PpigScience: Apollo

A citizen science project has identified the largest known prime number, made up of more than 23 million digits(Credit: mmaxer/Depositphotos)

Numbers might not sound like they need discovering, but a crowd-sourced project has now identified the largest prime number known. The number was discovered by the Great Internet Mersenne Prime Search (GIMPS), an online project of citizen scientists who spot and verify prime numbers using specialty software. It's been dubbed M77232917 – and if you're wondering why it needs a codename, well, we'd be here all day typing out the 23 million digits that make it up.

If it's been a while since high school math class, here's a quick refresher: Prime numbers are those that are only divisible by 1 and themselves. Small primes are fairly easy to identify through trial and error – 6 can be divided by 2 and 3, so it isn't prime, but 7 is – but as you look at larger and larger numbers it gets less obvious. It might take you a while to figure out, for example, that 11,319,033 isn't prime because it can be divided by 213 and 53,141. Finding the really large primes is a task best left up to computers running software like GIMPS.
As the MP in its acronym suggests, GIMPS is specifically searching for a rare class of prime numbers called Mersenne Primes. These are numbers that are one less than a power of 2, expressed as Mn = 2n - 1. That means that the newcomer M77232917 is calculated through a chain of 77,232,917 twos, and then subtracting 1. It's only the 50th known Mersenne Prime ever identified, and it's made up of 23,249,425 digits.

It was discovered on December 26, 2017 by electrical engineer Jonathan Pace, and it initially took six days of non-stop number crunching to show that it was indeed a prime number. Pace was using a consumer-level PC running an Intel i5-6600 processor, and after it was identified it was then independently verified by other users, with a range of other programs and hardware setups.

So what can we use this new number for? Not much, really. It mostly seems to be a curiosity for amateur mathematicians hoping for "the thrill of possibly discovering a record-setting, rare, and historic new Mersenne Prime." But then again, we didn't really have much use for prime numbers at all until relatively recently, and the Mersenne project points out that now they're the basis of cryptography algorithms.
If M77232917 isn't specific enough for you, you can download the numberitself as a plain text file – a 23 MB plain text file, we might add. Grab a coffee, because you'll be scrolling through it for a while.

Source: GIMPS, NewAtlas

Representatives of Congress and the National Space Council joined President Donald J. Trump, Apollo astronaut Jack Schmitt and current NASA astronaut Peggy Whitson for the signing of Space Policy Directive 1(Credit: NASA)

US astronauts are headed back to the Moon after President Donald J. Trump ordered NASA to focus on manned space missions. Today at a White House ceremony, the President signed White House Space Policy Directive 1, which directs NASA to work with commercial and international partners to send American astronauts to our satellite as the first step to going to Mars and beyond.

Today's signing marks another shift in US space policy, which has been seeking to recapture the success of the tightly focused Apollo program of the 1960s. In recent decades, NASA's manned spaceflight efforts have been marked by a series of false starts, neglect, and sudden changes with each incoming administration. In addition to setting new goals, the directive will influence NASA's Fiscal Year 2019 budget request.

In July, President Trump revived the National Space Council headed by Vice President Michael Pence to advise and implement the President's policy of redirecting US space efforts away from Earth studies and toward deep space exploration. The Council was disbanded in 1993 after protracted infighting during the George H W Bush administration.

According to the new directive, the NASA administrator will "lead an innovative and sustainable program of exploration with commercial and international partners to enable human expansion across the Solar System and to bring back to Earth new knowledge and opportunities."

The signing was attended by Representatives of Congress and the National Space Council; Buzz Aldrin, the second man to walk on the Moon; Senator Harrison Schmitt, the second to last astronaut to leave the Moon during the Apollo 17 mission; Peggy Whitson, who holds the record for the most numbers of days in space for any American astronaut; and Christina Koch, a member of the US astronaut class of 2013.

"The directive I am signing today will refocus America's space program on human exploration and discovery," said President Trump. "It marks a first step in returning American astronauts to the Moon for the first time since 1972, for long-term exploration and use. This time, we will not only plant our flag and leave our footprints – we will establish a foundation for an eventual mission to Mars, and perhaps someday, to many worlds beyond."