Is it safe for Santa up in the sky?
Prof. gary stutte
SANTA travels around the world from east to west, and so comes to Ireland from the UK. After his last drop-off there, probably around Liverpool on the west coast of England, the reindeer rapidly propel him to the edge of space, about 100 kilometres up, above the Irish Sea.
There he can watch the Earth rotate at 1,000 kilometres per hour and know he has less than 10 minutes before descending into Dublin.
While Santa travels within the Earth's atmosphere, he does get to the edge of space -- about 100 kilometres up
Here, the stars sparkle like diamonds and he can see the constellation Orion clearly. About 400 kilometres above, the International Space Station, bright as Venus, and twice the size of a rugby pitch, comes into view as it speeds around at 450 kilometres per minute.
A supply rocket launched from Russia in November carried food, fuel and Christmas goodies for the six men and women on board the station.
Among the countless gleaming stars, he can spot Hubble, a space telescope that was carried into orbit by a space shuttle in 1990 and remains in operation, capturing images and sending them back to scientists.
Santa can also see a handful of the 30,000 satellites orbiting the Earth, such as Galileo, and some of the Global Positioning System (GPS) NavStars, which provide all the information for our satnavs, including Santa's.
He can faintly spot the blinking of the newest light, SES-8, a 3,200kg communication satellite in geosynchronous orbit -- which means it orbits at the same speed as Earth's rotation, and so appears to never change position -- 35,000km above Earth.
This satellite will provide better television reception across India and China.
Sometimes the Earth's gravity pulls an old satellite out of orbit and turns into a shooting star when it hits the atmosphere. The fireball-effect could startle Santa and at those speeds, even a small collision could be deadly. Luckily, he has installed the forward-looking radar option on his new sleigh to warn him of such events.
The satnav beeps as the coast of Ireland comes into view and Santa points the sleigh down. He double checks the programming of the satnav system and activates flight tracking software to avoid the planes below.
Santa will encounter his first jet at 13,000 metres, then another at 10,000 metres and then yet another. The air-traffic controllers give him clear passage as the lights of Dublin come closer and he has less than a minute before his first landing.
As Santa switches on the front-, rear- and side-view cameras and activates the autopilot in the sleigh, he knows the silent beacons in the night will help him safely deliver his presents to the house of each boy and girl.
And that is what really matters on Christmas Day.
QProfessor Gary Stutte is a Marie Curie Research Fellow in Limerick IT. Professor Stutte, a senior scientist and principal investigator at Kennedy Space Centre, Florida, has been based in Limerick IT since 2011.
The Irish Research Council has announced an internship programme with NASA Research, starting next year, that will see early-stage researchers from Ireland being given the opportunity to work at NASA's world-leading facilities in the US. These internships will be of 10 to 15-week duration and will be based at the NASA Ames facility, which hosts 2,500 researchers, scientists and technology developers.