The HAYABUSA2 Project

The Crater Search Operation (Post-SCI): (CRA2)

The Small Carry-on Impactor (SCI) operation successfully took place on April 5. A 2kg copper mass was fired using the collision apparatus to collide with Ryugu. The gravel released from the surface of Ryugu was photographed by the deployable camera, DCAM3. However, the images from DCAM3 do not show how Ryugu’s surface has been altered by the impact. Hayabusa2 will therefore descend and make observations in the vicinity of the SCI collision area.

The CRA2 operation will take place from April 23 – 25, 2019, with preparation for the descent beginning on April 23, the descent itself starting on April 24 and the observations at the lowest altitude (about 1.7km) on April 25. The spacecraft will then rise on April 25. Figure 1 shows the location of the observations. The area to be observed is the same as that observed on March 22 in the Crater Search Operation (Pre-SCI) (CRA1).

The schedule for the CRA2 operation is shown in Figure 2. The spacecraft begins its descent at a speed of 0.4 m/s on April 24 at 16:42 JST (all times are onboard times). The speed is reduced to 0.1 m/s on April 25 at around 03:02. The descent will then continue and reach the lowest altitude (at about 1.7 km) at round 11:16 and continue to observe at this altitude for a while. The spacecraft will begin to rise at 12:53 and return to the home position. Please note that these are the planned times and the actual operation time may vary.

Figure 2: Schematic diagram of the CRA 2 operation. (Image credit: JAXA).
Note that the times listed here may differ during the actual operation.

 

OSIRIS-REx around Bennu

NASA’s OSIRIS-REx Spacecraft Enters Close Orbit Around Bennu

At 2:43 p.m. EST on December 31, while many on Earth prepared to welcome the New Year, NASA’s OSIRIS-REx spacecraft, 70 million miles (110 million kilometers) away, carried out a single, eight-second burn of its thrusters – and broke a space exploration record. The spacecraft entered into orbit around the asteroid Bennu, and made Bennu the smallest object ever to be orbited by a spacecraft.

“The team continued our long string of successes by executing the orbit-insertion maneuver perfectly,” said Dante Lauretta, OSIRIS-REx principal investigator at the University of Arizona, Tucson. “With the navigation campaign coming to an end, we are looking forward to the scientific mapping and sample site selection phase of the mission.”

Lauretta, along with his team, spent the last day of 2018 with his feet planted on Earth, but his mind focused on space. “Entering orbit around Bennu is an amazing accomplishment that our team has been planning for years,” Lauretta said.

Inching around the asteroid at a snail’s pace, OSIRIS-REx’s first orbit marks a leap for humankind. Never before has a spacecraft from Earth circled so close to such a small space object – one with barely enough gravity to keep a vehicle in a stable orbit.

Now, the spacecraft will circle Bennu about a mile (1.75 kilometers) from its center, closer than any other spacecraft has come to its celestial object of study. (Previously the closest orbit of a planetary body was in May 2016, when the Rosetta spacecraft orbited about four miles (seven kilometers) from the center of the comet 67P/Churyumov-Gerasimenko.) The comfortable distance is necessary to keep the spacecraft locked to Bennu, which has a gravity force only 5-millionths as strong as Earth’s. The spacecraft is scheduled to orbit Bennu through mid-February at a leisurely 62 hours per orbit.

Now that the OSIRIS-REx spacecraft is closer to Bennu, physical details about the asteroid will leap into sharper focus, and the spacecraft’s tour of this rubble pile of primordial debris will become increasingly detailed and focused.

“Our orbit design is highly dependent on Bennu’s physical properties, such as its mass and gravity field, which we didn’t know before we arrived,” said OSIRIS-REx’s flight dynamics system manager Mike Moreau, who is based at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.

“Up until now, we had to account for a wide variety of possible scenarios in our computer simulations to make sure we could safely navigate the spacecraft so close to Bennu. As the team learned more about the asteroid, we incorporated new information to hone in on the final orbit design,” he said.

The simulations have played a critical role. The OSIRIS-REx mission, after all, was designed based on complex computer programs that predicted — quite accurately, as it turns out — the properties of Bennu and how the spacecraft’s trajectory would behave. This diligent preparation allowed the team to navigate the vehicle safely to Bennu in December and put some questions to rest (there are, indeed, signs of ancient water preserved in Bennu’s rocks) and to fly over its poles and equator in a preliminary survey that led to some surprises (Bennu has many large boulders).

Having completed the preliminary survey of Bennu with a flyby of its south pole on December 16, the spacecraft moved to a safe 31 miles (50 kilometers) away from the asteroid to give the navigation team a chance to regroup and prepare for orbit insertion. Next, Lockheed Martin engineers programmed the spacecraft to begin moving back to a position about nine miles (15 kilometers) over Bennu’s north pole to prepare for three burns of its thrusters over the course of 10 days that would place the spacecraft into orbit.

Even though OSIRIS-REx is in the most stable orbit possible, Bennu’s gravitational pull is so tenuous that keeping the spacecraft safe will require occasional adjustments, said Dan Wibben, OSIRIS-REx maneuver and trajectory design lead at KinetX Aerospace in Simi Valley, California.

“The gravity of Bennu is so small, forces like solar radiation and thermal pressure from Bennu’s surface become much more relevant and can push the spacecraft around in its orbit much more than if it were orbiting around Earth or Mars, where gravity is by far the most dominant force,” he said.

The OSIRIS-REx navigation team will use “trim” maneuvers to slightly thrust the spacecraft in one direction or another to correct its orbit and counter these small forces. If the spacecraft drifts away from Bennu, or some other problem forces it into safe mode, it has been programmed to fly away from the asteroid to stay safe from impact.

“It’s simple logic: always burn toward the Sun if something goes wrong,” said Coralie Adam, OSIRIS-REx lead optical navigation engineer at KinetX. Engineers can navigate the spacecraft back into orbit if it drifts away, Adam said, though that’s unlikely to happen.

The navigation and spacecraft operations teams are focused on the first orbital phase. Their primary goal is to transition away from star-based navigation, which allowed the team to locate the spacecraft based on pictures of the star formations around it taken by the cameras onboard. Navigators use methods like this since there is no GPS in deep space and we can’t see the spacecraft from Earth-based telescopes. From this point forward, though, the OSIRIS-REx team will rely on landmarks on Bennu’s surface to track OSIRIS-REx, a more precise technique that will ultimately guide them to a sample-collection site clear of boulders and large rocks, said Adam.

“After conducting a global imaging and mapping campaign during our recent preliminary survey phase, the science team has created 3-D models of Bennu’s terrain that we’re going to begin using for navigation around the asteroid,” she said.

Another critical objective of this orbital phase, Adam said, is to get a better handle on Bennu’s mass and gravity, features that will influence the planning of the rest of the mission, notably the short touchdown on the surface for sample collection in 2020. In the case of Bennu, scientists can only measure these features by getting OSIRIS-REx very close to the surface to see how its trajectory bends from Bennu’s gravitational pull.

“The Orbital A phase will help improve our detailed models for Bennu’s gravity field, thermal properties, orientation, and spin rate,” said Wibben. “This, in turn, will allow us to refine our trajectory designs for the even more challenging flight activities we will perform in 2019.”

The December 31 maneuver to place the spacecraft into orbit about Bennu is the first of many exciting navigation activities planned for the mission. The OSIRIS-REx team will resume science operations in late February. At that point, the spacecraft will perform a series of close flybys of Bennu for several months to take high-resolution images of every square inch of the asteroid to help select a sampling site. During the summer of 2020, the spacecraft will briefly touch the surface of Bennu to retrieve a sample. The OSIRIS-REx mission is scheduled to deliver the sample to Earth in September 2023.

Goddard 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.

 

 

Asteroid Explorer “Hayabusa2”

Asteroid Explorer “Hayabusa2”

Hayabusa2 to clarify the origin and evolution of the solar system as well as life matter

Asteroid Explorer “Hayabusa2” is a successor of “Hayabusa” (MUSES-C), which revealed several new technologies and returned to Earth in June 2010.
While establishing a new navigation method using ion engines, Hayabusa brought back samples from the asteroid “Itokawa” to help elucidate the origin of the solar system. Hayabusa2 will target a C-type asteroid “Ryugu” to study the origin and evolution of the solar system as well as materials for life by leveraging the experience acquired from the Hayabusa mission.
To learn more about the origin and evolution of the solar system, it is important to investigate typical types of asteroids, namely S-, C-, and D-type asteroids. A C-type asteroid, which is a target of Hayabusa2, is a more primordial body than Itokawa, which is an S-type asteroid, and is considered to contain more organic or hydrated minerals — although both S- and C- types have lithologic characteristics. Minerals and seawater which form the Earth as well as materials for life are believed to be strongly connected in the primitive solar nebula in the early solar system, thus we expect to clarify the origin of life by analyzing samples acquired from a primordial celestial body such as a C-type asteroid to study organic matter and water in the solar system and how they coexist while affecting each other.

Establishing deep space exploration technology and new challenges

Hayabusa2 will utilize new technology while further confirming the deep space round-trip exploration technology by inheriting and improving the already verified knowhow established by Hayabusa to construct the basis for future deep-space exploration.
The configuration of Hayabusa2 is basically the same as that of Hayabusa, but we will modify some parts by introducing novel technologies that evolved after the Hayabusa era. For example, the antenna for Hayabusa was in a parabolic shape, but the one for Hayabusa2 will be flattened. Also, a new function, “collision device”, is considered to be onboard to create a crater artificially. An artificial crater that can be created by the device is expected to be a small one with a few meters in diameter, but still, by acquiring samples from the surface that is exposed by a collision, we can get fresh samples that are less weathered by the space environment or heat.
Hayabusa2 was launched on December 3, 2014. It should arrive at the C-type asteroid in mid 2018, staying around there for one and half years before leaving the asteroid at the end of 2019 and returning to Earth around the end of 2020.

Stereo image of asteroid Ryugu by Dr. Brian May

Brian May, the lead guitarist from the British rock band, Queen, has created a stereoscopic image of Ryugu from photographs captured with the ONC-T camera onboard Hayabusa2, so that the asteroid can be viewed in three dimensions. Brian May is an astronomer, with a doctoral degree in astrophysics from Imperial College London. He has a strong interest in planetary defense or space guard, which considers the potential threat to the Earth from meteorites. As part of this, May is a core member of “Asteroid Day”, that began about three years ago to increase awareness of asteroids and action that can be taken to protect the Earth.

Image to be used with red/blue stereo glasses.

JAXA Hayabusa2 Project