Artifacts in space, or space anthropo-archaeology

The purpose of this project is to list all human-made objects that were sent in deep space, way beyond the Earth’s orbit. Most of them are now orbiting celestial bodies such as the Sun, the planets or the moons while some are permanently set on their surfaces and others are leaving the solar system.

Please note that the Earth’s artificial satellites are not listed here, except those that were part of an interplanetary mission.

As of November 2021, over 4,500 objects have been identified, ranging from large probes to small pins and including spent injection stages, rovers, heat shields, parachutes, dust caps, weights, bolts, lanyards, hand tools, foam blocks, sample bags, etc.

The difficult task of making a comprehensive inventory

The exact number of artificial objects in outer space will never be known. It largely depends upon:

  • How objects are numbered, for instance a flag may be counted as one object or split into its elements (cloth, staff, crossbar, etc.);
  • The number of debris resulting from impacts, collisions and spent stage breakups, provided those events will ever be known;
  • The number of objects that emerge from deployments and separation of spacecraft (explosive bolts, lens caps, dust covers, clamp bands, fairings, shrouds, etc.);
  • Untold or unknown events such as classified missions and experiments, private belongings secretly left on the moon by the Apollo astronauts, family items hidden into space hardware by mission staff and technicians, or Apollo hardware unofficially returned to Earth as souvenirs by the astronauts.

    • Mission 1: Protecting outer space heritage

    All these objects are witnesses of human activity in space and are as valuable as archeological items buried several feet underneath us. Like Egyptian mummies on Earth, it is important that we protect them for both their historical and scientific value as space becomes more accessible to private enterprise, exposing them to inadvertent destruction or misappropriation. Because small items such as cameras, geology tools or detachable parts are more exposed than large rovers or landers, their presence must be emphasized.

    This catalogue, the most accurate to date, is a first step in preserving them by establishing what’s actually out there and where it is precisely.

    Mission 2: Mitigating outer space junk

    Before calling these relics ‘space junk’, it must be remembered that mass and space exploration are not compatible: a spacecraft can’t afford trailing unnecessary load, so items that are no more useful at one point into the mission become dead weight and must be shaved off quickly. As of today, there is no other viable option to guarantee mission success and there are no means to retrieve them.

    Space junk can be classified into three groups:

  • Visual pollution: items that are inert and immobile, for instance alumium parts or soft bags, in sterile environments, i.e. irradiated surfaces like the Moon;
  • Chemical pollution: spacecraft batteries and propellant tanks for example that are still loaded in probable organic worlds such as Venus, Mars and Titan;
  • Hazardous objects: items whether chemically active or not that are travelling at orbital speeds, thus representing a threat not only to space navigation but also to the surface of celestial bodies.

    • Both latter cases must be emphasized and remediated to mitigate consequences. This catalogue is also a first step in this direction.

    Additional information

    In order to ease reading, the data is split into several tables, each referring to a celestial body (sun, planet, moon, asteroid or comet) and a status (in orbit or on the surface). Additionally, each table displays the artificial objects in chronological order of deployment. The lists are as comprehensive as possible and we’re doing our best to complete them and keep them up to date. Before reading them, please take a look at this page.

    Should you have any question or remark, please drop us a line.