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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 253 records · Page 14
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NASA NTRS2009

Combinations of Earth orientation measurements : SPACE2007, COMB2007, and POLE2007.

Independent Earth orientation measurements taken by the space-geodetic techniques of lunar and satellite laser ranging, very long baseline interferometry, and the Global Positioning System have been combined using a Kalman filter. The resulting combined Earth orientation series, SPACE2007, consists of values and uncertainties for Universal Time, polar motion, and their rates that span from September 28, 1976, to March 29, 2008, at daily intervals and is available in versions whose epochs are given at either midnight or noon. The space-geodetic measurements used to generate SPACE2007 have then been combined with optical astrometric measurements to form two additional combined Earth orientation series: (1) COMB2007, consisting of values and uncertainties for Universal Time, polar motion, and their rates that span from January 20, 1962, to March 29, 2008, at daily intervals and which is also available in versions whose epochs are given at either midnight or noon; and (2) POLE2007, consisting of values and uncertainties for polar motion and its rate that span from January 20, 1900, to March 22, 2008, at 30.4375-day intervals.

Gross, R. S.↗
NASA NTRS2010

Combinations of Earth orientation measurements : SPACE2008, COMB2008, and POLE2008

Independent Earth orientation measurements taken by the space-geodetic techniques of lunar and satellite laser ranging, very long baseline interferometry, and the Global Positioning System have been combined using a Kalman filter. The resulting combined Earth orientation series, SPACE2008, consists of values and uncertainties for Universal Time, polar motion, and their rates that span from September 28, 1976, to July 2, 2009, at daily intervals and is available in versions whose with epochs are given at either midnight or noon. The space-geodetic measurements used to generate SPACE2008 have then been combined with optical astrometric measurements to form two additional combined Earth orientation series: (1) COMB2008, consisting of values and uncertainties for Universal Time, polar motion, and their rates that span from January 20, 1962, to July 2, 2009, at daily intervals and which areis also available in versions whose with epochs are given at either midnight or noon; and (2) POLE2008, consisting of values and uncertainties for polar motion and its rate that span from January 20, 1900, to June 22, 2009, at 30.4375-day intervals..

Gross, R. S.↗
NASA NTRS2011

Combinations of Earth Orientation Measurements : SPACE2010, COMB2010, and POLE2010

Independent Earth orientation measurements taken by the space-geodetic techniques of lunar and satellite laser ranging, very long baseline interferometry, and the Global Positioning System have been combined using a Kalman filter. The resulting combined Earth orientation series, SPACE2010, consists of values and uncertainties for Universal Time, polar motion, and their rates that span from September 28, 1976, to July 15, 2011, at daily intervals and is available in versions with epochs given at either midnight or noon. The space-geodetic measurements used to generate SPACE2010 have then been combined with optical astrometric measurements to form two additional combined Earth orientation series: (1) COMB2010, consisting of values and uncertainties for Universal Time, polar motion, and their rates that span from January 20, 1962, to July 15, 2011, at daily intervals and which are also available in versions with epochs given at either midnight or noon; and (2) POLE2010, consisting of values and uncertainties for polar motion and its rate that span from January 20, 1900, to June 22, 2011, at 30.4375-day intervals.

Gross, R. S.↗
NASA NTRS2013

Combinations of Earth Orientation Measurements: SPACE2011, COMB2011, and POLE2011

Independent Earth orientation measurements taken by the space-geodetic techniques of lunar and satellite laser ranging, very long baseline interferometry, and the Global Positioning System have been combined using a Kalman filter. The resulting combined Earth orientation series, SPACE2011, consists of values and uncertainties for Universal Time, polar motion, and their rates that span from September 28, 1976, to July 13, 2012, at daily intervals and is available in versions with epochs given at either midnight or noon. The space-geodetic measurements used to generate SPACE2011 have then been combined with optical astrometric measurements to form two additional combined Earth orientation series: (1) COMB2011, consisting of values and uncertainties for Universal Time, polar motion, and their rates that span from January 20, 1962, to July 13, 2012, at daily intervals and which are also available in versions with epochs given at either midnight or noon; and (2) POLE2011, consisting of values and uncertainties for polar motion and its rate that span from January 20, 1900, to June 21, 2012, at 30.4375-day intervals.

Gross, R. S.↗
NASA NTRS2015

Combinations of Earth orientation measurements: SPACE2014, COMB2014, and POLE2014

Independent Earth orientation measurements taken by the space-geodetic techniques of lunar and satellite laser ranging, very long baseline interferometry, and the Global Positioning System have been combined using a Kalman filter. The resulting combined Earth orientation series, SPACE2014, consists of values and uncertainties for Universal Time, polar motion, and their rates that span from September 28, 1976, to April 14, 2015, at daily intervals and is available in versions with epochs given at either midnight or noon. The space-geodetic measurements used to generate SPACE2014 have then been combined with optical astrometric measurements to form two additional combined Earth orientation series: (1) COMB2014, consisting of values and uncertainties for Universal Time, polar motion, and their rates that span from January 20, 1962, to April 14, 2015, at daily intervals and which are also available in versions with epochs given at either midnight or noon; and (2) POLE2014, consisting of values and uncertainties for polar motion and its rate that span from January 20, 1900, to March 23, 2015, at 30.4375-day intervals.

Gross, R.S.↗
NASA NTRS1972

Analytic short period lunar and solar perturbations of artificial satellites

A short period luni-solar theory was generalized for application to arbitrary obliquity of the ecliptic and inclination of the moon's orbit to the ecliptic. Analytic first order lunar perturbations to the elements were derived. The theory is illustrated by an application to the communication satellite Intelsat 3F3.

Fisher, D.↗
NASA NTRS1972

Analytic short period lunar and solar perturbations of artificial satellites.

The short period luni-solar theory of Kozai is generalized for arbitrary obliquity of the ecliptic and inclination of the moon's orbit to the ecliptic. Analytic first order lunar perturbations to the elements are derived. The theory is illustrated by an application to the communication satellite Intelsat 3F3.

Fisher, D.↗
NASA NTRS1978

Lunar occultation of Saturn. IV - Astrometric results from observations of the satellites

The method of determining local lunar limb slopes, and the consequent time scale needed for diameter studies, from accurate occultation timings at two nearby telescopes is described. Results for photoelectric observations made at Mauna Kea Observatory during the occultation of Saturn's satellites on March 30, 1974, are discussed. Analysis of all observations of occultations of Saturn's satellites during 1974 indicates possible errors in the ephemerides of Saturn and its satellites.

Dunham, D. W.↗
NASA NTRSDate not supplied

Investigation of Geomorphological Signatures of Permafrost in the Polar Lunar Areas With VIPER

A study of images of the polar regions shows that small craters near the poles of the Moon are distinguished by the following features: 1. they have a smoother shape - see Fig (a); 2. patterned ground (“wrinkled skin”) is often observed in and around the crater - see Figs (a,b,c); 3. outside the craters landslides and cracks are noticeable - see Fig (d); 4. layers or scarps are often visible on the inner slope - see Fig (e). These features (scarps and patterned ground) are typical for Martian craters in the permafrost zone (see Fig f), as well as for similar zones on Earth. It is hypothesized that these features of lunar craters are associated with the presence of permafrost in the polar regions of the Moon. In 2023, the VIPER rover will investigate the distribution of ice (volatile) deposits in the region of the Moon's South Pole. VIPER navigation cameras represent a unique opportunity for the geomorphological analysis of the lunar surface and the study of physical properties of regolith due to multiple key factors: - A large number of high-quality digital images with a good resolution of the South Pole of the Moon, which is a key region for the landing of manned expeditions. - A low position of the Sun, which generates long shadows, creates favorable conditions for object recognition algorithms. - A presence of a rover track in the images enables VIPER wheels to be used as tools for the study of the regolith and the development of a geotechnical model of regolith in the South Pole region. Rover navigation cameras will allow investigation of the distribution and shape of small craters and other structures along the path of the rover and test the hypothesis about geomorphological signatures of permafrost in the lunar polar areas. If a relationship between characteristics of lunar craters and the distribution of permafrost is confirmed, this will open a possibility to remotely determine the deposits of lunar ice from satellite imagery.

VIPER↗
NASA NTRS1978

Lunar tidal acceleration obtained from satellite-derived ocean tide parameters

One hundred sets of mean elements of GEOS-3 computed at 2-day intervals yielded observation equations for the M sub 2 ocean tide from the long periodic variations of the inclination and node of the orbit. The 2nd degree Love number was given the value k sub 2 = 0.30 and the solid tide phase angle was taken to be zero. Combining obtained equations with results for the satellite 1967-92A gives the M sub 2 ocean tide parameter values. Under the same assumption of zero solid tide phase lag, the lunar tidal acceleration was found mostly due to the C sub 22 term in the expansion of the M sub 2 tide with additional small contributions from the 0 sub 1 and N sub 2 tides. Using Lambeck's (1975) estimates for the latter, the obtained acceleration in lunar longitudal in excellent agreement with the most recent determinations from ancient and modern astronomical data.

Goad, C. C.↗
NASA NTRS1971

Lunar gravity derived from long-period satellite motion, a proposed method

A method was devised to determine the spherical harmonic coefficients of the lunar gravity field. The method consists of a two-step data reduction and estimation process. Pseudo-Doppler data were generated simulating two different lunar orbits. The analysis included the perturbing effects of the L1 lunar gravity field, the earth, the sun, and solar radiation pressure. Orbit determinations were performed on these data and long-period orbital elements were obtained. The Kepler element rates from these solutions were used to recover L1 lunar gravity coefficients. Overall results of the experiment show that lunar gravity coefficients can be accurately determined and that the method is dynamically consistent with long-period perturbation theory.

Ferrari, A. J.↗
NASA NTRS1978

Lunar tidal acceleration obtained from satellite-derived ocean tide parameters

Observation equations for the M2 ocean tide are computed from Geos 3 data for the long periodic variations of the inclination and node of the orbit. M2 ocean tide parameter values C22+ = 3.23 + or - 0.25 cm, epsilon 22+ = 331 + or - 6 deg, and epsilon 42+ = 113 + or - 6 deg are determined. With the assumption of zero solid tide phase lag, the lunar tidal acceleration is mostly (85%) due to the C22+ term in the expansion of the M2 tide with additional small contributions from the O1 and N2 tides. The calculated value for the tidal acceleration in lunar longitude is -27.4 + or - 3 arc sec/sq (100 yr) which is similar to values determined from astronomical data. The mean elements of Geos 3 are presented in tabular form.

Goad, C. C.↗