Trajectories to the outer planets via Jupiter swingby
Tabulations of trajectory data for one way trips from Earth to Saturn, Pluto, Uranus, and Neptune via Jupiter swingby
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Tabulations of trajectory data for one way trips from Earth to Saturn, Pluto, Uranus, and Neptune via Jupiter swingby
Minimum energy trajectory data for Jupiter, Saturn, Uranus, Neptune, and Pluto
Results are presented for infrared photometry of Pluto in the wavelength range from 1.2 to 2.2 microns, which includes the diagnostic absorption bands of water and methane frosts (designated as H1 and H2, respectively). Based on Pluto's observed J-H color and H1/H2 reflectance ratio as well as restrictions imposed by other observational and theoretical studies, it is concluded that methane frost is probably the dominant reflecting material on the planet's surface. It is suggested that this frost may be mixed with other materials, and some variation of the frost cover is indicated. Two plausible sources for the methane on Pluto are discussed, the average geometric albedo of the planet is assumed to be 0.4, and its diameter is estimated to be 3300 km.
The search for a possible tenth planet in our solar system is examined. The history of the discoveries of Uranus, Neptune, and Pluto are reviewed. Searches of the sky with telescopes and theoretical studies of the gravitational influences on the orbits of known objects in the solar system are discussed. Information obtained during the Pioneer 10 and 11 missions which could suggest the presence of an undiscovered planet and computer simulations of the possible orbit of a tenth planet are presented.
Pluto, discovered in 1930, is the largest of a class of primordial bodies at the edge of our solar system that have comet-like properties and remain relatively unmodified by warming from the sun. It is the only planet in the solar system not explored via robotic spacecraft. This lecture discusses the status of the Pluto Express preproject (science objectives, etc.), and its telecommunication subsystem.
The Wright Mons region of Pluto remains one of the most intriguing and enigmatic landscapes on the planet. Wright Mons is a large mountain ~150 km across that rises ~4 km above its surroundings, sports a central depression that is ~45 km across and ~4 km deep, and was tentatively assigned a cryovolcanic origin immediately following the New Horizons encounter in 2015 (Fig. 1) [1,2,3]. But the absence of obvious lateral flow features and the lack of unambiguously diagnostic characteristics of calderas or vents within the central depression have challenged the development of specific formation hypotheses. The pervasive cover of pillow-like hummocks, typically 7-20 km across, on the flanks and surroundings of Wright Mons have naturally figured into various working explanations for the formation of this region (Fig. 2). Individual hummocks themselves are covered by a km-scale blocky (or coalescing short ridge) texture. The similarity in size and shape of the convex hummocks and the style of their organization, such as forming avaguely concentric fabric near the summit, potentially lend themselves to an endogenic origin.
Voyager 2, launched in August 1977, will fly by Uranus in January, 1986, passing within 29,000 km of that planet's innermost moon, Miranda. It will subsequently encounter Neptune in August 1989, flying within 10,000 km of its inner satellite, Triton; images made of this moon by a high resolution camera are expected to reveal surface features as small as a few hundred meters in diameter. The composition of the Uranian moons will br inferred from their near-IR reflectance spectra and mean densities. While the spacecraft will not fly by Pluto, it is expected that the lessons learned from the Voyager encounters with Neptune and Uranus will expand current understanding of Pluto and its moon, Charon.
MEASURE-Jupiter is a new mission concept for the exploration of giant planets, with initial application to Jupiter. By flying sets of lightweight spacecraft with highly focused measurement objectives, it is designed to break the apparent impass in giant planet exploration beyond Cassini. The MEASURE-Jupiter concept is characterized by: 1) intensive exploration of a giant planet system, 2) multiple small missions flown in focused waves using spacecraft costing $100M to $200M, and 3) mission sets launched every 2 to 3 years. Why Jupiter? Jupiter is the most complex planetary system in the Solar System with many scientifically intriguing bodies and phenomena to explore. The Galileo mission will scratch the surface of the exploration of Jupiter, posing many questions for the MEASURE-Jupiter missions to address. Jupiter is also the easiest planet in the Outer Solar System to reach, making possible flight times of 2 years and total mission durations of 3 years or less. Concept design studies have uncovered a number of scientifically rewarding, simple, low-cost mission options. These options have the additional attraction of being able to launch on 2-year trajectories to Jupiter with low-cost Delta II expendable launch vehicles. A partial list of mission concepts studied to date include: Io Very Close Flyby, Jupiter Close Polar Pass, Mini-Orbiters, and Galilean Satellite Penetrators. Key to the realization of the MEASURE-Jupiter missions is the judicious use of the new low power consuming advanced technology and applicable systems from the Pluto Fast Flyby mission spacecraft design. Foremost of the new technologies planned for inclusion are the elements of hybrid solar array/battery power systems which make it possible to perform the identified missions without the need for Radioactive Thermoelectric Generators (RTGs). This relieves the mission design of the attendant programmatic complexities, cost, and constraints attendant with the use of RTGs.
Direct Fusion Drive (DFD) is a unique fusion engine concept based on the Princeton Field-Reversed Configuration (PFRC) fusion reactor conceived by Dr. Sam Cohen of the Princeton Plasma Physics Laboratory. DFD would enable the Pluto orbiter and lander context mission and more broadly enable true "rapid transit" to outer-planet and near interstellar space. The truly game-changing levels of thrust and power in a modestly sized package could integrate with our current launch infrastructure while radically expanding the science capability of these missions. Our Phase I was our first funded work on the DFD, with previous work at PSS occurring only under internal R&D. We established the feasibility of our Pluto mission trajectories using straight-line and planar models, including a departure spiral from Earth and insertion at Pluto. We developed our first thrust and specific impulse model using the results of the UEDGE multi-fluid code. Our specific power model was improved. During this Phase II effort, we continued our efforts to increase the fidelity of the designs for the RF, magnet, and shielding subsystems. Dedicated thrust augmentation experiments were run on the PFRC experiment, using a supersonic gas puffing valve. For the first time, we analyzed the design of a closed-loop operation mode and estimated the hardware that would be required for a dual-mode engine. In an exciting new development, we have invented a new thermophotovoltaic thermal conversion method that has the potential to have efficiencies of a Brayton or Stirling system. Our report presents details of these analyses. Our roadmap to bringing DFD to flight predicts that with sufficient support, a first flight unit could be built by 2040. We anticipate that three machine generations are required before this point: a ~1 T PFRC-3 machine hitting new plasma temperature and density levels, a ~5 T PFRC-4 machine with first demonstration of D-3He fusion, and a flight. (The current experiment, PFRC-2, is limited to about 0.1 T). In order to achieve a flight in 2035-2040, the TRL of the supporting systems must be increased in parallel, including low mass radiators, cryogenic propellant storage, and large (>100 kW) thermal conversion systems. Fortunately, many of these systems are dual-use and are required for other technologies including fission systems, so DFD would contribute to and benefit from those programs. This NIAC support and the results of our work have led to multiple follow-on contracts. We won two NASA STTRs focused on DFD subsystems, one on the RF system and one on the superconducting magnets, and our magnet STTR is now midway through a Phase II. We will be receiving a superconducting test magnet for experiments at PPPL this summer. In addition, we won an ARPA-E OPEN grant; this is the first time that OPEN has included fusion technologies, and we are part of a cohort of three alternative fusion companies now supported directly by DOE. We are very optimistic that if we are able to meet our experimental milestones in the next 12-18 months, we will be competitive for additional DOE grants to build PFRC-3.
High-power electric propulsion is a critical component of NASA s proposed missions to the outer planets. Mission studies have shown that high-power, high-specific-impulse propulsion systems can deliver 2000 kg of scientific payload to Pluto with trip times on the order of 10 years. Of greater significance is the ability of these propulsion systems to place this science payload in orbit around the planet, rather than making the fast fly-bys associated with traditional chemical propulsion systems. Significant ground test programs are required to develop the new technologies needed for thrusters operating at power levels exceeding 20 kW, an order of magnitude above the state of the art.
Widely varying paths of evolutionary history, atmospheric processes, solar fluxes, and temperatures have produced vastly different planetary atmospheres. The similarities and differences between the earth atmosphere and those of the terrestrial planets (Venus and Mars) and of the Jovian planets are discussed in detail; consideration is also given to the photochemistry of Saturn, Uranus, Pluto, Neptune, Titan, and Triton. Changes in the earth's ancient atmosphere are described, and problems of interest in the earth's present troposphere are discussed, including the down wind effect, plume interactions, aerosol nucleation and growth, acid rain, and the fate of terpenes. Temperature fluctuations in the four principal layers of the earth's atmosphere, predicted decreases in the ozone concentration as a function of time, and spectra of particles in the earth's upper atmosphere are also presented. Finally, the vertical structure of the Venus cloud system and the thermal structure of the Jovian planets are shown graphically.
Observations from different sources of Pluto occulting a 12th-magnitude star indicate an extended atmosphere around the planet. Here, data obtained from the 1 m telescope at the University of Tasmania, Hobart are interpreted in terms of a theory for occultation by an atmosphere whose thickness is comparable to the planetary radius. The data can be satisfactorily fitted with a methane atmosphere at plausible pressures and temperatures. The surface pressures inferred from this single chord are uncertain by an order of magnitude, but are consistent with spectroscopic constraints.
The solar system has been visited by space probes, ranging from the Mariner Mercury-Venus mission exploring inward toward the sun, and continuing through the Voyager probes out into interstellar space and (on its way now) the New Horizons probe to Pluto and the Kuiper belt. This talk examines what we know of the planets of the solar system from probes, and talks about where we will go from here.
JWST will enable breakthroughs in our understanding of the physical characteristics of cold bodies in the outer reaches of the Solar System. These objects include Pluto and other Kuiper Belt Objects (KBOs), the icy moons of the giant planets, and distant cometary nuclei. Recent discoveries of large objects in the Kuiper belt, along with many smaller members, make it clear that this region represents a major constituent of our Solar System, one that was hidden until recently because it is so remote and challenging to observe. The near-IR and mid-IR performance of JWST will be unique in its power to probe this region. This poster describes the science drivers for JWST observations of Solar System objects and plans for implementing this capability.
A new spectrum of Pluto in the region 1.4 to 1.9 microns provides confirmation of the presence of solid methane on the planet's surface. Considerations of the vapor pressure of methane gas above the solid indicate the presence of a tenuous atmosphere of this gas, the surface partial pressure of which is variable from perihelion to aphelion. The implication of a high surface albedo, the newly derived mass of Pluto, and inferences as to the range of plausible bulk mean densities indicate that the radius of Pluto should lie in the range 1200 to 1800 km.
The present time-resolved, 0.96-2.65-micron spectrophotometry for the Pluto-Charon system indicates night-to-night variations in the depths of the methane absorptions such that the bands' equivalent width is near minimum light. The interpretation of these data in terms of a depletion of methane in dark regions of the planet, relative to bright ones, is consistent with the Buie and Fink (1987) observations. The near-IR spectrum of Pluto seems to be dominated by surface frost. It is suggested that the dark equatorial regions of Pluto are redder than those of moderate albedo.
Recent models of the internal structure of Pluto and Charon, made possible by analysis of the Pluto/Charon mutual events are reviewed. At a mean density of just over 2 g/cu cm and a predicted rock mass fraction of roughly 0.7, the Pluto/Charon system is significantly rockier than the icy satellites of the giant planets, a contrast which may reflect its formation in a CO-rich outer solar nebula rather than a circumplanetary nebula. Pluto and Charon may in fact be so rocky that they lost volatiles early in their history (possibly during a Charon-forming impact event), although this is still an open issue.