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(9 September 2020 – JPL) When NASA’s OSIRIS-REx spacecraft arrived at asteroid (101955) Bennu, mission scientists knew that their spacecraft was orbiting something special. Not only was the boulder-strewn asteroid shaped like a rough diamond, its surface was crackling with activity, shedding small pieces of rock into space.

Now, after more than a year and a half up close with Bennu, they’re starting to better understand these dynamic particle-ejection events.

A collection of studies in a special edition of the Journal of Geophysical Research: Planets homes in on the asteroid and these enigmatic particles. The studies provide a detailed look at how these particles act when in space, possible clues as to how they’re ejected, and even how their trajectories can be used to approximate Bennu’s weak gravitational field.

Typically, we consider comets, not asteroids, to be the active ones. Comets are composed of ice, rock, and dust. As those ices are heated by the Sun, the vapor fizzes from the surface, dust and chunks of the comet nucleus are lost to space, and a long dusty tail forms. Asteroids, on the other hand, are composed mainly of rock and dust (and perhaps a smaller quantity of ice), but it turns out some of these space rocks can be surprisingly lively, too.

This mosaic image of asteroid Bennu is composed of 12 images collected on Dec. 2, 2018, by the OSIRIS-REx spacecraft’s PolyCam instrument from a range of 15 miles (24 kilometers). (courtesy: NASA/Goddard/University of Arizona)

“We thought that Bennu’s boulder-covered surface was the wild card discovery at the asteroid, but these particle events definitely surprised us,” said Dante Lauretta, the OSIRIS-REx principal investigator and a professor at the University of Arizona. “We’ve spent the last year investigating Bennu’s active surface, and it’s provided us with a remarkable opportunity to expand our knowledge of how active asteroids behave.”

Cameras on OSIRIS-REx (short for Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer) spotted rock particles being repeatedly launched into space during a January 2019 survey of the asteroid, which is about a third of a mile (565 meters) wide at its equator.

One of the studies, led by senior research scientist Steve Chesley at NASA’s Jet Propulsion Laboratory in Southern California, found that most of these pebble-size pieces of rock, typically measuring around a quarter-inch (7 millimeters), were pulled back to Bennu under the asteroid’s weak gravity after a short hop, sometimes even ricocheting back into space after colliding with the surface. Others took longer to return to the surface, remaining in orbit for a few days and up to 16 revolutions. And some were ejected with enough oomph to completely escape from the Bennu environs.

Using data collected by NASA’s OSIRIS-REx mission, this animation shows the trajectories of rock particles after being ejected from asteroid (101955) Bennu’s surface. (courtesy: M. Brozovic/NASA/JPL-Caltech/University of Arizona)

By tracking the journeys of hundreds of ejected particles, Chesley and his collaborators were also able to better understand what might be causing the particles to launch from the surface of Bennu. The particle sizes match what is expected for thermal fracturing (as the asteroid’s surface is repeatedly heated and cooled while it rotates), but the locations of the ejection events also match the modeled impact locations of meteoroids (small rocks hitting the surface of Bennu as it orbits the Sun). It may even be a combination of these phenomena, added Chesley. But to come to a definitive answer, more observations are needed.

While their very existence poses numerous scientific questions, the particles also served as high-fidelity probes of Bennu’s gravity field. Many particles were orbiting Bennu far closer than would be safe for the OSIRIS-REx spacecraft, and so their trajectories were highly sensitive to the irregular gravity of Bennu. This allowed researchers to estimate the Bennu’s gravity even more precisely than was possible with OSIRIS-REx’s instruments.

“The particles were an unexpected gift for gravity science at Bennu since they allowed us to see tiny variations in the asteroid’s gravity field that we would not have known about otherwise,” said Chesley.

On average, only one or two particles are ejected per day, and because they are in a very low-gravity environment, most are moving slowly. As such, they pose little threat to OSIRIS-REx, which will attempt to briefly touch down on the asteroid on Oct. 20 to scoop up surface material, which may even include particles that were ejected before dropping back to the surface.

If all goes as planned, the spacecraft will return to Earth in September 2023 with a cache of Bennu’s material for scientists to study further.

NASA’s Goddard Space Flight Center in Greenbelt, Maryland, provides overall mission management, systems engineering, and the safety and mission assurance for OSIRIS-REx. Dante Lauretta of the University of Arizona in Tucson is the principal investigator, and the University of Arizona also leads the science team and the mission’s science observation planning and data processing. Lockheed Martin Space in Denver built the spacecraft and provides flight operations. Goddard and KinetX Aerospace are responsible for navigating the OSIRIS-REx spacecraft. 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.

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OSIRIS-REx In the midst of sample stowage

OSIRIS REx In the midst of sample stowage

(28 October 2020 – NASA Goddard) Yesterday, NASA’s OSIRIS-REx mission successfully placed the spacecraft’s sample collector head into its Sample Return Capsule (SRC).

(courtesy: NASA)

The first image shows the collector head hovering over the SRC after the Touch-And-Go Sample Acquisition Mechanism (TAGSAM) arm moved it into the proper position for capture. The second image shows the collector head secured onto the capture ring in the SRC. Both images were captured by the StowCam camera.

Today, after the head was seated into the SRC’s capture ring, the spacecraft performed a “backout check,” which commanded the TAGSAM arm to back out of the capsule. This maneuver is designed to tug on the collector head and ensure that the latches – which keep the collector head in place – are well secured. Following the test, the mission team received telemetry confirming that the head is properly secured in the SRC.

Before the sampler head can be sealed into the SRC, two mechanical parts on the TAGSAM arm must first be disconnected – these are the tube that carried the nitrogen gas to the TAGSAM head during sample collection and the TAGSAM arm itself. Over the next several hours, the mission team will command the spacecraft to cut the tube and separate the collector head from the TAGSAM arm. Once the team confirms these activities have executed as planned, they will command the spacecraft to seal the SRC.

StowCam, a color imager, is one of three cameras comprising TAGCAMS (the Touch-and-Go Camera System), which is part of OSIRIS-REx’s guidance, navigation, and control system. TAGCAMS was designed, built and tested by Malin Space Science Systems; Lockheed Martin integrated TAGCAMS to the OSIRIS-REx spacecraft and operates TAGCAMS.

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Rocket Lab successfully launches 15th mission, deploys satellites for Planet, Canon Electronics

Rocket Lab successfully launches 15th mission deploys satellites for Planet

(29 October 2020 – Rocket Lab) Rocket Lab has successfully launched its 15th Electron mission and deployed Earth-imaging satellites for Planet and Spaceflight Inc. customer Canon Electronics.

The mission was Rocket Lab’s fifth for this year, making Electron the second-most frequently flown U.S. launch vehicle in 2020.

(courtesy: Rocket Lab)

The ‘In Focus’ mission launched from Rocket Lab Launch Complex 1 on New Zealand’s Māhia Peninsula at 21:21 UTC, 28 October 2020. The Electron launch vehicle successfully deployed ten commercial small satellites to a 500km circular orbit, bringing the total number of payloads deployed by Rocket Lab to 65.

The payloads on ‘In Focus’ included the latest flock of Planet’s Earth-imaging SuperDove small satellites, each integrated with and deployed from Rocket Lab’s Maxwell satellite dispensers. Flock 4e’ bolsters Planet’s constellation of Earth-observation satellites already on orbit providing medium-resolution global coverage and near-daily revisit. Canon Electronic’s mission objective with their CE-SAT-IIB microsatellite is to demonstrate the company’s Earth-imaging capability with a middle-size telescope equipped with an ultra-high sensitivity camera to take night images of the Earth and small size telescopes suitable for CubeSat use.

“Congratulations to Planet on the addition of their latest SuperDoves to their constellation and to the team at Canon Electronics on the deployment of their latest tech demonstration satellite,” said Rocket Lab founder and CEO, Peter Beck. “Electron has once again delivered a smooth ride to orbit and precise deployment for our individual rideshare customers. Continuing to launch in the face of global disruption and adversity, while at the same time becoming the second-most frequently flown U.S. launch vehicle this year, is the latest display our dedication in providing ongoing, easy access to space for our customers.

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OSIRIS-REx spacecraft collects significant amount of asteroid

OSIRIS REx spacecraft collects significant amount of asteroid

(23 October 2020 – NASA) Two days after touching down on asteroid Bennu, NASA’s OSIRIS-REx mission team received on Thursday, Oct. 22, images that confirm the spacecraft has collected more than enough material to meet one of its main mission requirements – acquiring at least 2 ounces (60 grams) of the asteroid’s surface material.

The spacecraft captured images of the sample collector head as it moved through several different positions. In reviewing these images, the OSIRIS-REx team noticed both that the head appeared to be full of asteroid particles, and that some of these particles appeared to be escaping slowly from the sample collector, called the Touch-And-Go Sample Acquisition Mechanism (TAGSAM) head. They suspect bits of material are passing through small gaps where a mylar flap – the collector’s “lid” – is slightly wedged open by larger rocks.

Captured by the spacecraft’s SamCam camera on Oct. 22, 2020, this series of three images shows that the sampler head on NASA’s OSIRIS-REx spacecraft is full of rocks and dust collected from the surface of the asteroid Bennu. They show also that some of these particles are slowly escaping the sampler head. Analysis by the OSIRIS-REx team suggests that bits of material are passing through small gaps where the head’s mylar flap is slightly wedged open. The mylar flap (the black bulge on the left inside the ring) is designed to keep the collected material locked inside, and these unsealed areas appear to be caused by larger rocks that didn’t fully pass through the flap. Based on available imagery, the team suspects there is plentiful sample inside the head, and is on a path to stow the sample as quickly as possible. (courtesy: NASA)

“Bennu continues to surprise us with great science and also throwing a few curveballs,” said Thomas Zurbuchen, NASA’s associate administrator for science at the agency’s headquarters in Washington. “And although we may have to move more quickly to stow the sample, it’s not a bad problem to have. We are so excited to see what appears to be an abundant sample that will inspire science for decades beyond this historic moment.”

The team believes it has collected a sufficient sample and is on a path to stow the sample as quickly as possible. They came to this conclusion after comparing images of the empty collector head with Oct. 22 images of the TAGSAM head after the sample collection event.

The images also show that any movement to the spacecraft and the TAGSAM instrument may lead to further sample loss. To preserve the remaining material, the mission team decided to forego the Sample Mass Measurement activity originally scheduled for Saturday, Oct. 24, and canceled a braking burn scheduled for Friday to minimize any acceleration to the spacecraft.

From here, the OSIRIS-Rex team will focus on stowing the sample in the Sample Return Capsule (SRC), where any loose material will be kept safe during the spacecraft’s journey back to Earth.

“We are working to keep up with our own success here, and my job is to safely return as large a sample of Bennu as possible,” said Dante Lauretta, OSIRIS-REx principal investigator at the University of Arizona in Tucson, who leads the science team and the mission’s science observation planning and data processing. “The loss of mass is of concern to me, so I’m strongly encouraging the team to stow this precious sample as quickly as possible.”

The TAGSAM head performed the sampling event in optimal conditions. Newly available analyses show that the collector head was flush with Bennu’s surface when it made contact and when the nitrogen gas bottle was fired to stir surface material. It also penetrated several centimeters into the asteroid’s surface material. All data so far suggest that the collector head is holding much more than 2 ounces of regolith.

OSIRIS-REx remains in good health, and the mission team is finalizing a timeline for sample storage. An update will be provided once a decision is made on the sample storage timing and procedures.

NASA’s Goddard Space Flight Center in Greenbelt, Maryland, provides overall mission management, systems engineering and the safety and mission assurance for OSIRIS-REx. Lockheed Martin Space in Denver built the spacecraft and is providing flight operations. Goddard and KinetX Aerospace of Tempe, Arizona, are responsible for navigating the OSIRIS-REx spacecraft. 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.

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