ВНИМАНИЕ! На форуме завершено голосование в конкурсе - астрофотография месяца ИЮЛЬ-АВГУСТ!
0 Пользователей и 1 Гость просматривают эту тему.
Американское космическое агентство сообщило, что зонд Dawn, направляющийся в самому крупному астероиду в Солнечной системе, как и было запланировано, сегодня отключил свой основной ионный двигатель. В феврале 2009 года Dawn облетит вокруг Марса, а затем направится к Весте... http://www.cybersecurity.ru/prognoz/59524.html
http://www.jpl.nasa.gov/news/news.cfm?release=2007-115Dawn успешно завершил первое испытание ионного двигателя. 7 октября в 1:07 UTC ионный двигатель был включен, и на протяжении следующих 27 часов в JPL следили за его работой. Двигатель был испытан на пяти различных режимах тяги. За время испытания он израсходовал менее 280 г ксенона.
Цитата: Sergiusz от 10 Окт 2007 [21:51:05]http://www.jpl.nasa.gov/news/news.cfm?release=2007-115Dawn успешно завершил первое испытание ионного двигателя. 7 октября в 1:07 UTC ионный двигатель был включен, и на протяжении следующих 27 часов в JPL следили за его работой. Двигатель был испытан на пяти различных режимах тяги. За время испытания он израсходовал менее 280 г ксенона. А неизвестно ли, каковы же основные параметры ионного движка, в т.ч. скорость истечения реактивной струи?
Господа, 17 февраля пролет Марса, не забываем! Конечно, почти никакого научного значения этот пролет иметь не будет, но все же..С большим трудом нашел в недрах сайта миссии уточненную точную дату пролета -17 февраля вот отсюда - http://dawn.jpl.nasa.gov/mission/journal_1_27_09.aspDawn’s unique propulsion system allows it to change its own speed by well more than this during its mission. Yet the famously gentle ion thrust means it would take quite a while to achieve these changes, and the mission itinerary, fit between the September 2007 launch and the February 2015 arrival at Ceres, does not afford enough uncommitted time. There are other technical reasons as well that making these changes only with its built-in capabilities would be impractical. The encounter with Mars is a free way to get significant help. Is it really free? Well, in these difficult economic times, there is a cost we are obligated to divulge in the interest of full disclosure. The changes to Dawn’s orbit come at the expense of Mars’s orbit. Just as when you throw a ball forward, you feel a “reaction” force backward, in pushing the spacecraft one way, Mars reacts by moving the other. Mars exerts a force on Dawn, but Dawn exerts an opposite force on Mars. As the planet’s mass is nearly 600 million million million times that of the spacecraft, the effect on our probe is far larger than on the fourth planet from the Sun. The cost of helping Dawn is that Mars will slow in its orbit enough that after 1 year, its position will be off by about the width of an atom. Adding up the growing deficit, it would take 180 million years for Mars to be out of position by 2.5 centimeters (1.0 inches). That is the cost, and, on behalf of Dawn and all who share in the eager anticipation of the mysteries it will reveal in the asteroid belt, we express our gratitude to Mars for its upcoming sacrifice! The control team’s best estimate now is that Dawn’s closest encounter with Mars will occur at about 4:28 pm PST on February 17. In the next log, we will cover some of the spacecraft’s activities during its short visit, but we conclude this one with a note about the plans. Many spacecraft have visited this intriguing planet already, and it has been studied extensively from orbit and from the surface for years and years. During its brief passage, Dawn cannot learn much that is new. On the other hand, Mars is so well characterized and familiar that it provides a useful reference for calibrating Dawn’s scientific instruments. As we will see, the calibration plan precludes obtaining the highest resolution images that might otherwise be attempted. Such a strategy may seem surprising to all those who appreciate spectacular pictures of Mars, but, of course, there are already many many such images, and future missions will produce even more that will continue to captivate and inspire us.