ them to enable groundbreaking lunar science. Lunar Science in the Next Decade: Lunar exploration during the next decade will see many opportunities for human and robotic missions. Some key next-decade mission goals currently under consideration include sample return, lunar network science, and exploring extreme environments (LEAG, 2016). The Moon's extreme environments that have thus far been identified through analysis of orbital data include: Permanently shadowed regions at the lunar poles; Steep topographic slopes; Extreme rocky regions; Lunar caves and pits, and the Lunar swirls. These extreme environments present significant challenges for accessibility, as well as potentially significant rewards for science. Small penetrators hold great potential for precursor and survey missions for the exploration of extreme lunar environments, producing early science data and geotechnic information crucial to science goals and later mission planning. One of the biggest remaining mysteries about the Moon are its polar volatile deposits. We have several lines of evidence that a range of volatiles are present in the Moon's permanently shadowed regions (
With current technology prediction errors in Low Earth Orbit (LEO) are frequently greater than th... more With current technology prediction errors in Low Earth Orbit (LEO) are frequently greater than the estimated separation distance between objects undergoing conjunction. Current predictions are thus frequently false alarms, and real collisions have been missed resulting in expensive losses. The February 2009 collision between the active Iridium 33 and the inert Kosmos-2251 was predicted to have a miss distance of 584 metres, but this was less than the error, and so the prediction was ignored, and the actual collision and destruction of Iridium-33 came as a complete surprise.
The concept of a space elevator dates back to Tsilokovsky, but they are not commonly considered i... more The concept of a space elevator dates back to Tsilokovsky, but they are not commonly considered in near-term plans for space exploration, perhaps because a terrestrial elevator would not be possible without considerable improvements in tether material. A Lunar Space Elevator (LSE), however, can be built with current technology using commercially available tether polymers. This paper considers missions leading to infrastructure capable of shortening the time, lowering the cost and enhancing the capabilities of robotic and human explorers. These missions use planetary scale tethers, strings many thousands of kilometers long stabilized either by rotation or by gravitational gradients. These systems promise major reduction in transport costs versus chemical rockets, in a rapid timeframe, for a modest investment. Science will thus benefit as well as commercial activities.
Space-beamed solar power (SSP) is a concept based on a solar power satellite, that is, a solar pa... more Space-beamed solar power (SSP) is a concept based on a solar power satellite, that is, a solar panel…
Instrumentation located on the Earth for monitoring, tracking, and communicating with satellites,... more Instrumentation located on the Earth for monitoring, tracking, and communicating with satellites, sp…
Introduction: With the recent expansion of plans for lunar exploration there has been increased i... more Introduction: With the recent expansion of plans for lunar exploration there has been increased interest in support of operations at and near the Moon (i.e., in Cislunar Space), including robotic and crewed missions to the lunar polar regions. Real time navigation and communication will be especially difficult on the heavily shadowed lunar polar regions, given the bad lighting, the frequent lack of line of sight to the Earth, the extreme Geometrical Dilution of Precision (GDOP) for any use of terrestrial GPS and the lack, at least in the near term, of continual overhead satellite coverage. Unlike the Apollo surface Extra-Vehicular Activities (EVAs), future astronauts on polar surface EVAs will need local relays to communicate with the home base, and to perform local navigation, and communication beyond the local line of sight to a central lander.
A Lunar Space Elevator [LSE] can be built today from existing commercial polymers; manufactured, ... more A Lunar Space Elevator [LSE] can be built today from existing commercial polymers; manufactured, launched and deployed for less than $2B. A prototype weighing 48 tons with 100 kg payload can be launched by 3 Falcon-Heavy's, and will pay for itself in 53 sample return cycles within one month. It reduces the cost of soft landing on the Moon at least threefold, and sample return cost at least ninefold. Many benefits would arise. A near side LSE can enable valuable science mission, as well as mine valuable resources and ship to market in cislunar space, LEO and Earth's surface. A far-side LSE can facilitate construction and operation of a super sensitive radio astronomy facility shielded from terrestrial interference by the Moon. The LSE would facilitate substantial acceleration of human expansion beyond LEO.
The Lunar Space Elevator, a Near Term Means to Reduce Cost of Lunar Access
Read More: https://a... more The Lunar Space Elevator, a Near Term Means to Reduce Cost of Lunar Access
Extra-terrestrial space elevators are technically feasible with current materials and can be part... more Extra-terrestrial space elevators are technically feasible with current materials and can be part of a transportation network to fulfill NASA's strategic exploration goals for the next three decades.
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Papers by charles radley
Read More: https://arc.aiaa.org/doi/abs/10.2514/6.2017-5372
Read More: https://arc.aiaa.org/doi/abs/10.2514/6.2017-5372