Q2. How much is the orbit maintenance budget?
The orbit maintenance, numerically simulated taking into account gravitational and solar radiation pressure perturbations, leads to a Δv budget of about 0.3 m/s per month.
Q3. How far away is the asteroid from the primary?
Observation of the Didymos system begins from a formation-flying quasi-orbit at a distance of around 35 km from the primary allowing for a safe distance, out of the sphere of influence of both Didymos components.
Q4. When will the AIDA mission be launched?
AIDA will target the binary NearEarth asteroid Didymos with two independently launched spacecraft, with the deflection experiment to occur in October, 2022.
Q5. how many ejecta are launched below the escape velocity?
If the ejecta are launched below the escape velocity, vesc ¼ ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi 2GM=R p , then the authors put vinf ¼
Q6. What is the common compositional group of NEOs?
Ground-based reflectance spectroscopy of Didymos shows it to be a member of the “S complex” of asteroids, the most common compositional group of NEOs.
Q7. What are the techniques used to deflect a NEO?
Some elegant techniques like the “gravity tractor” or changing a target's albedo and allowing the Yarkovskyforce [4] to change the target's orbit require decades or more for a deflection to be achieved, whereas the so-called “impulsive” techniques achieve immediate effect.
Q8. What are the current surveys to meet this mandate?
Surveys to meet this Congressional mandate are underway via ground-based and a space-based telescopes, and programs are in place to characterize the sizes, shapes, rotation periods, compositions, and other properties of NEOs.
Q9. How can the authors study the ejecta emplacement?
If the AIM spacecraft arrives at the binary after the impact, it may be possible, via comparison with DART images of the surface prior to impact, to study the ejecta emplacement.
Q10. What is the cratering efficiency of a spherical impactor?
The authors consider a spherical impactor of mass Mi and velocity vi incident on a much larger target of mass M and radius R, with the impact occurring along the centerline.
Q11. How far away is the impact of the DART spacecraft?
in the AIDA scenario, the impact of the DART spacecraft will be observed from a third characterization point of about 100 km distance to Didymos in order to avoid any damage by impacting debris.
Q12. What is the cratering efficiency of a projectile?
These scaling relations give reasonable estimates of cratering efficiency under a wide range of impact conditions, when the projectile size and the initial coupling time are small such that the impact can be regarded as a point source of energy and momentum [13].
Q13. How much time can the impact change the period of the asteroid?
The DART impact is expected to change the period by 0.5%, and this change can be determined to 10% accuracy within months of observations.
Q14. What is the trajectory of the DART spacecraft?
Such a trajectory is based on a launch with a Soyuz 2.1b/Fregat MT from Kourou allowing a 21-day launch window and will lead the spacecraft to a maximum Sun distance of up to 2.2 AU and a maximum Earth range of 3.2 AU.
Q15. What is the science return of the interceptor spacecraft?
Science return is maximized if the AIM rendezvous spacecraft is present before, during and after impact, but the science goals can be met even if the rendezvous occurs after the impact.