In 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.
Tonight’s launch window opens at 7:05 p.m. EDT, one hour from now. All activities are on schedule for liftoff of the United Launch Alliance Atlas V 411 rocket carrying NASA’s OSIRIS-REx spacecraft from Space Launch Complex 41.
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.”
Countdown clocks just passed the T-1 hour mark and activities are proceeding smoothly. Tanking operations continue, and in case you missed it, Launch Weather Officer Clay Flinn has upgraded the forecast to reflect a 90 percent chance of “go” weather at the 7:05 p.m. liftoff time.
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-meterfairing, 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.”
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.
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.
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.
Forecasters from the U.S. Air Force 45th Weather Squadron continue to predict an 80 percent chance of favorable conditions for launch of the Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer (OSIRIS-REx) spacecraft atop a United Launch Alliance Atlas V rocket at 7:05 p.m. EDT from Space Launch Complex 41 at NASA’s Kennedy Space Center in Florida.
NASA Television starts coverage of launch events at 3:30 p.m. with the NASA Edge live broadcast, followed by live views of Space Launch Complex 41accompanied by countdown net audio.
Countdown coverage begins at 5:30 p.m. here on the OSIRIS-REx blog and on NASA Television.