which was never confirmed. Radio signals from spacecraft in orbit around Mars and/or on its surface have been used to estimate the mass of Pallas from the tiny perturbations induced by it onto the motion of Mars. The Dawn team was granted viewing time on the Hubble Space Telescope in September 2007 for a once-in-twenty-year opportunity to view Pallas at closest approach, to obtain comparative data for Ceres and Vesta. Name and symbol 2 Pallas is named after Pallas Athena (), an alternate name for the Greek goddess Athena. In some versions of the myth, Athena killed Pallas, the daughter of Triton, then adopted her friend's name out of mourning. The adjectival form of the name is Palladian. The d is part of the oblique stem of the Greek name, which appears before a vowel but disappears before the nominative ending -s. The oblique form is seen in the Italian and Russian names for the asteroid, and (). The stony-iron pallasite meteorites are not Palladian, being named instead after the German naturalist Peter Simon Pallas. The chemical element palladium, on the other hand, was named after the asteroid, which had been discovered just before the element. The old astronomical symbol of Pallas, still used in astrology, is a spear or lance, (), one of the symbols of the goddess. The blade was most often a lozenge (), but various graphic variants were published, including an acute/elliptic leaf shape, a cordate leaf shape (: ), and a triangle (); the last made it effectively the alchemical symbol for sulfur, (). The generic asteroid symbol of a disk with its discovery number, , was introduced in 1852 and quickly became the norm. The iconic symbol was resurrected for astrological use in 1973. Orbit and rotation Pallas has unusual dynamic parameters for such a large body. Its orbit is highly inclined and moderately eccentric, despite being at the same distance from the Sun as the central part of the asteroid belt. Furthermore, Pallas has a very high axial tilt of 84°, with its north pole pointing towards ecliptic coordinates (β, λ) = (30°, −16°) with a 5° uncertainty in the Ecliptic J2000.0 reference frame. This means that every Palladian summer and winter, large parts of the surface are in constant sunlight or constant darkness for a time on the order of an Earth year, with areas near the poles experiencing continuous sunlight for