Out Like a Good Knight
"He thought it fit and proper...to travel through the world with horse and armour in search of adventures...redressing all manner of wrongs and exposing himself to chances and dangers, by the overcoming of which he might win eternal honor and renown...he was anxious to wait no longer...impelled to this by the thought of the loss of the world suffered by his delay..." --Cervantes, Don Quixote
|Impact of the Tunguska explosion is visible even after 90 years.
Credit: Galena HS
In early July, the Near-Earth Object Mission Advisory Panel recommended that the European Space Agency (ESA) place a high priority on developing a mission to actually move an asteroid. The conclusion was based on the panel's consideration of six near-Earth object mission studies submitted to the Agency in February 2003.
Of the six studies, three were space-based observatories for detecting near-earth objects (NEOs) and three were rendezvous missions. All addressed the growing realization of the threat posed by NEOs and proposed ways of detecting or discovering more about them from a close distance.
A panel of six experts, known as the Near-Earth Object Mission Advisory Panel (NEOMAP) assessed the proposals. Alan Harris, German Aerospace Centre (DLR), Berlin, and Chairman of NEOMAP, says, "The task has been very difficult because the goalposts have changed. When the studies were commissioned, the discovery business was in no way as advanced as it is now. Today, a number of organizations are building large telescopes on Earth that promise to find a very large percentage of the NEO population at even smaller sizes than visible today."
|An aerial view of Meteor Crater, Arizona.
Credit: Jim Hurley, 1978
As a result, the panel decided that ESA should leave detection to ground-based telescopes for the time being, until the share of the remaining population not visible from the ground becomes better known. The need for a space-based observatory will then be re-assessed. The panel placed its highest priority on rendezvous missions, and in particular, the Don Quixote mission concept. "If you think about the chain of events between detecting a hazardous object and doing something about it, there is one area in which we have no experience at all and that is in directly interacting with an asteroid, trying to alter its orbit," explains Harris.
The Don Quixote mission concept will do this by using two spacecraft, Sancho and Hidalgo. Both are launched at the same time but Sancho takes a faster route. When it arrives at the target asteroid it will begin a seven-month campaign of observation and physical characterisation during which it will land penetrators and seismometers on the asteroid's surface to understand its internal structure.
Sancho will then watch as Hidalgo arrives and smashes into the asteroid at very high speed. This will provide information about the behavior of the internal structure of the asteroid during an impact event as well as excavating some of the interior for Sancho to observe. After the impact, Sancho and telescopes from Earth will monitor the asteroid to see how its orbit and rotation have been affected.
|Fragments of Comet P/Shoemaker-Levy 9 colliding with Jupiter (July 16-24, 1994).
Harris says, "When we do actually find a hazardous asteroid, you could imagine a Don Quixote-type mission as a precursor to a mitigation mission. It will tell us how the target responds to an impact and will help us to develop a much more effective mitigation mission."
On 9 July, the findings were presented to the scientific and industrial community. Representatives of other national space agencies were also invited in the hope that they will be interested in developing a joint mission, based around this concept.
Andrés Galvez, ESA's Advanced Concepts Team and technical officer for the NEOMAP report says, "This report gives us a solid foundation to define programmatic priorities and an implementation strategy, in which I also hope we are joined by international partners".
With international cooperation, a mission could be launched as early as 2010-2015.
Related Web Pages
Great Impact: Part I
Great Impact: Part II
Great Impact: Part III
Great Impact: Part IV
Impact Hazards Website
NASA/JPL Near Earth Object Program