Atira-Class Asteroids
Also known as Interior-Earth Objects (IEOs), Atiras are a rare class of Near-Earth Asteroids whose orbits are completely contained inside the orbit of Earth. Their aphelion (furthest point from the Sun) is less than 0.983 AU.
Mining Viability Profile
The Challenge: High Delta-V
Because they are deep within the Sun's gravity well, it takes a massive amount of energy (Delta-V) to brake a spacecraft coming from Earth to match an Atira's orbit. They are also notoriously difficult to detect from Earth because they are always lost in the Sun's daylight glare.
The Opportunity: Inner System Hubs
While poor targets for bringing materials back to Earth, Atiras are bathed in intense, constant solar energy. They are considered prime candidates for building autonomous solar-refineries or serving as forward-operating bases for future missions to Venus or Mercury.
Notable Atira Candidates
To date, only a few dozen Atiras have been discovered, making them the smallest known group of NEAs.
| Designation | Discovery | Est. Diameter | Unique Characteristics |
|---|---|---|---|
| 163693 Atira | 2003 | ~4.8 km | The namesake of the class. It is a binary asteroid system, accompanied by a small 1km moon. |
| 2020 AV2 | 2020 | ~1.5 km | A sub-class called a "Vatira" — its orbit is entirely inside the orbit of Venus. |
| 434326 (2004 EA21) | 2004 | ~1.2 km | One of the closest known approaches to the Sun, subjected to extreme thermal stresses. |
| 2021 PH27 | 2021 | ~1.0 km | Holds the record for the shortest orbital period of any known asteroid (113 days). |