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Scientific investigation of solar system with instrumented, unmanned spacecraft to fly, orbit and land on planets - Voyager project
NASA's Juno mission launched in 2011 and will explore the Jupiter system starting in 2016. Juno's suite of instruments is designed to investigate the atmosphere, gravitational fields, magnetic fields, and auroral regions. Its low perijove polar orbit will allow it to explore portions of the Jovian environment never before visited. While the Juno mission is not orbiting or flying close to Europa or the other Galilean satellites, planetary protection requirements for avoiding the contamination of Europa have been taken into account in the Juno mission design.The science mission is designed to conclude with a deorbit burn that disposes of the spacecraft in Jupiter's atmosphere. Compliance with planetary protection requirements is verified through a set of analyses including analysis of initial bioburden, analysis of the effect of bioburden reduction due to the space and Jovian radiation environments, probabilistic risk assessment of successful deorbit, Monte-Carlo orbit propagation, and bioburden reduction in the event of impact with an icy body.
This paper presents a perspective of Automation and Robotics (A&R) research and developments at NASA in terms of its history, its current status, and its future. It covers artificial intelligence, telerobotics and planetary rovers, and it encompasses ground operations, operations in earth orbit, and planetary exploration.
Deep Space Network /DSN/ data accuracy limitations relation with ability to determine orbit of probe, examining improvements after Mariner 2 and trends
A design is presented for an earth-orbiting facility for the analysis of planetary return samples under conditions of maximum protection against contamination but minimal damage to the sample. The design is keyed to a Mars sample return mission profile, returning 1 kg of documented subsamples, to be analyzed in low earth orbit by a small crew aided by automated procedures, tissue culture and microassay. The facility itself would consist of Spacelab shells, formed into five modules of different sizes with purposes of power supply, habitation, supplies and waste storage, the linking of the facility, and both quarantine and investigation of the samples. Three barriers are envisioned to protect the biosphere from any putative extraterrestrial organisms: sealed biological containment cabinets within the Laboratory Module, the Laboratory Module itself, and the conditions of space surrounding the facility.
Models of planet formation and of the orbital stability of planetary systems are used to predict the variety of planetary and satellite systems that may be present within our galaxy. A new approximate global criterion for orbital stability of planetary systems based on an extension of the local resonance overlap criterion is proposed. This criterion implies that at least some of Uranus' small inner moons are significantly less massive than predicted by estimates based on Voyager volumes and densities assumed to equal that of Miranda. Simple calculations (neglecting planetary gravity) suggest that giant planets which acrete substantial amounts of gas while their envelopes are extremely distended ultimately rotate rapidly in the prgrade direction.
The concept of orbital assembly and launch of oversized planetary (or lunar) spacecraft from a Space Station is rapidly coming of age. This prospect raises a host of new problems demanding timely resolution. The one most serious issue involved in launch from a rapidly precessing Space Station orbit (about -7.2 deg/day) is the need to cope with the generally out-of-plane orientation of the V-infinity departure vector. Methods dealing with single or multiple injection maneuvers, deep space plane changes, nodal shift caused by reboost strategy modifications, and departure window duration analysis are discussed.
Numerical integrations of fictitious objects are carried out in order to elucidate the dynamical behavior of potential short-period comets when they move in orbits at distances from the Sun comparable to those of Uranus and Neptune. As in the case of observed short-period comets, close encounters with the planets play a major role for the orbital evolution, and this is especially true for encounters with initial orbits nearly tangent to that of the planet. A comparison with integrations in which the planetary masses are larger by a factor 10 shows that, in the latter case, the orbital evolution is greatly accelerated, but the dynamical paths in phase space followed by the comets are altered.
Spacecraft speed increment requirements for circular parking orbit about Mars and earth
We review the current state of knowledge regarding Pluto's orbital motion.
The origin of orbital resonances is shown in the demonstration of the evolution of a pair of planetary satellites through a commensurability of the mean motions by a sequence of diagrams of constant energy curves in a two-dimensional phase space; the closed curve corresponding to the motion in each successive diagram is identified by its adiabatically conserved area. It is found that two-body resonances serve as a basis in the solution of the problem of the origin and evolution of the three-body Laplace resonance among the Galilean satellites of Jupiter. The unusual rotation state of Saturn's satellite Hyperion which is expected to tumble chaotically for an indefinite amount of time is discussed.
The science orbit for a future mission to Europa requires low eccentricity, low altitude, and high inclination. However, high inclination orbits around planetary satellites are unstable due to third-body perturbations. Without control, the orbiter impacts Europa after few weeks. To minimize control, a tour over the stable-unstable, averaged manifolds of unstable frozen orbits has been suggested. We proceed with the unaveraged equations and study the manifolds of unstable orbits that are periodic in a rotating frame attached to Europa. Massive numerical computation helps in understanding the unstable dynamics close to Europa, and, thus, in selecting long lifetime high inclination orbits. A final test of a selected set of initial conditions on a high fidelity, ephemeris model, validate the results.
All methods for extra-solar planet detection have their advantages and drawbacks. In photometry, for a planet to be detectable, it must pass in front of its star along the line of sight to the star. This may seem at first to be an unusual event, when in fact it has been shown to be equal to d*/D, or about 1% for planetary systems like our own (d* is the stellar diameter and D is the orbital diameter). Planetary scientists are interested in the complexities of an entire system rather than just a single planet. At first it might seem extremely unlikely that multiple planets would be detectable. But imagine having detected a planet in transit and that the relative inclinations, phi, of all the orbits is smaller than d*/D. Then, if you detect one planet, you should detect nearly all of them. However, for the solar system phi greater than d*/D, but still small. The exact derivation will be presented for the occurrence of multiple plane's in transit. A good approximation to the result is found to be given by (4/pi(phi)(d*/D(sub 2)), where D(sub 2) is the orbit of the second planet. For example if phi is 2 deg, then the probability for finding a second planet if it has an inclination less than phi will be equal to 36 d*/D(sub 2). For inner planets around solar-like stars, this turns out to be on the order of 20% of the systems detected. Extending this to three planets, such as for Venus, Earth and Mars, the probability would be 4%.
Restricted three-body problem for motion analysis of planetoid orbiting around triangular equilibrium point
Mission system and subsystem specifications for Mars probe deployed from planetary vehicle orbiting around Mars
The influence of gas drag and gravitational perturbations by a planetary embryo on the orbit of a planetesimal in the solar nebula was examined. Non-Keplerian rotation of the gas causes secular decay of the orbit. If the planetesimal's orbit is exterior to the perturber's, resonant perturbations oppose this drag and can cause it to be trapped in a stable orbit at a commensurability of order j/(j + 1), where j is an integer. Numerical and analytical demonstrations show that resonant trapping occurs for wide ranges of perturbing mass, planetesimal size, and j. Induced eccentricities are large, causing overlap of orbits for bodies in different resonances with j greater than 2. Collisions between planetesimals in different resonances, or between resonant and nonresonant bodies, result in their disruption. Fragments smaller than a critical size can pass through resonances under the influence of drag and be accreted by the embryo. This effect speeds accretion and tends to prevent dynamical isolation of planetary embryos, making gas-rich scenarios for planetary formation more plausible.
Guidance laws for propellant efficiency with optimum thrust program and error analysis for Voyager mission orbit insertion
Results presented are intended to assist planners and the mission analysis community in assessing the performance impact (pro or con) of launching planetary missions from an orbiting space station as compared to the usual, ground-based Shuttle launch of such missions. The analyses comprising this assessment include: (1) a basic understanding and description of the space station launch problem; (2) examination of alternative injection strategies and selection of the most appropriate strategy for minimizing performance penalties; and (3) quantitative comparison of station-launched and Shuttle-launched performance over a wide energy/mass range of planetary mission opportunities. Data for each mission covers a full 360 deg of possible nodal location of the space station orbit. The main results are that planetary missions can be launched from a space station within acceptable penalty bounds, and that the station serving as a staging base/propellant depot can benefit some missions requiring large payload mass or high injection energy.