OSIRIS-REx – A Sample Return Mission To Asteroid Bennu

Tomorrow, September 8, 2016, NASA’s Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer (OSIRIS-REx) is slated to launch from Cape Canaveral. It will take two years for the craft to reach its destination, the asteroid Bennu, where it will collect a sample and return it to Earth. The mission is a partnership between the University of Arizona, NASA’s Goddard Space Flight Center and the Lockheed Martin Company.

OSIRIS-REx Mission Logo - Source: NASA

OSIRIS-REx Mission Logo – Source: NASA

The OSIRIS-REx mission will send a spacecraft to 101955 Bennu (hereafter referred to simply as Bennu), a potentially Earth-impacting asteroid with an average diameter of 492 meters (1,614 ft; 0.306 mi). The mission has five primary science objectives (the mission, OSIRIS-REx, takes its name from an acronym of these objectives):

• Origins: Return and analyze a pristine carbon rich
asteroid sample
• Spectral Interpretation: Provide ground truth or
direct observations for telescopic data of the
entire asteroid population
• Resource Identification: Map the chemistry and
mineralogy of a primitive carbon rich asteroid
• Security: Measure the effect of sunlight on the
orbit of a small asteroid, known as the Yarkovsky
effect—the slight push created when the asteroid
absorbs sunlight and re-emits that energy as heat
• Regolith Explorer: Document the regolith (layer
of loose, outer material) at the sampling site at
scales down to the sub-centimeter

The $800-million (not including launch vehicle costs) mission budget will support the program through the return of the sample capsule in 2023, and two years of analysis and cataloging.

The spacecraft, built by Lockheed Martin Space Systems Company at its facility near Denver, Colorado, is 6.2 meters (20.25 feet) long with its solar arrays deployed, and 2.43 meters (8 feet) by 2.43 meters (8 feet) wide. It’s 3.15 meters (10.33 feet) tall. The total weight of the spacecraft, including fuel, is 2,110 kilograms (4,650 pounds)–unfueled, it weighs 880 kilograms (1,940 pounds). It boasts two solar panel generators that produce between 1,226 watts and 3,000 watts of electrical power depending on its distance from the Sun.

Following its September 8, 2016 launch, the spacecraft will undergo an Earth flyby in September of 2017, before arriving at Bennu in August of 2018. According to the program fact sheet, “[t]he spacecraft will begin a detailed survey of Bennu two months after slowing to encounter Bennu. The process will last over a year, and, as part of it, OSIRIS-REx will map potential sample sites. The sample is expected to occur in July of 2020, when the craft’s sampling arm will contact Bennu’s surface, release a burst of nitrogen gas, and capture the resulting particles. It’s expected to collect up between 60 grams (2 ounces) and 2 kilograms (4.4 pounds). After the sample is taken, OSIRIS-REx’s Sample Return Capsule will wait for a proper alignment with Earth for the return trip home. The sample is expected to re-enter Earth’s atmosphere on September 24, 2023–just over seven years after its 2016 launch.

OSIRIS-REx Survey Animation - Source: University of Arizona

OSIRIS-REx Survey Animation – Source: University of Arizona

Why Bennu?

In addition to Bennu being a good candidate to study the building blocks of our solar system (“An uncontaminated asteroid sample from a known source would enable precise analyses, revolutionizing our understanding of the early solar system, and cannot be duplicated by spacecraft-based instruments or by studying meteorites“), I mentioned above that Bennu is a “potentially Earth-impacting asteroid”. The chances of Bennu impacting Earth are slim–0.037%, and that’s not even until the period between 2175 – 2196–but it still serves as a good model to use to understand both the hazards and resources that coincide with near-Earth asteroids.

Here’s to a successful launch tomorrow, and a successful mission over the next seven years!

Godspeed OSIRIS-REx! Ad Astra!

Want more information on the mission? The NASA Press Kit has a wealth of information.