Past studies: Don Quijote

More detailed information on the Don Quijote mission is available on the Executive Summary

Overview

Don Quijote is an asteroid investigation , geophysical characterisation and deflection technological experiment mission. The mission will contain the following elements:

  • Two spacecraft which are to be launched in separate interplanetary trajectories.

  • One spacecraft, which will be referred to as Hidalgo, will impact an asteroid of approximately 500 m diameter at a relative speed of at least 10 km/s.

  • The other spacecraft, called Sancho, will arrive earlier at the same asteroid along a very different route, perform a rendez-vous and remain in orbit around the asteroid for several months before and after the impact.

  • Sancho will also deliver a number of penetrators to form a seismometernetwork on the asteroid.

  • At the time of the impact, Sancho will retreat to a safe distance to observe the impact without taking unnecessary risk (with an attitude appropriate to its name)

  • It will later return to a close orbit, to observe the changes in the asteroid internal structure, shape, orbit and rotation state of the asteroid.

Mission rationale

It has been acknowledged by the scientific community that NEO may represent a hazard to Earth. Although the probability of a big impact is very small, for the first time in human history we have the means of avoiding such a catastrophic event. But it is essential that we improve our knowledge of asteroids. We must know in detail the internal structure of asteroids, and how they respond to impacts before we can design effective mitigation methods.

Seismic tomography is one of the possible ways of investigating the interior of planetery and small bodies. Seismic waves resulting by both the impact of Hidalgo and the detonation of small explosive devices will be recorded by seismometers.Seismologyis an effective technique, already used by the Apollo astronauts to study the Moon interior more than thirty years ago. It is also used everyday on Earth to look for minerals, gas and oil. Technology exchange in this area could benefit applications both down here and in space.

Mission objectives

The mission has a very high scientific value, but it will also help in testing technologies required for future deflection missions and raise interest in people for space exploration. The mission will in particular:

  • measure the mass of the asteroid, the ratio of the moments of inertia and the low order harmonics of its gravity field.

  • model the asteroid shape before and after the impact, to detect changes (if any).

  • determine the asteroid internal structure, especially the size the main solid pieces, the average particle size and thickness of regolith and of the debris layers in the space left between the main pieces.

  • constrain the mechanical properties of the asteroid material.

  • measure the orbital deflection of the asteroid as a result of the impact of Hidalgo

  • measure the asteroid rotation state before and immediately after the impact.

  • detect the dissipation of the non-principal axis rotation after the impact.

  • determine the asteroid large scale mineralogical composition.

Spacecraft

The Don Quijote mission is divided in four dedicated mission elements. There is the orbiter Sancho that carries the combined camera/TIR-imager, the IR spectrometer, the Penetrators/Surface elements (P/SE), and the seismic sources. The P/SE and the seismic sources (SS) are considered as separate elements, since they perform the "landing" and surface operation on the asteroid, which in itself is a complex "sub-mission" of Don Quijote. The P/SE carry a seismometer, an accelerometer, and a temperature sensor as scientific payload, whereas the seismic sources comprise merely an explosive charge and a timed detonator. The fourth element is Hidalgo, which serves solely as impactor and its main task is to hit the asteroid with a given accuracy and relative velocity.

The S/C Sancho is carrying the scientific instruments and will arrive at the asteroid about 6 month before the impact of Hidalgo. While Sancho is orbiting the asteroid, the seismic network is deployed and different scientific measurements are conducted.

Hidalgo will in principle be a rebuild of the Sancho S/C omitting the instruments, launch mechanisms for the penetrators and seismic sources, and probably the HGA. Due to the reduced power demand the electrical power system, and in particular the solar arrays, may also be reduced in size and mass. The same is true for the propulsion system. For Hidalgo no orbit capture is necessary. Therefore the orbit corrections can be done with thrust vectoring using the AOCS thrusters. Due to these changes, the Hidalgo S/C will be simpler than Sancho except the autonomy/FDIR concept, since it must perform the final targeting prior to the impact without substantial ground support and with a very high reliability.

Instruments

The main task for the camera is the imaging of the asteroid at high resolution when Sancho is in orbit around it. In addition, it will be used for navigational purposes during the far and close approach phases. In addition a TIR channel with a micro-bolometer array will be implemented. For the design variation the NAC/WAC design of BepiColombo is considered as possible instrument.

The IR-spectrometer is primarily used for the classification of the asteroid and a high diversity of the soil is not expected. Thus, the requirements with respect to spatial and spectral resolution are moderate. Therfore, a SIR-type micro-spectrometer was selected as baseline. For the design variation the IR spectrometer of BepiColombo was selected, which covers also the TIR region of the spectrum.

The Ka-Transponder is needed for the precise determination of the trajectory and its changes of the asteroid. The seismometers and accelerometers carried by the penetrators are dedicated to the seismic experiments conducted in the course of the mission in order to determine the internal structure of the asteroid.

Seismic tomography is one of the possible ways of investigating the interior of planetery and small bodies. Seismic waves resulting by both the impact of Hidalgo and the detonation of small explosive devices will be recorded by seismometers.Seismologyis an effective technique, already used by the Apollo astronauts to study the Moon interior more than thirty years ago. It is also used everyday on Earth to look for minerals, gas and oil. Technology exchange in this area could benefit applications both down here and in space.

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