[Note: In the interest of full disclosure, I am friends with many of the folks on both teams described below. I have tried to be scrupulously fair to both missions, and to be honest - as I say below - the best thing to happen would be for both missions to be locked, loaded, and looking for potentially hazardous rocks.]

The B612 Foundation is a group of scientists, astronauts, astronomers, and engineers who have come together to do nothing less than literally save the world: they want to find and deflect asteroids that can potentially hit the Earth. While really big asteroids are rare after all, the one 10 km (6 miles) across that wiped out the dinosaurs only hits Earth every few hundred million years smaller ones in the 100 meter range are far more common and can still do devastating damage. Even one just 50 meters across (smaller than a football field) can impact and explode with the yield of millions of tons of TNT. Thats in the range of the biggest nuclear weapons ever detonated.

Finding these asteroids is notoriously difficult. Theyre small and dim, and sometimes only discovered once theyve already passed us! The best way to find them in large numbers is to launch a space telescope to survey the sky, tuned to the infrared where these asteroids are far brighter and easier to spot.

Today, B612 made a big announcement: they want to build just such a mission. They call it Sentinel, and it will be the first privately funded deep space mission ever launched. Built by Ball Aerospace and launched on a SpaceX Falcon 9 rocket, it will be placed into a Venus-like orbit, giving it a good view of the volume of space where these asteroids prowl:

[Click to chixchulubenate.]

The plan is to raise the money philanthropically, like museums do: donations from private funders. Observatories have long been funded this way, and the proposed cost of a few hundred million dollars is roughly on par with many civic projects. Their target launch date is 2017 to 2018, and the mission will last about 5 years.

Interestingly, a group of scientists and engineers with NASA/JPL is planning a similar mission! Called NEOCam (for Near Earth Object Camera), its based on previous missions like WISE and Hubble.

Sentinel and NEOCam have many similarities: they both use a 50 cm or so telescope, both are tuned to infrared, and both will launch into orbit to get a better view of potentially threatening asteroids. Unlike Sentinel, NEOCam will stick closer to the Earth, placed into an orbit that keeps it about a million miles away. The advantage of this is that being closer, the rate at which data can be sent to Earth is very high. That allows more and higher-resolution observations to be made. While Sentinel is designed to look at one broad region of the infrared spectrum, NEOCam will look in multiple wavelengths, giving it the ability to characterize the size and chemical composition of asteroids more accurately.

This part is important: the two missions do two different things! Sentinel is designed to find and get accurate positions and orbits for these asteroids. NEOCam will also find lots of asteroids, but is optimized for science, to understand the asteroids physical characteristics. Both of these factors are critical and complementary. We need both.

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Privately and publicly looking for Earth-threatening asteroids | Bad Astronomy