The Magic of the Gravity Assist


IN MusicOScience_470
The Music of Science: a spaceprobe passing a planet gets the cheapest of all possible lunches. Oliver Morton hitches a ride

From INTELLIGENT LIFE March/April 2015

It will be the most far-flung rendezvous in history—and the end of the most taxing uphill trip ever made. On Bastille Day 2015, NASA’s New Horizons spaceprobe will reach Pluto after a slog of more than 5 billion kilometres, with the sun’s gravity pulling against it every step of the way. That such a trip is possible at all is remarkable. That it could be managed in less than a decade is a tribute both to the most brute force and the most subtle calculation.

First the force. As interplanetary missions go, this is a small one, weighing half a tonne. But when it was launched in January 2006, it was sitting on top of one of America’s largest rockets, an Atlas V. The launcher burned more than a tonne of rocket fuel and oxygen for every kilo of the craft’s mass. As a result New Horizons headed off to Pluto faster than any previous space mission: 45km a second. Puck boasted that he could put a girdle round the Earth in 40 minutes. At that rate New Horizons could have done it in 14.

The need for speed was simple; as the probe headed to the solar system’s outer edge, the centring sun pulled it back. Its gravity was not so strong as to bring the spacecraft to a halt—New Horizons will be the fifth human spacecraft to leave the system entirely—but it was enough to slow it down, draining away the kinetic energy the mighty Atlas had given it at lift-off day by day. By the time it reached Jupiter, about a year later, New Horizons had lost more than half its initial speed.

This is where the cleverness came in. Jupiter did not just provide a target on which New Horizons could test its cameras and other instruments. It also sped it back up. This pick-me-up, known as a gravity-assist manoeuvre, knocked five years off the time taken to get to Pluto. And unlike the Earth-shaking, sky-splitting $200m-or-more expense of an Atlas launch, it needed no fuel and no money.

Gravity assists are a beautiful example of the conservation of momentum, one of the most fundamental ideas of Newtonian mechanics: for every action, there is an equal and opposite reaction. When a spacecraft swings past a planet, the pull of the planet’s gravity changes its momentum so that it ends up moving not just in a different direction, but also faster than before. Because Newton, God and all other relevant authorities insist there should be no such thing as a free lunch, the speeding up of the spacecraft is balanced by a slowing down of the planet. But because momentum depends on mass as well as velocity, the slowing of the planet is smaller than the quickening of the spacecraft to the exact extent that the one outweighs the other, and that makes the lunch pretty remarkably cheap. Since New Horizons weighs less than a car and Jupiter weighs 300 times as much as the Earth, the planet’s lost momentum is as close to imperceptible as you can get. Fly a momentum-pinching New Horizons past Jupiter every day for a billion years and you would only slow the planet down by two millimetres a second.

The brute force of rockets has been known for centuries, and the idea of using them to visit other worlds has a heritage that stretches back at least as far as Cyrano de Bergerac. The subtlety of gravity assists is a more recent romance. It was discussed by a few enthusiasts early in the 20th century, but the first person to become deeply enthused by it was Michael Minovitch, a physicist at JPL, the Californian lab that has handled most of NASA’s planetary exploration, in the 1960s. At a time when most in the fledgling field of astrogation treated the gravitational influences of other planets as a problem to be minimised, Minovitch saw that, with the right geometry, you could use such perturbations to find quicker or more fuel-efficient routes to any of the planets bar Venus (too close). Working obsessively at night, in little contact with his colleagues, he came up with trajectory after trajectory, including the “grand-tour” approaches that used a gravity assist from Jupiter to get to Saturn, one from Saturn to get to Uranus and one from Uranus to get to Neptune.

Minovitch saw himself as inventing a whole new type of space travel. He didn’t see that less zealous colleagues could come up with the same solutions even if ignorant of all that he had done (the grand-tour orbits were discovered by someone else independently). He felt he was being written out of history; he left JPL and threatened to sue it.

To Minovitch the gravity assist was an invention to be owned. To most people it was a discovery which, once made, was just a fact about the world. It is not an uncommon tension in science. There is a time when only one mind has had an idea, at least as far as that mind knows; then there is a time when everyone thinks it. There is something wonderful about both, but the path between them is all too often strewn with arguments about priority and plagiarism, its trajectories and turnabouts far less satisfactory than the routes around the planets.

Although gravity assists are now standard, finding a truly clever new trajectory, or one that lets you use a smaller rocket for the same mission, remains a creative and satisfying act whether an invention or a discovery. Some astrogators will see their trajectories as cunning ways of outsmarting the limits that the sheer scale of space missions would otherwise impose, others as nature itself offering a helping hand. Either way, their existence makes the vast mechanism of the solar system just that bit more accessible to explorers—a little more quirky, a tad more user-friendly, a touch more like home.

Oliver Morton is briefings editor for The Economist and the author of “Eating the Sun”

Illustration Pete Gamlen


Another Great Story about Chuck Bednarik

Chuck Bednarik, greatest Eagle, dies at 89


PHILADELPHIA – So it turns out that nobody is too tough to die.

If Chuck Bednarik wasn’t, then nobody is. Because Bednarik was a tough man. Tough enough to fly as a waist gunner in missions over Nazi Germany during World War II. Tough enough to play center and linebacker in 1960. Tough enough to win championships in polite, patrician Philadelphia.

Bednarik is perhaps best known for a hit he put on New York Giants star Frank Gifford during that 1960 season. Gifford caught a pass over the middle. Bednarik dropped a shoulder into Gifford, knocking the ball out of Gifford’s grasp and knocking him out cold.

The photo of Bednarik celebrating the fumble, which clinched an Eagles victory, is iconic. Gifford is flat on his back, unconscious. Bednarik’s body is contorted, his fist pumping, in a primal act of celebration. Giants quarterback Charlie Conerly criticized Bednarik for celebrating the injury to Gifford. But Bednarik was celebrating the fumble and the victory.

Chuck Bednarik’s hit on Frank Gifford in 1960 is one of the most famous in NFL history.
That was him. He wasn’t thinking about Gifford much, if at all. For what it’s worth, Gifford said it was a clean hit. He was knocked out when his head struck the ground. Gifford missed the rest of the 1960 season and all of 1961 before returning to the field.

It was significant that the play occurred in New York. For most of its history, Philadelphia has suffered from its proximity to the Big Apple. The site of the nation’s founding and once its capital city, Philadelphia developed an inferiority complex when compared to its ever-expanding neighbor to the north.

Chuck Bednarik didn’t do inferiority complexes. He was born in Bethlehem, Pennsylvania, near the Bethlehem Steel works. After serving in World War II, he played his college football at the University of Pennsylvania. The Penn Quakers shared a home stadium, Franklin Field, with the Philadelphia Eagles.

He won a championship with the Eagles in 1949 as a rookie. He won another in 1960 as a 35-year-old veteran. In between, he played out a Hall of Fame career as a center and middle linebacker.

Bednarik was that old veteran when he tackled Green Bay’s Jim Taylor inside the 10-yard line on the last play of the championship game. He played every down of that game and still had the energy to hold Taylor down until the clock ran out. Then he let him up, because “this game is over.”

Much later, when players like Roy Green and Deion Sanders were taking a few snaps on the other side of the ball, reporters called Bednarik for his reaction. How did the last of the two-way players see these new-school two-way guys?

Bednarik didn’t see them at all, frankly. Running around at wide receiver and cornerback made them more like ballet dancers than like two-way football players in Bednarik’s eyes. He made sure to let it be known that they were earning way too much money doing it, too.

He was “Concrete Charlie” because he was tough, yes, but also because of his offseason job selling concrete.

He was also, arguably, the greatest Eagles player of all time. When the Eagles built their training facility, the NovaCare Complex, owner Jeff Lurie wanted the wall of the auditorium to feature four all-time Eagles greats. He chose Reggie White, Tommy McDonald, Steve Van Buren and Bednarik.

White, the youngest, died first. Van Buren was next. McDonald, the happy-go-lucky Hall of Fame wide receiver, is still with us.

At 89, Bednarik proved that even the toughest among us have to die.
Phil Sheridan
ESPN Philadelphia Eagles reporter
Spent a decade as sports columnist
at Philadelphia Inquirer
Philadelphia native has covered Eagles
in various roles since 1985

“Concrete Charlie” of the Philadelphia Eagles Dies at age 89

Chuck Bednarik, a Pro Football Hall of Famer and one of the last great two-way NFL players, died early Saturday, the Philadelphia Eagles said. He was 89.

Bednarik, known as “Concrete Charlie,” epitomized the tough-guy linebacker and also was an outstanding center for the Eagles from 1949 to 1962.

He is best remembered for a game-saving tackle at the 9-yard line on the final play of the 1960 title game, and it was typical Bednarik. He threw Green Bay running back Jim Taylor to the ground and refused to let him up while the final seconds ticked off as the Eagles held on for a 17-13 win.

“Everybody reminds me of it and I’m happy they remind me of it,” Bednarik once said. “I’m proud and delighted to have played in that game.”

He died at an assisted living facility in Richland, Pennsylvania, following a brief illness, the Eagles said in a statement.

Bednarik, who frequently criticized modern athletes, said he played on all but two kickoffs against the Packers and could have kept playing if he needed to, unlike today’s players who “suck air after five plays.” He missed only three games in his 14-year career.

The tackle on Taylor actually was the second hit that season that drew headlines. Earlier in 1960, he knocked out New York Giants running back Frank Gifford with a blow so hard that Gifford suffered a concussion and didn’t play again until 1962.

An iconic photograph captured Bednarik pumping his fist over Gifford’s prone body, though the linebacker insisted he wasn’t gloating. He said he didn’t notice what happened to Gifford after the hit and only saw that he had fumbled and another Eagle recovered the ball.


The Eagles tweeted out a tribute to Bednarik, calling him “Forever an Eagle,” with the photo of him towering over Gifford.

Bednarik was the last NFL starter to play regularly on both offense and defense until Deion Sanders did so for Dallas in 1996. Sanders’ achievement hardly impressed Bednarik.

“The positions I played, every play, I was making contact, not like that … Deion Sanders,” Bednarik said. “He couldn’t tackle my wife. He’s back there dancing out there instead of hitting.”

Born May 1, 1925, in Bethlehem, Pennsylvania, Bednarik flew 30 combat missions over Germany as a gunner during World War II. He then played center for Penn from 1945 to 1948, and was selected first overall in the 1949 NFL draft by the Eagles.

In 1950, he was All-NFL as a center, then he was voted All-NFL as a linebacker in 1951 through 1957, and again in 1960.

Bednarik, whose gnarled fingers in retirement stood as a reminder of the ruggedness of his profession, said he never made more than $27,000 in a season and supplemented his income by selling concrete, earning his nickname. At one point, he pawned his championship ring and his Hall of Fame ring.

[+] EnlargeChuck Bednarik

AP PhotoChuck Bednarik, who played both center and linebacker during his 14-year career with the Eagles, was one of the NFL’s last two-way players.

“I have had the opportunity to spend time with Chuck Bednarik, who is truly one of the most unique players that this game has ever seen,” Eagles coach Chip Kelly said in a statement released by the team. “The foundation of this organization and this league is built on the backs of past greats, with Chuck at the forefront.

“The way he played the game with an endless passion and tenacity helped establish the standard of excellence that this organization stands for; one that we strive to achieve each and every day.”

In early 2005, when the Eagles won the NFC championship and had Philadelphia in a Super Bowl frenzy, Bednarik was bitter enough to root for the Patriots in the Super Bowl. He later apologized to owner Jeff Lurie and was a welcomed visitor at training camp and other alumni functions.

“Philadelphia fans grow up expecting toughness, all-out effort and a workmanlike attitude from this team and so much of that image has its roots in the way Chuck played the game,” Lurie said in a statement released by the team.

The Maxwell Football Club presents an award in Bednarik’s honor to the defensive player of the year in college football.

Bednarik is survived by his wife, Emma, and five daughters — Charlene Thomas, Donna Davis, Carol Safarowic, Pam McWilliams, and Jackie Chelius, as well as 10 grandchildren and a great-grandchild.

The Associated Press contributed to this report.

The Ethics of Rhetoric

The best book I have ever read on this topic


Over the years I have worn out five copies of this work by Richard M. Weaver.  I finally splurged on the hardcover which I will never, I hope, highlight or underline.  I do use post it notes however.  The book is comprised of nine chapters, each covering a separate topic; in a way it has the feel of a masters thesis and might well have been.

The first chapter uses the Phaedrus to flesh out the nature of rhetoric.  Chapter two uses the Scopes “evolution” trial in Tennessee to illustrate the importance of the dialectic choices in advancing one’s rhetorical position.  I had read about and seen a motion picture presentation of the trial.  Weaver’s analysis made it clear to me that there was no way, absent a massive mistake by government counsel that the defendant could have prevailed.

Chapters three and four compare and contrast the way Edmund Burke and Abraham Lincoln formed arguments .  The author uses Burke’s arguments to conclude that, while Burke’s contemporaries viewed his a a leading proponent of conservatism, he was, philosophically, a liberal.  Abraham Lincoln, viewed as a liberal (in some respects for helping abolish slavery in the United States) was actually a conservative.  In Weaver’s view, Burke’s arguments where what he called arguments from circumstance which, in his opinion, were the liberals way of arguing.  In contrast, Weaver believed Lincoln argued from underlying principles as opposed to circumstance.  Weaver strongly believed that arguing from first or primary causes demonstrated a conservative philosophy.

Chapters five through nine deal with rhetorical aspects of grammatical categories, John Milton’s prose, what Weaver describes as the spaciousness of old rhetoric, the rhetoric of social sciences (and why writers of social science studies are often deemed rhetorically ineffective.  The final chapter discusses ultimate terms in contemporary rhetoric.  I was particularly impressed with his discussion of how rhetoric is applied by opposing sides in time of war.

I unreservedly recommend this book all readers.  An understanding of the topics covered in this book will make anyone a better reader:  a reader who can ask why a writer or speaker might have chosen certain words when framing arguments or stating implied facts.

This book is becoming increasingly difficult to find.  In the United States, Amazon is probably the best choice.

Vietnam Memorial at State Capital in Austin Texas

The Deep in the Heart Foundry recently completed a Vietnam War Memorial that has been placed in a park near the Capitol.  I took this picture yesterday.

Vietnam Memorial3small

I was in the USAF during the Vietnam era serving as a Russian Linguist in Security Service and did not make it to Vietnam.  Many of my high school friends did.  Several did not make it back.

A State for Kurdistan

Kurdistan’s right to secede

Set the Kurds free


The case for a new state in northern Iraq
Feb 21st 2015 | From the print edition

THE Kurds, at least 25m-strong, are one of the world’s most numerous peoples without a state. Other small nations in their region have a home alongside the Arabs, the Persians and the Turks: the Jews created (or, in their book, recreated) Israel after the second world war; Armenia and Georgia re-emerged as independent as the Soviet Union fell apart.

The Kurds have twice come close to fulfilling their dream, once after the first world war and the Ottoman empire’s collapse, when they were promised a state by the treaty of Sèvres, and again after the second world war, when for ten brief months the Kurdish republic of Mahabad rose up in what is now north-western Iran. Today the Kurdish Region of Iraq, home to at least 6m people, is independent in all but name (see article). It is that benighted country’s only fully functioning part. Since 1991, when the West began to protect it from Saddam Hussein, it has thrived. In due course, it deserves its place in the community of independent nations.

The principle, promoted by America’s President Woodrow Wilson a century ago, is that nations should have the “unmolested opportunity of autonomous development”. A country should be able to gain independence if it can stand on its own feet, has democratic credentials and respects its own minorities. To qualify, Iraq’s Kurds should confirm (again) in a vote that they want their own homeland. As well as being economically and democratically viable, the new state must be militarily defensible and disavow any intention to create a Greater Kurdistan by biting chunks off Turkey, Iran and Syria. It needs its neighbours’ endorsement. And it must settle terms with Iraq’s government, including where to draw its boundary.

Marriage misguidance
A sustainable economy is within the Kurds’ grasp. They are exporting increasing amounts of oil, and Iraq’s central government in Baghdad has at last agreed a formula that will let them keep the lion’s share of the profits. Soon they hope to produce 800,000 barrels a day, worth $17 billion a year at today’s prices.

Democracy is established, though still rough-edged. Iraqi Kurdistan has regular elections, a boisterous parliament, an array of political parties and a raucous media. Certainly its courts are weak, its leaders’ habits feudal, its journalists sometimes harassed and its human-rights record far from spotless. But it is more democratic than most of the region—and far safer than the rest of Iraq, even though the fanatics of Islamic State press against its long border. Suicide-bombings and atrocities of the sort committed by sectarian militias in Baghdad and elsewhere in Arab Iraq are mercifully rare.

The regional politics are trickier. Turkey and Iran have long been opposed to an independent Kurdistan carved out of Iraq, lest their own Kurds try to follow suit, if Iraqi Kurdistan becomes a magnet for neighbouring Kurdish rebel movements.

Yet even here there has been progress for the Kurdish cause. Syria, which is unlikely soon to recreate a centralised state, is hardly in a position to object to secession for Iraq’s Kurds. Iran has forged a pragmatic relationship with them. Relations between Iraqi Kurdistan and Turkey, the most concerned of its neighbours, have warmed remarkably. For now, the Kurds of south-east Turkey, far more numerous than those in Iraq, seem genuinely to have forsaken their desire for a separate state, seeking autonomy instead. Moreover, most of Turkey’s Kurds, assimilated in Istanbul and elsewhere, do not want secession. Hence Turkey might accept an independent Kurdistan across its south-eastern border.

The longer-term prospects are also good. Other countries based on an ethnic group—Albania, for instance—have resisted the temptation to incorporate the territory of their brethren in neighbouring states. Landlocked Iraqi Kurdistan will need access to markets for its oil, making it all the more vital that it is on decent terms with its neighbours, especially Turkey. Western countries should make plain that an independent Kurdistan will get no help if it stirs up secessionist Kurds across its border.

As for Iraq’s Arabs, the longer they fail to govern their bit of the country the less right they have to stop the Kurds governing theirs. Secession sets a precedent in the Middle East. Even so, the Iraqi Kurds know they must work with the powers in Baghdad and go through a difficult negotiation over oil. Since the fall of Mosul (where Islamic State holds sway), Kurdistan has crept towards de facto independence, with its capital in Erbil. While Islamic State’s maniacs are howling at the gates of Baghdad, a divorce cannot take place. But in due course separation would give the Kurds international protection from any violent Iraqi Arab attempt to reassert control. The Kurds want a country of their own. They have earned it.

From the print edition: Leaders

Objects That Make Artists Tick

Edmund de Waal’s netsuke, Peter MacDiarmid/Getty
~ Posted by Alix Christie, February 13th 2015


Peering inside 14 different artists’ studios and marvelling at the objects they collect is a fine idea for a show. “Magnificent Obsessions”, at the Barbican in London, appears to promise a satisfying gawk at the cabinets of curiosities assembled by both the world-famous (Andy Warhol, Damien Hirst) and the less well known (Dr Lakra, Jim Shaw). What it turns out to be is its own kind of curiosity. Like any collection, the show contains both gems and duds. It is entrancing in many small ways, but doesn’t always hit the larger goal of illuminating an artist’s work by “spelunking through [their] consciousnesses”, in Shaw’s memorable phrase.

Go for the opportunity to see things you’d otherwise never get close to. These include: the hare with amber eyes, a netsuke made famous by the potter Edmund de Waal’s eponymous memoir; Warhol’s kitschy array of ceramic cookie jars; surreal postcards and Soviet space-dog memorabilia assembled by the photographer Martin Parr; and a riot of puppets, masks, freaky creatures and elephant figurines amassed by the self-described “collecting junkie” Peter Blake, best known for designing the album cover for the Beatles’ “Sgt. Pepper’s Lonely Hearts Club Band”.

The notoriety, or not, of the chosen artists is part of what makes the show baffling at times. Visitors are given few clues to the kind of work each artist is best known for: one or two paintings, sculptures or photos are juxtaposed with each collection. Those without deep art-historical knowledge are left to guess. The pieces selected to represent heavyweights like Sol Lewitt and Hanne Darboven, for example—dismembered pages from their photographic books—do not help much to link their overall creative activities to the objects they collected. Darboven’s space is a riot of furniture, sculpture and bric-a-brac that looks just like it was pulled from her overstuffed Hamburg house and attic, as it was. Hirst’s taxidermy collection (stuffed owl, lion, vulture, seven-legged lamb), skulls and unusual creatures (a giant pangolin, not unlike an armadillo) are displayed alongside his “Lost Kingdom” (2012), a six-by-six-foot mirrored display of back-lit butterflies and insects. Looking between them, one is hard-pressed to see much difference, except that the contemporary dead creatures are glitzier and more expensive.

Lydia Yee, the curator, says the objective was never to draw clear links or identify specific inspirations for specific works. It was more about showing the things artists compulsively choose and imbue with personal meaning, which then provides a glimpse into their inner worlds. As a curator who visits artists at work, she’d long been struck by how many surround themselves with special things. I would have enjoyed seeing such studio photos too, to place these objects in their living context. There are several of these, and some nice interview snippets, in the free app visitors can download. But to see them all, you have to buy the catalogue.

The brute openness of the Barbican’s main gallery makes a show this intimate a challenge. Head upstairs: the warren of individual rooms is much more fun. Here we get a feeling for the personal passion that drives collecting, and each cell offers a particular pleasure. Several are true connoisseurs who built world-class collections of African masks and Indian painting. Others offer intriguing tasters: Shaw’s surreal paintings with his hideous yard-sale finds; Dr Lakra’s bizarre ink-on-skin drawings and the LP covers that inspire him; a roomful of mid-century scarves by the American graphic artist Vera, collected in their thousands by Pae White. I was most amazed by a collection of kitsch and mementos amassed by the deceased painter Martin Wong that the artist Danh Vo has turned into a piece of installation art in its own right. There’s something for everyone in this succession of caves, each as close and personal as the secretive, obsessive act of collecting.

Magnificent Obsessions: The Artist as Collector is at the Barbican in London until May 15th

Alix Christie is a journalist and author of the new novel “Gutenberg’s Apprentice”. She has also reviewed “Germany: Memories of a Nation” at the British Museum and “Magnificent Maps: Power, Propaganda and Art” at the British Library


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