Illustration of a combined gravity tractor and kinetic impactor mission. (Image credit: Airbus Defence and Space)
On the 20th of May the Mission Definition Requirements Review took place. This Review was an important milestone for all NEOShield-2 partners to agree on the reference mission scenarios and the major requirements. It was the first big step to ensure a common and well consolidated baseline as input for the following activities in NEOShield-2, e.g. the development of advanced GNC concepts.
In general there are two major mission scenarios. One mission shall demonstrate the deflections of a NEO the other one shall collect samples from the NEO.
The deflections of a NEO
One option to deflect a NEO is the “Two-S/C Kinetic Impactor Demo Mission” with the deflection by a Kinetic Impactor spacecraft hitting the NEO and transferring linear momentum to it. By this momentum transfer the orbit of the NEO can be affected and its separation from the earth be increased during its close encounter.
Using a Kinetic Impactor, the magnitude of the achieved NEO deflection is difficult to predict, in particular due to the unknown momentum imparted by ejecta produced by the kinetic impact. A sufficiently precise orbit determination of a NEO from Ground is difficult and may take years. Therefore an Explorer spacecraft characterising the NEO before the impact, observing the impact and measuring the deflection provides an added value for a Kinetic Impactor mission.
An optional mission concept is the “Itokawa Impactor Demo Mission” with the goal of presenting a reduced cost option while maintaining a large part of the mission utility. Target characterisation is achieved by selecting Itokawa, an object that has been visited by the Japanese space probe Hayabusa in 2005.
Deflection validation is achieved by means impacting the target far from the centre of mass and measuring the resulting spin rate change. Above a certain threshold this can be achieved by brightness curve measurements from terrestrial observations. In addition sub-satellites and potentially observations from a fly-by module are considered for additional measurements and images of the impact.
Overview of Itokawa Impactor Demo Mission terminal approach configuration
The sample return mission
The primary objective of a Sample Return Mission is to collect one or more samples from the surface of an Asteroid and return them to Earth for performing in depth investigations and analyses using the advanced terrestrial laboratories.
The trade‐off includes scenarios as full landing and re-ascent, touch and‐go or just hovering directly above the NEO surface (no contact with the asteroid surface). This trade‐off takes also into account the description of different types of sampling concepts (e.g. drilling, contactless) depending on the selected sample‐return scenario and on soil characteristics.
The sample return mission can be a stand-alone mission. But it could be also part of the Explorer S/C from the “Two-S/C Kinetic Impactor Demo Mission” scenario.
Marco Polo-R Sampling Campaign [ASTRIUM]