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Diehl, R. E.

Publications and source records attributed to Diehl, R. E..

14 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS2004

The 2009 Mars Telecommunications Orbiter

The first spacecraft with a primary function of providing communication links while orbiting a foreign planet has begun development for a launch in 2009. NASA's Mars Telecommunications Orbiter would use three radio bands to magnify the benefits of other future Mars missions and enable some types of missions otherwise impractical. It would serve as the Mars hub for a growing interplanetary Internet. And it would pioneer the use of planet-to-planet laser communications to demonstrate the possibility for even greater networking capabilities in the future. With Mars Telecommunications Orbiter overhead in the martian sky, the Mars Science Laboratory rover scheduled to follow the orbiter to Mars by about a month could send to Earth more than 100 times as much data per day as it could otherwise send. The orbiter will be designed for the capability of relaying up to 15 gigabits per day from the rover, equivalent to more than three full compact discs each day. The same benefits would accrue to other future major Mars missions from any nation.

Wilson, G. R.↗
NASA NTRS1985

Satellite tour design for the Cassini mission

The mission design for the Cassini satellite tour of Saturn is described. The use of Titan encounters for gravity-assisted trajectory shaping to satisfy atmosphere, magnetosphere, and satellite science requirements is discussed. Three candidate satellite tours that illustrate the tradeoffs between different strategies to satisfy the science objectives are presented. Tour characteristics for a 4yr mission include at least 30 Titan encounters to provide a minimum of 90 deg orbit rotation for either a magnetotail petal orbit or noon petal orbit; evenly distributed Titan ground tracks for radar mapping coverage; at least 2 Iapetus and 1 Enceladus close flybys; inclined orbits during the first 3 yr to provide Earth and Sun occultations by Saturn and its rings; and Polar orbits during the fourth year.

Diehl, R. E.↗
NASA NTRS1983

Satellite tour design for the Galileo mission

The design of Galileo's tour of Jupiter's Galilean satellites is discussed. The Galileo mission is reviewed, and the gravity-assist trajectory design is described. Attention is given to mission constraints and science requirements, several tour design strategies, and a strawman satellite tour. The software used to design a satellite tour is examined.

Diehl, R. E.↗
NASA NTRS1982

Long-term motion of resonant satellites with arbitrary eccentricity and inclination

A first-order, semi-analytical method for the long-term motion of resonant satellites is introduced. The method provides long-term solutions, valid for nearly all eccentricities and inclinations, and for all commensurability ratios. The method allows the inclusion of all zonal and tesseral harmonics of a nonspherical planet. We present here an application of the method to a synchronous satellite including J2 and J22 harmonics. Global, long-term solutions for this problem are given for arbitrary values of eccentricity, argument of perigee and inclination.

Nacozy, P. E.↗
NASA NTRS1981

Touring the satellites of Saturn

A set of possible options is being considered for the next mission to Saturn after the Voyager flybys. Many of these options will include a Saturn orbiter which will provide detailed investigations of the atmosphere, magnetosphere, ring system and satellites of Saturn. The feasibility of designing Saturnian satellite tours which satisfy the science objectives and are consistent with mission requirements and constraints is explored. An orbiter mission is possible through using gravity assist trajectories to target the spacecraft from one satellite encounter to the next. A challenge in designing trajectories to encounter all the satellites is that Titan is the only massive satellite available for gravity assist. Two reference tours are presented illustrating different strategies to achieve the science objectives.

Diehl, R. E.↗
NASA NTRS1979

Trajectory description

The launch, interplanetary, encounter, and Mars orbit phases of the Viking 1 and 2 spacecraft trajectories are described. Time history plots of several parameters relative to the trajectories are presented along with tables of the geocentric, heliocentric, aerocentric, and injection orbital elements appropriate to each of the spacecraft trajectories.

Farless, D. L.↗
NASA NTRS1979

Galileo Jupiter encounter and satellite tour trajectory design

The trajectory design process for the Galilean satellite probe, expected to be launched in January 1982, is examined and its interplanetary path, emphasizing arrival dates and the Mars flyby, is presented. The Galileo spacecraft is of dual spin design, combining features of Pioneer, a spinning craft, and Voyager which was 3-axis stabilized. The design of the initial orbit from Orbiter deflection through Jupiter to the beginning of the satellite tour is discussed as well as the use of an Io gravity assist flyby to achieve Jupiter orbit insertion, and the effects of solar perturbation on the initial orbit. Detail is given to the entire satellite tour trajectory design process, starting from the requirements and constraints placed on the tour through the conic design to the final numerically integrated trajectories.

Diehl, R. E.↗
NASA NTRS1978

A semianalytical theory for the long-term motion of Pluto

The semianalytical approach to long-term solutions of resonant systems with three degrees of freedom, proposed by Giacaglia in 1965, is used to study the long-term motion of Pluto. The study takes into account the effects of Jupiter, Saturn and Uranus on the motion of Pluto. Modified periodic orbits of the third kind constitute the solutions; Pluto is found to librate about one of these periodic solutions. The long-term eccentricity, inclination, perihelion and librational amplitude of the planet are discussed.

Nacozy, P. E.↗
NASA NTRS1978

A discussion of the solution for the motion of Pluto

The semianalytical solution for Pluto given by Nacozy and Diehl (1978) is compared with the numerical solution obtained by Williams and Benson (1971). The effect of the Pluto-Uranus near resonance is discussed along with how it can be incorporated into the solution. Details are given on the calculation of certain quantities in the long-term solution. A calculation of librational periods of the perihelion, eccentricity, and inclination is performed. The calculation is based on the method of Giacaglia and Hori (1968).

Nacozy, P. E.↗
NASA NTRS1978

Viking first encounter of Phobos - Preliminary results

Viking Orbiter-1 (VO-1) made a series of close flybys of the Martian satellite Phobos in February and May 1977. A description is presented of the results obtained during the flybys in February. The flyby geometries for the encounter period in February are shown in a graph. The trajectory design gave flybys on the illuminated side of Phobos within 80 to 300 km during the entire encounter period. The primary encounter observations of Phobos included visual and infrared imaging as well as radio tracking of VO-1 while it was under the gravitational influence of Phobos. Visual imaging was obtained from two narrow-angle television cameras. Infrared observations were obtained from an infrared thermal mapper. Radio data included S- and X-band Doppler and ranging data to VO-1 with a 10-second Doppler count. Assuming for Phobos a volume of 500 + or - 900 cu km, a mean density of 1.9 + or - 0.6 g/cu cm is obtained for it on the basis of the processed data.

Tolson, R. H.↗
NASA NTRS1978

Phobos encounter trajectory and maneuver design

In February 1977, the Viking 1 Orbiter made repeated flybys of the Martian satellite Phobos at distances near 100 kilometers. These close encounters allowed a detailed scientific investigation of the nature and origin of Phobos. A sequence of three maneuvers was required to achieve the encounters. This paper presents the trajectory analysis performed to accommodate the scientific objectives and the spacecraft propulsive maneuver strategy used to achieve the desired trajectory while satisfying operational constraints. The actual maneuvers executed and the resultant Phobos encounter conditions are presented.

Diehl, R. E.↗
NASA NTRS1977

The motion of a satellite in resonance with the second-degree sectorial harmonic

The solution to the motion of a satellite in an eccentric orbit and in resonance with the second-degree sectorial harmonic of the potential field is developed. The method of solution used parallels the well known von Zeipel method of general perturbations. The solution consists of expressions for the variations of the Delaunay variables. These expressions are composed of the perturbations developed by Brouwer in 1959 for the motion of an artificial satellite plus first-order perturbations due to the second-degree sectorial harmonic (in terms of the Legendre normal elliptic integrals of the first and second kind).

Dallas, S. S.↗
NASA NTRS1975

Solutions of the motion of synchronous satellites with arbitrary eccentricity and inclination

A first order, semianalytical theory for the long term motion of resonant satellites is presented. The theory is valid for all eccentricities and inclinations and for all commensurability ratios. The method allows the inclusion of all the zonal and tesseral harmonics as well as luni solar perturbations and radiation pressure. The method is applied to a synchronous satellite including only the J sub 2 and J sub 22 harmonics. Global, long term solutions for this problem, eccentricity, argument of perigee, and inclination are obtained.

Nacozy, P. E.↗