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Roberts, P. H., Jr.

Publications and source records attributed to Roberts, P. H., Jr..

7 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1979

The Saturn Orbiter Dual Probe mission concept

This paper presents the results of a mission design study for NASA of the next Saturn mission to follow Voyager. The Saturn Orbiter Dual Probe (SO2P) mission combines three spacecraft - a Saturn orbiter, a Saturn probe, and a Titan probe/lander - into a multipurpose Saturn exploration package. The mission is to conduct a survey from orbit around Saturn and to physically probe bodies in the Saturnian system, the first such mission to do so. The mission has many possible options including: combining solar electric propulsion with earth gravity assist, assembling of IUS stages in orbit, and aerocapture at Titan to insert into Saturn orbit.

Roberts, P. H., Jr.↗
NASA NTRS1977

Lunar far side sample return missions using the Soviet Luna system

The paper assesses the feasibility of using the Soviet Lunar Sample Return vehicle in cooperation with the United States to return a sample of lunar soil from the far side of the moon. Analysis of the orbital mechanics of the Luna system shows how landing sites are restricted on the moon. The trajectory model is used to duplicate the 3 Luna missions flown to date and the results compared to actual Soviet data. The existence of suitable trajectories for the earth return trip is assessed, including landing dispersions at earth. Several possible areas of technical difficulty are identified.

Roberts, P. H., Jr.↗
NASA NTRS1977

1983 and 1985 multi-revolution opportunities to Mars

The use of Earth-Mars trajectories requiring more than one revolution about the Sun is discussed. Such trajectories appear to merit consideration in the next mission to Mars. Some unfamiliar mechanics of these orbits are explained and a nomenclature developed for them. Two candidate multi-revolution opportunities are discussed in some detail and compared to ordinary trajectories. It is shown that such trajectories can yield significantly better payloads in the mid-1980s than ordinary trajectories.

Roberts, P. H., Jr.↗
NASA NTRS1977

Jupiter Orbiter and Probe project - Synthesis of the mission design

The Jupiter Orbiter Probe (JOP), scheduled to be launched by the Shuttle IUS in 1981, is described in terms of its scientific mission objectives. These include: analysis of the chemical composition and physical state of Jupiter's atmosphere, the chemical composition and physical state of Ganymede and Callisto, and the topology and behavior of the magnetic field and energetic particle fluxes. Attention is given to an atmospheric probe which will be launched from the main probe, and to the navigation requirements necessary to 'bounce' the JOP around the Jovian moons.

Beckman, J. C.↗
NASA NTRS1975

Trajectory design for Saturn orbiter missions in the mid 1980s

The special orbital techniques recently developed for Jupiter orbiter mission were studied for application to a Saturn orbiter mission. The direct opportunities from 1985 through 1990 are compared, and the 1985 opportunity is discussed in detail as an example. The impact of various Shuttle upper stages is considered. Gravity-assisted interplanetary flights can more than double payloads delivered to a Saturn orbit at a cost of about two years of flight time. The uncertainty of the particle environment near Saturn's rings and the desire to use Titan for gravity assistance to decrease orbital period prompted the study of several orbit-insertion schemes. Titan gravity assistance is more powerful than that of Jupiter's satellites. Titan can save 700 m/s of velocity change during orbit insertion if a high periapsis is necessary. Titan can be used to maneuver the line of apsides and orbital inclination to explore Saturn, its environment, and Titan itself at various solar phase angles and to set up occultations.

Roberts, P. H., Jr.↗
NASA NTRS1973

Computer-Generated Movies for Mission Planning

Computer-generated movies help the viewer to understand mission dynamics and get quantitative details. Sample movie frames demonstrate the uses and effectiveness of movies in mission planning. Tools needed for movie-making include computer programs to generate images on film and film processing to give the desired result. Planning scenes to make an effective product requires some thought and experience. Viewpoints and timing are particularly important. Lessons learned so far and problems still encountered are discussed.

Roberts, P. H., Jr.↗