A spacecraft carrying a comet probe developed by four Japanese organizations will try to intercept a comet that has never approached the sun.

“We want to clarify the mysteries about the formation of the solar system by observing the core of a comet that has never been seen by anyone,” said Hideyo Kawakita, professor of comet science at Kyoto Sangyo University.

The mission, set to launch in 2028 at the earliest, is an international project led by the European Space Agency (ESA).

The spacecraft will sit on a stakeout in space until a comet suitable for exploration comes along, with the mission set to last two to three years.

The four organizations that are creating the probe are Kyoto Sangyo University, the Japan Aerospace Exploration Agency (JAXA), the University of Tokyo and Rikkyo University.

Comets circle the sun on oval trajectories. Their cores contain ice, dry ice and rocks and are like “dirty snowmen.” Every time they approach the sun, they melt and discharge gases.

But comets that have not yet come close to the sun still possess many of their original properties.

If pristine comets can be investigated, it could clarify how they were formed.

How long a wait it will be to find a pristine comet is difficult to pin down as it's impossible to forecast when one might appear. Their trajectories are also unknown.

Launching a probe after a comet has been found is not a good option because by the time the probe makes contact, the comet may have approached the sun and been damaged by the intense heat.

Because of that, probes have so far been launched to explore comets whose periods of approaching the sun and trajectories are already known.

In the project set for 2028, the spacecraft will wait for two to three years on the back side of the Earth seen from the sun.

During the period, researchers on the ground will be searching the skies for a suitable comet. If they find one, the spacecraft will approach it and release two small probes. One of the probes is being developed by the four Japanese organizations.

Using the probe, the Japanese team will study the volume of water on the comet and volumes of elements in its gases.