Don Quijote (spacecraft)

Did You Know?

• ESA considered two design options: the 'Cheap Option' using chemical propulsion and the 'Flexible Option' using electric propulsion.
• The 'Cheap Option' was targeted to the Amor asteroid 2003 SM84, the 'Flexible Option' to 99942 Apophis.

Overview

The mission would have consisted of two spacecraft performing maneuvers around a small, 500-metre asteroid. The first spacecraft, Sancho, was intended to orbit the asteroid for several months, studying it using a single xenon ion engine. After a few months, the second spacecraft, Hidalgo, would have collided with the asteroid at about 10 km/s, steering itself with optical sensors for 50-meter accuracy after a mostly dormant journey. Sancho would retreat to a safe distance during impact, then return to close orbit to observe changes in the asteroid's shape, internal structure, orbit, and rotation. Sancho would then release the Autonomous Surface Package, a lander that would free-fall for two hours to the interior of the impact crater to investigate surface properties. Don Quijote was one of six Near Earth Object precursor studies funded by ESA's General Studies Programme, alongside EUNEOS, Earthguard-I, NERO, SIMONE, and ISHTAR.

Instrumentation

The orbiter’s essential tools for the main mission were a Radio Science Experiment, a camera, an Imaging Laser Altimeter, and a LIDAR. For later goals, it would have added an IR Spectrometer, a Thermal IR Imager, an X-Ray Spectrometer, a Radiation Monitor, and the Autonomous Surface Package. The Hidalgo impactor aimed to stay as heavy as possible when it hit the asteroid, so it kept its propulsion module attached. It had very few parts, no moving solar panels or similar gear, and steered only with its RCS thrusters. A high-resolution camera gave it about 50-meter targeting precision. The LISA Pathfinder design served as an early reference.

Target

Originally, ESA identified two near-Earth asteroids as possible targets: (10302) 1989 ML and another; neither threatened Earth. A subsequent study selected the Amor asteroid (612600) and 99942 Apophis, the latter making close approaches in 2029 and 2036. In 2005, the proposed mission was combined with AIDA, targeting a binary asteroid so deflection effects could be observed from Earth by monitoring the binary period. The current AIDA target is the binary asteroid 65803 Didymos.

Names

The mission was named after Don Quixote, the fictional Spanish knight who charged a windmill thinking it a giant. The Hidalgo spacecraft was to 'attack' an object much larger than itself, while Sancho was named after Sancho Panza, Quixote's squire who watched from a safe distance. Hidalgo was a minor Spanish title, roughly equivalent to a Baronet, which Alonso Quijano held before becoming Don Quijote in the novel.