Why Visit Bennu?

Animation still comparing, from left to right, the asteroid Bennu, the Empire State Building and the Eiffel TowerOSIRIS-REx is headed to Bennu, a roughly spherical asteroid measuring about 1,614 feet (492 meters) in diameter. All asteroids represent remnants of the building blocks of our solar system, so why did scientists decide to send a mission to this one?

Location, location, location. For a sample return mission, accessibility is key. Bennu travels in an Earth-like orbit that varies between .9 and 1.4 astronomical units from the sun (an astronomical unit, or AU, is the average distance between Earth and the sun, about 93 million miles). This puts it within the ideal range of .8 AU to 1.6 AU.

Larger diameter means slower rotation. Smaller asteroids – those measuring less than 650 feet in diameter – tend to rotate faster, ejecting surface materials and making it difficult for a spacecraft to get close enough for a sample. With its larger diameter, Bennu completes its day in just over four hours, slow enough for OSIRIS-REx to approach and do its work.

Carbon-rich composition. Measurements taken from telescopes indicate Bennu is carbon-rich. This is important because primitive asteroids like these may contain volatiles and organic molecules that could trace the origins of life on Earth and the potential for life elsewhere.

Image credit: NASA’s Goddard Space Flight Center Conceptual Image Lab


A Nationwide Effort

OSIRIS-REx mission logoOverall mission management for OSIRIS-REx, including systems engineering as well as safety and mission assurance, is provided by NASA’s Goddard Space Flight Center in Greenbelt, Maryland. Dante Lauretta is the mission’s principal investigator at the University of Arizona, and the spacecraft was built by Lockheed Martin Space Systems in Denver.

Launch management is the responsibility of the Launch Services Program, or LSP, at NASA’s John F. Kennedy Space Center in Florida. LSP selects the appropriate launcher for the agency’s science missions, provides oversight as the rocket and spacecraft come together, and conducts the countdown.

“Working alongside our United Launch Alliance colleagues, the engineers and analysts of NASA LSP take great pride in launching OSIRIS-REx,” NASA Launch Manager Tim Dunn said earlier in the week.

OSIRIS-REx is the third mission in NASA’s New Frontiers Program, which is managed by NASA’s Marshall Space Flight Center in Huntsville, Alabama, for the agency’s Science Mission Directorate in Washington.

View of Space Launch Complex 41

Atlas V on SLC 41 venting gaseous oxygen during tanking for OSIRIS-REx launchIn the image above from NASA TV, viewers can clearly see gaseous oxygen venting away from the Atlas V booster. This is normal and is caused when small amounts of cryogenic liquid oxygen boil off and are vented away.

“All the fueling operations have gone perfectly fine today,” NASA Launch Commentator Mike Curie reported.

The OSIRIS-REx Spacecraft

Solar array illumination test being performed on the OSIRIS-REx spacecraft inside the PHSF.Built by Lockheed Martin Space Systems in Denver, Colorado, the spacecraft measures 10.33 by 8 feet and will be powered in space by two solar panels generating 1,226 watts to 3,000 watts, depending on the distance from the sun. With both of its arrays deployed, the spacecraft extends to 20.25 feet long. Learn more about the spacecraft and its instruments.

OSIRIS-REx is expected to reach Bennu in August 2018, collect a sample from the asteroid in July 2020, depart in March 2021, and return the sample to Earth with a parachute landing in Utah in September 2023.

“We’re following on the heels of successful NASA missions like Stardust. In fact, our return capsule is using the same technology that the Stardust mission did to bring those amazing materials back,” said Dante Lauretta, OSIRIS-REx principal investigator at the University of Arizona, Tucson, referring to the mission that launched in 1999, collected particle samples from comet Wild-2, and returned those particles to Earth in 2006.

The OSIRIS-REx mission includes seven years of spacecraft operations and two years of sample analysis in laboratories on Earth.

“We’ve got great science ahead of us,” Lauretta said Tuesday. “I’m really excited to get to this milestone — to get OSIRIS-REx launched on its journey to Bennu and back.”

Photo credit: NASA/Cory Huston


Atlas V: OSIRIS-REx’s Ride to Orbit

OSIRIS-REx rollout to the Pad 41 for the upcoming launch.The United Launch Alliance Atlas V rocket comprises a first-stage booster, a Centaur upper stage and a protective payload fairing that houses the spacecraft during the critical early minutes of flight.

The Atlas V vehicle is available in several configurations, but the one poised to launch OSIRIS-REx is an Atlas V 411: it’s topped by a 4-meter fairing, and has only one solid rocket booster and one Centaur engine. The 411 configuration has flown three times before, but OSIRIS-REx will be its first launch with a NASA payload.

Tonight’s liftoff and the 13th time an Atlas V launched a NASA spacecraft, the 65th launch of an Atlas V overall.

“NASA has a terrific record flying on the Atlas V,” NASA Launch Director Tim Dunn said Tuesday.

“We’ve successfully launched 12 missions on this rocket: missions to Pluto, Jupiter, the moon, the sun, the radiation belts, three spacecraft to Mars — and now, the asteroid Bennu.”

Photo credit: NASA/Kim Shiflett

What’s in a Name? New Mission, Age-old Questions

This artist's concept shows the OSIRIS-REx spacecraft contacting the asteroid Bennu.Spelled out in full, the name of the OSIRIS-REx spacecraft hints at the many goals scientists envision for this mission: to map asteroid Bennu using 3-D laser imaging, retrieve samples from its surface and return those samples to Earth.

“The mission name is an awesome acronym that describes our primary science objectives,” said Dante Lauretta, OSIRIS-REx principal investigator.

Let’s take a closer look:

  • Origins – Return an asteroid sample for laboratory analysis. “This really is what drives our program. We’re going to asteroid Bennu because it’s a time capsule from the earliest stages of solar system formation, back when our planetary system was spread across as dust grains in a swirling cloud around our growing protostar.”
  • Spectral Interpretation – Provide 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 Yarkovsky effect, in which the asteroid absorbs the energy in sunlight, then emits that energy in the form of heat. “That causes a small thrust on the asteroid, changing its trajectory over time,” Lauretta explained Tuesday. A better understanding of this phenomenon could not only help scientists know more about Bennu, but could be applied to asteroids throughout our solar system.
  • Regolith Explorer – Document the loose blanket of gravel and dirt on the surface, known as regolith.

Image credit: NASA’s Goddard Space Flight Center. See it in high resolution at https://www.nasa.gov/image-feature/osiris-rex-grabs-a-sample

OSIRIS-REx Countdown Coverage Starts Now

Launch Day Signs showing the countdown complete for the OSIRIS-REx mission.NASA’s OSIRIS-REx spacecraft — currently sealed inside the payload fairing of a United Launch Alliance Atlas V rocket — is on track to leave Earth behind and kick off an ambitious voyage to asteroid Bennu.

Liftoff is scheduled for 7:05 p.m. EDT from Space Launch Complex 41 at Cape Canaveral Air Force Station in Florida. Countdown clocks just ticked past the T-80 minute mark – T-1 hour, 20 minutes. Launch Weather Officer Clay Flinn with the U.S. Air Force Weather Squadron now is predicting a 90 percent chance of weather cooperating for launch this evening.

OSIRIS-REx stands for Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer, and it’s the United States’ first mission to collect a sample from an asteroid’s surface and return it to Earth, where it could help answer questions about how our solar system formed and how life on our planet began.

Mission officials and launch team members are gathered in the Atlas Spaceflight Operations Center, where controllers have been stationed at their consoles since midday. NASA’s Launch Blog originates from a console in nearby Hangar AE. We’ll tell you more about the OSIRIS-REx mission — and the Atlas V rocket that’s sending it on its way — as the countdown continues, so stay with us.

Photo credit: NASA/Bill White



Tanking in Progress

Propellants are being loaded into the Atlas V rocket, a process known as tanking. It begins with chilldown of the ground equipment and transfer lines prior to the flow of supercool, cryogenic propellants. The Atlas booster’s single RD-180 engine uses 48,860 gallons of liquid oxygen, or LOX, in combination with a refined kerosene fuel called RP-1. The Centaur’s RL10-A-4-2 engine runs on 4,150 gallons of LOX and 12,680 gallons of liquid hydrogen, or LH2. RP-1 is not a cryogenic propellant like the others and was loaded into the first stage yesterday afternoon.

Countdown clocks are at T-1 hour, 39 minutes and counting.