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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 235 records · Page 13
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NASA NTRS2008

Chasing a Comet with a Solar Sail

Solar sail propulsion systems enable a wide range of missions that require constant thrust or high delta-V over long mission times. One particularly challenging mission type is a comet rendezvous mission. This paper presents optimal low-thrust trajectory designs for a range of sailcraft performance metrics and mission transit times that enables a comet rendezvous mission. These optimal trajectory results provide a trade space which can be parameterized in terms of mission duration and sailcraft performance parameters such that a design space for a small satellite comet chaser mission is identified. These results show that a feasible space exists for a small satellite to perform a comet chaser mission in a reasonable mission time.

Stough, Robert W.↗
NASA NTRS1983

Comet Halley ephemeris uncertainties in 1985-1986

For the planned flyby missions to Comet Halley in March 1986, the comet's ephemeris uncertainties completely dominate the spacecraft-comet miss distance. In an effort to determine realistic Comet Halley ephemeris uncertainties, a statistical covariance analysis was conducted using the actual data in 1909-1910-1911 and simulated data in 1984-1985-1986. In 1985-1986, Comet Halley's ephemeris uncertainties are very sensitive to the comet's orbital position, the optical data noise, data schedule, and whether or not the old data is included in the orbital solutions. The comet's ephemeris uncertainties in March 1986 are relatively insensitive to reasonable center of light/center of mass offsets and also to possible radar data taken in late November 1985. Accurate Space Telescope observations made in early March 1986 might significantly improve upon the comet's position uncertainties for the various intercepting spacecraft.

Yeomans, D. K.↗
NASA NTRS1987

The Comet Rendezvous Asteroid Flyby project

The first Mariner Mark II (MMII) mission, the Comet Rendezvous Asteroid Flyby (CRAF), is described in detail. The comet Tempe 2 has been selected as the rendezvous target. The CRAF payload will include a cometary retarding ion mass spectrometer, a cometary ice and dust experiment, a penetrator/lander, a thermal IR radiometer, and a visual IR mapping spectrometer.

Draper, Ronald F.↗
NASA NTRS1963

Comet Intercept Study

STL (Space Technology Laboratories, Inc.) has been studying, during the past year, the problems of carrying out a comet intercept mission. During the course of this study, the properties of 31 short-term comets have been examined to determine the feasibility of a mission to any of them during the next 15 years. In the process of selecting these comets, injection energies for each of these comets at a suitable launch period were determined. In addition, the distance of the earth at intercept, the transit and flight times, and the guidance requirements were evaluated. Also, to determine the effectiveness of such a mission, possible scientific instruments which could be used to measure the various characteristics of the comets have been studied. Finally, to determine the present feasibility of such a mission, the payload capability of available boosters was examined, and a spacecraft configuration with appropriate subsystems was also studied.

INTERCEPTION↗
NASA NTRS1972

Introduction: Mission Opportunities and Models

NASA's current plans and priorities through the mid-1980s are briefly presented including the fly-thru mission to Comet d'Arrest in 1976, Grand-Tour missions to the outer planets, and the Venus Explorer program.

Sirri, N.↗
NASA NTRS1985

A cometary and interplanetary dust experiment on the Vega spacecraft missions to Halley's Comet

The dust counter and mass analyzer on board both the Vega 1 and Vega 2 spacecraft scheduled to encounter Halley's Comet are discussed. The operational modes, data formats, telemetry modes and data acquisition, and scientific measurements planned for this experiment both at encounter and during interplanetary travel are described. The initial postlaunch calibration and experiment status are summarized in an appendix.

Perkins, M. A.↗
NASA NTRS1987

A comet nucleus sample return mission

A joint ESA/NASA proposal for the acquisition and delivery of samples of the cometary nucleus is considered, and the importance of such samples in providing input as to the origin of the solar system is underlined. Mission options employing all-chemical propulsion, solar electric propulsion, and a combination of the two are explored in detail. Conceptual spacecraft designs have been developed and mass performance estimates made for a wide range of possible targets. The importance of the use of some form of aerobraking during return to earth is noted. Methods for acquiring the nuclear samples are discussed, and characteristics of the mission operations are reviewed.

Kerridge, Stuart J.↗
NASA NTRS1991

Sungrazing comets observed by the Solar Maximum Mission coronagraph

The 10 sun-grazing comets (all members of the Kreutz group) detected by the white-light coronagraph of the SMM satellite during its 6-year operational lifetime are described. Numerical data are summarized in tables, and images are provided. Consideration is given to the question of detectability, apparent motions and orbits, coma brightness variations, tail behavior, and occurrence rates. The data are shown to confirm the episodic nature of sun-grazing events, as suggested by Marsden (1967).

Macqueen, R. M.↗
NASA NTRS1972

Mission strategy for combined comet-asteroid flybys.

Review of the currently consolidating interest in one or more relatively inexpensive small body exploration missions, and discussion of a proposed ballistic flyby of two asteroids and the periodic comet Forbes, to be launched in 1977. Trajectory data and target encounter conditions are presented for a selected set of missions which are compatible with the propulsion capabilities of a modified Pioneer F & G spacecraft.

Brooks, D. R.↗
NASA NTRS1977

A mission design for the Halley comet rendezvous using Ion Drive

The Ion Drive propulsion system, a derivative of the old Solar Electric Propulsion (SEP) technology is considered adequate to perform all mission objectives of a proposed Halley's comet rendezvous (scheduled for launch in 1982) except one: control of thermal energy from the concentrating solar arrays. This problem can be solved, however, by adding a separable tail probe to the baseline system. The system consists of an Ion Propulsion Module (IPM) and a Mission Module (MM). Scientific objectives include a determination of the structure of the comet nucleus, an evaluation of nucleus evolution, an assay of the comet's atmosphere and ionosphere, and a study of the interaction between the comet and the interplanetary medium. Attention is given to the navigation parameters necessary for heliocentric transfer and post-rendezvous circumnavigation of the comet.

Boain, R. J.↗
NASA NTRS1986

Observations of Halley's Comet by the Solar Maximum Mission (SMM)

Solar Maximum Mission coronagraph/polarimeter observations of large scale phenomena in Halley's Comet are discussed. Observations of the hydrogen coma with the UV spectrometer are considered. It is concluded that coronograph/polarimeter observations of the disconnection event, in which the entire plasma tail uproots itself from the head of the comet, is convected away in the solar wind at speeds in the 50 to 100 km/sec range (relative to the head), and is replaced by a plasma tail constructed from folding ion-tail rays, are the most interesting.

Niedner, M. B.↗
NASA NTRS1994

Cometary coma chemical composition (C4) mission

Cometary missions are of enormous fundamental importance for many different space science disciplines, including exobiology. Comets are presumed relics of the earliest, most primitive material in the solar nebula and are related to the planetesimals. They undoubtedly provided a general enrichment of volatiles to the inner solar system (contributing to atmospheres and oceans) and may have been key to the origin of life. A Discovery class, comet rendezvous mission, the Cometary Coma Chemical Composition (C4) Mission, was selected for further study by NASA earlier this year. The C4 Mission is a highly focused and usefully-limited subset of the Cometary Rendezvous Asteroid Flyby (CRAF) Mission, concentrating exclusively on measurements which will lead to an understanding of the chemical composition and make-up of the cometary nucleus. The scientific goals of the Cometary Coma Chemical Composition (C4) Mission are to rendezvous with a short-period comet and (1) to determine the elemental, chemical, and isotopic composition of the nucleus and (2) to characterize the chemical and isotopic nature of its atmosphere. Further, it is a goal to obtain preliminary data on the development of the coma (dust and gas composition) as a function of time and orbital position.

Carle, G. C.↗
NASA NTRS2012

New Mission Old Spacecraft: EPOXI's Approach to the Comet Hartley-2

NASA's Deep Impact mission ended successfully in 2005 after an impact and close flyby of the comet 9P/Tempel-1. The Flyby spacecraft was placed in hibernation and was left to orbit the sun. In 2007, engineers at the Jet Propulsion Laboratory brought the spacecraft out of hibernation and successfully performed two additional missions. These missions were EPOCh, Extra-solar Planetary Observation and Characterization, a photometric investigation of transiting exo-planets, and DIXI, Deep Impact eXtended Investigation, which maneuvered the Flyby spacecraft towards a close encounter with the comet 103P/Hartley- 2 on 4 November 2010. The names of these two scientific investigations combine to form the overarching mission's name, EPOXI. The encounter with 103P/Hartley-2 was vastly different from the prime mission's encounter with 9P/Tempel-1. The geometry of encounter was nearly 180 ? different and 103P/Hartley-2 was approximately one-quarter the size of 9P/Tempel-1. Mission operations for the comet flyby were broken into three phases: a) Approach, b) Encounter, and c) Departure. This paper will focus on the approach phase of the comet encounter. It will discuss the strategies used to decrease both cost and risk while maximizing science return and some of the challenges experienced during operations.

science return↗
NASA NTRS2013

Shape, Density, and Geology of the Nucleus of Comet 103P/Hartley 2

Data from the Extrasolar Planet Observation and Deep Impact Extended Investigation (EPOXI) mission show Comet 103P/Hartley 2 is a bi-lobed, elongated, nearly axially symmetric comet 2.33 km in length. Surface features are primarily small mounds <40 m across, irregularly-shaped smooth areas on the two lobes, and a smooth but variegated region forming a “waist” between the two lobes. Assuming parts of the comet body approach the shape of an equipotential surface, the mean density of Hartley 2 is modeled to be 200–400 kg /cubic m.. Such a mean density suggests mass loss per orbit of >1%. The shape may be the evolutionary product of insolation, sublimation, and temporary deposition of materials controlled by the object’s complex rotation.

Extrasolar↗
NASA NTRSDate not supplied

The Stardust Sample Return Mission

The NASA Discovery-class Stardust comet sample return mission collected samples from the coma of Comet 81P/Wild 2 and returned them to Earth for study in 2006. The samples were collected at hypervelocities using low-density aerogel as the spacecraft did a flyby of the comet’s nucleus. In this talk, I will begin by giving an overview of the mission that covers (i) the mission design, (ii) the spacecraft, and (iii) the spacecraft’s encounter with Comet/81P Wild 2 and its subsequent return to Earth. This will be followed by a discussion of many of the principal scientific discoveries that resulted from both the comet flyby and the study of the returned samples in terrestrial laboratories (discoveries that will continue to grow as the returned samples continue to be studied in the future).

Comets↗