Space Sunday: to touch the face of the Sun

Ignition! The three main stages of the Delta 4 Heavy fire, starting the Parker Solar Probe on its mission to examine the Sun up close and personal. Credit: NASA

On the morning of Sunday, August 12th, 2018, NASA launched the Parker Solar mission, which it describes as being “to touch the face of the Sun”. It will be the first mission to fly through the Sun’s corona – the hazardous region of intense heat and solar radiation in the Sun’s atmosphere that is visible during an eclipse, and it will gather data that could help answer questions about solar physics that have puzzled scientists for decades. Over the course of its initial 7-years the Parker Solar Probe mission will allow us to better understand the fundamental processes going on in, on, and around the Sun, improving our understanding how our solar system’s star influences, affects and changes the space environment, through which we travel as the Earth orbits the Sun.

The probe and mission are named for Dr Eugene Parker, an American solar astrophysicist, who in 1958 first posited  the theory of the supersonic solar wind, and who also predicted the Parker spiral shape of the solar magnetic field in the outer solar system. Now 91, he was present at NASA’s Kennedy Space Centre as a distinguished guest of the agency, to witness the probe’s launch, the mission (and vehicle) being the first in NASA’s history to be named after a still-living person.

The Delta 4 Heavy carrying the Parker Solar Probe sits on the pad of Space Launch Complex (SLC) 37 at Canaveral Air Force Station, Florida, following the aborted launch attempt of Saturday, August 11th, 2018. Credit: Vikash Mahadeo / SpaceFlight Insider

Lift-off came at 03:31 EDT (6:31 GMT / 7:31 BST) on Sunday, August 12th, after the initial launch attempt was scrubbed on Saturday, August 11th, when a troubled countdown was halted just one-minute, 55 seconds before the engines on the United Launch Alliance (ULA) Delta 4 Heavy rocket were to ignite. The halt was called following a gaseous helium red pressure alarm, and investigations into its cause extended beyond the 65-minute launch window, resulting in the launch scrub.

The Sunday morning launch countdown proceeded without any significant hitches, and the Delta 4 Heavy – the most powerful rocket in ULA’s fleet of launch vehicles, comprising 3 Delta 4 first stages strapped side-by-side, the outer two functioning as “strap-on boosters” – lit up the Florida coastline as it took to the early morning skies.

Although a flight to the Sun might sound an easier proposition than reaching the outer solar system, it actually isn’t; it actually requires 55 times more launch energy than a launch to Mars. Hence why the relative small and light Parker Solar Probe, weighing just 685 kg (1,510 lb) at launch, required the massive Delta 4 and a rarely-used Star 48BV variant of the Payload Assist Module (PAM).

Originally developed as the upper stage for Delta 2 launch vehicles in the 1965, the Star family of solid-fuel PAM units were commonly used with the space shuttle for satellite launches from orbit: the shuttle would carry them aloft, release the PAM / Satellite combination, then move to a safe distance before the PAM motor was ignited to push the satellite on to its require Earth orbit. For the Parker Solar Probe, the Star 48BV was used to impart as much velocity as possible into the vehicle at is starts on it journey.

Dr. Eugene Parker, now 91, watches the launch of the probe named in his honour as it lifts-off from SLC-37, Sunday, August 12th, 2018. Credit: NASA / Glenn Benson

What makes a flight to the Sun so hard is that the Earth is moving “sideways” relative to the Sun at about 107,000 km/h (67,000 mph), and the probe has to cancel out a whopping 84,800 km/h (53,000 mph) of that “sideways” motion as it makes its way to the Sun in order to achieve orbit. At the same time, the probe needs to gain velocity as it moves in towards the centre of the solar system in order for it to balance the Sun’s enormous gravitational influence and achieve the required elliptical orbit.

The use of the Delta 4 / Star 48BV combination got both of these requirements started, by pushing the probe towards Venus in an arc that will both start to shed the “sideways” velocity, whilst also accelerating the craft in towards the Sun. But it will be Venus that does the real grunt work for the mission.

On October 1st, 2018, the probe will make the first of a series of flybys of Venus, where it will use the Venusian gravity to shed still more of the angular velocity imparted by Earth’s orbit and increase its velocity towards the Sun.

In all, seven such fly-bys of Venus will occur  over the 7 year primary mission for the probe, and while only the first is required to shunt the vehicle into its core heliocentric orbit, the remaining six play an important role in both maintaining the vehicle’s average velocity across the span of the mission and in gradually shrinking its elliptical orbit around the Sun as the mission progresses.

The first pass around the Sun  – and the start of the science mission – will occur in November / December 2018. At perihelion, the vehicle will be just 6.2 million km (3.85 million mi) from the Sun’s photosphere (what we might call its “surface”). During this time, the vehicle will be well within the corona, and will also temporarily become the fastest human-made vehicle ever made, achieving a velocity of around 700,000 km/h (430,000 mph) – that’s 200 km per second (120 mi/s), or the equivalent of travelling between London and Tokyo in around 50 seconds! At aphelion – the point furthest from the Sun, and brushing Earth’s orbit, the craft will be travelling a lot slower.

The corona is a very hot place – hotter than the “surface” of the Sun, however, it is also comparatively thin as far as an “atmosphere” goes. The distance at which Parker Solar Probe will be travelling from the Sun at perihelion, combined with its speed, mean that the ambient heat of the corona isn’t a significant issue. Direct sunlight radiating out from the Sun, however, is a significant problem.

Continue reading “Space Sunday: to touch the face of the Sun”

Trains, elephants, drugs, myths and ghosts in Second Life

Seanchai Library

It’s time to highlight another week of storytelling in Voice by the staff and volunteers at the Seanchai Library. As always, all times SLT, and events are held at the Library’s home at Holly Kai Park, unless otherwise indicated.

Sunday, August 12th

13:30: Tea-Time on the Orient Express – Conclusion

Join Seanchai Library and friends As they reach their final destination: a climatic 90-minutes session that sees a stranded train rescued and Hercule Poirot reaches his conclusions regarding a case most perplexing.

It should have been a route trip aboard the luxurious carriages of the Compagnie Internationale des Wagons-Lits’, Simplon-Orient Express. Yes, arrangements have been made in a rush, yes, it looked as if he would have to make the journey in the confines of 2nd class, but at least Poirot would make it back to London and the business requiring his urgent attention. Then his friend, M Bouc, who just happens to be a director of the company and travelling on the same train, arranges to have Poirot “upgraded” to first class and his accustomed comforts.

The locomotive trapped in a snow bank; a passenger murdered; a mystery for Poirot! Murder on the Orient Express

All is set for a most agreeable journey, but for the presence of one man: Samuel Ratchett, a noisome American, also aboard the train, and who accosts Poirot, claiming someone is trying to kill him, and demanding Poirot aid him. Refusing on account of finding Ratchett a disagreeable fellow and not at all whom he appears to be, the detective endeavours to enjoy the journey, finding his fellow first-class passengers a most curious group.

Ratchett, however has other ideas – or at least, someone does. With the train caught in a snow drift, the American is found dead in his sleeping cabin, and Poirot, now convinced of “Ratchetts” true identity – that of a child kidnapper and murderer known as  Cassetti –  finds himself cast into a familiar role of determining who is responsible.

But who – who among the group of travellers killed “Ratchett”? The hard, but quintessentially polite Englishman, Colonel Arbuthnot? The suspiciously acting Count and Countess Andrenyi? The cool and unruffled  Mary Debenham? The mysterious and distracting Mrs. Hubbard, who herself probably is not whom she appears to be? The Russian Princess Dragomiroff, frequently giving to lying?

Or might it have been Cyrus Hardman, the flamboyant detective from New York City, whose “assistance” in the case seems less than genuine? Or perhaps it was  Hector McQueen, “Ratchett’s” personal assistant – or any one of five other possible suspects? All of them appear to have a link either to “Ratchett” or to his most heinous of crimes and a reason for wanting him dead. Was it one of them? Some of them? All of them? Or – none of them?!

Board the Orient Express one last time in a special setting, as Seanchai library reaches the conclusion of this most famous and engaging of Agatha Christie’s novels!

18:00: Magicland Storytime

When a fortune-teller’s tent appears in the market square of Baltese city, orphan Peter Augustus Duchene knows the questions that he needs to ask: Does his sister still live? If so, how can he find her?

The fortune-teller’s mysterious answer that an elephant – an elephant! – will lead him to his sister, sets off a chain of events so remarkable, so impossible, that you will hardly dare to believe it’s true. And thus we’re off on a wondrous adventure of the kind only Newbery Medalist Kate DiCamillo could tell.

In this timeless fable, she evokes the largest of themes — hope and belonging, desire and compassion — with the lightness of a magician’s touch, and we are joined in a world of What if? Why not? Could it be?

Join Calaedonia Skytower at the Golden Horseshoe for this most enchanting of stories.

Monday, August 13th 19:00: The R-Master

In the 21st century utopia has arrived in the form of a repressive but seemingly benevolent, if omnipresent, bureaucracy. Their perfectly ordered world, seemingly run for the benefit of all, is actually ruled with an iron fist.  In claiming to have people’s best interest at heart, those in power keep the population occupied and docile with menial tasks and the promise of advancement with the aid of the strictly controlled drug, R-47.

For the vast majority, R-47 actually does nothing.But for a special few, observed and selected by the ruling Council, it can massively enhance their intellect, elevating them to the status of “R-Masters” allowing them to solve problems, see advancements, and help ensure – wittingly or not – the Council’s control over the world, cosseted and pampered well away from the drudgery of ordinary life.

However, there is a darker side to R-47: just as it can elevate the intellect of some of those chosen to receive it, so to can it reduce them to imbeciles – and there is no way of knowing who the outcome might be in advance. Wally Ho is one selected to receive R-47 – and suffers the latter fate.

Determining it will raise his problem-solving abilities and restore his brother, Etter Ho obtains R-47 and takes it. But, once elevated to the privileged ranks of the R-Masters and witness the truth behind the Council’s rule, Etter determines the established status quo cannot allowed to continue, and Big Brother must be brought to heel.

Join Gyro Muggins as he reads Gordon R. Dickson’s 1973 novel about life in what is now our times!

Tuesday, August 14th

The Library is closed for the evening.

Wednesday, August 15th 19:00: Mythos

The Greek myths are the greatest stories ever told, passed down through millennia and inspiring writers and artists as varied as Shakespeare, Michelangelo, James Joyce and Walt Disney.

They are embedded deeply in the traditions, tales and cultural DNA of the West. In Stephen Fry’s hands the stories of the titans and gods become a brilliantly entertaining account of ribaldry and revelry, warfare and worship, debauchery, love affairs and life lessons, slayings and suicides, triumphs and tragedies.

Through them, you’ll once again fall in love with Zeus, marvel at the birth of Athena, wince at Cronus and Gaia’s revenge on Ouranos, weep with King Midas and hunt with the beautiful and ferocious Artemis.

Thursday, August 16th

14:00: Fireside Tales: The Ghost of the Bridge

Caledonia shares more from her latest short story, inspired by Pfaffenthal 1867 in SL, and a legendary ghost from Luxembourg.

The Virtual Pfaffenthal, July 2015 – blog post

19:00 FLAMING ANGEL (a Tale of Suspense)

Shandon Loring reads Frederick C. Davis’s tale. Also presented in Kitelyhop://grid.kitely.com:8002/Seanchai/144/129/29.

 


Please check with the Seanchai Library’s blog for updates and for additions or changes to the week’s schedule.

The current charity is Feed a Smile.