An international exercise to simulate an asteroid striking Earth has come to an end. With just six days to go before a fictitious impact, things don’t look good for a 298 km-wide region between Prague and Munich…
This may sound like a grim role-playing game, but it’s very serious business. Led by NASA’s Jet Propulsion Laboratory’s Centre for Near Earth Object Studies, the asteroid impact simulation is meant to prepare scientists, planners, and key decision makers for the real thing, should it ever occur…
…A key takeaway from this year’s simulation was the dramatic way in which key variables, such as the probable impact area and affected population size, were affected by new observations. At one point, for example, North Africa, the UK, and much of Scandinavia were inside the possible strike zone…
Previous tabletop exercises provided many years of warning time, but not this one. Accordingly, the focus of exercise was geared toward the disaster response and the importance of identifying dangerous asteroids in advance.
RTFA. Be prepared! Even if the only response possible in real time is RUN LIKE HELL!
Eideard 
“The exercise played out that we basically had to take the hit,” said Lindley Johnson, NASA’s Planetary Defense Officer, in a call, noting that it was among the “more challenging scenarios” ever presented at the conference. https://www.vice.com/en/article/5dbbz8/scientists-tried-and-failed-to-stop-a-hypothetical-deadly-asteroid-in-an-exercise
…New observations of the hypothetical asteroid 2021 PDC revealed that it had a 100 percent chance of hitting Europe or northern Africa in just six months.
The extremely short notice made it impossible for the tabletop team, which involved hundreds of people, to develop and launch a mission that could deflect or disrupt the hazardous space rock in time.
“To mount a campaign, even a single mission, given our current state of the technology and how we do these deep space missions, we need a lead time, I would say, of a minimum of two years, and we’d be much more comfortable if it were five years,” Johnson said.
8AM MDT, tomorrow morning, 5th