Is it possible not to see an asteroid?

QUESTION FROM ATANAS

Hello,

My name is Atanas Kostovski, I’m 18 years old, and I’m from Skopje, Macedonia. I study computer engineering, but I love astronomy.

My question is related to not being able to see asteroid headed to Earth. I guess we are not watching the literally whole sky, literally all the time. If we are watching certain areas at a time, is it possible to fully miss to see asteroid rushing towards us? And if we see it and we know it is coming, can we actually do something? I guess we have the technology to at least make an explosion so the impact will be less powerful, but do we have anything ready at any moment, that can react instantly at this moment?

Thank you for your attention, I’m looking forward to your answers.

Greetings,
Atanas Kostovski

ANSWER BY RUSTY SCHWEICKART (ADXP)

Dear Atanas,

Thanks for your question.  Astronomy and engineering go well together, especially re planetary defense.  It’s a kind of applied astronomy!

The goal of “seeing” asteroids is not to see them just before they hit us.  Most of the time we’re seeing them the same way we see planets; simply orbiting the Sun in well-behaved ways. What we do then is to mathematically determine their orbits and project out 100 years to see if they (each one of those whose orbits cross Earth’s orbit, i.e. NEOs) will, at any time in the future, be in the same place as the Earth at the same time.  If so, we will (once the capability is proven) initiate a deflection campaign to cause them to miss the Earth.  This is a long term process which depends on developing a full inventory of all NEOs which can do serious damage if they impact.  Take a look at the JPL Sentry website to get a more complete picture of this process.

However, until this inventory is complete we will also be looking at the night sky for asteroids headed for an Earth impact within a few days or weeks.  Our calculations show that we should be able (once the system is deployed) to discover about 60% of them prior to impact, and with enough warning time (i.e. short term warning) to allow people to protect themselves.  People regularly protect themselves today from hurricane or tornados by evacuating the danger zone or sheltering in their basements.  One short term warning system in development today is the ATLAS system. Given even a few hours of warning, and some understanding of what to do, the people of Chelyabinsk could have avoided being cut by flying glass.  Hopefully in the future, such knowledge and warning will be in place.

Perhaps you can help us get to that level of preparedness.

Rusty Schweickart