© 2010 PhysOrg.com According to the Japanese Space Agency, JAXA, the space probe has successfully fired its thrusters for its third Trajectory Correction Maneuver (TCM) to set it on course for a landing at the Woomera Test Range in the South Australian outback. Only one more correction maneuver remains, and is scheduled for later this week.The spacecraft’s sample return capsule containing any samples is scheduled to detach from the probe and land at Woomera at about 1400 GMT on June 13. The US space agency, NASA, is sending a DC-8 flying laboratory from California to South Australia to record the re-entry and landing using its barrage of image and spectrographic cameras.There is no guarantee of success of the return mission but Hayabusa has already transmitted detailed images and scientific observations from on and around the asteroid Itokawa, which will help scientists to better understand the asteroids. Until the capsule is opened scientists will not know for certain if the probe succeeded in gathering any samples, but scientists are hopeful the capsule may contain at least small residues for analysis.The asteroid Itokawa was discovered in 1998 and named after a Japanese scientist Hideo Itokawa, a pioneer of the Japanese space program nicknamed “Dr Rocket”. It is a mere 540 meters wide and orbits about 300 million kilometers from Earth.Hayabusa cost around 138 million USD to develop. It reached Itokawa in 2005 and landed twice to collect samples of surface materials, but it apparently failed to fire a metal bullet that was designed to dislodge samples for collection. It left behind a time capsule wrapped in film and bearing the names of 880,000 people from 149 countries who had all responded to JAXA’s public invitation to be listed.The craft has had other problems including a leaking thruster, battery problems, broken wheels, and a fuel leak in 2005 that drained the craft’s propellant tanks, leaving only the ion thrusters to guide the craft back to Earth. The ion thrusters have low acceleration, which has meant each trajectory correction has taken longer than it would have done with the chemical engines. The problems and malfunctions resulted in the mission lasting longer than originally planned because communications with Earth were lost for several weeks in late 2005 when the craft was due to head home. When communications were restored it was too late, and the craft had to wait until April 2007 for the positions of the asteroid and Earth to be ideal again.Hayabusa, which means falcon in Japanese, is currently around 3,600,000 km away from Earth. The sample return capsule will land on Earth but the spacecraft itself will burn up as it re-enters Earth’s atmosphere. The mission has fueled the public imagination in Japan, and the spacecraft has a large following of fans. There are also proposals the spacecraft be granted a National Honor award. Hayabusa is the world’s first spacecraft to land on a body other than the moon and take off again. (PhysOrg.com) — Hayabusa, the Japanese space probe launched in 2003, is returning home from its five-billion-kilometer round-trip journey to collect samples from the asteroid 25143 Itokawa. Explore further Artist’s impression of Hayabusa in proximity to Itokawa’s surface. Japanese spacecraft to land in Australian outback Citation: Japanese space probe Hayabusa close to home (2010, June 8) retrieved 18 August 2019 from https://phys.org/news/2010-06-japanese-space-probe-hayabusa-home.html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.
© 2016 Phys.org Journal information: Proceedings of the Royal Society A Citation: Statistics suggests that unanimous agreement in witnessed events may be sign of an error (2016, March 23) retrieved 18 August 2019 from https://phys.org/news/2016-03-statistics-unanimous-agreement-witnessed-events.html Overwhelming evidence? It’s probably a bad thing (Phys.org)—A team of researchers with The University of Adelaide and one with University of Angers has found that the probability of a unanimous agreement in witnessed events is low enough that instances of such are likely a sign of an error. In their paper published in Proceedings of the Royal Society A, the researchers suggest their findings could have an impact on fields as diverse as legal proceedings, archaeological assessments and even cryptographic testing. Explore further When a jury is given testimony by many witnesses to a crime, all fingering the same person, the consensus is generally that the police have caught the right person. But, a statistical assessment of such instances by the research team suggests that may not always be the case. They suggest that the opposite may in fact be true, that the more witnesses fingering the same person, the greater likelihood there is that the wrong person has been caught.The reasoning by the team goes along the lines of logic; if 100 people observe an apple sitting on an otherwise bare table and all confirm it was an apple, than there is a strong likelihood that it was an apple sitting there. But, what happens when the observation is not so simple—for example, what if 100 people see a man carrying a bag of money out of a bank after a robbery, and all 100 agree that it was the man police have identified as the robber. That might be a problem because prior research has shown that when asked to identify a person that witnesses have seen for just a few seconds, especially if that person is running away, can be as low as 50 percent correct. When performing Bayesian analysis on such scenarios, the team reports, the numbers grow worse as the number of people unanimously agrees on something they believe they have seen. Put another way, statistically speaking, it is nearly impossible for 100 people to all correctly identify a person in such a situation—thus, if they do, it calls into question the validity of the results.The researchers note that their findings apply to other areas as well—if 100 archeologists agree on the source of a find, for example, the odds are great that there is an error somewhere, because statistics suggests there should be at least some differences in the results. More information: Lachlan J. Gunn et al. Too good to be true: when overwhelming evidence fails to convince, Proceedings of the Royal Society A: Mathematical, Physical and Engineering Science (2016). DOI: 10.1098/rspa.2015.0748AbstractIs it possible for a large sequence of measurements or observations, which support a hypothesis, to counterintuitively decrease our confidence? Can unanimous support be too good to be true? The assumption of independence is often made in good faith; however, rarely is consideration given to whether a systemic failure has occurred. Taking this into account can cause certainty in a hypothesis to decrease as the evidence for it becomes apparently stronger. We perform a probabilistic Bayesian analysis of this effect with examples based on (i) archaeological evidence, (ii) weighing of legal evidence and (iii) cryptographic primality testing. In this paper, we investigate the effects of small error rates in a set of measurements or observations. We find that even with very low systemic failure rates, high confidence is surprisingly difficult to achieve; in particular, we find that certain analyses of cryptographically important numerical tests are highly optimistic, underestimating their false-negative rate by as much as a factor of 280. Credit: George Hodan/Public Domain This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.