Matches in SemOpenAlex for { <https://semopenalex.org/work/W93332009> ?p ?o ?g. }
Showing items 1 to 69 of
69
with 100 items per page.
- W93332009 abstract "Despite 127 years of observations, there is still room for improvement in the ephemeris of the Martian satellite Phobos. Early in this history, Earth-based astrometric observations of Phobos and Deimos were used to estimate the mass and oblateness of Mars. As more data accumulated, it became clear that a secular acceleration in the longitude of Phobos was occurring, and this was attributed to tidal dissipation within Mars, yielding rough estimates of the tidal quality factor, or Q. At the epoch of the earliest spacecraft observations of Phobos, from Mariner 9 and the Viking Orbiters and Landers, the gravitational field of Mars, and resulting forces on Phobos, were still not particularly well known. Thus observations of natural and artificial satellite motions continued to contribute, each in their own way, to knowledge of the mass distribution within Mars. Improvements in tracking system accuracy, and the placement of satellites, like the 1996 Mars Global Surveyor and 2001 Mars Odyssey, in circular polar orbits has lead to dramatic improvements to knowledge of the Mars gravity field. The direct gravitational influence on Phobos is no longer expected to be a limiting factor in predicting its orbital motion. Despite that progress, a variety of observations of Phobos from recent orbiters and landers suggest that the best satellite ephemeris still has along-track orbit errors which are accumulating at a rate of 1.75 kilometers per year, with Phobos gaining on the predicted positions. These recent observations alone do not span sufficient time to separately resolve the positional error into changes in mean motion and changes in secular acceleration. However, combining them with earlier observations will allow improvements in both the mean motion and its first derivative. This latter parameter is particularly interesting, as it relates to tidal dissipation, and thus uniquely constrains the internal structure of Mars. The current best estimate of the secular acceleration rate of Mars implies a surprisingly low value for the tidal dissipation factor Q = (94 plus or minus 1). For the Earth, most tidal dissipation occurs within the oceans. The terrestrial mantle tidal Q is 280. An issue of interest is then: why, where, and how does Mars dissipate tidal energy so effectively." @default.
- W93332009 created "2016-06-24" @default.
- W93332009 creator A5018571347 @default.
- W93332009 creator A5047333821 @default.
- W93332009 creator A5082397314 @default.
- W93332009 creator A5085737159 @default.
- W93332009 date "2004-01-01" @default.
- W93332009 modified "2023-09-24" @default.
- W93332009 title "Phobos Ephemeris Improvement from Recent Spacecraft Observations" @default.
- W93332009 hasPublicationYear "2004" @default.
- W93332009 type Work @default.
- W93332009 sameAs 93332009 @default.
- W93332009 citedByCount "0" @default.
- W93332009 crossrefType "journal-article" @default.
- W93332009 hasAuthorship W93332009A5018571347 @default.
- W93332009 hasAuthorship W93332009A5047333821 @default.
- W93332009 hasAuthorship W93332009A5082397314 @default.
- W93332009 hasAuthorship W93332009A5085737159 @default.
- W93332009 hasConcept C121332964 @default.
- W93332009 hasConcept C122523270 @default.
- W93332009 hasConcept C127313418 @default.
- W93332009 hasConcept C1276947 @default.
- W93332009 hasConcept C13280743 @default.
- W93332009 hasConcept C14257148 @default.
- W93332009 hasConcept C19269812 @default.
- W93332009 hasConcept C2780554747 @default.
- W93332009 hasConcept C64828349 @default.
- W93332009 hasConcept C68702407 @default.
- W93332009 hasConcept C83260615 @default.
- W93332009 hasConcept C87355193 @default.
- W93332009 hasConceptScore W93332009C121332964 @default.
- W93332009 hasConceptScore W93332009C122523270 @default.
- W93332009 hasConceptScore W93332009C127313418 @default.
- W93332009 hasConceptScore W93332009C1276947 @default.
- W93332009 hasConceptScore W93332009C13280743 @default.
- W93332009 hasConceptScore W93332009C14257148 @default.
- W93332009 hasConceptScore W93332009C19269812 @default.
- W93332009 hasConceptScore W93332009C2780554747 @default.
- W93332009 hasConceptScore W93332009C64828349 @default.
- W93332009 hasConceptScore W93332009C68702407 @default.
- W93332009 hasConceptScore W93332009C83260615 @default.
- W93332009 hasConceptScore W93332009C87355193 @default.
- W93332009 hasLocation W933320091 @default.
- W93332009 hasOpenAccess W93332009 @default.
- W93332009 hasPrimaryLocation W933320091 @default.
- W93332009 hasRelatedWork W1482626348 @default.
- W93332009 hasRelatedWork W1504612845 @default.
- W93332009 hasRelatedWork W1989147094 @default.
- W93332009 hasRelatedWork W2030783245 @default.
- W93332009 hasRelatedWork W2039161696 @default.
- W93332009 hasRelatedWork W2047098615 @default.
- W93332009 hasRelatedWork W2106945947 @default.
- W93332009 hasRelatedWork W2159516452 @default.
- W93332009 hasRelatedWork W2307708357 @default.
- W93332009 hasRelatedWork W2571054893 @default.
- W93332009 hasRelatedWork W2992984232 @default.
- W93332009 hasRelatedWork W3012395299 @default.
- W93332009 hasRelatedWork W3014005237 @default.
- W93332009 hasRelatedWork W3080710252 @default.
- W93332009 hasRelatedWork W3095039862 @default.
- W93332009 hasRelatedWork W3112700842 @default.
- W93332009 hasRelatedWork W3205789914 @default.
- W93332009 hasRelatedWork W780451593 @default.
- W93332009 hasRelatedWork W787090775 @default.
- W93332009 hasRelatedWork W3126363820 @default.
- W93332009 isParatext "false" @default.
- W93332009 isRetracted "false" @default.
- W93332009 magId "93332009" @default.
- W93332009 workType "article" @default.