Notes on May 5, 2022

High-speed shuttle system between the US Air Force and the Moon

Dawn? Microvision aerospace? 2022-05-05 06:00

The US Air Force recently established the 19 Space Defense Squadron in Virginia. The new army will focus on the spatial domain perception of the earth-moon space, build relevant sensors and systems, improve space security and strengthen defense capabilities. As more and more countries strengthen their capabilities in space activities between the Earth and the Moon, the space forces will strengthen their response to possible threats in space between the Earth and the Moon.

In 20 19, the us military formally established the space air force as the sixth service after the army, navy, air force, marine corps and coast guard.

According to the plan, the Space Air Force will launch a new space situational awareness experiment on the Earth and the Moon this summer to observe and track objects in this area. In the long run, the agency will also establish a high-speed round-trip system between the earth and the moon, and use small satellites to implement space situational awareness and military logistics.

Original: Jesse Ames Parker

Translation: Mou Xinxiang? Zhou Xueyun

Although the Perseid meteor shower in August this year is the most eye-catching, the Aquarius η meteor shower that comes from late April to mid-May every year can also bring a long list of spectacular meteors.

The peak of this year's η meteor shower in Aquarius appears on May 6th, and the best observation time is from the evening of May 6th to the early morning of May 7th.

According to Bill Cook, director of the Meteor Environment Office of NASA, the theoretical peak flow of meteors this year can reach 50 meteors per hour. The brightness of meteor shower is not very bright, so the darker the sky, the more meteors you can see. Try to find a place far away from the city lights so as not to interfere with observation.

Cook also said: "The η meteor shower in Aquarius is not the kind of celestial phenomenon that can be seen just after sunset, because the radiation point has not yet risen." So it is more appropriate to go out and observe around 2 am. From then on, the occurrence rate of meteors will continue to increase until dawn.

And fortunately, today's moon phase is the moth eyebrow moon. The moon sets at night 12 and rises at 9: 30 tomorrow morning, which will not affect the observation.

These meteors seem to come from a bright star in Aquarius-η (the point where meteors originate is called radiation point). For people in middle and high latitudes, the position of the radiation point in the sky will not be very high, so if you are in high latitudes, you need to look above the southern horizon at night, and the sky should be clear at that time, so as to get better observation results.

Observers near the equator will have the best observation experience, but the influence of light pollution on observation is far more significant than latitude. Even in Mohe, far north, you can see more meteors than in big cities with serious light pollution such as Shanghai or Guangzhou. Astronomical observers in the southern hemisphere will have the best view and can see the radiation points in the north. As the summer solstice approaches in the northern hemisphere, the nights in the southern hemisphere become longer and longer. Observers in the northern hemisphere will see that the radiation point is located in the southeast and will be lower. ?

How to observe

Although all the η meteors in Aquarius seem to emanate from the radiant point, you should not look directly at the radiant point and wait for the meteor-you may miss the bright long meteor across the sky.

Cook said that the best way to watch meteors is to lie flat on the ground and look up. In this way, you can see a wider sky without getting tired to your neck.

Where did the η meteor shower in Aquarius come from?

Meteor shower is the light emitted by burning dust particles in the atmosphere. When a comet crosses the inner solar system, it will leave dust in its orbit. Meteor showers occur when the earth revolves around the sun and passes through the dust clouds left by comets. This is why meteor showers always occur on specific dates and seem to originate at specific points in the sky. The η meteor shower in Aquarius is related to Halley's comet, but their dust cloud orbits parted ways with Halley's comet a long time ago.

"All meteors will deviate from the original orbit of comets," Cook said. "When they leave the comet, their speed will change slightly, which will change the orbit slightly ... Besides, other factors will also affect the orbit, such as radiation pressure and even interplanetary gas."

The meteor shower η in Aquarius does not have as many meteors per hour as the more famous Perseid meteor shower in August, but they are as bright as Perseid. Cook said that meteoroids (dust particles) are about one millimeter in diameter and they can't hit the ground. These tiny space debris are too small, but they are fast, and the heat generated by friction with the atmosphere will burn themselves out.

Meteorites, that is, space stones that reach the ground, are often massive asteroids, and their speed is usually slow relative to the earth (taking the earth as the reference system). Cook said: "They often come from behind, just like chasing us."