Adam Hibberd
Today it was back to potentially hazardous asteroid (PHA) 2024 YR4 which was discovered quite recently and has a comparatively high chance (depending on the source ~ 1.3%, with some sources quoting higher probabilities) of colliding with Earth in 2032. Furthermore this collision has the potential of causing many human deaths, though I must emphasize that this would be a very local catastrophe, with an explosion on a similiar scale to Tunguska.
I remind you that the latter figure (1.3%), if correct, amounts to around a 1 in 100 chance and the question is naturally would the authorities do anything to mitigate the dangers in view of these likely odds (at least relative to most asteroids and relative to most PHAs for that matter)?
The almost willful ignorance of my work is reminding me of the quite recent Hollywood film 'Don't look Up!' The irony is depressing but more seriously alarming. What if it DOES strike the Earth? What if humans are killed, and no mission was sent? People would be justifiably annoyed. VERY ANNOYED!
Anyhow, returning to my role in all this: a mission.
I have investigated so far the possibility of a flyby mission to 2024 YR4, but a colleague of mine asked the next obvious question: 'What about a sample return?' A sample return is a mission where the spacecraft returns to Earth in order to deliver, by parachute a sample of the target celestial body (whatever that may be) usually in a protective canister of some kind.
You must remember the book and film 'The Andromeda Strain' by Michael Crichton which explored this very eventuality, with potentially disastrous consequences on humanity.
Anyway, what makes a trajectory a sample return? It turns out that if the trajectory has a time period of 'n' years, where 'n' is a whole positive number, that means as well as encountering the target at some point over this 'n' year period, the spacecraft will also return to the Earth in precisely the same location in Earth's orbit (i.e. same date - so both month and day) as the initial launch date of the spacecraft, just a whole number 'n' years later.
This interesting astrodynamical fact opens up the entire set of asteroids, at least within the orbit of Jupiter, for sample return missions, as long as we select the appropriate value of 'n' accordingly for the particular asteroid in question.
There are constraints however. You see we must send the spaceraft on a trajectory that is REACHABLE BY A LAUNCHER (i.e. whose 'Characteristic Energy' C3 is sufficiently low). Furthermore the return speed of the spacecraft at sample return will be the same as that with which it departed Earth, which could make returning the sample rather problematic - we don't want the return canister's re-entry speed to be so high that the whole thing burns up in Earth's atmosphere.
Anyway much more work to do on this. Let's see where my research goes on these sample return missions and their awesome potential.