Seven questions of humanity bombing Comet would threaten the safety of the Earth

United States launch depth impact, Comet probe, fans are watching.

Data chart: impact of instantaneous and the appearance of impact craters.

4 July, the "deep impact" probe will impact "Temple," the comet. "Deep impact" is the United States on January 12 this year launched the value 3.3 billion. This is unprecedented in human history "bombard" Comet space experiments, but also the actual human exposure for the first time and explore the comet's space activities. At present "bombard" comets have countdown, a reporter with the public interest: an interview with the China Academy of space technology II-HO, senior engineer.

Why choose "Temple" No. 1 hit?

II-HO, "Temple," the Comet was discovered in 1867, a circle round the Sun run 5.5 years. Chose "Temple," is justified: first human beings on it already has more than 100 years of knowledge, more familiar with its orbital characteristics, rotation feature, and currently it is in the middle age period, compared with representative; secondly, it compares the Earth, a spacecraft reaches it near Comet nucleus takes only half a year. It is not a new entry into the solar system's activities-Comet, not continuously to the gas eruption, easier to see the Comet nucleus of external characteristics, to study the internal structure of Comet nuclei; also, it can fly to from the earth near place, impact on Earth, after suitable public observation.

This impact will threaten the safety of the Earth?

II-Ho said that this impact is in the distance Earth 15000 million meters when, although by then will have the equivalent of 4.5 tons of TNT explosive energy, but relative to such a distance, this energy is definitely not a threat to Earth. Contact the "Temple," the comet's size, we can conclude that a parable, "depth of impact" impact "Temple," comet like mosquito rushed into a Boeing 747 aircraft. Impact for impact Comet nucleus of relative velocity is 10.2 km/sec, this will cause the change of the speed of the Comet 0.0001 mm/sec, making the comet's perihelion less 10 meters, the number distant orbit cycle reduction is less than 1 second. In contrast, when a comet in 2024, passed near Jupiter, its perihelion will change to 3400 million meters. In other words, the "Temple," comet impact because of the "depth" of changes compared with the comets through Jupiter can be ignored altogether.

How to ensure that the impact is accurately hit a comet nucleus?

Impact for carrying offers 25 m/s propelling speed of hydrazine propulsion systems, to promote the necessary orbit and attitude control. Navigation system uses hydrazine thrusters will flight path change control to 1 mm/sec accuracy. In addition, once in "deep space 1" detectors tested on automatic navigation software also "help" impact device accurately performed tasks. "Deep impact" detector experts believe that the chance of missing the target is less than 1%.

Why is the main material for impact is copper?

The Comet appears to be a blaze of fireballs, but in reality it is made of frozen water, rocks and gaseous substances condense into its component does not contain copper element. Thus, copper as the main material of the impact with Comet Comet nucleus will not confuse the Comet material composition, scientists can more easily areas don't detect the Comet components.

Impact after the success of what might occur?

About 6 species may occur: (1) according to projections, in Comet nucleus formed a football field in such a big impact craters, 75% of the projected landing to the comet's surface material. This situation illustrates the major nuclear is loose, the original, the material is not affected. (2) If a comet nucleus is made from solid ice substance, impact will form a normal room size crater, 50% of the projected landing to the comet's surface material. This situation illustrates the major nuclear is not the original, is not affected by substance that a comet impact can keep together. (3) impact crater diameter smaller than expected, hang a deep, but produces a small projection cone angle, the Comet material is too loose. (4) If a comet nucleus by some and bubble sandstone similar hard many empty rock, the Comet collision can only put the squeeze on nuclear material. (5) If a comet nucleus is made of high density of the powder-like substances that impact may have been without the "wear star." (6) after the comet impact are washed up.

If the impact is not successful?

NASA had prepared, if there is no impact of the "depth" of the program hit as expected "Temple," the Comet, it will continue to fly, to explore the other six alternative Comet.

The Tempel plan have any significance?

Comet Comet nucleus of a comet is saved within the formation and evolution of important information, for research of comets and the origin and evolution of the solar system are very important. This human intimacy "engagement" Comet, not only for the first time a comet nucleus debris samples to human exploration of the solar system to provide new clues to the origin, but also for the Earth to avoid collision with small celestial bodies provide useful data.