Tuesday , June 28 2022

Travel to the heart of the red planet to listen to your vital signs


"It is good to renew our ability to wonder," said the philosopher, "the interplanetary journey has given us back into childhood."

The phrase, which precedes a traditional edition of Ray Bradbury
Chronicarciana (Minotauro, 1976, preface by Borges), it is very appropriate to wait for the ineffable encounter that will take place today in the vast space. At 17 local time, after traveling for more than six months, the NASA Insight probe will land on the Martian surface to begin a 2-year Earth mission that will allow us to understand the processes that have shaped the rocky planets of the Earth. The Solar System (Mars itself, Venus, Mercury and also the Earth), 4,500 million years ago.

"It's a static, not a rover, like Viking," explains Miguel San Martín, an experienced Argentine engineer who, after directing four successive descendants to our cosmic neighbor, is part of the group of advisers who supervised the design and testing of this mission – So far most of the probes and satellites that have focused on surface exploration and the discovery of whether or not there has ever been life on Mars has nothing to do with it, but exploring the interior: The Red Planet does not have a strong magnetic field like Earth, which is fundamental to protect the atmosphere of the solar wind. "

"Why did you lose him?" It is a mystery, on the other hand, Earth is a planet so active that the evidence of its formation is already contaminated, while where things are not so dynamic, we can better analyze them. It's like studying Earth's past on Mars and understanding why they have differentiated, "he adds.

The planet of the solar system was made up of a disk of stones, ice and debris that orbits around our inner star. Mars is by far the most studied after Earth, but astronomers know virtually nothing inside it. So far, the multiple missions that followed, in 1971, NASA sent its first dazzling, Mariner 9 (which returned 7300 images of its surface and two months, Phobos and Deimos) their storms of dust and life signs sought (unsuccessful).

With the planned 2016 scheduled launch, which should have been postponed due to a vacuum leak in one landing gear, Insight (which corresponds to "Internal Exploration Using Seismic, Geodesy, and Thermal Transport") has three main tools .

A seismograph will hear minor earth vibrations, fractions of a nanometer (billions of meter), due to seismic waves traveling on the planet and allowing a 3D image of its interior.

A drill will drill about five meters of Martian crust to analyze the heat from the deep and give an idea of ​​its work. Another experiment will try to determine precisely how much the Martian pole is "shifted" while orbiting the Sun. These observations will provide detailed information about the magnitude of the iron-rich nucleus of Mars and will help to determine whether it is liquid and what other elements contain.

"The most interesting thing about these missions is that they allow us to understand our world more," says Diego Bagú, an astronomer at La Plata National University and director of the Planetarium in that city. "This is the first time we can drill the Martian soil and find out if it has seismic movements and what is the heat flow, although it does not have a fractured crust like the Earth and therefore there is no movement tectonic plates, there may be geological activity due to the impact of meteorites, for example, studying how seismic waves propagate will allow us to know what the interior of the planet is. "

Seven minutes of terror

After arriving at the destination, Insight will undertake one of the essential milestones of the entire mission: to carry out its solar panels. Thus, with a height of about one meter and a weight of 360 kilograms, it will reach six meters in length (equivalent to half to two-thirds of the length of a collective). With these "wings" you can capture the sun's rays (which at this distance shines 50% less than on Earth) to give energy to the instruments.

Unlike other probes, you will need to use an articulated robotic arm to slowly place instruments on the surface, which will take about three months.

But to do this, you must first overcome the entry, lowering and landing sequence (EDL), an operation that makes adrenaline flow in the control center, because, although it has been repeated, it is absolutely guaranteed.

"Although Insight is an almost identical copy of Phoenix in 2007 and we know design is solid, there may always be a mistake in the workforce," argues San Martin, a veteran of these laws. but sometimes something happens to us. The Mars atmosphere varies depending on the seasons, as is the case here. The pressure may increase or decrease. When it is less dense, landing becomes more complicated. And there may be storms of dust. For this reason, a team from NASA's Jet Propulsion Laboratory (JPL) followed the approach trying to make an estimate of the crucial moment, because theoretically the parameters of the descent system could be modified to make it more robust. of opportunity, for example, we had an upset atmosphere and made small adjustments to maximize chances of success, "he adds.

In fact, at the last minute yesterday, the Insight team decided to run the last trajectory correction to move the landing point about 16 km.

In addition, there are other obstacles. For the ship to descend correctly, it must enter at a correct angle: if it is too steep, it could be incinerated; if, on the contrary, it is too open, it will reflect the atmosphere and will remain in space.

"In about six and a half minutes, the module will go from a speed of nearly 20,000 km / h to eight," says Bagú, "and must go through a" window "of about 10 km of 20 each , a smaller city area ".

Although the Mars atmosphere is 100 times thinner than terrestrial, at the entrance the module must be protected from friction with a heat shield prepared to withstand over 1300 ° C Then it will deposit the parachute and about 40 seconds before coming in contact with the ground, will break out of both, extend the legs and lightning 12, to lower the speed of descent and repel an area known as Elysium Planitia, chosen because it is dusty and flat and relatively free of rocks.

Marco Polo on Mars

Another innovation of this mission is that the probe travels with two minisites (or
CubeSat) of the approximate size of a Marco-A and Marco-B shoe box (which the technicians of the mission call Marco / Polo), which will be responsible for providing ground-based communications services as the module continues to run after the landing stage and are proof of the concept of being used in exploring the interplanetary space.

"In 1999, a ship told us" come and see each other on the surface, "and never heard of it," says San Martin, "so that NASA has stipulated that each descent must have telemetry so that, if it fails, it did not work well and resolved it on later trips. We usually have spacecraft that are in orbit and do
relay. Insight wears these two
CubeSat which separated after the launch and flies in parallel, but from behind. During the landing, these small satellites will receive the signal and transmit it to Terra. And the good stuff is that if it works, we will not have to worry that there is always a "live" satellite on Mars in the right geometry for landing. "

Contrary to what can be said, the international success rate in decks is not high, around 40%. "Sometimes it seems that these things are already common," concludes Bagu, "but in reality it is an extraordinary challenge."

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