Ideas and words flew around like a cluster of meteors as 500 or so researchers of small solar-system bodies from 44 countries gathered this past week in Helsinki at ACM, the largest conference in the field.
Some of the most renowned guests included Bruno Sicardy, a French researcher on the first team to detect a ring system around an asteroid, Makoto Yoshikawa, leader of the Japanese mission that guided a sample return robot to and from an asteroid, as well as Anders Johansen from Sweden, who recently stirred the scientific community with his challenge to the theory of turbulence. The theory has been proposed as an explanation for how concentrations of mass, which later gave rise to planets, may have formed in the debris disks of the early solar system.
How to break up a celestial body?
At the ACM (Asteroids, Comets, Meteors) conference, basic research on the movement of comets meets practical applications, which aim to prevent celestial bodies from hitting the Earth.
“The structure of the small body is the big issue here,” says Professor of Astronomy Karri Muinonen, the main scientific organiser of the conference. “If it is sandbag-like, consisting of several parts, a minor shove can break up the body and hurl part of it into space. If the body is monolithic, more powerful measures are needed to break it up.”
Mining is a new topic of interest to the small-body community. By the end of this century, rare earth metals, which are used in small concentrations in products such as strong magnets and computer displays, may be extracted profitably from asteroids.
Before that, however, a more mundane substance – water – will be an even more valuable find.
“Water is a heavy element to send into space, each kilogram costing thousands of dollars,” explains astronomy researcher Mikael Granvik, one of the conference organisers.
In the future, research robots and spacecraft may be able to produce fuel from water found on asteroids.
“Asteroid water can be vaporised by heating it and further broken down into oxygen and hydrogen using electricity generated by solar cells. There’s all the fuel you need.”
Names dating back to the telescope era
The classification of celestial bodies into asteroids and comets – also used in the conference title – is somewhat artificial. These definitions date back to a time when telescopes were the only way to study space. Asteroids showed up as specks, while comets either looked hazy or appeared to have a tail.
As Professor Muinonen underscores, one of the conference’s goals is to gather the asteroid, comet and meteor research communities under one roof.
A small glossary of small bodies:
- Asteroid = A small body orbiting the Sun, found mainly in the asteroid belt between Mars and Jupiter.
- Comet = A small body, which sometimes features a tail. Comets are usually “dirty snowballs” from the outer solar system. Their tail is the result of ice vaporising as the bodies approach the inner solar system.
- Dormant comet = A small icy body that, for any number of reasons, does not have a tail.
- Active asteroid = A body in the asteroid belt that features a tail even though no water has been detected on it.
- Meteoroid = A small asteroid, less than one metre in diameter, whose orbit may put it on a collision course with the Earth.
- Meteor = A meteoroid that burns or explodes upon entry into the Earth’s atmosphere.
- Meteorite = A small solar-system body that survives impact with the Earth’s surface.