A near-Earth object (NEO) is any small Solar System body orbiting the Sun whose closest approach to the Sun (perihelion) is less than 1.3 times the Earth–Sun distance. This definition applies to the object's orbit around the Sun, rather than its current position, thus an object with such an orbit is considered an NEO even at times when it is far from making a close approach of Earth. If an NEO's orbit crosses the Earth's orbit, and the object is larger than 140 meters (460 ft) across, it is considered a potentially hazardous object (PHO). Most known PHOs and NEOs are asteroids, but about 0.35% are comets.
NEODyS is an Italian service that provides information on near-Earth objects with a Web-based interface. It is based on a continually and (almost) automatically maintained database of near earth asteroid orbits. This site provides a number of services to the NEO community. The main service is an impact monitoring system (CLOMON2) of all near-Earth asteroids covering a period until the year 2100.
Marco Polo was a proposed space mission concept studied between 2005 and 2015 that would return a sample of material to Earth from the surface of a Near Earth asteroid (NEA) for detailed study in laboratories. It was first proposed to the European Space Agency in collaboration with the Japan aerospace exploration agency JAXA. The concept was rejected four times between 2007 and 2015 for the Cosmic Vision programme "M" medium-class missions.
The Jupiter Icy Moons Explorer is an interplanetary spacecraft on its way to orbit and study three icy moons of Jupiter: Ganymede, Callisto, and Europa. These planetary-mass moons are planned to be studied because they are thought to have beneath their frozen surfaces significant bodies of liquid water, which would make them potentially habitable for extraterrestrial life.
The Asteroid Impact and Deflection Assessment (AIDA) missions are a proposed pair of space probes which will study and demonstrate the kinetic effects of crashing an impactor spacecraft into an asteroid moon. The mission is intended to test and validate impact models of whether a spacecraft could successfully deflect an asteroid on a collision course with Earth.
Patrick Michel is a French planetary scientist, Senior Researcher at CNRS, leader of the team TOP of the CNRS and Université Côte d'Azur Lagrange Laboratory at the Côte d'Azur Observatory in Nice (France), and also a Global Fellow of the University of Tokyo.
The Space Safety Programme, formerly the Space Situational Awareness (SSA) programme, is the European Space Agency's (ESA) initiative to monitor hazards from space, determine their risk, make this data available to the appropriate authorities and where possible, mitigate the threat.
A flyby is a spaceflight operation in which a spacecraft passes in proximity to another body, usually a target of its space exploration mission and/or a source of a gravity assist to impel it towards another target. Spacecraft which are specifically designed for this purpose are known as flyby spacecraft, although the term has also been used in regard to asteroid flybys of Earth for example. Important parameters are the time and distance of closest approach.
Double Asteroid Redirection Test (DART) was a NASA space mission aimed at testing a method of planetary defense against near-Earth objects (NEOs). It was designed to assess how much a spacecraft impact deflects an asteroid through its transfer of momentum when hitting the asteroid head-on. The selected target asteroid, Dimorphos, is a minor-planet moon of the asteroid Didymos; neither asteroid poses an impact threat to Earth, but their joint characteristics made them an ideal benchmarking target. Launched on 24 November 2021, the DART spacecraft successfully collided with Dimorphos on 26 September 2022 at 23:14 UTC about 11 million kilometers from Earth. The collision shortened Dimorphos' orbit by 32 minutes, greatly in excess of the pre-defined success threshold of 73 seconds. DART's success in deflecting Dimorphos was due to the momentum transfer associated with the recoil of the ejected debris, which was substantially larger than that caused by the impact itself.
Gerhard Drolshagen is a German physicist at the University of Oldenburg, Germany, specializing in space environment and near-Earth objects (NEO). He has been a staff member at the European Space Agency (ESA), European Space Research and Technology Centre (ESTEC), Noordwijk, The Netherlands (1987–2016) and is known for his work in space environment, NEO and for the asteroid named after him: the asteroid 332733 Drolshagen.
2006 QV89 (also written 2006 QV89) is an Apollo near-Earth asteroid roughly 30 meters (100 feet) in diameter. It was discovered on 29 August 2006 when the asteroid was about 0.03 AU (4,500,000 km; 2,800,000 mi) from Earth and had a solar elongation of 150 degrees.
2020 OY4 is a very small asteroid classified as a near-Earth object that passed within 21,850 miles (35,160 km) of the surface of Earth on July 28, 2020, with a fly-by speed of 12.4 kilometres (7.7 mi) per second. The car-sized asteroid posed no risk of impact to Earth, but it did pass within the orbit of satellites in the geostationary ring at 35,785 kilometres (22,236 mi) above Earth's equator.
2020 HS7 is a very small asteroid classified as a near-Earth object of the Earth-crossing Apollo group. When it was discovered by the Pan-STARRS 2 survey on 27 April 2020, the asteroid was initially calculated to have a 10% chance of impact with Earth before being ruled out by improved orbit determinations from additional observations. Although there is now no risk of impact with Earth, it did make a close approach 42,700 kilometres (26,500 mi) from Earth on 28 April 2020, with a flyby speed of 15.6 kilometres per second (9.7 mi/s) relative to Earth. The asteroid will not make any close encounters within 1 lunar distance (380,000 km; 240,000 mi) of Earth in the next 100 years.
2022 AE1 is a Tunguska event-sized asteroid, classified as a near-Earth object of the Apollo group, approximately 70 meters (230 feet) in diameter. It was discovered by the Mount Lemmon Survey on 6 January 2022, when it was 0.09 AU (13 million km) from Earth. On 9 January 2022 with an observation arc of 3 days, it was rated with a Torino scale of 1 for a virtual impactor on 4 July 2023 16:28 UTC. Nominal approach is expected to occur 1 July 2023 01:13 ± 1 day. With a Palermo scale rating of as high as –0.66 at the European Space Agency on 11 January 2022, the odds of impact peaked at about 4.6 times less than the background hazard level. NEODyS was the first risk-page to drop to Torino scale 0 on 12 January 2022 followed by ESA on 13 January 2022, but by January 14 both returned to Torino scale 1. On 14 January 2022 the waxing gibbous moon was as little as 3 degrees from the asteroid delaying observations of the asteroid from January 12–19. On 20 January 2022 with a 16-day observation arc, using JPL #11 the Sentry Risk Table dropped the asteroid to Torino scale 0 and then later that day JPL #12 resulted in it being removed from the risk table.
NEO-MAPP is a project for studying planetary defence and asteroid exploration.
Hera is a space mission in development at the European Space Agency in its Space Safety program. Its primary objective is to study the Didymos binary asteroid system that was impacted by DART and contribute to validation of the kinetic impact method to deviate a near-Earth asteroid in a colliding trajectory with Earth. It will measure the size and the morphology of the crater created and momentum transferred by an artificial projectile impacting an asteroid, which will allow measuring the efficiency of the deflection produced by the impact. It will also analyze the expanding debris cloud caused by the impact.
2022 QX4 is a Tunguska event-sized asteroid, classified as a near-Earth object of the Aten group, approximately 40 meters (130 feet) in diameter. It was discovered by ATLAS on 24 August 2022, when it was 0.03 AU (4.5 million km) from Earth. On 4 September 2022 with an observation arc of 8 days, it was listed with a 1-in-109 chance of impacting Earth with a Torino scale of 1 for a virtual impactor on 4 September 2068 00:52 UTC. Five precovery images from August 2013 were published on 11 September 2022 extending the observation arc to 9 years and 2022 QX4 was removed from the Sentry Risk Table. The nominal approach is expected to occur 26 August 2068.
