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Lecture

Solar System: Satellite Swarms and Asteroids

In course

PHYS-643: Astrophysics VI : The variable Universe

Introduction to time-variable astrophysical objects and processes, from Space Weather to stars, black holes, and galaxies. Introduction to time-series analysis, instrumentation targeting variability, and the importance of the time domain for astronomy, cos ...

Description

This lecture covers the challenges and risks posed by satellite swarms in low Earth orbit, including light pollution and space debris. It also delves into the study of near-Earth asteroids, such as Apophis, and their potential impact on Earth. The instructor discusses the impact of satellite constellations on astronomical observations and the need for international cooperation to address these issues.

Instructor

Richard Irving Anderson

Official source

Related concepts (32)

Asteroid

An asteroid is a minor planet—an object that is neither a true planet nor a comet—that orbits within the inner Solar System. They are rocky, metallic or icy bodies with no atmosphere. Sizes and shapes of asteroids vary significantly, ranging from 1-meter rocks to a dwarf planet almost 1000 km in diameter. Of the roughly one million known asteroids the greatest number are located between the orbits of Mars and Jupiter, approximately 2 to 4 AU from the Sun, in the main asteroid belt.

Near-Earth object

A near-Earth object (NEO) is any small Solar System body whose orbit brings it into proximity with Earth. By convention, a Solar System body is a NEO if its closest approach to the Sun (perihelion) is less than 1.3 astronomical units (AU). If a NEO's orbit crosses the Earth's orbit, and the object is larger than across, it is considered a potentially hazardous object (PHO). Most known PHOs and NEOs are asteroids, but a small fraction are comets. There are over 30,503 known near-Earth asteroids (NEAs) and over a hundred known short-period near-Earth comets (NECs).

Low Earth orbit

A low Earth orbit (LEO) is an orbit around Earth with a period of 128 minutes or less (making at least 11.25 orbits per day) and an eccentricity less than 0.25. Most of the artificial objects in outer space are in LEO, with an altitude never more than about one-third of the radius of Earth. The term LEO region is also used for the area of space below an altitude of (about one-third of Earth's radius). Objects in orbits that pass through this zone, even if they have an apogee further out or are sub-orbital, are carefully tracked since they present a collision risk to the many LEO satellites.

Medium Earth orbit

A medium Earth orbit (MEO) is an Earth-centered orbit with an altitude above a low Earth orbit (LEO) and below a high Earth orbit (HEO) – between above sea level. The boundary between MEO and LEO is an arbitrary altitude chosen by accepted convention, whereas the boundary between MEO and HEO is the particular altitude of a geosynchronous orbit, in which a satellite takes 24 hours to circle the Earth, the same period as the Earth’s own rotation.

High Earth orbit

High Earth orbit (HEO) is a region of space around the Earth where satellites and other spacecraft are placed in orbits that are very high above the planet's atmosphere. This area is defined as an altitude higher than 35,786 km (22,236 mi) above sea level, which is the radius of a circular geosynchronous orbit. HEO extends to end of the Earth's sphere of influence. Satellites in HEO are primarily used for communication, navigation, scientific research, and military applications.

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