Reaching for the Asteroids

Press Release From: Royal Astronomical Society
Posted: Thursday, April 10, 2003

Humans hopping over the surface of asteroids. Extraction of minerals from Earth-grazing chunks of rock. Sounds like science fiction, but scientists are already looking ahead and trying to identify the nearest objects whose resources may be exploited by future entrepreneurs.

During the UK/Ireland Astronomy Meeting in Dublin, Dr. Apostolos Christou (Armagh Observatory) will be presenting new results concerning the most easily reachable Near Earth asteroids (NEAs) so far discovered.

"Near Earth asteroids constitute the most accessible source of pristine extraterrestrial material in the solar system, apart from the Moon,” he said.

"These bodies hold, in their chemical makeup, fundamental information about the conditions under which the planets formed and evolved. For a modest cost, inexpensive missions can be mounted to rendezvous with or return samples from a selection of these objects.

"Human missions to NEAs are also seen as a logical first step to the utilization and settlement of the solar system," he added.

"Finally, the acquisition of data on the composition and internal structure of NEAs is also a necessary prequisite to developing an effective strategy to protect the Earth from asteroid impacts."

Christou and his colleagues studied 27 candidate asteroids that had previously been discovered through recent observational surveys. They included boulder-sized objects no more than 40 metres across (1998 KY26), fragments of the large main-belt asteroid Vesta (3361 Orpheus) and binary asteroids (1996 FG3).

They then assessed the asteroids in order to find out which are the easiest to reach and the most accessible to visiting spacecraft. Using a method similar to that used in designing transfer paths to the planets, they found that one object (1999 AO10) requires less energy to achieve a rendezvous than placing an orbiter around the Moon. A further four of the Earth-grazers are easier to reach than Mars or Venus.

Based on these results, Christou concluded that there are no insurmountable technical challenges to launching small, inexpensive satellites to scrutinize these objects. Such missions would typically require 1-2 years to reach their targets before spending several months orbiting or on the surface of the asteroid, studying composition, geology and internal structure.

Eventually, these NEAs may prove to be valuable targets for human expeditions. However, detailed knowledge of their physical properties is currently available for only a small fraction of the known NEA population and only one quarter of the asteroid sample studied by Christou's group.

"We need to know more about these small, elusive objects, so ground-based observational studies of NEA sizes, rotations and spectral types should be a near-term priority," concluded Christou.


On the afternoon of Thursday 10 April and on Friday 11 April Dr. Christou can be contacted via the NAM press office (see above).

Normal contact details:

Dr. Apostolos Christou
Armagh Observatory
College Hill
BT61 9DG
Northern Ireland
Tel: +44 (0)2837-522928
Fax: +44 (0)2837-527174


Interplanetary Travel – Astrodynamics page (from Friday 4 April) -

Steve Ostro's asteroid radar site -

Scott Hudson's asteroid shape modelling site (including a shape model for 1998 KY26) -  

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