Monday, September 27

‘Perseverance’: ‘Ingenuity’: a helicopter flies over Mars | Science


The robot Perseverance, who has been in Jezero crater for more than a month, he is not alone. He carries with him a small helicopter, christened Ingenuity. Until now it has been hanging under the chassis, folded to take up as little space as possible and hidden by a cover that protects it from dust and rocks raised during landing.

These weeks have been spent testing and calibrating the on-board cameras and mechanisms, a long and complicated task. It has moved about a hundred meters, looking for a flat place to deposit the helicopter, a heliport. You have discarded the shield and disconnected the cables that connect you to the helicopter. Later, Perseverance it has freed the jaws that hold it, allowing it to unfold its four fragile legs and fall to the ground. The vehicle will then reverse and withdraw to a safe distance leaving a clear field for Ingenuity for the sun to charge your batteries. And you will have all the air of Mars at your disposal so that you can take the first flight, that NASA plans to be tomorrow Monday at 3.30 in the morning, US East Coast Time, 9:30 a.m., Spanish Peninsular Time. Here are some answers about this novel way to explore the red planet:

Why a helicopter on Mars?

Ingenuity it’s just a proof of concept, an engineering test. He is not assigned science or exploration assignments. It’s just about proving that it can fly in an environment as hostile and unfamiliar as the Martian atmosphere.

Does it work like a conventional helicopter?

Generally speaking, yes. It uses a double counter-rotating rotor: some blades turn to the right and others to the left so that their movement is compensated and the reaction does not make the entire vehicle spin. That is why it does not need a tail rotor. In that sense, it is more like a drone than a helicopter.

Will it be able to move in the thin atmosphere of Mars?

That is what you are trying to check. The density of the air is barely one hundredth that of the Earth, equivalent to that which exists here at 30,000 meters above sea level. No conventional aircraft reaches them. And much less a helicopter, whose operational ceiling (landing and taking off) is well below 8,000.

In the future, other models may understand more complex orders. ‘Ingenuity’ is just an obedient robot but without a lot of lights.

To get up, the rotors of Ingenuity They have to rotate at a crazy 2,400 revolutions per minute, almost like the blades of a mixer and five times more than in a conventional helicopter. It is such a precarious situation that flights are planned for just before local noon, when it is estimated that the density of the air will have gained a few thousandths and can offer a little more lift.

Why has this design been adopted and not the typical one for quadcopter drones?

For a very simple reason: it did not fit. To rise in the thin Martian air, Ingenuity It needs very large blades, more than a meter in diameter, although its weight (on Mars) does not reach a kilo. They are not foldable and fit very tightly under the belly of Perseverance. A quadcopter had not been able to accommodate there.

Has it been tested on the ground?

As far as possible. In large part, its design is based on mathematical models of what is known of the Martian atmosphere and climatology. The prototype has flown inside a vacuum chamber, but at the cost of lightening its weight to simulate less gravity (on Mars it weighs just over half a kilo, compared to almost two kilos on Earth). For this reason, the tests were carried out only with the propulsion system and the landing gear; the control electronics and batteries remained on the ground, connected to the helicopter by a cable. So tests under real conditions can only take place on Mars.

Are you autonomous?

It has to be. Radio signals take more than ten minutes to reach Mars. Such a delay makes it impossible to control a helicopter – or almost any other type of vehicle – from here.

Now, in that case, autonomous doesn’t mean “smart.” The flights of Ingenuity are planned in advance. Instructions for takeoff, altitude, and route are stored in its memory long before the flight begins. And he should follow them as best as possible. Its decision-making capacity is limited to correcting deviations due, for example, to gusts of wind.

In the future, other models may be able to understand more complex orders, such as “go to that rock avoiding overhangs on the ground” (which it does know how to do -to a certain point- Perseverance). Ingenuity it is just an obedient robot but without many lights.

Do you have a flight computer on board?

Yes. It is a commercial unit, very similar to the one that probably equips the mobile that you carry in your pocket. And there is no excess memory: 2 gigabytes of RAM and 32 of ROM, which corresponds to a low-end phone. Of course, it has a lot more battery and, in addition, a small panel of solar cells to recharge it together with some heaters to protect them from the freezing Martian night.

Perhaps this can give you an idea of ​​the power that your mobile contains: in IngenuityThis processor controls two inertial navigation units, an inclinometer, a laser altimeter, and two television cameras. All, commercial products. If you’re interested, you can get an identical gyro sensor for less than $ 600 and an altimeter for $ 150.

Illustration of 'Ingenuity' work on Mars, with 'Perseverance' in the background.
Illustration of ‘Ingenuity’ work on Mars, with ‘Perseverance’ in the background.AP

It is the first time that an interplanetary ship uses Linux as an operating system. It is programmed in JPL’s own language called “F-prime”, suitable for flight control applications. If you are a computer buff, you probably don’t know it. But it is available for download on the Internet, with sources, tutorials and all the details.

Will it transmit images?

Yes. Directly to Perseverance and from there, to Earth. One of its cameras, in black and white, points vertically downwards. It offers a modest quality, like the VGA of our old computers. The helicopter estimates its speed by comparing the speed at which the terrain features (or its own shadow) are moving in successive images. The other high-definition camera looks straight ahead at an oblique angle. It is the one that promises more spectacular views, with a quality superior to 4K

What autonomy does it have?

Ninety seconds of flight. Its small electric batteries do not give for more. In that time you can reach a maximum ceiling of ten meters and move away at most 300 meters.

The first flight will be limited to a vertical rise up to about three meters, it will turn on itself as if exploring the horizon and will settle again. Nothing spectacular. In subsequent attempts you must go higher and further.

Will you accompany ‘Perseverance’ in his exploration of the crater?

No. Perseverance it has its own set of experiments, and the helicopter, a last-minute stowaway, is not one of them. The flight team has been given about a month for its tests. In total, five flights are planned. Later, Ingenuity you will land more or less where you are now and Perseverance he will go off to do his things, leaving him abandoned, although his equipment is still in perfect condition.

Rafael Clemente He is an industrial engineer and was the founder and first director of the Barcelona Science Museum (now CosmoCaixa). He is the author of ‘A small step to [un] man ‘(Dome Books).

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