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Another near miss – Skywatching



This autumn, we will have a close encounter with the asteroid 2006 QV89

At its closest, it is estimated to be about 6.7 million kilometers away Earth and moon)

Taking into account possible errors in the orbit calculations, the chance it would come closer, and actually hit us, is around 1 in 7,300. mass roughly 80,000 tonnes. This is far smaller than the one that sealed the fate of the dinosaurs, 64 million years ago, but it is still not to be taken lightly

If it was moving at, say, 20 km / sec, its impact would liberate about the same amount of energy as a four megaton nuclear bomb. If it misses us this time, as is most likely, it will swoop by us again in 2032, 2045 and 2062.

The moon is covered

It is not yet possible to predict exactly how close these encounters will be. with craters formed by impacts like these. We can find similar scars on Earth, for example, on the Canadian Shield and in Arizona, although weather erosion and plate tectonics remove them, which does not happen on the airless, tectonically-quiet moon

On July 30, 1

908 something fairly large plowed into the atmosphere over the Tunguska River in Siberia and exploded. The blast flattened 2,000 square kilometers of trees.

The object is believed to have been 50-100 meters across, depending on what it was made of.

As our ways of life become more interconnected and interdependent, our vulnerability to natural disasters increases. The historical record shows that over the human time-scales, asteroid impacts are very rare, but their consequences make it worth doing our best to avoid them

There are three facets to this

First we need to detect and identify asteroids

The final step is to estimate the threat potential of each close encounter, preferably in sufficient time to do something about it

The final step

Work on the first step is well advanced, and there are purpose-built instruments sweeping the sky for asteroids, especially those with orbits that cross or get close to Earth's. potential in time to do something to mitigate the situation is more difficult. At the moment, we usually see the asteroids as they move in for their close approaches, which leaves us with little time to do anything

We need predictions years in advance. With the asteroid orbits being constantly perturbed by the gravitational attractions of the giant planets, especially Jupiter and Saturn, this is proving a challenge

Work on this continues

Mitigation is difficult.

Instead of being hit by one object at one location, we would instead be hit by multiple objects, all over the earth. The idea is to identify the threats long enough for us to send a space mission to install a low-thrust rocket engine on the asteroid's surface

It could use asteroid's material as fuel. The efficiency and thrust would be low, but the engine would run for years, gradually nudging the asteroid into a different orbit.

Of course, to make this solution feasible we will need a launcher big enough to get to the asteroid in a reasonable time

We are nowhere near there yet.

  • At 8:54 am June 21, the sun reaches its northernmost point in its annual travels – the summer solstice
  • Jupiter, shining brilliantly, rises around 10 pm
  • Saturn rises at 11 pm
  • The moon will reach Last Quarter on the 25th .

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