{"id":492,"date":"2016-09-29T12:49:04","date_gmt":"2016-09-29T12:49:04","guid":{"rendered":"https:\/\/blogs.mathworks.com\/headlines\/?p=492"},"modified":"2017-02-27T12:09:39","modified_gmt":"2017-02-27T12:09:39","slug":"mission-accomplished-now-its-time-to-crash","status":"publish","type":"post","link":"https:\/\/blogs.mathworks.com\/headlines\/2016\/09\/29\/mission-accomplished-now-its-time-to-crash\/","title":{"rendered":"Mission accomplished, now it’s time to crash?"},"content":{"rendered":"

Imagine traveling twelve years in pursuit of a comet that is streaking along at 24,600 miles per hour only to crash into the comet. Twelve years. 4.9 billion miles. Untold hours of science and engineering manpower invested in this project and it\u2019s going to crash?<\/p>\n

Yet that is exactly what\u2019s about to happen to the Rosetta comet chaser. That is, as long as everything goes according to plan. And BBC<\/em> will be covering it live<\/a>.<\/p>\n

Tomorrow, the twelve-year-long\u00a0European Space Agency (ESA)<\/a> mission\u2019s probe is going to intentionally crash land, albeit slowly, into the comet it has been trailing.<\/p>\n

The mission <\/span><\/strong><\/h2>\n

ESA\u2019s Rosetta probe was launched on 2 March 2004 in order to rendezvous with comet 67P<\/a>. Rosetta’s prime objective is to help understand the origin and evolution of the Solar System. \u00a0According to ESA, “The comet\u2019s composition reflects the composition of the pre-solar nebula out of which the Sun and the planets of the Solar System formed, more than 4.6 billion years ago. Therefore, an in-depth analysis of comet 67P by Rosetta and its lander will provide essential information to understand how the Solar System formed.”<\/p>\n

<\/a>

Artist\u2019s impression of the Rosetta orbiter deploying the Philae lander to comet 67P\/Churyumov\u2013Gerasimenko. Image credit: ESA\u2013C. Carreau\/ATG medialab<\/p><\/div><\/p>\n

The probe required three earth fly-by\u2019s to gain momentum through gravity assists. In ten years, Rosetta traveled over 6.4 billion kilometers before its rendezvous with 67P.<\/p>\n

Rosetta then dispatched the Philae lander<\/a>, a small robotic probe it had carried to the comet, to the surface. Philae collected data from the comet’s surface and sent it to Rosetta,\u00a0still in orbit around the comet. Rosetta then relayed the information back to scientists on Earth.<\/p>\n

Corrections needed along the way<\/span><\/strong><\/h2>\n

According to ESA, \u201cEnsuring that the spacecraft survives the hazards of travelling through deep space<\/a> for more than ten years is therefore one of the great challenges of the Rosetta mission.\u201d<\/p>\n

After Rosetta awoke from its planned 3-year hibernation designed to conserve power, the team discovered a loss of efficiency in one of the thrusters. They were able to retune the controller to better cope with encountered performance. For this, they used the structured MATLAB and the H-infinity<\/a> in Robust\u00a0Control Toolbox<\/a>, as detailed in this paper, \u201cSystematic design methods of robust and structured controllers for satellites: Application to the refinement of Rosetta\u2019s orbit controller.<\/a>\u201d<\/p>\n

The redesigned 8-state controllers were uploaded to Rosetta. They performed a test maneuver and were able to confirm that better overall performance was achieved. The video below shows the Rosetta orbit path as it deployed the Philae lander in 2014.<\/p>\n