Space diary FALCON FETCH by Kamal Lodaya Falconry has been known in central Asia for at least 3000 years. There are falconers everywhere, in Japan from the 4th century CE, to India as well. The picture shows Maharaja Suraj Mal of Bharatpur in Rajasthan with a hawk. The peregrine falcon (baaj in Hindi, hayabusa in Chinese and Japanese) is found all over the world, almost as widely as its common prey, pigeons. It was trained by falconers to hunt rabbits, hares, squirrels, small reptiles and birds. Female falcons are twice as large as males, they could hunt larger birds like ducks, swans and fowl, as well as foxes and wolves. Swooping down in dives at 320 km per hour, these are the fastest movers on Earth. Before the advent of handguns, this was how hunting was done by kings and rich people. Falcons are found in the earliest civilizations, from Mesopotamia, Egypt and China. We know how humans domesticated wolves into dogs. They also domesticated falcons, perhaps from as long ago. Zooarchaeology is a discipline which studies these questions. In the novels of J.K. Rowling, Harry Potter used Hedwig, an owl, to transport letters. Owls have been used in falconry, although training them is different, since they rely on sound rather than sight. It is carrier pigeons which were used to transport mail, not owls. Ryugu As we reported in Jantar Mantar, the Japanese spacecraft Hayabusa2 reached the 1-kilometre diamond-shaped asteroid Ryugu, whose orbit ranges from somewhere close to Earth's, to somewhere close to the planet Mars's. Asteroids appear to be all over the solar system. It is now thought there may be some between Venus and Earth also. Soon after, the spacecraft Osiris Rex (more about it in a later Space diary) reached another diamond-shaped asteroid Bennu. Their pictures look alike, though Bennu is smaller. Ryugu's south pole has a large boulder formation called Otohime Saxum (see the picture). Ryugu and names of its features are from Japanese children's stories. Ryugu is a palace, and Otohime is a princess. Hayabusa2's "home station" is to remain 20 kilometres from Ryugu. But it can come much closer to within metres of the surface. It first came down and released two Minerva hoppers, later given the names Hibou and Owl, which took pictures. (Hibou is "owl" in French.) Then it released a lander, called Mascot, which took pictures coming down and sitting on the surface before its batteries ran out. After doing some preliminary trials, Hayabusa2 did a "touchdown". A sampling horn hanging down from the spacecraft touched its surface. (The painting is by Akihiro Ikeshita based on images of Ryugu taken by the rovers.) A tantalum bullet was fired into Ryugu, raising a lot of material, some of which fell into the horn. Then the horn was lifted up and the scooped-up sample stowed away in the spacecraft. This will be returned to Earth in 2020, the first large sample of asteroid material. The Hayabusa1 spacecraft earlier only succeeded in bringing back a few dust grains from the asteroid Itokawa. Meanwhile it so happened that the Earth, moving faster in its orbit than Ryugu, came to a position such that the Sun was between them. This meant that communications between Hayabusa2 and us would stop, so it took a long detour going closer to the Sun and coming back to Ryugu. The dates had been calculated using the laws of Johannes Kepler and the equations of Isaac Newton before the spacecraft left Earth. What is Ryugu made of? One thing which interests astronomers a great deal is what asteroids like Ryugu and Bennu are made of. Both are carbonaceous chondrites, with rubble-like material similar to meteorites which fall on Earth, with many organic compounds, which have plenty of carbon atoms. The colour spectrum of Ryugu from Earth, from where it is just a point of light like a star, suggested that it may have hydrated compounds, those formed in the presence of water. Perhaps, we thought, Ryugu might have water? Perhaps impacts from asteroids like Ryugu brought water to Earth? Could we bring these compounds back to Earth and check? The spectrum of Ryugu taken by Hayabusa2 from much closer, also shows the presence of hydrated compounds. But detailed photographs of Ryugu over months show no presence of water on its surface. It looks quite dry. In this respect, Bennu seems to be different, its surface has clayey regions which may have hydrated compounds. This suggests that the hydrated compounds are inside Ryugu, not on the surface. We will have to dig. But Hayabusa2 does not have drilling and mining machinery. All it has is its scooping arm. Looking under Ryugu The amazing thing is that even before it left Earth, Japanese scientists had anticipated that things might turn out so. So the spacecraft carried a 2.5-kg copper impactor with explosive material inside. This was released (the picture from Hayabusa2 shows it descending), exploding above Ryugu to make a crater on its surface. The new crater brings material from inside the asteroid out on the surface. Now Hayabusa2 can go to the crater and pick up the fresh material using its sampler. Not so fast! These things are dangerous. One pebble from the surface, hitting Hayabusa2 very fast, can severely damage it. That would jeopardize the whole operation of going to Ryugu and fetching samples. So the impactor was released to slowly fall onto Ryugu, which is easy because its gravity is very weak. Meanwhile the spacecraft fired its rockets and went around Ryugu. So Ryugu itself protected it from any shrapnel which could hit it. Then Hayabusa2 took a loop, going closer to the Sun and coming back like it did earlier, and after 3 weeks came back to look. ----- Box: India's destruction of a satellite Recently the Indian government fired a missile and destroyed one of its own satellites, sent to space in January. This shows the sophisticated aiming possible by our defence forces. Unfortunately the satellite broke into hundreds of pieces which generated a lot of space litter. The picture shows the tracks of 85 pieces being followed by T.S. Kelso of Celestrak. This junk can hit other equipment in space and damage them. Such tests were done by the US, Russia and China earlier, and they invited anger from space management agencies which are not connected with defence. The Indian tests were also criticized by Nasa. End of box----- Did we have to wait that long to find out whether the impactor worked? No. After sending down the impactor and before vanishing behind Ryugu, Hayabusa2 also dropped a small camera, a little away from the scene. This camera could see on the horizon of Ryugu the place where the impact was supposed to happen. It worked on batteries for only a short time, but it did see pebbles and dust being thrown up. So we know that the impactor worked! On April 25, Hayabusa2 returned to the scene of its crime and found a crater, nearly 10 metres across, with disturbed rubble for around 20 metres. The picture shows "before" and "after" images. Soon it will land near the crater and pick up more material in its sampling horn. So now it has managed to do a dig on Ryugu without any digging equipment. Are you wondering why metals like tantalum and copper were used? From Ryugu's spectrum we know that they are absent on the asteroid. So there is no confusion about what compounds in the sample are from Ryugu and which have come from Earth. In December 2020, the falcon returns to Earth and its samples will be parachuted down to Earth in a capsule. Since it is expected to have fuel left, there is a proposal to then send the spacecraft on a hunt to another asteroid (which does not have a name yet, it is only called 2001 WR1), reaching it in 2023. Hayabusa2 is a busy little mission. In India we are talking about sending men to the Moon, following the achievements of the United States and Russia 50 years ago. Japan shows us the sophistication in technology that is possible with robotic spacecraft, with little or no risk to human life and to the money put into the mission. Like our ancestors thousands of years ago, such robotic falcons can help our species master targets in space.