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Spadoni, D. J.

Publications and source records attributed to Spadoni, D. J..

8 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1983

Cost estimation model for advanced planetary programs, fourth edition

The development of the planetary program cost model is discussed. The Model was updated to incorporate cost data from the most recent US planetary flight projects and extensively revised to more accurately capture the information in the historical cost data base. This data base is comprised of the historical cost data for 13 unmanned lunar and planetary flight programs. The revision was made with a two fold objective: to increase the flexibility of the model in its ability to deal with the broad scope of scenarios under consideration for future missions, and to maintain and possibly improve upon the confidence in the model's capabilities with an expected accuracy of 20%. The Model development included a labor/cost proxy analysis, selection of the functional forms of the estimating relationships, and test statistics. An analysis of the Model is discussed and two sample applications of the cost model are presented.

Spadoni, D. J.↗
NASA NTRS1980

Cost reduction in space operations - Structuring a planetary program to minimize the annual funding requirement as opposed to minimizing the program runout cost

An approach is proposed for the structuring of a planetary mission set wherein the peak annual funding is minimized to meet the annual budget restraint. One aspect of the approach is to have a transportation capability that can launch a mission in any planetary opportunity; such capability can be provided by solar electric propulsion. Another cost reduction technique is to structure a mission test in a time sequenced fashion that could utilize essentially the same spacecraft for the implementation of several missions. A third technique would be to fulfill a scientific objective in several sequential missions rather than attempt to accomplish all of the objectives with one mission. The application of the approach is illustrated by an example involving the Solar Orbiter Dual Probe mission.

Herman, D. H.↗
NASA NTRS1973

Cost estimation for unmanned lunar and planetary programs

A basic model is presented for estimating the cost of unmanned lunar and planetary programs. Cost data were collected and analyzed for eight lunar and planetary programs. Total cost was separated into the following components: labor, overhead, materials, and technical support. The study determined that direct labor cost of unmanned lunar and planetary programs comprises 30 percent of the total program cost. Twelve program categories were defined for modeling: six spacecraft subsystem categories (science, structure, propulsion, electrical power, communications, and guidance and integration, test and quality assurance, launch and flight operations, ground equipment, systems analysis and engineering, and program management). An analysis showed that on a percentage basis, direct labor cost and direct labor manhours compare on a one-to-one ratio. Therefore, direct labor hours is used as the parameter for predicting cost, with the advantage of eliminating the effect of inflation on the analysis.

Dunkin, J. H.↗
NASA NTRS1972

Advanced mission applications of nuclear electric propulsion

Current analysis of advanced unmanned planetary missions in the 1980's and beyond indicate the need for propulsion systems with performance capabilities beyond those of current and near state-of-art. One propulsion system concept being considered to fill this need is nuclear electric low thrust propulsion (NEP). Two different NEP system power levels are considered for performance analysis: 100 kw and 250 kw. The 100 kw NEP system uses a Centaur(D-1T) chemical stage for injection to an interplanetary transfer and the 250 kw system uses a spiral escape maneuver. Performance comparison is in general made on the basis of net payload at the target as a function of flight time. NEP performance is shown for unconstrained and constrained (20,000 hours) thrusting time. Specific impulse is optimized and ranges from 4000 sec to 7000 sec.

Spadoni, D. J.↗
NASA NTRS1971

Preliminary radar systems analysis for Venus orbiter missions

A short, preliminary analysis is presented of the problems involved in mapping the surface of Venus with radar from an orbiting spacecraft. Two types of radar, the noncoherent sidelooking and the focused synthetic aperture systems, are sized to fulfill two assumed levels of Venus exploration. The two exploration levels, regional and local, assumed for this study are based on previous Astro Sciences work (Klopp 1969). The regional level is defined as 1 to 3 kilometer spatial and 0.5 to 1 km vertical resolution of 100 percent 0 of the planet's surface. The local level is defined as 100 to 200 meter spatial and 50-10 m vertical resolution of about 100 percent of the surfAce (based on the regional survey). A 10cm operating frequency was chosen for both radar systems in order to minimize the antenna size and maximize the apparent radar cross section of the surface.

Brandenburg, R. K.↗
NASA NTRS1971

Mars surface sample return missions via solar electric propulsion

The characteristics and capabilities are described of solar electric propulsion (SEP) for performing Mars Surface Sample Return (MSSR) missions. The scope of the study emphasizes trajectory/payload analysis and the comparison of mission/system tradeoff options. The MSSR mission is examined only for the 1981-82 launch opportunity. Several other study constraints which bear directly on the results obtained are: (1) return samples in the range 5-25 kg, (2) use of lifting (offset C.G.) atmospheric entry at Mars which allows a low ratio (1.25) of entry weight to landed weight, and (3) rendezvous and docking in Mars orbit. Major results of the study are presented as performance curves of earth departure mass versus sample size for a number of different mission/system options. These options represent a spectrum of trip time, launch vehicle capability, combinations of low-thrust and ballistic maneuvers, chemical retro type, and earth recovery mode.

Spadoni, D. J.↗