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Time-warp: Why June 30 will be a bit longer

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Washington: Strictly speaking, a day lasts 86,400 seconds. On June 30, the day will officially be a bit longer than usual because an extra second or “leap” second will be added and NASA has an explanation for this.

“The Earth’s rotation is gradually slowing down a bit, so leap seconds are a way to account for that,” said Daniel MacMillan, NASA’s Goddard Space Flight Center in Greenbelt, Maryland.

This is the case according to the time standard that people use in their daily lives – Coordinated Universal Time or UTC.

UTC is “atomic time” — the duration of one second is based on extremely predictable electromagnetic transitions in atoms of cesium.

These transitions are so reliable that the cesium clock is accurate to one second in 1,400,000 years.

However, the mean solar day — the average length of a day, based on how long it takes the Earth to rotate — is about 86,400.002 seconds long.

“That is because the Earth’s rotation is gradually slowing down a bit owing to a kind of braking force caused by the gravitational tug of war between the Earth, the Moon and the Sun,” the US space agency said in a statement.

Scientists estimate that the mean solar day has not been 86,400 seconds long since the year 1820 or so.

This difference of two milliseconds, or two thousandths of a second — far less than the blink of an eye — hardly seems noticeable at first.

But if this small discrepancy were repeated every day for an entire year, it would add up to almost a second.

Typically, a leap second is inserted either on June 30 or December 31.

Normally, the clock would move from 23:59:59 to 00:00:00 the next day. But with the leap second on June 30, UTC will move from 23:59:59 to 23:59:60, and then to 00:00:00 on July 1.

In practice, many systems are instead turned off for one second.

Previous leap seconds have created challenges for some computer systems and generated some calls to abandon them altogether.

“In the short term, leap seconds are not as predictable as everyone would like,” said Chopo Ma, geophysicist at Goddard.

“The modelling of the Earth predicts that more and more leap seconds will be called for in the long-term but we cannot say that one will be needed every year,” Ma said.

From 1972, when leap seconds were first implemented, through 1999, leap seconds were added at a rate averaging close to one per year.

Since then, leap seconds have become less frequent.

This June’s leap second will be only the fourth to be added since 2000.

(IANS)

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NASA Curiosity Rover Gets its Drilling Groove Back on Mars

It lets Curiosity drill using the force of its robotic arm, a little more like the way a human would drill into a wall at home

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NASA Curiosity Rover Gets its Drilling Groove Back on Mars
NASA Curiosity Rover Gets its Drilling Groove Back on Mars. Pixabay

After a mechanical problem took NASA Mars rover Curiosity’s drill offline in December 2016, it has now successfully tested a new drilling method on the Red Planet, making a 50-millimetre deep hole in a target called “Duluth”, NASA has said.

Engineers working with the Curiosity Mars rover have been hard at work testing a new way for the rover to drill rocks and extract powder from them.

On May 20, that effort produced the first drilled sample on Mars in more than a year, NASA said in a statement on Wednesday.

The new technique, called Feed Extended Drilling, keeps the drill’s bit extended out past two stabiliser posts that were originally used to steady the drill against Martian rocks.

It lets Curiosity drill using the force of its robotic arm, a little more like the way a human would drill into a wall at home.

“The team used tremendous ingenuity to devise a new drilling technique and implement it on another planet,” said Curiosity Deputy Project Manager Steve Lee of NASA’s Jet Propulsion Laboratory in Pasadena, California.

Representational image.
Representational image. Pixabay

“Those are two vital inches of innovation from 60 million miles away. We’re thrilled that the result was so successful,” Lee said.

Drilling is a vitally important part of Curiosity’s capabilities to study Mars.

Inside the rover are two laboratories that are able to conduct chemical and mineralogical analyses of rock and soil samples.

The samples are acquired from Gale Crater, which the rover has been exploring since 2012.

“We’ve been developing this new drilling technique for over a year, but our job isn’t done once a sample has been collected on Mars,” said JPL’s Tom Green, a systems engineer who helped develop and test Curiosity’s new drilling method.

Also Read: NASA Probe to ‘Touch’ the Sun Will Carry 1.1 mn Names

“With each new test, we closely examine the data to look for improvements we can make and then head back to our test bed to iterate on the process.”

There’s also the next step to work on — delivering the rock sample from the drill bit to the two laboratories inside the rover.

As soon as this Friday, the Curiosity team will test a new process for delivering samples into the rover’s laboratories, NASA said. (IANS)

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