H. Manche

INPOP06: a new numerical planetary ephemeris

INPOP06 is the new numerical planetary ephemeris developed at the IMCCE-Observatoire de Paris. INPOP (Integrateur Numerique Planetaire de l’Observatoire de Paris) is a numerical integration of the motion of the nine planets and the Moon fitted to the most accurate available planetary observations. It also integrates the motion of 300 perturbing main belt asteroids, the rotation of the Earth and the Moon libration. We used more than 55 000 observations including the latest tracking data of the Mars Global Surveyor (MGS) and Mars Odyssey (Odyssey) missions. The accuracy obtained with INPOP06 is comparable to the accuracy of recent versions of the JPL DE ephemerides (DE414, Standish 2003, JPL IOM, 312N, 03; Konopliv et al. 2006, Icarus, 182, 23) and of the EPM ephemerides (EPM2004, Pitjeva 2005, Sol. Syst. Res., 39, 176).

Use of MESSENGER radioscience data to improve planetary ephemeris and to test general relativity

The current knowledge of Mercury orbit has mainly been gained by direct radar ranging obtained from the 60s to 1998 and by five Mercury flybys made by Mariner 10 in the 70s, and MESSENGER made in 2008 and 2009. On March 18, 2011, MESSENGER became the first spacecraft to orbit Mercury. The radioscience observations acquired dur- ing the orbital phase of MESSENGER drastically improved our knowledge of the orbit of Mercury. An accurate MESSENGER orbit is obtained by fitting one-and-half years of tracking data using GINS orbit determination software. The systematic error in the Earth- Mercury geometric positions, also called range bias, obtained from GINS are then used to fit the INPOP dynamical modeling of the planet motions. An improved ephemeris of the planets is then obtained, INPOP13a, and used to perform general relativity tests of PPN- formalism. Our estimations of PPN parameters ( and ) are more stringent than previous results.

Constraints on the location of a possible 9th planet derived from the Cassini data

To explain the unusual distribution of Kuiper belt objects, several authors have advocated the existence of a super-Earth planet in the outer solar system. It has recently been proposed that a 10 M⊕ object with an orbit of 700 AU semi major axis and 0.6 eccentricity can explain the observed distribution of Kuiper belt objects around Sedna. Here we use the INPOP planetary ephemerides model as a sensor for testing for an additional body in the solar system. We test the possibility of adding the proposed planet without increasing the residuals of the planetary ephemerides, fitted over the whole INPOP planetary data sample. We demonstrate that the presence of such an object is not compatible with the most sensitive data set, the Cassini radio ranging data, if its true anomaly is in the intervals [−130°: −100° ] or [−65°:85° ]. Moreover, we find that the addition of this object can reduce the Cassini residuals, with a most probable position given by a true anomaly v = 117.8°+11°-10° .

Electron density distribution and solar plasma correction of radio signals using MGS, MEX, and VEX spacecraft navigation data and its application to planetary ephemerides

The Mars Global Surveyor (MGS), Mars Express (MEX), and Venus Express (VEX) experienced several superior solar conjunctions. These conjunctions cause severe degradations of radio signals when the line of sight between the Earth and the spacecraft passes near to the solar corona region. The primary objective of this work is to deduce a solar corona model from the spacecraft navigation data acquired at the time of solar conjunctions and to estimate its average electron density. The corrected or improved data are then used to fit the dynamical modeling of the planet motions, called planetary ephemerides. We analyzed the radio science raw data of the MGS spacecraft using the orbit determination software GINS. The range bias, obtained from GINS and provided by ESA for MEX and VEX, are then used to derive the electron density profile. These profiles are obtained for different intervals of solar distances:

New analytical planetary theories VSOP2013 and TOP2013

Context. The development of precise numerical integrations of the motion of the planets, taking into account the most recent observations, lead us to improve the two families of analytical planetary theories built in the Institut de mecanique celeste et de calcul des ephemerides (IMCCE), the Variations Seculaires des Orbites Planetaires (VSOP) and the Theory of the Outer Planets (TOP) theories. Aims. We have built the solutions VSOP2010 and TOP2010 fitted to the Jet Propulsion Laboratory (JPL) numerical integration DE405 and the solutions VSOP2013 and TOP2013 fitted to the European recent numerical integration INPOP10a. This paper specifically considers VSOP2013 and TOP2013. Methods. We have improved the construction of VSOP by analytically computing the pertubations due to the asteroids and to Pluto. We have increased the precision of the VSOP solutions of Jupiter and Saturn by using TOP solutions. We have also improved the construction of TOP by computing the perturbations due to the telluric planets from VSOP solutions. Moreover, TOP contains a solution of the motion of the Pluto-Charon barycenter. Results. From 1890 to 2000, the precision of VSOP2013 goes from a few 0:01 mas (planets except Mars and Uranus) up to 0.7 mas (Mars and Uranus). Compared to the previous solution (VSOP2000), this represents an improvement of a factor of 2 to 24, depending on the planet. From4000 to 8000, the precision is of a few 0:1 00 for the telluric planets (1:6 00 for Mars), i.e. an improvement of about a factor of 5 compared to VSOP2000. The TOP2013 solution is the best for the motion of the major planets from4000 to 8000. Its precision is of a few 0:1 00 for the four planets, i.e. a gain between 1.5 and 15, depending on the planet compared to VSOP2013. The precision of the theory of Pluto remains valid up to the time span from 0 to 4000. The VSOP2013 and TOP2013 data are available on the WEB server of the IMCCE.

A ring as a model of the main belt in planetary ephemerides

Aims. We assess the ability of a solid ring to model a global perturbation induced by several thousands of main-belt asteroids. Methods. The ring is first studied in an analytical framework that provides an estimate of all the ring’s parameters excepting mass. In the second part, numerically estimated perturbations on the Earth-Mars, Earth-Venus, and Earth-Mercury distances induced by various subsets of the main-belt population are compared with perturbations induced by a ring. To account for large uncertainties in the asteroid masses, we obtain results from Monte Carlo experiments based on asteroid masses randomly generated according to available data and the statistical asteroid model. Results. The radius of the ring is analytically estimated at 2.8 AU. A systematic comparison of the ring with subsets of the main belt shows that, after removing the 300 most perturbing asteroids, the total main-belt perturbation of the Earth-Mars distance reaches on average 246 m on the 1969−2010 time interval. A ring with appropriate mass is able to reduce this effect to 38 m. We show that, by removing from the main belt ∼240 asteroids that are not necessarily the most perturbing ones, the corresponding total perturbation reaches on average 472 m, but the ring is able to reduce it down to a few meters, thus accounting for more than 99% of the total effect.

Tests of GR with INPOP15a planetary ephemerides: estimations of possible supplementary advances of perihelia for Mercury and Saturn

Planetary ephemerides are a good tool for studying general relativity at the scale of our solar system. We present here new evaluations of advances of perihelia for Mercury and Saturn.

INPOP06: a new planetary ephemeris

observationsare also presented.INPOP06 is a numerical integration of the motion of the nine planets and the Moon(Moyer 1971) fitted to the most accurate available observations. It also integrates themotion of 300 perturbing main belt asteroids, the Earth’s rotation and Moon libration.Interactions between non-spherical objects and point-mass objects are also taken intoaccount.We used more then 45000 observations including the last tracking data of the