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(6 August 2020 – NASA Goddard) NASA’s first asteroid sampling spacecraft is making final preparations to grab a sample from asteroid Bennu’s surface.

Next week, the OSIRIS-REx mission will conduct a second rehearsal of its touchdown sequence, practicing the sample collection activities one last time before touching down on Bennu this fall.

On Aug. 11, the mission will perform its “Matchpoint” rehearsal – the second practice run of the Touch-and-Go (TAG) sample collection event. The rehearsal will be similar to the Apr. 14 “Checkpoint” rehearsal, which practiced the first two maneuvers of the descent, but this time the spacecraft will add a third maneuver, called the Matchpoint burn, and fly even closer to sample site Nightingale – reaching an altitude of approximately 131 ft (40 m) – before backing away from the asteroid.

This artist’s concept shows the trajectory and configuration of NASA’s OSIRIS-REx spacecraft during Matchpoint rehearsal, which is the final time the mission will practice the initial steps of the sample collection sequence before touching down on asteroid Bennu. (courtesy: NASA/Goddard/University of Arizona)

This second rehearsal will be the first time the spacecraft executes the Matchpoint maneuver to then fly in tandem with Bennu’s rotation. The rehearsal also gives the team a chance to become more familiar navigating the spacecraft through all of the descent maneuvers, while verifying that the spacecraft’s imaging, navigation and ranging systems operate as expected during the event.

During the descent, the spacecraft fires its thrusters three separate times to make its way down to the asteroid’s surface. The spacecraft will travel at an average speed of around 0.2 mph (0.3 kph) during the approximately four-hour excursion. Matchpoint rehearsal begins with OSIRIS-REx firing its thrusters to leave its 0.5-mile (870-m) safe-home orbit. The spacecraft then extends its robotic sampling arm – the Touch-And-Go Sample Acquisition Mechanism (TAGSAM) – from its folded, parked position out to the sample collection configuration. Immediately following, the spacecraft rotates to begin collecting navigation images for the Natural Feature Tracking (NFT) guidance system. NFT allows OSIRIS-REx to autonomously navigate to Bennu’s surface by comparing an onboard image catalog with the real-time navigation images taken during descent. As the spacecraft approaches the surface, the NFT system updates the spacecraft’s predicted point of contact depending on OSIRIS-REx’s position in relation to Bennu’s landmarks.

The spacecraft’s two solar panels then move into a “Y-wing” configuration that safely positions them up and away from the asteroid’s surface. This configuration also places the spacecraft’s center of gravity directly over the TAGSAM collector head, which is the only part of the spacecraft that will contact Bennu’s surface during the sample collection event.

When OSIRIS-REx reaches an altitude of approximately 410 ft (125 m), it performs the Checkpoint burn and descends more steeply toward Bennu’s surface for another eight minutes. At approximately 164 ft (50 m) above the asteroid, the spacecraft fires its thrusters a third time for the Matchpoint burn. This maneuver slows the spacecraft’s rate of descent and adjusts its trajectory to match Bennu’s rotation as the spacecraft makes final corrections to target the touchdown spot. OSIRIS-REx will continue capturing images of Bennu’s landmarks for the NFT system to update the spacecraft’s trajectory for another three minutes of descent. This brings OSIRIS-REx to its targeted destination around 131 ft (40 m) from Bennu – the closest it has ever been to the asteroid. With the rehearsal complete, the spacecraft executes a back-away burn, returns its solar panels to their original position and reconfigures the TAGSAM arm back to the parked position.

During the rehearsal, the one-way light time for signals to travel between Earth and the spacecraft will be approximately 16 minutes, which prevents the live commanding of flight activities from the ground. So prior to the rehearsal’s start, the OSIRIS-REx team will uplink all of the event’s commands to the spacecraft, allowing OSIRIS-REx to perform the rehearsal sequence autonomously after the GO command is given. Also during the event, the spacecraft’s low gain antenna will be its only antenna pointing toward Earth, transmitting data at the very slow rate of 40 bits per second. So while the OSIRIS-REx team will be able to monitor the spacecraft’s vital signs, the images and science data collected during the event won’t be downlinked until the rehearsal is complete. The team will experience these same circumstances during the actual TAG event in October.

Following Matchpoint rehearsal, the OSIRIS-REx team will verify the flight system’s performance during the descent, including that the Matchpoint burn accurately adjusted the spacecraft’s descent trajectory for its touchdown on Bennu. Once the mission team determines that OSIRIS-REx operated as expected, they will command the spacecraft to return to its safe-home orbit around Bennu.

The mission team has spent the last several months preparing for the Matchpoint rehearsal while maximizing remote work as part of its COVID-19 response. On the day of rehearsal, a limited number of personnel will monitor the spacecraft from Lockheed Martin Space’s facility, taking appropriate safety precautions, while the rest of the team performs their roles remotely. The mission implemented a similar protocol during the Checkpoint rehearsal in April.

On Oct. 20, the spacecraft will travel all the way to the asteroid’s surface during its first sample collection attempt. During this event, OSIRIS-REx’s sampling mechanism will touch Bennu’s surface for approximately five seconds, fire a charge of pressurized nitrogen to disturb the surface and collect a sample before the spacecraft backs away. The spacecraft is scheduled to return the sample to Earth on Sept. 24, 2023.

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, 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 is providing 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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NRAO joins space mission to the far side of the Moon to explore the early universe

NRAO joins space mission to the far side of the

(22 September 2020 – NRAO) The National Radio Astronomy Observatory (NRAO) has joined a new NASA space mission to the far side of the Moon to investigate when the first stars began to form in the early universe.

Artist illustration of the Dark Ages Polarimetry Pathfinder (DAPPER), which will look for faint radio signals from the early universe while operating in a low lunar orbit. Its specialized radio receiver and high-frequency antenna are currently being developed by NRAO. (courtesy: NRAO/AUI/NSF, Sophia Dagnello)

The universe was dark and foggy during its “dark ages,” just 380 thousand years after the Big Bang. There were no light-producing structures yet like stars and galaxies, only large clouds of hydrogen gas. As the universe expanded and started to cool down, gravity drove the formation of the stars and black holes, which ended the dark ages and initiated the “cosmic dawn,” tens of millions of years later.

To learn more about that dark period of the cosmos and understand how and when the first stars began to form, astronomers are trying to catch energy produced by these hydrogen clouds in the form of radio waves, via the so-called 21-centimeter line.

But picking up signals from the early universe is extremely challenging. They are mostly blocked by the Earth’s atmosphere, or drowned out by human-generated radio transmissions. That’s why a team of scientists and engineers have decided to send a small spacecraft to lunar orbit and measure this signal while traversing the far side of the Moon, which is radio-quiet.

The spacecraft, called the Dark Ages Polarimetry Pathfinder (DAPPER), will be designed to look for faint radio signals from the early universe while operating in a low lunar orbit. Its specialized radio receiver and high-frequency antenna are currently being developed by a team at the NRAO’s Central Development Laboratory (CDL) in Charlottesville, Virginia, led by senior research engineer Richard Bradley.

“No radio telescope on Earth is currently able to definitively measure and confirm the very faint neutral hydrogen signal from the early universe, because there are so many other signals that are much brighter,” said Bradley. “At CDL we are developing specialized techniques that enhance the measurement process used by DAPPER to help us separate the faint signal from all the noise.” This project builds upon the work of Marian Pospieszalski who developed flight-ready low noise amplifiers at the CDL in the 1990s for the highly-successful Wilkinson Microwave Anisotropy Probe (WMAP), a spacecraft that gave the most precise figure yet for the age of the universe.

DAPPER will be part of the NASA Artemis program with the goal of landing “the first woman and the next man” on the Moon by 2024. It will likely be launched from the vicinity of the Lunar Gateway, the planned space station in lunar orbit intended to serve as a communication hub and science laboratory. Because it is able to piggy-back off of the surging interest in sending humans to lunar soil, DAPPER will be much cheaper to build and more compact than a full-scale NASA mission.

NRAO will spend the coming two years designing and developing a prototype for the DAPPER receiver, after which it will go to the Space Sciences Laboratory at UC Berkeley for space environmental testing.

“NRAO is very pleased to be working on this important initiative,” said Tony Beasley, director of the NRAO and Associated Universities Inc. vice president for Radio Astronomy Operations. “DAPPER’s contributions to the success of NASA’s ARTEMIS mission will build on the rapid growth of space-based radio astronomy research we’ve seen over the past decade. As the leading radio astronomy organization in the world, NRAO always looks for new horizons, and DAPPER is the start of an exciting field.”

DAPPER is a collaboration between the universities of Colorado-Boulder and California-Berkeley, the National Radio Astronomy Observatory, Bradford Space Inc., and the NASA Ames Research Center. Jack Burns of the University of Colorado Boulder is Principal Investigator and Science Team Chair. Project website for DAPPER.

The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.

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JPL meets unique challenge, delivers radar hardware for Jupiter mission

JPL meets unique challenge delivers radar hardware for Jupiter mission

(21 September 2020 – JPL) Engineers at NASA’s Jet Propulsion Laboratory met a significant milestone recently by delivering key elements of an ice-penetrating radar instrument for an ESA (European Space Agency) mission to explore Jupiter and its three large icy moons.

While following the laboratory’s stringent COVID-19 Safe-at-Work precautions, JPL teams managed to build and ship the receiver, transmitter, and electronics necessary to complete the radar instrument for the Jupiter Icy Moons Explorer (JUICE) mission.

NASA’s Jet Propulsion Laboratory built and shipped the receiver, transmitter, and electronics necessary to complete the radar instrument for JUICE, the ESA (European Space Agency) mission to explore Jupiter and its three large icy moons. Here the transmitter undergoes vibration testing at JPL. (courtesy: NASA/JPL-Caltech)

Set to launch in 2022, JUICE will orbit Jupiter for three years, perform multiple flybys of moons Callisto and Europa, then orbit Ganymede. The spacecraft will observe Jupiter’s atmosphere up close as well as analyze the surfaces and interiors of the three moons, which are believed to harbor liquid water under their icy crusts.

One of 10 instruments, the radar is key to exploring those moons. Called Radar for Icy Moon Exploration, or RIME, it sends out radio waves that can penetrate the surface up to 6 or 7 miles (10 kilometers) and collects data on how the waves bounce back. Some of the waves penetrate the crust and reflect off subsurface features – and the watery interiors – enabling scientists to “see” underneath.

In the case of Europa, which is believed to have a global ocean beneath its crust, the radar data will help gauge the thickness of the ice. NASA’s Europa Clipper mission, set to launch in the mid-2020s, will arrive around the same time as JUICE and collect complementary science as it performs multiple flybys of Europa.

Building RIME During a Pandemic

A collaboration between JPL in Southern California and the Italian Space Agency (ASI), JUICE’s RIME is led by Principal Investigator Lorenzo Bruzzone of the University of Trento in Italy. JPL’s responsibility was to make and deliver the transmitter and receiver – the pieces that send out and pull in radio signals – as well as the electronics that help those pieces communicate with RIME’s antenna. Now that the components have been delivered to ASI in Rome, the next steps are to test and integrate them before assembling the instrument.

“I’m really impressed that the engineers working on this project were able to pull this off,” said JPL’s Jeffrey Plaut, co-principal investigator of RIME. “We are so proud of them, because it was incredibly challenging. We had a commitment to our partners overseas, and we met that – which is very gratifying.”

In mid-March, engineers had just finished building the transmitter and its corresponding set of electronics. They were about to run an exhaustive regimen of tests to ensure the equipment would survive deep space – including vibration, shock, and thermal vacuum testing, which simulates the vacuum and extreme temperatures of space.

Then the coronavirus pandemic forced most JPL’s employees to work remotely. The tests would have to wait.

About a month later, RIME engineers and technicians came back on-site after JPL put in place its Safe-at-Work protocols, including – among other measures – social distancing, mask-wearing, and frequent hand-washing. Now the team had a schedule crunch, plus other new challenges. As one of the first teams to re-enter JPL (most employees continue to work remotely), they needed to figure out new ways to do things that used to be easy. Just finding screws and other fasteners, when the usual supply shop wasn’t open, became a puzzle to solve.

Project Manager Don Heyer had new human challenges as well.

“We needed to keep people not just safe – but comfortable being there,” Heyer said. “That was important, because otherwise they wouldn’t be able to do the job successfully.”

The key to moving forward was clearly defining next steps, he said. At the same time, they needed to make safety requirements thorough, but not too much of an additional burden for the staff. It was a learning experience, he said.

“But we got there pretty quickly.”

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SwRI instruments aboard Rosetta help detect unexpected ultraviolet aurora at a comet

SwRI instruments aboard Rosetta help detect unexpected ultraviolet aurora at

(21 September 2020 – SwRI) Data from Southwest Research Institute-led instruments aboard ESA’s Rosetta spacecraft have helped reveal auroral emissions in the far ultraviolet around a comet for the first time.

At Earth, auroras are formed when charged particles from the Sun follow our planet’s magnetic field lines to the north and south poles. There, solar particles strike atoms and molecules in Earth’s atmosphere, creating shimmering curtains of colorful light in high-latitude skies. Similar phenomena have been seen at various planets and moons in our solar system and even around a distant star. SwRI’s instruments, the Alice far-ultraviolet (FUV) spectrograph and the Ion and Electron Sensor (IES), aided in detecting these novel phenomena at comet 67P/Churyumov-Gerasimenko (67P/C-G).

Data from Southwest Research Institute-led instruments aboard ESA’s Rosetta spacecraft helped reveal unique ultraviolet auroral emissions around irregularly shaped Comet 67P. Although these auroras are outside the visible spectra, other auroras have been seen at various planets and moons in our solar system and even around a distant star. (courtesy: ESA/Rosetta/NAVCAM)

“Charged particles from the Sun streaming towards the comet in the solar wind interact with the gas surrounding the comet’s icy, dusty nucleus and create the auroras,” said SwRI Vice President Dr. Jim Burch who leads IES. “The IES instrument detected the electrons that caused the aurora.”

The envelope of gas around 67P/C-G, called the “coma,” becomes excited by the solar particles and glows in ultraviolet light, an interaction detected by the Alice FUV instrument.

“Initially, we thought the ultraviolet emissions at comet 67P were phenomena known as ‘dayglow,’ a process caused by solar photons interacting with cometary gas,” said SwRI’s Dr. Joel Parker who leads the Alice spectrograph. “We were amazed to discover that the UV emissions are aurora, driven not by photons, but by electrons in the solar wind that break apart water and other molecules in the coma and have been accelerated in the comet’s nearby environment. The resulting excited atoms make this distinctive light.”

Dr. Marina Galand of Imperial College London led a team that used a physics-based model to integrate measurements made by various instruments aboard Rosetta.

“By doing this, we didn’t have to rely upon just a single dataset from one instrument,” said Galand, who is the lead author of a Nature Astronomy paper outlining this discovery. “Instead, we could draw together a large, multi-instrument dataset to get a better picture of what was going on. This enabled us to unambiguously identify how 67P/C-G’s ultraviolet atomic emissions form, and to reveal their auroral nature.”

“I’ve been studying the Earth’s auroras for five decades,” Burch said. “Finding auroras around 67P, which lacks a magnetic field, is surprising and fascinating.”

Following its rendezvous with 67P/C-G in 2014 through 2016, Rosetta has provided a wealth of data revealing how the Sun and solar wind interact with comets. In addition to discovering these cometary auroras, the spacecraft was the first to orbit a comet’s nucleus, the first to fly alongside a comet as it travelled into the inner Solar System and the first to send a lander to a comet’s surface.

Additional instruments contributing to this research were Rosetta’s Langmuir Probe (LAP), the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA), the Microwave Instrument for the Rosetta Orbiter (MIRO) and the Visible and InfraRed Thermal Imaging Spectrometer (VIRTIS).

Rosetta is an ESA mission with contributions from its member states and NASA. Rosetta’s Philae lander is provided by a consortium led by DLR, MPS, CNES and ASI. Airbus Defense and Space built the Rosetta spacecraft. NASA’s Jet Propulsion Laboratory (JPL) manages the U.S. contribution of the Rosetta mission for NASA’s Science Mission Directorate in Washington, under a contract with the California Institute of Technology (Caltech). JPL also built the Microwave Instrument for the Rosetta Orbiter and hosts its principal investigator, Dr. Mark Hofstadter. SwRI (San Antonio and Boulder, Colorado) developed the Rosetta orbiter’s Ion and Electron Sensor and Alice instrument and hosts their principal investigators.

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