EPSC: Martian Moon Phobos Formed by Catastrophic Blast

Find out the latest thinking about our universe.
Post Reply
User avatar
bystander
Apathetic Retiree
Posts: 21571
Joined: Mon Aug 28, 2006 2:06 pm
Location: Oklahoma

EPSC: Martian Moon Phobos Formed by Catastrophic Blast

Post by bystander » Mon Sep 20, 2010 10:35 pm

The Martian Moon Phobos May Have Formed by Catastrophic Blast
European Planetary Science Congress | 20 Sept 2010
Scientists now have firm indications that the Martian satellite Phobos formed relatively near its current location via re-accretion of material blasted into Mars’ orbit by some catastrophic event. Two independent approaches of compositional analyses of thermal infrared spectra, from ESA’s Mars Express and NASA’s Mars Global Surveyor missions, yield very similar conclusions. The re-accretion scenario is further strengthened by the measurements of Phobos’ high porosity from the Mars Radio Science Experiment (MaRS) on board Mars Express. These results will be presented by Dr. Giuranna and Dr. Rosenblatt at the European Planetary Science Congress in Rome, on Monday 20th September.

The origin of the Martian satellites Phobos and Deimos is a long standing puzzle. It has been proposed that both moons may be asteroids formed in the outer part of the main asteroid belt (between Mars and Jupiter) and were subsequently captured by Mars' gravity. Alternative scenarios suggested that both moons were formed in situ by the re-accretion of rocky-debris blasted into Mars’s orbit after a large impact or by re-accretion of remnants of a former moon which was destroyed by Mars’s tidal force. “Understanding the composition of the Martian moons is the key to constrain these formation theories”, says Dr. Giuranna of the Istituto Nazionale di Astrofisica in Rome, Italy.

Previous observations of Phobos at visible and near-infrared wavelengths have been interpreted to suggest the possible presence of carbonaceous chondritic meteorites, carbon-rich “ultra primitive” materials, commonly associated with asteroids dominant in the middle part of the asteroid belt. This finding would support the early asteroid capture scenario. However recent thermal infrared observations from the Mars Express Planetary Fourier Spectrometer, show poor agreement with any class of chondritic meteorite. They instead argue in favor of the in-situ scenarios.
New Theory Says Phobos Formed From Re-Accretion of Impact Debris
Universe Today | Mars | 20 Sept 2010
Most theories on the formation of Phobos and its sister moon of Mars, Deimos, hold that the two moons did not form along with Mars, but were captured asteriods. However, new research indicates that Phobos formed relatively near its current location via re-accretion of material blasted into Mars’ orbit by some catastrophic event, such as a huge impact. Thermal infrared spectra data from two Mars missions, ESA’s Mars Express and NASA’s Mars Global Surveyor have provided independent researchers similar new conclusions of how Phobos formed.

The origin of the two Martian satellites has been a long standing puzzle. Previous researchers have postulated that because of Phobos small size and highly cratered surface, as well as the fact that Mars is reasonably close to the asteriod belt, that Phobos was a captured asteroid. Recently, alternative scenarios suggested that both moons were formed in situ by the re-accretion of rocky-debris blasted into Mars’s orbit after a large impact or by re-accretion of remnants of a former moon which was destroyed by Mars’s tidal force.

Today, Dr. Giuranna from the Istituto Nazionale di Astrofisica in Rome, Italy, and Dr. Rosenblatt from the Royal Observatory of Belgium presented their new findings at the European Planetary Science Congress in Rome, saying that the thermal data from the two spacecract, as well as the measurements of Phobos’ high porosity from the Mars Radio Science Experiment (MaRS) on board Mars Express, supports the re-accretion scenario.

Post Reply