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Asteroids - life from above

Where do we come from? This is one of the oldest and most profound questions that mankind has asked.

By: Dr Christopher Marker, Lead Data Scientist

On 24 September 2023 a capsule from the OSIRIS-Rex spacecraft returned to Earth from its mission to the Bennu asteroid bearing a small but precious sample of dust from the asteroid. A leading theory for the source of the organic molecules that make up all life on Earth is that asteroids that impacted the early earth contained many of the key materials. Studying the dust from Bennu may thus give clues into the origin of life on Earth.

The study may also shed light on where the water in oceans and the air in our atmosphere came from. Bennu is seen as the most dangerous rock in the Solar System as its path through space gives it the highest probability of impacting Earth of any known asteroid.

A 2022 space mission however may be our saviour should Bennu ever come to close to comfort.

Asteroids - death from above

The dinosaurs were one of the most successful dominant groups of creatures to live on this planet and yet they ultimately met their end most likely due to an asteroid impacting the earth’s surface.

Humans have since taken the dinosaurs’ mantle and although we are much more technologically adept until very recently, we too could have been wiped out by an asteroid.

In September 2022 the Nasa DART (Double Asteroid Redirection Test) probe smashed into the Dimorphos asteroid destroying itself in the process. 

This collision was not some random chance or terrible accident rather it was entirely by design with the object of the mission being to see if the asteroid could be pushed slightly off its trajectory.

Hitting such a small target (diameter of 170 metres) as an asteroid at such a distance from Earth required precision calculations of flight trajectory and onboard navigation software to adjust the closing trajectory with thruster firings to ensure a head-on collision.

A few weeks after the initial impact measurements from a range of space and Earth-based telescopes were made studying the changes to the orbit of Dimorphos around another asteroid known as Didymos.

These measurements proved that the Darts probe impact had deflected Dimorphos slightly changing its orbit. This mission shows that if we spot a dangerous asteroid on a collision course with us early enough, we could deflect it out of harm’s way if it’s not too big that is!

Humanity thus has the beginnings of a working planetary defence system.

Asteroids - the future and past

Asteroids have been observed for more than 200 years and comets for thousands of years.

Over 2,500 comets and more than 370,000 asteroids have been discovered. These bodies have traditionally been studied using ground-based optical means. However, radar has now come into its own (through the imaging of surfaces and the detection of asteroid satellites) and spacecraft have carried out studies of the surfaces and environments of various asteroids and comets.

Space missions are in progress and being planned to visit asteroids and comets to collect and return samples to Earth. These missions are important because comets are composed of pristine material unaltered from the time of formation of the planets.

One current mission is called Psyche which launched 13 October 2023. This mission will visit the 16 Psyche asteroid which is in the main asteroid belt in the solar system, between Jupiter and Mars. 16 Psyche is unusual amongst asteroids as unlike most which we know to be icy and rocky it is thought to be the exposed metallic heart of a dead planet.

Indeed, its core is thought to be made up of iron, nickel, and gold worth well over a quadrillion pounds! Such an unusual asteroid should give us more information about the formation of planets and the early solar system.

Developments over the last few decades in this field include: the extraordinary impact of Comet D/1993 F2 (Shoemaker-Levy 9) on the planet Jupiter in 1994 July, the spectacular encounter of the Deep Impact spacecraft with Comet 9P/Tempel in 2005, the discovery of asteroid satellites, and the discovery of objects belonging to the Kuiper belt in the outer solar system.

The last few decades or so have also thrown light on a reason for the demise of the dinosaurs (at the Cretaceous-Tertiary boundary 65 million years ago) as being due to an asteroid (or asteroids) colliding with the Earth. The crater of the main impactor has been found in Central America at Chicxulub.

Asteroids and Inspec

Inspec provides coverage of comets and asteroids, their observations and properties.

In Section A (Physics Abstracts), the following parts of the classification scheme contain relevant information:

The most important controlled terms from the Thesaurus are:

  • asteroids
  • astrometry
  • astronomical ephemerides
  • astronomical instruments
  • astronomical photometry
  • astronomical polarimetry
  • astronomical spectra
  • astrophysical plasma
  • astrophysical jets
  • cometary nuclei
  • comets
  • cosmic dust
  • infrared astronomy
  • interplanetary magnetic fields
  • Kuiper belt objects
  • meteorite craters
  • meteoroids
  • meteors
  • planetary atmospheres
  • planetary interiors
  • planetary magnetism
  • planetary remote sensing
  • planetary satellites
  • planetary surfaces
  • radioastronomy
  • solar wind
  • space vehicles
  • submillimetre astronomy
  • ultraviolet astronomy
  • astronomy

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