Why do we need to think about redirection of a space object & why now? DART - Deep dive & learnings from it

DART -  Also an acronym for Double Astroid Redirection Test. 

Every planetary and non-planetary object revolves around the sun and for the major part their axees never intercept. But what if one day that happens - is there a way to get around it? (it's not expected to happen in next 100 years though). That's the question - this mission exercise is hoping to answer. 

DART is basically targeting an astroid which will not be hitting earth but will be the right candidate(s) in terms of size and placement to allow for testing a decisioning system to make that change for it to deflect from it's intended virtual path of intercept.

Before we can talk about the way in which this is being actioned, let's understand how we identify an incoming astroid impact. The simple way is to take pictures and understand the relative positions of the objects moving in the sky. The stars don't move, but the planets and small bodies do which includes astroids. First identify - if it's moving, second identify it's orbit & then understand if they are intercepting the earth's orbit. 

Okay now that we got the above, what's DART's target astroid - it's basically a binary astroid - Didymos - Deimos & Dimorphos - first one - 800 meters across, second one is 105 metres - three quarters of a mile apart.

Mission is to use a satellite  - DART executing a kinetic impact to hit Dimorphos, which can be considered as a small football stadium filled with rocks. DART being a golf cart full of cameras (as Tom describes it). DART will hit Dimorphos & impart a momentum to it, that will change the orbit of the moonlet Dimorphos around the astroid.

After the kinetic impact (15000 mph) - the clock will run faster than it usually does. 

It's called a double test - as we are testing two things - testing technological ability to collide with an actual astroid but we are also testing how does a real astroid react to that kinetic impact.

Hitting the moonlet orbit head-on drops it into a tighter orbit around the primary body which takes less time to go around (faster) just like a retro rocket dropping a spacecraft on a lower orbit.

Transits and eclipses will get information on how successful was the impact.

Didymos is right now - 2.5 astronomical units from sun right now but when DART arrives there it will be 0.72 astronomical units to the earth.

High bandwidth, short distance communication is key to get the information post the impact.

DRACO camera uses images to identify Diamorphos and then transmits the signal to decision an impact. 

The interesting part is nothing is know about Diamorphos - regarding it's shape, size, where to hit or typography of the surface where it will hit the moonlet. So in short a lot of data and then decisioning on the data received is involved.

Post impact & destruction of the impacting satellite, there will be the effort of measurement of the changes that happened. 

Also in order to capture the images post collision - ASI (Italian Space Agency) would be flying a Cube SAT(LICIA) - with imagers Luke and Leia - will be able to take images of the ejecta plume that will give some information on the momentum enhancement which was caused post impact. It will also give the view of the back side of the astroid giving more information of the data captured.

The DART spacecraft will demonstrate NASA Evolutionary Xenon Thruster - Commercial(NEXT-C) solar electric propulsion system.

Launch with F9 is probably set for - 23rd to 24rth Nov 21 and less than a year for impact on the astroid. 

In all this is going to be a fascinating test which will prove a lot of things apart from the main objective of astroid redirection capability.

What do we learn from the mission? 

This mission is a perfect example of both a) learning  and b) application of learning to make a decision which c) might be the only decision that matters - doing all 3 things in a very short amount of time. 

Very little known about the moonlet and astroid's have a completely different surface and texture and this exercise will give the DART small time frame to study it, analyze with some inherent understanding and principles and then take the action - which is quite fascinating as the mission itself.

Insight & take way - from technological perspective - we do encounter scenarios where quick action needs to be taken wherein the area being worked on is fairly new, purpose might be straight forward but not so simple because you don't know the challenges involved, question is - how we segment the decisioning to make sure that the one simple purpose is fulfilled.

References - nasa.gov (mission DART) & talks from mission  program scientist - Tom Statler & https://dart.jhuapl.edu

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PS: The views expressed in this article are completely my own & information is taken from the published articles given in references.