June 26, 2022
Meet the mission that will deflect an asteroid to defend our planet

Meet the mission that will deflect an asteroid to defend our planet

this week US space agency NASA is launching one of its most important and ambitious missions yet. It’s called Dart (Double Asteroid Redirection Test), and it will send a small spacecraft to crash Dimorphos, the “moon” of the asteroid Didymus, trying to change your course.

The test will assess the feasibility of solving a question that has been asked by many astronomers or not – at some point: if an asteroid came our way, We can blow it up? If not, can we convert it?

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If memories of the past are playing in your head from the movie disaster, with Bruce Willis, above all, sorry to putThisSong From the Aerosmith set in mind. Second, let’s take it simple: The premise of the film is the detonation of an asteroid that threatens life on Earth. In real life, the world’s space agencies have even considered this possibility, but now they all agree that shifting it to a safer orbit would be the best course of action.

To give scientific meaning to the expression “a slap will do”, NASA wants to send a spacecraft to hit an asteroid in space with all its might (Image: NASA/Publishing)

This is because, if we did blow up an asteroid, we’re not sure what might happen. Instead of one big rock, we could end up with hundreds of smaller ones, but they’re still big enough to destroy cities. Instead of a single impact, say, in the central Pacific, which would threaten most coastal areas, we might end up facing the possibility of multiple impacts in, say, several cities in the hemisphere.

knowing the goal

The DART target is a binary system consisting of two asteroids: the larger, DidymusIts length is about 780 meters while its “moon”, Dimorphos160 meters. The DART mission will target this smaller rock, hoping that a direct impact on it will be enough for Earth observation satellites to analyze potential changes in its path.

“This will show us the feasibility of a technology called a ‘kinetic collider’ to alter the asteroid’s orbit and determine if this is a viable option, at least on smaller asteroids, which are among the most at risk of collision. [com a Terra]Lindley Johnson, NASA’s Planetary Defense Officer, said earlier this year to Space.com.

What Johnson says is true: When we think of the “asteroid impact,” pop culture has forced us to think of the catastrophic event of a space rock across several kilometers, through which a single shock would wipe humanity out of existence.

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Not that this is impossible: the valbulid that created Chicxulub crater and caused the extinction of the dinosaurs when it crashed into what is now Mexico’s Yucatan Peninsula, no more than 10 kilometers away, and see what he did. But today, things much smaller than these are already on our radar and prediction strategies can be implemented quickly.

However, smaller asteroids can be a problem: Not all of our technology can detect them from afar, and only see the problem when you get close…well, that doesn’t give us a window of time conducive to a response.

There is no danger of Didymus and his companion colliding with Earth, but if there is a danger, it will not destroy humanity. However, it will be able to cause significant damage: it is estimated that a 150-meter asteroid, the size of Demorphos, could destroy the US state in the event of a direct undiluted impact.

In other words: If we get it wrong, nothing will change with the asteroid that will not collide with us. If we get it right, it will be far from us, with the trade-off that we will have a proven defense against future influences.

Test techniques

DART also serves as a testing platform for new technologies, two of which could significantly impact future exploration missions. It’s an ionic fuel based on Xenon and a new, more flexible type of solar panel (ROSA, Roll-Out Solar Array).

One ion impulse Ionizes a neutral gas by extracting some electrons from its atoms, creating a “cloud” of positive ions, which are accelerated by an electric field and fling them into space. Under the law of action and reaction, this generates a thrust with the same intensity and in the opposite direction in the spacecraft.

This thrust is imperceptible at first, but since there is no friction in space, the acceleration builds up as millions of ions exit, making it possible to accelerate a spacecraft to great speeds using a portion of the fuel that would be required in conventional chemical fuels. . It’s the old saying “from grain to grain, chicken fills the crop” applied in the space.

Solar panels similar to iROSA newly installed On the International Space Station over several tracks in space. But conventional cells are interspersed with new solar cells, developed by the Applied Physics Laboratory (APL) at Johns Hopkins University, which produce three times more energy than conventional panels.

DART will travel 1 year before the effect

The DART mission will launch at 3:21 a.m. Wednesday (24) Brasilia time, and depart from US Space Force Base Vandenberg, California, aboard a rocket. Falcon 9 Give SpaceX. After reaching space, the long journey to the goal begins: the impact is estimated to occur between September 26 and October 1, 2022, when the asteroids will be at a distance of 11 million km from Earth.

If all goes according to plan, DART should collide with Dimorphos at 24,000 km/h. The spacecraft will be destroyed on impact, but due to the small size (“cube” of about 130 cm on one side, excluding the antennas and solar panels) and weight (550 kg upon impact) of the asteroid, the impact will be more like a “snap” rather than a Roberto Carlos kick. However, the slightest thrust is enough, over time, to significantly affect the asteroid’s path.

DART will not travel alone: ​​a second spacecraft, operated by the Italian Space Agency (ISA), called “Italian CubeSAT Light Asteroid Imaging System“,” or “LICIACube”, for close ones, will be in the immediate vicinity, in order to record images of the result of the impact.

We are not in danger yet

Space agencies actively monitor so-called PHAs (potentially hazardous asteroids). As defined by the International Astronomical Union (IAU), all objects up to 1.3 astronomical units (one astronomical unit, or AU equivalent to about 150 million km) whose orbit passes Earth’s orbit at a distance of less than 7.5 million km (0.05 AU) and which It has the potential to cause significant regional damage in the event of a collision, which occurs with asteroids over 140 meters in height.

But we can rest assured. At least among the known asteroids, no one is in danger of colliding with our planet in the next 100 years.

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