Why have countries recently piled up to Mars? A text on the Mars launch window.

The recent Mars launch was a bit full. The UAE’s “hope” is the first to start, China follows the “question of heaven” and the United States keeps “perseverance” until the end of July. Had it not been for the delay, ESA and Russia’s “Rosalind Franklin” would have been buzzing. Why do you have to pile up on Mars? It turned out that late July to early August 2020 was the launch window for this round of Mars, and missed that time, as ESA did, after 26 months.

The Mars launch window is related to the relative position of Mars, the Earth and the Sun. To grasp the “mystery of these celestial bodies” can we find the best route to save time and fuel.

ground fire recently.

As we all know, the solar system now has eight planets, from the inside out, the Earth row three, Mars row four, is a small block than the earth’s red neighbor.

Based on the centripetal and gravitational formulas, we can conclude that the outer circle of the planet’s angular velocity is smaller. As a result, Mars orbits the sun more slowly than Earth, with a rotation period of about 687 Earth days. Earth is sometimes catching up with Mars, and sometimes away from Mars, meeting about once every 26 months. The fire was 56 million kilometers from the nearest hour and reached a maximum of 400 million kilometers. From earth’s perspective, Mars will briefly “reverse” during the period of Earth’s “overtaking” Mars.

Because of this, Mars in China’s ancient name “glow”: the color of the screen like fire, the whereabouts of the confusing. Interstitial, from the retrograde/reverse-turned-time period, Mars will visually present a brief stay. If the location of the stay is just the heart of the house (Scorpio), is the ancients think that the murderous star “the screen bewilderment.”

The words are true. To find out the Mars launch window, our first intuitive consideration is the closest distance between Mars and Earth, the “closest to the earth fire.”

Every 26 months or so, the Earth travels between the sun and Mars, in a straight line called the “Mars Day.” During this time, whenever the sun has just set from the west, Mars rises from the east. And every time the sun rises from the east, Mars falls right in the west, so it’s visible all night. And mars is bright in the night sky and is the best chance to see it.

If the orbit of the planet is a positive circle, it is clear that the earth’s fire is the closest to the earth’s fire at three o’clock. But in reality, the orbits of Earth and Mars are elliptical, and the orbits of Mars are slightly flatr than those of Earth. As a result, the “Mars Day” and the earth’s fire do not necessarily overlap recently.

Why have countries recently piled up to Mars? A text on the Mars launch window.

“Ground Fire Recently” and “Mars Day” Source: NASA

As can be seen from the image above, a Mars burst occurred on May 22, 2016, but May 30 thinly the closest to a ground fire.

About every 15 to 17 years, the Martian sunburst occurs near the Mars point of origin, known as the “Mars Rush.” At this point, the ground fire is also particularly close. Since the Earth orbit and the Mars orbit are not entirely on the same plane, and are constantly fine-tuned by the gravitational influence of other celestial bodies, the distance of the Earth fire at the “Mars Great Strike” is not fixed.

Why have countries recently piled up to Mars? A text on the Mars launch window.

The Mars orbit and the Earth’s orbit are not in a plane.

The last two Mars storms took place in July 2018 and August 2003. In 2003, the Martian storm, the distance of the earth fire reduced to about 55.76 million kilometers, the shortest in nearly 60,000 years!

Fuel-efficient track.

So should we launch a Mars rover at the time of the fire? Not really. In addition to time costs, scientists and engineers also have to consider important fuel costs.

The Mars rover does not pounce in a straight line on Mars, and under the influence of the Earth’s gravity and launch force, it enters space with a curve, ignites into an orbit, then stallings into inertial sliding, waiting for Mars to arrive before igniting.

There can be several route slots in between, but one of the most fuel-efficient is the Homan Transfer Track. In this way, the aircraft can turn off the longest distance of the engine to glide.

As shown in the figure below, Homan’s transfer orbit is an elliptical orbit with the sun as one of its focal points, intersecting both low orbits (Earth orbits) and high orbits (Mars orbits).

The earth moves to the nearpoint of Homan’s transfer orbit, where the vehicle initiates a launch and accelerates its departure from low orbit, while when Mars moves to the far point of Homan’s transfer orbit, the vehicle initiates the transfer and accelerates into high orbit.

Why have countries recently piled up to Mars? A text on the Mars launch window.

Homan shifts the track.

Of course, the spacecraft must be launched within a precise window of time before it can meet Mars at the far point of Homan’s transfer orbit and be captured by the Martian gravity. It’s like a wide spread of passing, requiring a teammate’s running position. The right chance to play is also every 26 months.

The next red planet will arrive at Homan’s distant day is February 11, 2021. In other words, the expedition warriors, who launched this expedition, will have to drift for nearly seven months.