# Intercept a NEO trajectory

I need help with an exercise in the book that I can't tackle. I need to calculate how much time we have to intercept and eliminate a NEO. I got the following orbital parameters:

• a=-2791.44 km (semi-major axis),
• i=22.3 deg /Hyperbolic),
• e=2.77
• v=247.96 deg,
• r= 2,106,101.331 km (radius from Earth's center of mass)

My problem is that I don't know where to begin, but I did an attempt. I assume that the intercept with the target only can happen when the phase angle between Earth and the NEO are the same. I know that one can calculate the velocity of the S/C with ($m_y$=gravitational param.): $$v=\sqrt{(2m_y/r)-(m_y/a)}$$ If we calculate the escape velocity of the Earth with $V_e=\sqrt{2GM_e/r}$, we will get the difference in velocity. With this information, we can calculate the time needed. Anyone that can help me?

Assuming that you have a phaser array sufficiently powerful to pulverize the NEO into a harmless meteor storm, I read this as a question of when an object with those geocentric orbital elements arrives at perigee. However, I get a different value for $r$ if I treat that $\nu$ value as a true anomaly; it could be a mean anomaly or hyperbolic anomaly instead.
I suppose your textbook covers this stuff in detail, but for other readers these lecture notes by M. Peet at ASU, using $f$ instead of $\nu$, may help.