A spacecraft heading for Pluto will take pictures of several other planets on its way. The above equation gives the distance, ddd, in millions of kilometers, of the craft from its first photo opportunity with Mars in terms of the time, ttt, in days. What is the meaning of the 212212212 in this equation

The maximum number of days for the trip

Explanation:

Given

--- Missing Equation

Required

What does d represent?

From the question, we understand that t represent the number of days;

So, by default 212 represent days

Going further:

For the equation, to be valid; the value of t must be within the interval;

When

that is the beginning of the journey

As t increases;

212 - t decreases

Until the point where t = 212,

This signifies the end of the journey

So: 212 - t indicates a particular day between 0 and 212.

Hence, 212 represents the maximum number of days for the trip.

because growing process had stoped after 4-5 year

there are no contact forces mentioned on the list of choices that you've provided.