Its orbit is in a plane that is an angle of 18 degrees to the plane of the ecliptic and it spends about 98% all of its life on the southern side of the ecliptic. Only when the comet approaches the Sun does it loop over onto the northern side of the ecliptic. The orbit of comet 46P/Wirtanen around perihelion, in the Earth's co-orbital reference frame, as seen from above (top panel) and in the ecliptic plane (bottom panel). The black circle denotes the comet's position at perihelion (Dec 12, 2018) and the open circles show positions at 30-day intervals.
Comet Orbit Simulation
BEIJING - China will discuss building a defense system against near-Earth asteroids, a senior space agency official said Saturday, as the country steps up its longer-term space ambitions.
Zhang Kejian, head of the China National Space Administration, did not provide further detail in his opening remarks at a ceremony for China's Space Day in the eastern city of Nanjing.
China has made space exploration a top priority in recent years, aiming to establish a program operating thousands of space flights a year and carrying tens of thousands of tons of cargo and passengers by 2045.
The European Space Agency last year signed a deal worth 129 million euros ($156 million) to build a spacecraft for a joint project with NASA examining how to deflect an asteroid heading for Earth.
China is pushing forward a mission where one space probe will land on a near-Earth asteroid to collect samples, fly back toward Earth to release a capsule containing the samples, and then orbit another comet, the official Xinhua News Agency reported, citing Ye Peijian, an academic at the Chinese Academy of Sciences.
The mission could take about a decade to complete, Ye said. China and Russia signed a memorandum of understanding last month to set up an international lunar research station.