Late veneer and late accretion to the terrestrial planets

In this chapter, the author summarizes the properties of the Solar System, and how these were uncovered. Over centuries, the arrangement and properties of the Solar System were determined. The distinctions between the terrestrial planets, the gas and ice giants, and their various moons are discussed. Whereas humans have walked only on the Moon, probes have visited all the planets and several moons, asteroids, and comets; samples have been returned to Earth only from our moon, a comet, and from interplanetary dust. For Earth and Moon, seismographs probed their interior, whereas for other planets insights come from spacecraft and meteorites. We learned that elements separated between planet cores and mantels because larger bodies in the Solar System were once liquid, and many still are. How water ended up where it is presents a complex puzzle. Will the characteristics of our Solar System hold true for planetary systems in general?

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Imaging terrestrial planets with a free-flying occulter and space telescope: an optical simulation

10.1117/12.506192 ◽

2003 ◽

Author(s):

Alfred B. Schultz ◽

Richard G. Lyon ◽

Mark Kochte ◽

Dorothy A. Fraquelli ◽

Frederick Bruhweiler ◽

...

Keyword(s):

Optical Simulation ◽

Terrestrial Planets ◽

Space Telescope

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An Update on The Problem of Small Comets

Highlights of Astronomy ◽

10.1017/s1539299600020657 ◽

1998 ◽

Vol 11 (1) ◽

pp. 237-238

Author(s):

J.C. Brandt ◽

M.F. A’Hearn

Keyword(s):

Recent Work ◽

Terrestrial Planets ◽

Indirect Methods ◽

Earth’S Atmosphere ◽

Direct Observations ◽

Icy Bodies ◽

Earth's Atmosphere ◽

Search Program ◽

Volatile Materials

The evidence for a major population of small comets (SCs) is summarized in two steps. First, we briefly summarize our previous work. Second, we describe recent work that continues to find SCs. When new capabilities become available that can detect SCs, we expect to find them and this is occurring. At present, their detection is a haphazard process and we advocate a dedicated, optimized search program. We define SCs as those icy bodies (i.e., sublimating bodies) with radius less than 1000 meters. Often the existence of SCs is inferred from effects ascribed to them. These “effects” include: lunar cratering; cratering on Ganymede; excess interplanetary hydrogen; delivery of volatile materials to the terrestrial planets; and a source of fragile bodies entering the Earth’s atmosphere. While some of these indirect methods support the existence of SCs, direct observations are clearly preferred.

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