Nicholas Moskovitz In 2008 the asteroid 2008 TC3 was discovered 19 hours before it impacted the Earth and delivered meteorites to the Nubian desert in northern Sudan. This was a seminal event providing for the first time the direct means to connect telescopic observations of an asteroid to meteoritic samples from that body. Such events will be repeated as current and next generation discovery surveys (e.g. PanSTARRS, ATLAS, Catalina, LSST) find more objects like TC3. For every impacting asteroid, hundreds of others are found undergoing near-Earth flybys. These events are also scientifically valuable as a probe of the gravitational effects imparted on an asteroid during planetary encounters. IRTF plays and will continue to play a key role in collecting observations during these important events. I will describe a long-running target of opportunity (ToO) program that focuses on rapid response observations of noteworthy near-Earth asteroids during planetary encounters. The combination of ToO rapid response capability, the excellent non-sidereal tracking performance of the IRTF, and the efficiency of operating SpeX+MORIS to collect photometry and spectral data simultaneously, makes IRTF an ideal asset for observing these time critical events. Looking ahead, these capabilities coupled with new instrumentation will ensure IRTF remains at the forefront of time-domain, asteroid science.