Mars lander on course for Monday's touchdown – Astronomy Now



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HISTORY WRITTEN FOR CBS NEWS AND USED WITH PERMISSION

The InSight spacecraft approaches Mars in the concept of this artist. Credit: NASA / JPL-Caltech

After a six-month journey from Earth, NASA's InSight Mars module will hit Monday's Martian atmosphere to begin a six-and-a-half-mile descent to the surface. , kicking off a billion-dollar mission to investigate the hidden interior of the red planet.

"The goal of InSight is nothing less than to better understand the birth of the Earth, the birth of the planet we live in, and we will do that by going to Mars," said lead researcher Bruce Banerdt.

On Earth, tectonic plates and the constantly agitated mantle have altered the deep interior of the planet, obscuring its history and evolution. But Mars is a smaller planet and much less active than the Earth, maintaining the "fingerprints" of these previous processes.

"By mapping these boundaries, these various different sections of the interior of the planet, we can better understand how the planet formed and how our planet came to be where we can actually live and play and have fun. So, let's go to Mars.

A final correction maneuver was planned on Sunday afternoon to lightly adjust the InSight trajectory and ensure a landing on the target on a broad plain known as the Elysium Planitia.

But as with all landings on Mars, InSight's fully automated descent to 90 million miles away will occur far beyond any direct control – or help – of Earth's engineers. In fact, it will take 8.1 minutes for the radio signals to arrive at the Jet Propulsion Laboratory in Pasadena, Calif., Where eager scientists and engineers will wait to find out if the spacecraft has managed to hit the surface successfully.

"We've done everything we can, we've done everything we can to ensure success," said Tom Hoffman, InSight project manager. "But you never know what's going to happen."

Nestled inside a flying saucer-shaped aeroshell and protected by a state-of-the-art heat shield, InSight will begin its dive around 1947 GMT Monday, supporting braking forces up to 7.4 times the force of Earth's gravity . decelerates and heats around 2,700 degrees Fahrenheit.

Four minutes later, at an altitude of 7.5 miles and now moving to a still supersonic 928 mph, a 39-foot wide parachute will expand, inflating with a force of 15,000 pounds per square foot to delay the aircraft to a much more manageable 295 mph or more.

The heat shield no longer needed will be discarded by exposing the bottom of the grounding module to the environment and, 10 seconds later, the three landing legs will unfold and lock in place.

A few seconds later, about one minute before landing, the InSight descending radar will be activated by measuring the altitude and descent rate of the spacecraft and feeding it into the probe landing computer.

Finally, less than a mile above the surface and descending to about 134 mph, InSight will be released from the aeroshell and parachute to fall freely on its own.

A second later, 12 small rocket engines will fire, each generating about 68 pounds of thrust while pulsating in and out 10 times per second, first by moving the spacecraft to one side to avoid falling parachutes and aeroshell.

Nulling its horizontal speed and decelerating to around 5 mph, InSight is expected to land Elysium Planitia around 1954 GMT, about 2 pm local time on Mars.

Artistic illustration of the spaceship InSight on Mars. Credit: NASA / JPL-Caltech

Fifteen minutes later, after waiting for the dust from the propellers to return to the ground, InSight's two circular solar panels will unfold to begin recharging the batteries of the spacecraft. The arrays would generate about 1,300 watts of energy on Earth, but on Mars, with its relatively dusty atmosphere, they would only manage 300 to 600 or more.

The entry, descent, and landing sequence was programmed to coincide with NASA's Mars Reconnaissance Orbiter flight schedule, scheduled to record Insight's radio-transmitted UHF telemetry during surface dive. This data will be stored on board the orbiter and retransmitted back to Earth about three hours after landing.

The real-time data will be transmitted from two experimental ships known as Mars Cube One – MarCO-A and B, which were launched with InSight in May. They are the first CubeSats to make an interplanetary trip and are the main way flight controllers can follow the descent of InSight.

Unlike the much more sophisticated Mars Reconnaissance Orbiter, the MarCO spacecraft, which cost about $ 18.5 million to build, has radio equipment that can receive UHF signals from InSight and immediately relay them back to Earth at frequencies of band X.

"If it works, the two MarCO spacecrafts will transmit the data for entry, descent and landing of InSight almost as it is happening, which will be very cool for both the MarCO team and the InSight team to find out what's going on with the rig as soon as possible, "said Anne Marinan, Mars Cube One project manager at JPL.

Regardless, InSight – the convolute acronym for Indoor Exploration using Seismic Investigations, Geodesy, and Heat Transport – will send a computer-generated "tone" directly to Earth seven minutes after landing to indicate its general health.

But the detailed telemetry will not arrive until the Mars Reconnaissance Orbiter transmits its stored data three hours after the landing. Confirmation that normally deployed solar arrays will be relayed by NASA's Mars Odyssey spacecraft about five-and-a-half hours after landing.

"I'm completely excited and completely nervous at the same time, because everything we've done to this day makes us feel comfortable landing on Mars," Hoffman said. "But everything has to go perfectly. Mars could always throw us a curved ball.

But if it works, InSight will pay with the first detailed look at the interior of Mars, providing long-sought answers to questions about how the planets were assembled when the solar system joined a debris cloud 4.5 billion years ago .

InSight is equipped with two primary instruments: Seismometer Interior Structure, supplied by the French space agency CNES, and the Heat Heat and Physical Properties Probe – HP3 – supplied by the German Aerospace Agency (DLR). The two instruments cost the European space agencies about $ 180 million.

To function properly, both instruments must be lowered to the surface of Mars with a robotic arm and both require a relatively flat, rock-free area near the base of the probe. The landing site Elysium Planitia was chosen because it provides just that.

"As landing engineers, we really like this landing site," said Rob Grover, InSight entry, descent and landing manager at Elysium Planitia. "It's flat, it does not have many rocks, it's a very safe place to land."

Engineers will use cameras on the probe to accurately examine the area around the spacecraft to ensure the instruments are placed in the best possible location.

But it will not be fast.

"It's a slow and relaxed mission compared to many things we've done before," Banerdt said. "It will probably take two or three months at least to lower our instruments. We have to survey the area in front of our spacecraft, make sure not to put the instruments on a rock or a hole or something.

"And then we're very, very careful about how we put the instruments down. … So it will probably take a month or two for the seismograph to drop and another month for the heat flow probe to go down and penetrate the surface. We're probably looking at the beginning of next spring when we're really going to start bringing back that kind of Mars science. "

The seismograph is able to detect motions smaller than the width of a hydrogen atom, to record the weak vibrations of remote marsquakes, meteor strikes, and even the slight tidal pulls caused by the passage of the two small moons of Mars, Phobos and Deimos, to map the internal structure of the planet.

InSight spacecraft diagram. Credit: NASA / JPL-Caltech

The automatic pounding temperature probe will reach a depth of up to 15 feet to measure temperature changes and, by extrapolation, determine how much heat is flowing out of the deep core below.

In a third investigation, precise analysis of the probe's radio signals as Mars rotates will allow scientists to determine the exact orientation of their polar axis as it slowly swings, or precesses, due to the nucleus "spinning around" deep inside . From these data, they expect to determine the size, density, and composition of the nucleus.

The goal is to help scientists understand how the terrestrial planets of the solar system – Mercury, Venus, Earth and Mars – have formed and how they evolved into the different worlds we see today.

"Venus is hot enough to melt lead," Banerdt told reporters last week. "Mercury has a surface burned by the sun. Mars is very cold today, but Earth is a good place to take a vacation. We would love to know why a planet goes to one side and another to another. These answers are in the details of the structure that formed early in the history of the planet. "

On Earth, this structure was "scrambled by both plate tectonics and convection of the mantle," he said. "And so the evidence of the early lawsuits has been eliminated."

But on Mars, a planet half the size of Earth, where tectonic plates and a moving mantle are not working, evidence of the planet's early history is still preserved deep inside.

"These processes that do this all happen in the first tens of millions of years," Banerdt said. "We would like to be able to understand what happened and the clues to this are in the structure of the planet that sets in those early years."

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