Event Reports

Event Reports

Asteroid Day 2016 in Japan, Event Report.

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This event report was submitted by Makoto Yoshikawa (an Asteroid Day Expert) who ran several events across Japan as part of Asteroid Day 2016. You can read the original report, here.

=== The importance of Hayabusa and Hayabusa2 from the point of spaceguard ===

June 30th is Asteroid Day, which is a global awareness campaign for the hazard caused by asteroid collision to Earth. June 30th is the anniversary of the Tunguska event in Siberia on June 30, 1908. Mr. Grigorij Richters, one of the organizers of Asteroid Day, asked to JAXA to do something related to Asteroid Day. This is the trigger for the event reported here.

Hayabusa2 Project holds “Talk Live”, a kind of talk show, once in two months. We present various issues related to Hayabusa2 project. On June 12, 2016, we held the third Talk Live at Sagamihara City Museum. On the same day, we also had some events that celebrated the Earth return of Hayabusa, which was on June 13, 2010. Therefore, the main topic of the Talk Live on this day was set to Spaceguard (Planetary Defense), especially the role of Hayabusa and Hayabusa2 from the point of Spaceguard.

About 180 people came to the Talk Live (Fig.1). At first, I explain why we took spaceguard as the topic of today’s Talk Live, and then I presented many things related spaceguard, such as, recent impacts to the Earth, NEOs (Near Earth Objects), observations, orbits, mitigations, etc. I also explained the reason why Hayabusa and Hayabusa2 are important for spaceguard. You can see the video of this Talk Live in YouTube (https://youtu.be/BA1rEkmV4fw), although the talk is in Japanese.

Fig.1 Hayabusa2 Talk Live on June 12, 2016 at Sagamihara City Museum
Fig.1 Hayabusa2 Talk Live on June 12, 2016 at Sagamihara City Museum

In this report, I quickly summarize about the role of Hayabusa and Hayabusa2 in the context of spaceguard or planetary defense.

  • Hayabusa

Hayabusa, which was launched in 2003 and returned to Earth in 2010, was the world-fist sample return mission from an asteroid. The target asteroid is (25143) Itokawa, a small S-type asteroid (Fig.2). Itokawa is one of the NEOs. NEAR Shoemaker spacecraft was first to rendezvous with an NEO, Eros. Eros is about 38km in the length and it is not supposed that such a large NEO will collide to Earth in the near future. However, the size of Itokawa is just about 500m, and such object is what we must consider for the planetary defense.

Fig.2 Asteroid Itokawa
Fig.2 Asteroid Itokawa

After the exploration of Hayabusa, we concluded that the structure of Itokawa was a rubble pile (Fig.3), not the one single block of mass. We came to this conclusion not only from its surface feature with numerous boulders but also its density. The estimated density of Itokawa is about 1.9 g/cm3, while the density of the surface material of Itokawa, that is the ordinary chondrite, is about 3.2 g/cm3. If we assume that whole body of Itokawa consists of ordinary chondrite, then the macro-porosity is about 40%. Form this fact, we concluded that Itokawa has the rubble pile structure. This conclusion is very interesting for planetary science, and also it is very important information when we try to deflect an Earth-colliding asteroid like Itokawa.

Fig.3 Rubble pile structure of Itokawa
Fig.3 Rubble pile structure of Itokawa

Another interesting attempt for spaceguard in Hayabusa mission is to estimate the landing position of the reentry capsule on Earth. Of course, the landing position was estimated precisely by the radio navigation. However, assuming that Hayabusa was an asteroid that moved along the collision trajectory to Earth, we tried to estimate the landing (or colliding) position by optical observations. Optical observations by the ground-based telescopes were successful in the observatories of Tenaga, Mt. Lemon, Subaru, and CFHT. We got 23 data 10 to 8 hours before the landing. Using only these optical data without the information from the radio navigation, we estimated the landing position of the reentry capsule. The result was that the landing position was estimated with the error of about 560km (Fig.4).

Fig.4 Estimated the landing area of the reentry capsule by using only the optical observation data. The size of this estimated area is about 560km. (Cradited by T. Yamaguchi & M. Yoshikawa)
Fig.4 Estimated the landing area of the reentry capsule by using only the optical observation data. The size of this estimated area is about 560km. (Cradited by T. Yamaguchi & M. Yoshikawa)
  • Hayabusa2

Now let’s move on to Hayabusa2. Hayabusa2 is also an asteroid sample return mission. It was launched on December 3, 2014, and now it is on the way to the target asteroid (162173) Ryugu. Hayabusa2 will arrive at Ryugu in June – July 2018, and return to the Earth at the end of 2020 (Fig.5).

Fig.5 Mission scenario of Hayabusa2
Fig.5 Mission scenario of Hayabusa2

From the point of Spaceguard, the most important role of Hayabusa2 is to reveal the nature of small C-type asteroid. Asteroid Ryugu was selected because it is C-type. The science purpose of Hayabusa2 is to study organic matters and water, which may be in the surface material of Ryugu. The size of Ryugu is estimated as 900m and it approach Earth closely (Fig.6). Therefore, Ryugu is another realistic candidate that will collide to Earth. Is the structure a rubble pile again like Itokawa? Hayabusa2 will give us the answer to this question.

Fig.6 Asteroid Ryugu
Fig.6 Asteroid Ryugu

Another interesting attempt of Hayabusa2 is its impactor. Hayabusa2 has an impactor on board, and it will be released near the surface of Ryugu. The impactor will explode a few hundred meters above the surface of Ryugu and a lump of copper (2kg) will hit the surface at the speed of 2 km/s. Then we can create a small crater there. The purpose of this experiment is to get the sub-surface material. From the point of spaceguard, this is the exactly the same idea of the kinetic impactor. Of course the impactor of Hayabusa2 is quite small so we cannot change the orbit of asteroids. But I think this is a very interesting experiment for spaceguard, too.

In fact, in the early planning phase of Hayabusa2, we were discussing to have a much larger impactor. It was one spacecraft. Our idea was that Hayabusa2 and the impactor spacecraft would launched at the same time by the same launcher, and the impactor spacecraft would hit Ryugu after Hayabusa2 would observe it and get the sample from it (Fig.7). This is the similar idea that is now discussed as AIDA mission by ESA and NASA. In this case, we cannot change the orbit of Ryugu largely because Ryugu is too large to change its orbit by such a small spacecraft. But our analysis shows that such impactor spacecraft will be effective to change the orbit of asteroids in the size of 60 m. This is the similar size of the body that impacted at Tunguska in 1908.

Fig.7 Scenario of Hayabusa2 with an impactor spacecraft This scenario was studied in the early phase of the planning Hayabusa2.
Fig.7 Scenario of Hayabusa2 with an impactor spacecraft This scenario was studied in the early phase of the planning Hayabusa2.

The principal purposes of Hayabusa and Hayabusa2 are to develop technologies for sample return from small NEOs and to study the origin and evolution of the solar system bodies and the life. In addition to these, Hayabusa and Hayabusa2 will contribute to the activities of the spaceguard.

Makoto Yoshikawa, Hayabsua2 Talk Live Coordinator

 

 

 

 

 

 

 

 

Makoto Yoshikawa, Hayabsua2 Talk Live Coordinator
June 28, 2016

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Event Reports

Outstanding participation across Chile for the second Asteroid Day

GRupo Meteoritos y Ciencias Planetarias 1 (1)

This article was written by the Millenium Institute of Astrophysics which was an Asteroid Day 2016 Premier Event partners.

For the second year in a row, 15 national institutions in Chile joined to celebrate Asteroid Day led by astrophysicist and Queen guitarist, Brian May (view the Our Team page). Just like in 2015, MAS played an essential role in the organisation of these events where many of its researchers participated.

Almost twenty activities across Chile hosted by fifteen different institutions joined one cause and the audience was eager to participate and mark the second International Asteroid Day in Chile.

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Without a doubt, one of the most outstanding events this 2016 was the first Asteroid Day Short Stories Contest which was organised by the Millennium Institute of Astrophysics MAS along with UC’s Institute of Astrophysics and in collaboration with Universidad de Santiago’s Planetarium and the Museo Interactivo Mirador. This contest invited primary and secondary students from different parts of Chile to write a short story of no more than 108 words, making reference to the 108 years since the Tunguska event that is commemorated every June 30th. After receiving 200 story submissions, we met the two winners of the first prize: Catalina Piña, primary student of 8th grade at Colegio San Adrián de Quilicura (winner of the Primary Student Category), and Damaris Ruiz, secondary student of 2nd grade at Liceo Bicentenario de Coronel (winner of the Secondary Student Category). The Award Ceremony was held at the Planetarium, where there was also a public screening of the film: ‘51 Degrees North,’ and where later the audience could discuss about asteroids with MAS Associate Researcher and leader of this celebration in Chile, Alejandro Clocchiatti, and Universidad del Desarrollo’s Geologist, Cristhián Salazar.

For its part, MAS Deputy Director, Dante Minniti, gave a master lecture at Universidad Andrés Bello’s Casona Las Condes Campus. The Dean of the Faculty of Exact Sciences, Pierre Paul Romagnoli, was among the audience since this lecture also kicked off a series of talks organized by his University.

Additionally, also supported by MAS, researcher Millarca Valenzuela was in Peine –II Region of Chile– to talk about the importance of preserving the Monturaqui Crater, the biggest meteorite crater in Chile and one of the few confirmed collisions in South America, located 200km southwest from Antofagasta which is constantly damaged by cars entering this site.

The institutions involved in the celebration of the second International Asteroid Day this year were the Millennium Institute of Astrophysics MAS, UC’s Institute of Astrophysics, Universidad Austral’s Institute of Earth Sciences, Universidad Andrés Bello, the Center For Excellence in Astrophysics and Associated Technologies, Universidad Santo Tomás, Museo Interactivo Mirador, Universidad de Santiago de Chile’s Planetarium, UdeC’s Department of Astronomy, the Group of Meteorites and Planetary Sciences, the Chilean Geological Society, Universidad Pedro de Valdivia, FCFM U. de Chile’s Department of Astronomy, Universidad Católica del Norte and Universidad Mayor, which all together carried out almost twenty activities in different parts of Chile.

You can view some of the event pictures on Flickr here and visit their website: http://www.astrofisica.cl

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Why are we supporting Asteroid Day?

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This article was written by M. Martínez-Jiménez and J. M. Trigo-Rodríguez from the Institute of Space Sciences (IEEC-CSIC), Meteorites, Minor bodies and Planetary Science Group, Barcelona. J. M. Trigo-Rodríguez is an Asteroid Day supporter and organiser of the Asteroid Day Premier event in Barcelona, Spain.

 

IT IS ABOUT POPULARIZING ASTEROID SCIENCE AND IMPACT HAZARD

Asteroid Day is a global movement where people from around the world come together to give awareness of asteroids to the society. Thus, the aim of this annual ephemerid is to learn about asteroids, from the threat they represent to our Planet, to the study of these amazing bodies that can provide the clues for understanding the Solar System origin and evolution. Besides, recently, there is another branch that starts to be considered, which is mining mineral resources in asteroids, for example Platinum Group Elements (PGEs), as well as water for human life supply in space exploration. From the Institute of Space Sciences (IEEC-CSIC) in Barcelona we are dealing with the study of the physico-chemical properties and the dynamic origin of meteorites, our available asteroid-forming materials, to contribute to answer some of the open questions on these issues.

Our implication in the Asteroid Day movement started in 2015 with our involvement in the organization of a Barcelona double event: a scientific workshop dealing with hot topics in impact hazard, and an outreach talk given by Spanish astronaut Pedro Duque. These activities took place respectively in our research institute and in the Parc de Recerca de la Universitat Autònoma de Barcelona (UAB). As a significant product of the 2015 scientific encounter, this year Springer will release a proceedings book titled “Assessment and Mitigation of Asteroid Impact Hazards” edited by J.M. Trigo-Rodríguez, Maria Gritsevich and Herbert Palme and to be published in the Astrophysics and Space Science Proceedings Series.

Why are we committed to celebrate this event every June 30th? Simply because we want to put a key reminder in our agenda: the anniversary of the Tunguska event, the largest contemporary asteroid impact recorded so far, which occurred in 1908 and devastated over 2000 km 2 of Siberian taiga. We are exposed to asteroid hazard as many other atmospheric explosions have been recorded since then. We now probably care more about this hazard because we start to be conscious: instrument sensitivity to detect them has improved considerably over the last decades, using different techniques. Also our ability to detect them has significantly increased. Telescopic surveys have achieved a quite complete database of Near Earth Asteroids (NEAs) up to sizes larger than about 300 meters, and are constraining the population of bodies that suppose a direct risk to us. So far 1,706 Potentially Hazardous Asteroids (PHAs) have been discovered, being asteroids experiencing close approaches to the Earth and hence that are potentially threatening our planet. Unfortunately, this number only represents a small percent of the total number of objects that can strike Earth. Indeed, Earth-based surveys are not able to detect most bodies in determinate entry geometries (e.g. towards the direction of the Sun), and we still miss part of the high-inclination population. These are factors causing that some asteroids or extinct comets experiencing close approaches to Earth are discovered with just few weeks of margin. All these are reasons to claim for a dedicated infrared space telescope that can deal with the challenging properties of these bodies: low reflectivity, and larger impact velocities. In front of this, Asteroid Day claims people from all over the world to discuss and debate this important issue in order to rise the awareness about asteroid impacts.

With events like Chelyabinsk (~20 m diameter, 15th February 2013), where more than 1200 people were injured, it was demonstrated the significant power of a relatively small asteroid impact, and the big danger associated with its shock wave. Although statistics about asteroid size impacts in specific time scales are not clear since we have a short historic memory, it is expected that a Chelyabinsk-class impact happens few times per century.

Our research group has also identified that some PHAs can be sources of meter-sized projectiles, probably as consequence of the disruption of their weak structures that are characteristic of rubble piles during close approaches to the terrestrial planets. The success of the Stardust NASA mission to sample materials from comet 81P/Wild 2 promoted the development of space missions addressed to the exploration and sample return of minor bodies. The golden age of the exploration of asteroids has probably started with Hayabusa (JAXA) mission to asteroid 25143 Itokawa who was not only a great scientific achievement to understand rubble piles, but which also included successful sample return. That specific goal, bringing back to Earth pristine materials from undifferentiated bodies, will concentrate the efforts of the forthcoming Hayabusa 2 (JAXA) and OSIRIS-REx (NASA) missions addressed respectively to asteroids 162173 Ryugu and 101955 Bennu. Hopefully NASA and ESA will join soon efforts in the AIDA joint mission to binary asteroid 65803 Didymos. Such joint mission will test for the first time the kinetic impact techniques needed to deflect future asteroid close encounters with the Earth. Consequently, there is no doubt that we are living a new era in the exploration of Solar System minor bodies, and we want take part of this international movement. This year our contribution wants to popularize the AIDA mission in Spain, and our Barcelona event will include a round table about asteroid deflection techniques, and an open debate with the public after the invited conference describing AIDA by Michael Küppers (ESAC). We encourage you to join AD events worldwide for being part of this unique movement to save us from our grazing rocky neighbors. Really, it is time for action!

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