We tend to usually think about asteroids when one is reported-mostly in sensational media headlines-to be on a collision course to Earth. Our view is also influenced by all the sci-fi movies and TV shows about the impending doom. Yes, the dinosaurs were likely wiped out by an asteroid strike, but the chance of a repeat strike of that magnitude is small. But I am not trying to minimize the threat of asteroids. Currently, the probability of an asteroid striking the Earth is not zero. And as such, the human civilization can ill-afford to take a chance on that risk. At some level, we need to prepare for an asteroid heading our way. One way to do that would be more research and observations of asteroids. Organizations, such as the Planetary Society, a leading space science advocacy group, prioritizes asteroid tracking and mitigation strategies as one of its top goals.
Asteroids shouldn't be thought of only as destructive forces of nature. These spatial bodies are relics from the beginning of the Solar System and have a lot to teach us. They also contain all kinds of minerals and resources, such as water. They crisscross our vast Solar System and are plentiful, especially in the asteroid belt region, between the orbits of Mars and Jupiter. Could we someday exploit these resources for the benefit of humanity?
All that we know about asteroids come almost exclusively by studying them from afar. As we venture out further in space and visit planets and their moons, priority should also be given to asteroid explorations. Learning more about their composition will allow us to not only prepare appropriate risk mitigation strategies but also extract the resources that these asteroids provide for in situ utilization. A human mission to an asteroid is probably not necessary or cost-effective, therefore unmanned missions are the way to go. While numerous missions have had flybys of asteroids, here are the four missions that touched an asteroid.
1. NEAR Shoemaker - Landed on a near-earth asteroid (NEA) Eros in February 2001; operated by NASA
2. Hayabusa - Landed on asteroid Itokawa in November 2005; operated by JAXA (Japanese Aerospace Exploration Agency); it returned back to the Earth with sample in 2010
3. Hayabusa 2 - Landed multiple times (first landing February 2019) on asteroid Ryugu to collect samples for return to Earth; operated by JAXA
4. OSIRIS-REx - A sample return mission to asteroid Bennu (which has a small chance to impact Earth in the late 22nd century); landed in October 2020; operated by NASA
A couple of observations from various asteroid flybys and visits. (1) Asteroid missions are still the purview of governmental agencies because there are so far no obvious economic benefits for private investments. And (2) we need to continue to visit different types of asteroids to study asteroid deflection and resource extraction technologies. One such mission in the works is to the 16 Psyche asteroid, which is a unique type of metal asteroid. Another reason I am excited for this mission is the testing of Deep Space Optical Communication (DSOC) technology which will use photons instead of radio waves to communicated to Earth.
In summary, we are at the beginning of a golden age in asteroid exploration. In not-too-distant future, this could become the new "Gold Rush" moment.