Category Archives: Engineering

Engineering, Science Centres, space, technology

Evocative Endeavour – Space Shuttle Endeavour at the California Science Center

January 24, 2013 Tim Jones 4 Comments

Space Transportation System (Shuttle) at the California Science Center ©Tim Jones — Space Transportation System STS-47 (Endeavour Space Shuttle) at the California Science Center.

Evocative Endeavour

I did kind of wish for a second or two today, staring up at the big, black, underbelly of Space Shuttle Endeavour – boxed away at the California Science Center in Los Angeles – that I’d made more of an effort to see she or her sisters performing live.

Am I getting all mushy and romantic about a spacecraft now? Well, maybe just a bit. My wife Erin said she felt unexpectedly moved after our visit. I’d set myself to appreciative-engineer-mode before I went in, but still felt like I was standing on the rim of the Grand Canyon for the first time; you’ve seen all the postcards and videos, and can’t imagine the real deal adding anything new – but it does. That’s twice I’ve been emotionally sucked in by an iconic cliché. Shocking.

Space Shuttle Endeavour at the California Science Center ©Tim Jones — Space Shuttle Endeavour at the California Science Center.

Objects are evocative. At one point I found myself back in my lab as a research student in Birmingham in 1986, hearing about the Challenger accident. Then I’m back imagining all those tiles, engines, doors, and windows flying apart.

And there on Endeavour is that area of wing leading-edge, damaged on Columbia by falling debris during launch, causing her demise on re-entry in 2003 (more on that in this earlier post).

First Impressions

There is of course plenty of engineering to appreciate, and science behind it to ponder. But my gut reaction is how big she is, the length of the cargo bay, and how….dirty . It looks like she’s been treated like some science fiction fan might treat an Airfix model of the Millennium Falcon: roughed up, artificially distressed – so it looks like the real thing. Except the distress, evidently manageable, is real.

Size perception is odd too. I’ve seen video of the shuttle during ascent (in fact you can see it in Matt Mellis’s movie/iPad App called ‘Ascent’), where the ‘body flap’ – that piece below the engine in the picture below – is vibrating violently; it’s positively oscillating. The flap looks small and flimsy on the film, but it’s a huge construction; the forces must be tremendous.

Cargo Door Hinges ©Tim Jones — Cargo Door Hinges

Engines

RS-25 Space Shuttle Main Engines (SSME), Gimbal area. ©Tim Jones — RS-25 Space Shuttle Main Engines (SSME), Gimbal area

Gimbal area close-up ©Tim Jones — Gimbal area close-up

Thrusters

Orbital Maneuvering System (OMS) Pods with thrusters ©Tim Jones — Orbital Maneuvering System (OMS) Pods with thrusters

Tiles

The famous tiles, part of the Shuttle’s Thermal Protection System (TPS), are unmistakable. Designed not to ablate like the heat shields on the Apollo capsules, tiles do suffer wear and damage, and some had clearly been replaced with new ones for display.

The complexity and variation of tile design is striking. If you think tiling round the bathroom wash-basin is tricky, take a look at the area round the main engine gimbals and thrusters of the Shuttle. No wonder maintenance costs were high.

Tiles (part of Space Shuttle Thermal Protection System TPS) ©Tim Jones — Tiles (part of Space Shuttle Thermal Protection System TPS)

Tiles (part of Space Shuttle Thermal Protection System TPS) Close-up ©Tim Jones — Tiles (part of Space Shuttle Thermal Protection System TPS) Close-up

Earthquake Protection

Several sliding bearings, or seismic isolators, sit between the Shuttle and its supporting pillars, insulating Endeavour from the perils of Los Angeles’ earthquakes. The idea is the Shuttle rocks around harmlessly until the shaking ground settles down.

Endeavour is mounted on Seismic Isolators to protect it from earthquake damage. ©Tim Jones — Endeavour is mounted on Seismic Isolators to protect it from earthquake damage.

Seismic Isolator Bearing Surfaces. ©Tim Jones — Seismic Isolator Bearing Surfaces

Visiting

We saw Endeavour in temporary accommodation; it’s destined to be mounted vertically in a custom-designed building. That said, the exhibition as it stands doesn’t feel temporary, and the associated display areas and accompanying audio-visuals describing California’s particular role in the Shuttle story and showing off various artifacts from the program – including, importantly, the Shuttle’s WC or ‘space potty’, are excellent.

Entry to the California Science Center is free, but there’s a very reasonable $2 entry charge or ticket booking fee to see Endeavour.

Entrance to Endeavour Area ©Tim Jones — Entrance to Endeavour Display Area

Simulated Mission Control ©Tim Jones — Simulated Mission Control

Space Shuttle Wheels ©Tim Jones — Space Shuttle Wheels

Display Area ©Tim Jones — California and artifacts display area

Parting Impressions

Even as we celebrate, the Space Shuttle program is criticised, particularly around issues of cost and safety, but also the scope of its achievements. As always, it’s easy to find fault in hindsight, and judge historical decisions by the political and economic expedients of the present day. Personally, I reckon we’d be in a much sorrier state had the program not gone ahead. The Shuttle was the workhorse behind the International Space Station, the full learning from which I suspect has yet to be converted. And Endeavour personally, so to speak, enabled the repair of the Hubble Space Telescope.

The Hubble Space Telescope can see clearly now thanks to Endeavour. (Model at Cal.Science.Center) ©Tim Jones — The Hubble Space Telescope can see clearly now thanks to Endeavour. (Model at Cal.Science.Center)

NASA is at a turning point, collaborating more closely with private partners and, most recently, other nations on its manned space program. While the arrival of new entrants, working methods, and relationships are culturally refreshing, surely much of the knowledge and expertise behind them has its roots in the Shuttle and related programs.

Hopefully this note’s been short and sweet. There’s no point my repeating loads of technical and historical information you can get from many sources: not least the NASA and California Science Center websites, which, like Endeavour, are both worth a visit.

ALL PHOTOGRAPHS BY TIM JONES

Of Related Interest on Zoonomian

Matt Mellis Shares 30 Years of the Space Shuttle at the London Science Festival

Art, Engineering, Experiments, Fun, Materials

Musings on Structural Gingerbread

January 3, 2013 Tim Jones 1 Comment

It’s still the holiday season, so no apologies for doodling on about gingerbread, which, as it turns out, can be pretty strong stuff – if a bit bendy.

Cue my wife Erin’s first attempt at a gingerbread house (above). Pretty good, huh? The heat from the incandescent fairy lights has kept it from turning mushy, and nicely spiced up the room at the same time. The house is only eight inches tall, but prompts the obvious question: “How high can you build with gingerbread?”

A structural analysis of a full-on house with walls, windows and doors is too tall an order, even with finite element techniques, so I settled on calculating a ballpark maximum height based on standard engineering equations for a free-standing gingerbread column.

There’s no wind blowing through our lounge, so we can ignore sideways forces and focus on the two likely failure modes a column of gingerbread might suffer – just because of its own weight as it gets taller, i.e.:

(a) the construction materials can disintegrate under their own weight: a function of compressive strength, or

(b) the column can buckle, which is more related to the material’s elastic, or tensile properties.

The heights at which these two failures occur can be found from, respectively:

$H_{max} = \frac {P_f} {\rho\times g}$

$H_c =\left(\frac{9 E I}{4\rho g A}j^2\right)^{(1/3)}$

where $H_{max}$ =column height at compressive failure (m), $P_f$ is the failure pressure (N/m²) = compressive strength of the gingerbread, g=gravity (9.8 ms^-2), and $\rho$ is gingerbread density (kg m^-3). And for buckling: $H_c$ is the critical height, E is Young’s Modulus of elasticity calculated as tensile stress/strain, I is the Area Moment of Inertia³, and $j\approx 1.8663$ is a factor called a Bessel function, used to solve this type of equation (Ref.2)

Using published gingerbread properties data¹ (amazingly, there actually are some) for compressive strength and tensile stress/strain, I calculated values of:

$H_{max} = 50metres$

$H_c=3metres$

(Workings in box below if you’re interested.)

which essentially means a gingerbread column will start to lean over and buckle sideways long before the gingerbread breaks up through compression under its own weight (I used an arbitrary but realistic 20 cm column diameter). You might think there’s no reason why a uniform, vertical, column would start to lean, but in real life the weight distribution is never uniform and, if the column is sufficiently slim, a turning moment will establish and drive a progressive buckle.

So if you’re going to build a gingerbread house out of free-standing columns, better stop at 3 metres.

Buckling is clearly the limiting factor, but the 3 metre figure is based on a relatively small 0.2m column diameter, and buckling is particularly sensitive to cross-sectional area (whereas compressive fracture of a column under its own weight is independent of area). Also, most real buildings are more complex than a bunch of pillars, and I’d expect the right combination of interconnecting members building up from a broad foundation could reduce buckling potential, making a full-size gingerbread house a reality.

Indeed, the Guinness Book of Records ‘Worlds largest gingerbread house’ is 18.28m (60ft) on a 13.86m by 10.8m base; but closer inspection shows it’s built around a steel frame that presumably keeps incipient buckling in check. But then it’s more of a gingerbread and steel house – a bit of a con really.

Anyhow, our room’s about 3 metres high, so nothing stopping a more ambitious project next year: Empire State Building or Cathédrale Notre Dame ?

Workings

Note that for compressive failure of a column under its own weight, the area of the column A (m²) cancels and isn’t relevant: i.e $P_f = \frac {m\times g}A$ so, $P_f * A = H_{max} A\times \rho\times g$ and $H_{max} = \frac {P_f} {\rho\times g}$ as above.

I couldn’t measure my own gingerbread density easily (although it for sure floated in water, so < 1000 kg m^-3), and used a middle value of 700 kg m^-3 from this unlikely study by students at the University of British Columbia (UBC)¹. In addition to the UBC data for $P_f$ of 346 kPa, I measured my own value for $P_f$ by pressing a sample (squirrel-shaped in this case, but taking the narrowest foot area as 1*10^-4m²) vertically downwards onto a balance and recording when it crumbles.Still intact when the balance read 6kg, I took my $P_f$ to be at least 6 * 9.8 / 1*10^-4, or 588 * 10³ N/m² (588 kpascal kPa). In fact, for compressive strength, my numbers and the published data are conservative, as in neither case did the gingerbread actually fail at these values. So:

$H_{max} = \frac {346\times 10^3}{700\times 9.8}=50 m$ (UBC data)

$H_{max} = \frac {588\times 10^3}{700\times 9.8}=85 m$ (my gingerbread)

Whether it buckles first, at a lower height, depends on the elasticity of the gingerbread and the slenderness of the column: i.e. the ratio of column area to length.

The height at which buckling occurs can be found from Cox & McCarthy²:

$H_c =\left(\frac{9 E I}{4\rho g A}j^2\right)^{(1/3)}$

where $H_c$ is the critical height for buckling, E is Young’s Modulus of elasticity calculated as tensile stress/strain, and I is the Area Moment of Inertia³.

To calculate $H_c$ , I chose an arbitrary column diameter of 20 cm diameter, and used stress/strain data from the Canadian study¹ to calculate E = 9790 kPa; i.e. 219/0.02237 (the change in dimensions of my squirrel under tension are too small to measure with the kit I have).

The Area Moment of Inertia for a circular cross-section $I = \frac{\pi}{4} r^4$ , which for a 0.2m dia. column gives $I= 7.85\times 10^-5$ . And ( $j\approx 1.8663$ , is the appropriate Bessel function of order -1/3 (Ref.2) Note: in the source equation, weight density is specified; hence g added here.) So:

$H_c =\left(\frac{9\times 9790\times 10^3\times7.85\times 10^-5}{4\times 700 \times 9.8\times \pi\times 0.1^2}\times1.8663^2\right)^{(1/3)}$

$H_c = 3 metres$

A more complex structure would best be assessed computationally using finite element analysis, but I’m not getting into that.

References
1. ‘Building with gingerbread: Engineering students put holiday delight to the test’ refers to ‘Structural Analysis of Gingerbread. Engineering Design Project Term 2’ by Mercedes Duifhuis and Sean Heisler (pdf)
2. The Shape of the Tallest Column. Steven J.Cox, C.Maeve McCarthy, Society for Industrial and Applied Mathematics. Vol29,No.3. pp.547-554. (Also see Wikipedia page on buckling.)
3. Engineering Fundamentals efunda.com/math)

Of related interest
How to create the perfect sand castle Nature Scientific Reports 2, Article number:549, doi:10.1038/srep00549

Aviation, Engineering, events, science communication, space, technology

Matt Melis Shares 30 Years of the Space Shuttle at the London Science Festival

October 28, 2011 Tim Jones 3 Comments

There are so many science events going on in London at the moment, it’s hard to know what to join and what to skip. But last night’s London Science Festival talk by NASA’s Matt Melis was a no-brainer – and quite excellent.

Matt Melis, NASA Glenn Research Center at London Science Festival 2011 — Matt Melis, NASA Glenn Research Center at London Science Festival (Photo:Tim Jones)

Not only is Melis an ‘insider’ who’s up for sharing those tidbits of information and video clips you don’t normally see; but he’s also an engineer with a math and physical modelling background that resonates a little with my own research roots; so I guess I’m a fan. The event was organised by Francisco Diego (UCL Physics & Astronomy) and Melis was introduced by writer/film-maker Chris Riley (In the Shadow of the Moon, First Orbit, Space Shuttle the Final Mission). Melis collaborated with Riley on his production Final Mission with Kevin Fong, and has his own movie Ascent out on YouTube (embedded below).

Francisco Diego, Chris Riley, Matt Melis at London Science Festival Photo:Tim Jones — Francisco Diego, Chris Riley, Matt Melis at London Science Festival (Photo:Tim Jones)

Kicking off with an all-round engineering tour of the shuttle, the focus soon turned to the intensive ‘return to flight’ programme NASA pursued after the STS-107 Columbia disaster of 2003.

The cause of the accident was traced to a wing leading-edge being damaged by a briefcase-sized piece of insulating foam detached from the fuel tank during launch. Melis described the variety of model tests used to confirm the analysis and help pre-empt future impact scenarios. So, lots of high speed film of various projectiles, from foam to ice, impacting various bits of Shuttle; the whole thing made more real by the samples of foam, orbiter leading-edge material, and a cross-section of the aluminium/foam fuel tank composite he passed around the audience.

Feeling the foam’s super-lightness in your hand brings home just how counter-intuitive reality can be. Travelling fast enough – over 500 mph in this case – the impact of an apparently harmless piece of foam is devastating. Melis showed the clip in this video of a full-scale impact test of foam hitting an actual Shuttle leading-edge section:

The key take-away for NASA, and I guess for all of us, is that we learn most through failure – painful as that can be.

Vulture falls away after impact with STS-114, 2005 (Photo:NASA)

Management systems and general attitudes, as well as technology, changed over the Shuttle’s 30 year life. Melis showed a photo of icicles hanging off the gantry of the ill-fated Challenger launch-pad: they weren’t the cause of the disaster – that was the booster O-rings – but they could have been if they’d got caught up in the turbulence of the launch. Nobody thought that way back then though, or the information didn’t get to the right people. Similarly, on one of the HD videos that NASA started using extensively post-Columbia, Melis showed a bunch of vultures sitting on the gantry at launch, at least one of whose number (all six foot wing-span of him), spooked by the engine start-up, ended up smashing into the rising fuel tank.

All in all a great evening, but not one I’m going to recount in its entirety here. Here’s a flavor though in Melis’s Ascent:

Bonus Clips from Ascent:

Biography, Book reviews, Engineering, History, History of Science

Unweaving the Waterfall – Erasmus Darwin at Vauxhall Gardens

September 2, 2011 Tim Jones 1 Comment

vauxhallpenandink_1 — Vauxhall Gardens (artwork Tim Jones)

Grandson Charles and Grandfather Erasmus Darwin had at least one thing in common besides their illustrious name: they both took delight in figuring out how the world works – which isn’t to say they always followed the same interests.

Charles, we know, focused on the natural world – often in great, great, detail. Erasmus, less fixated but still very much the naturalist, engaged also with just about every aspect of science, technology and the trials and tribulations of the human condition you can imagine.

As happy in the botanical garden as the coachmaker’s yard or canal digger’s trench – it was all the same to him, many are the fields where Erasmus Darwin’s substantive contributions, too often unsung, resonate to the present day.

And while Charles was doubtless adventurous in mind and deed – he did afterall make the voyage of the Beagle – Erasmus, in the broader sense I would argue, ‘got out more’.

No surprise then, one evening in 1756, to find a 24 years young Erasmus Darwin at the epicentre of London society and entertainment: the pleasure gardens at Vauxhall. Less surprising still to find him back at his Nottingham lodgings pre-occupied with reverse-engineering the Gardens’ then prize crowd-pulling spectacle: the artificial waterfall, or Cascade – more of which later.

Vauxhall Gardens in 1751 (five yrs before Erasmus’s visit) Samuel Wale (Wikicommons)

The twelve acre Vauxhall Gardens operated from 1661 to 1859, and enjoyed a fantastically diverse clientele. Anyone who was anyone – or aspired to be – had to show their face: from Kings and Queens to honest tradesmen, to a dependable spattering of pick-pockets and prostitutes.

Entertainments at Vauxhall (Photo:Tim Jones. Exhibit at Museum of London)

All mixed shoulder to shoulder, intent on enjoying music, dancing, or one of the many laid-on spectacles: illuminations, fireworks, circus acts, mechanical wonders, balloon rides, battle recreations and panoramas celebrating the fetes of great explorers. Top of the list for many would be a romantic diversion with a favoured beau or belle under the tree-covered walkways.

Vauxhall Gardens by David Coke and Alan Borg

Incidentally, if you’re wondering what prompted this post – digging around in a pleasure garden – it’s down to my latest reading: a new History of Vauxhall Gardens, by David Coke and Alan Borg¹: a beautifully presented, comprehensive, and accessible read. Check out the book’s website here and write-ups in the Guardian here and here

I’ve suffered from amateur social historian syndrome since arriving in London eleven years ago – it’s hard to avoid when the place drips with the stuff; but the Vauxhall interest is closer to home – literally; my old flat on the Vauxhall Bridge Road overlooked the former Gardens’ site. Now home to a plain-vanilla grassed park, the only reminder of former glories is the yearly bonfire night sputter of fireworks launched by good-natured, if boisterous, locals. (On which theme, check out this earlier post).

Echo of past glories. View from my flat in 2003: fireworks rising from the former site of Vauxhall Gardens (Photo: Tim Jones)

Reading the new history though, I was intrigued by how few famous scientists (natural philosophers in their day) or technical folk are associated with the Gardens, either as self-reporting visitors or through third-party narratives .

Maybe the great and the good of the scientific establishment eschewed egalitarian Vauxhall in favour of the more exclusive (and expensive) Ranelagh Gardens across the river in Chelsea? At least there was a stone bust of Isaac Newton on permanent display at Vauxhall.

Anyhow, it’s entirely possible a trawl through the personal letters of individuals, where they’re catalogued, would turn up further references.

For my part, I checked out Erasmus’s letters – and he didn’t disappoint.

Coming back to the artificial waterfall or cascade for a moment. Installed in 1752, Coke & Borg say of it:

To add to its theatricality, the Cascade was concealed behind a curtain which was drawn back at a particular time in the evening, as night fell, to reveal a three-dimensional illuminated scene of a landscape with a precipitous waterfall; the illusion was created with sheets of tin fixed to moving belts, turned by a team of Tyer’s [the owner] lamplighters; when it was running, the noise and spectacle must have been terrific¹.

Then I found this letter from Erasmus, dated 9th Septemebr 1756, describing his interpretation of the operation of the spectacle to his friend Albert Reimarus, drawing and all:

Erasmus’s drawing of the artifiicial waterfall or cascade at Vauxhall Gardens (Picture credit: The Collected Letters of Erasmus Darwin, Cambridge University Press, 2007, Letter 56-6)

“The artificial Water-fall at Vaux Hall I apprehend is done by pieces of Tin, loosely fix’d on the Circumferences of two Wheels. It was the Motion not being perform’d at Bottom in a parabolic Curve that first made me discover it’s not being natural. The Velocity at Top is not so great to my rememberance as at the Bottom half of the fall, as I suspect the top Wheel is less than the lower one; a Shade is put where the Wheels join. At Bottom are many less Wheels I conjecture. Now the Velocity of the fall from a to b not being encreased was another thing that shock’d my Eye. What you mean when you say “let the Water fall over a Parabola etc”, I don’t understand.“

Photo:Tim Jones. Exhibit at Museum of London.

I’m taking expressions like “The Velocity at Top is not so great to my remembrance….” as evidence Erasmus actually visited the Gardens himself in the summer of 1756, possibly accompanied by Reimarus.

For Erasmus, the waterfall ‘game’ was given away by the shape of the flow – something other than parabolic, and not moving at the expected relative speeds.

In fairness to the designer (the concept likely derived from Francis Hayman’s theatrical stagecraft), that exposing the spectacle as anything other than natural required such analysis seems high praise indeed! Incidentally, Coke & Borg maintain no visual representation of the cascade exists, so this might be as close as we get.

(As an aside, there’s also evidence Erasmus’s sister Susannah (Sukey) visited the Gardens. In a letter of 12th June 1759 to his wife Mary (Polly), Erasmus accuses his sister of exagerating the number of people attending, 30,000, saying that number would not fit³ (although audiences of 12,000 are known to have gathered). There’s also a much later association with Charles Darwin, that appears in the correspondence⁴; not that he visited the Gardens but, as a twelve year old boy, having watched one of Vauxhall’s favourite performers, a ventriloquist named Mr Alexandre, did imitations of animal calls – interesting eh?)

We should take care when talking about Erasmus in this period not to visualise him along the lines of the podgy, red-cheeked albeit aimiable 38 year old captured by Joseph Wright and hanging in the National Portrait Gallery. In 1756, Erasmus was 24 years old, single (he married Mary/Polly Howard the following year), and largely unknown; he’d only two months earlier unpacked his bags in Nottingham to start his first medical practice.

So this is before he moved to Lichfield, and way before the invitation to become the King’s physician, his rivalry with Samuel Johnson (of dictionary fame and a regular at Vauxhall Gardens to the degree he appears in contemporary prints), or his adulation as England’s best loved poet. Moreover, the brief spell Erasmus spent in Nottingham is sparsley covered in the literature, with no mention in the standard biographies of trips to London or the Gardens. There’s just the one letter as far as I can tell.

In conclusion, it’s nice to see Erasmus’s early credentials as both engineer and bon viveur reinforced in the one story (however much, as a fan, that assessment might be tainted by confirmation bias :-)).

In their longevity, Vauxhall Gardens represent a unique microcosm, a laboratory for the study of change in societal norms, fashion, culture, politics and contemporary opinion. Coke’s and Borg’s analysis refreshes our insight on these, and placing Erasmus Darwin at the scene adds to our understanding of his early life.

Update 4/9/11

Twitter friends have suggested Samuel Pepys as an example of a ‘scientist’ known to have visited Vauxhall. He for sure counts as one of the establishment great and the good, and was a president of the Royal Society to boot. Coke and Borg do talk about Pepys, who wrote at some length about Vauxhall Gardens in his famous diaries. I’m afraid I associate Pepys so strongly with the Gardens, and for all his other interests and achievements – not just in science, that I completely forgot to mention him – poor chap. Still, he’s one guy, and it would be interesting to see if any of the other famous scientific names of the day including Newton, Wren, or, as Rebekah Higgitt (@beckyfh) suggested via twitter, Edmund Halley or Joseph Banks made mention of Vauxhall experiences in their letters. I must say, if I had my bust up there in all its glory like Newton did, I’d be checking up on it every friday night.

Of related interest on Zoonomian: The Other Darwin Genius

References

1) Vauxhall Gardens A History, Coke, David., Borg, Alan., Yale, 2011

2) King-Hele, Desmond (Ed.), The Collected Letters of Erasmus Darwin, Cambridge, 2007, [56-6] p.35

3) King-Hele, Desmond (Ed.), The Collected Letters of Erasmus Darwin, Cambridge, 2007, [59-1] p.47

4) Darwin Correspondence Database,
http://www.darwinproject.ac.uk/entry1 accessed on Thu Sep 01 2011 15:56:18 GMT+0100 (BST)

Other Sources

King-Hele, Desmond, Erasmus Darwin 1731-1802, Macmillan, 1963

King-Hele, Desmond, The Essential Writings of Erasmus Darwin, MacGibbon & Kee, 1968

King-Hele, Desmond, Erasmus Darwin A Life of Unequalled Achievement, Giles de la Mare, 1999

astronomy, Engineering, science communication

Science Communication – Over the Garden Fence

May 5, 2011 Tim Jones 1 Comment

Last week’s Public Attitudes to Science report from Ipsos MORI and BIS says a lot about how the public feel about and engage with science.

The Summary is worth five minutes of anyone’s time.

But what came unbidden to my mind, as I pondered how informed or uninformed people are about science, was a visit from a neighbour last week, and a reminder that we don’t need to appear on the telly or be called Brian Cox to do our own bit for science communication.

Basically, the guy spots me over the fence messing around with my telescopes, and invites himself over for a look-see. And, yes, he has been ‘Wonderised’ by Brian.

So I drop plans to photograph the ISS – I’ve got enough of those anyhow – and instead show him Saturn through the little ETX-90. For a first view through a telescope we could hardly do better.

We talk about the earth’s rotation and why the telescope’s axis points at the pole – watching Saturn scoot across the view with the drive turned off. We talk about the cost of kit, magnification, aperture, and what can be achieved with a pair of binoculars.

The forgotten ISS appears. Ultra-bright. Fantastic stuff.

The truth is that astronomy could have been designed for engagement, with other areas of science and engineering not lending themselves to a hands-on demo in quite the same way. I’ve worked with everything from fluid mechanics, to ultrasonics, to high-power lasers and the thermodynamics of steelmaking slags. It’s all fascinating stuff (believe me :-P); and while earthbound, still somehow less accessible than the stars.

This is where good science writing steps in; but TO MY POINT: if you know something cool – don’t wait for an invite to the Royal Society or the BBC to share it. And have a peep over your neighbours fence; you might see something interesting. (But don’t get arrested either.)

astronomy, Engineering, Experiments, Nostalgia, Photography

Easter Telescope Resurrection

April 27, 2011 Tim Jones Leave a comment

With a diameter of 120,000 kilometres and a bright reflective surface, Saturn is an unmissable object in the night sky right now. But at 1.3 billion kilometres away from us, it looks only a hundreth the size of the full moon. Which means the screen width of my Saturn video below represents one third of a lunar diameter across (for best view, click to full screen):
[jwplayer mediaid=”9786″]

I recorded the movie through my old but capable 1978-vintage 6″ Fullerscopes reflector – specially resurrected for Easter after 30 years in storage. (See my efforts with the moon and the smaller ETX-90 telescope in Armchair Astronomy.)

Fullerscopes 6″ at left, after the clean-up, ETX-90 at right

Getting the telescope up and running really required nothing more than (literally) brushing away some cobwebs and giving the mirrors a wash – something I’d be more hesitant of doing had I not just read a step-by-step ‘how to’ in Sky at Night magazine.

Although thick with dust and grime, I’d reason to believe the mirrors’ coatings beneath were o.k., as I remember having them vacuum re-aluminised and silica coated just before I abandoned the instrument and disappeared off to university. Some gentle soaking, swabbing, and rinsing down with distilled water, and all was shiny once again.

Fullerscopes’ german equatorial mountings were all built like tanks – this ‘Mark II’, rated to carry a 10″ reflector, is still in good order save for some rust on the exposed steel shafts.

The RA drive, that ordinarily would drive the telescope counter-rotational to the Earth’s axis, wasn’t operational for a variety of reasons; but the fine adjustment on the declination axis was working.

All of which goes to explain why on the clip Saturn appears to fly across the screen.

I’d forgotten how stunning to the eye Saturn is through this telescope. In better seeing conditions I’ve seen the gap in the rings – the Cassini Division – quite clearly. Now, Saturn’s moon Titan was unmistakable.

Filming what you see with your eye is a little more challenging, although the ‘live view’ on the Canon 7D makes life a lot easier. Rather than watch the live feed through a computer, on this occasion I used the camera’s LCD display directly to focus with the help of a magnifying glass. The clip was made by projecting the image onto the camera’s CCD sensor via a 12.5mm orthoscopic eyepiece; the main mirror’s focal length is about 1250mm. The scene could have stood higher magnification, but I was limited by the eyepiece focal length and size of the projection tube.

All in all, considering the state of the equipment at the start of the day, I’m happy with the end result. The gap between the disk of Saturn and the rings is clear enough; but no Cassini division – so still some work to do! All the same, a fun day messing around with telescopes and engineering – no better way to spend the Easter hols.

1. Saturn Fact Sheet (NASA)

2. To be exact: the angular size of Saturn on 25/4/2011 was 19 seconds (“) of arc, approximately a third of a minute. There are 60 seconds in a minute, and the moon is typically 30 minutes across; so Saturn appears one ninetieth of the moons diameter.

astronomy, Biography, Book reviews, Books, Engineering, History, Physics

Book Review: Collider – the search for the world’s smallest particles, by Paul Halpern

October 22, 2010 Tim Jones 1 Comment

Hardcover: 272 pages
Publisher: John Wiley & Sons (28 July 2009)
Language English
ISBN-10: 0470286202
ISBN-13: 978-0470286203
Product Dimensions: 23.6 x 16.3 x 3.3 cm

Good luck I say to anyone setting out to write a popular science book on particle physics. The concepts are weird, the math is hard; and on publishing timescales there’s not a whole lot of new stuff worth talking about.

Moreover, it’s a tall order that’s less about content and more about the way you tell it. Happily, in Collider: The Search for the World’s Smallest Particles– Paul Halpern tells it well.

Anchoring the core physics around a theme is helpful: whether it’s Brian Greene on string theory or Paul Davies on the search for extra terrestrial life or, as in Halpern’s case, the physics, technology and people that have advanced our understanding of the subatomic world.

Collider is a story of impressive people building big machines to smash small particles together to reveal big truths. With CERN’s Large Hadron Collider (LHC) limbering up under the Franco-Swiss countryside, the timing couldn’t be better.

At 232 pages before the notes, Collider is manageable without being superficial, and has sufficient pace and variety to engage even those for whom memories of high-school science induce a cold sweat (and for whom leptons is just another brand of tea).

Tracts of quantum weirdness interspersed with biographical vignettes and discussions on collider engineering should ensure a broad spectrum of readers stay the distance. Those led out of their depth, however gently, will find delightful pangs of (at least partial) understanding along the way. Personally, the engineer in me found particular joy in the mix of ethereal concept and enabling technology that particle physics, perhaps more than any other field, embodies. Halpern as a physicist clearly enjoys and respects all aspects of the endeavour. Indeed, Collider stylistically is quite polymathic, even poetic in a Saganish sort of way:

“Alas, summer’s heat sometimes shapes cruel mirages. After modifying its equipment and retesting its data, the HPWF team’s findings vanished amid the desert sands of statistical insignificance. Skeptics wondered if electroweak unity was simply a beautiful illusion.”

Poetry aside, the physics kicks in early with unification, theories of everything (TOE), and the limitations of an incomplete Standard Model.

The better known particles are introduced via their discoverers’ stories: Thompson’s electron, Roentgen’s X-Rays, Becquerel and the decomposition products of uranium, Rutherford’s proton, and Chadwick’s neutron.

By describing relatively simple experiments from the early era, like the measurement of alpha and beta particle size, Halpern gives his subject a tangibility, a graspable air that prepares the mental ground for later complexities.

Following the evolution of particle sources, accelerators, and detectors, Collider takes us through a chronology starting with unaccelerated decay products striking stationary targets, to linear accelerators, to the various circular synchrotron variants like Ernest Lawrence’s Bevatron and Cosmotron, ending with the contra-rotating particle streams and super-cooled magnets of the LHC.

As beam energies increased, detectors became more complex, sensitive, and selective, allowing the existence of myriad new particles to be confirmed or discovered. Cloud and bubble chambers joined hand-held scintillation detectors and Geiger counters in the particle physicists’ armory, and as the forerunners of the giant counters, traps and calorimeters stacked up today in CERN’s ATLAS and ALICE experiments.

Halpern devotes the last three chapters to a discussion of dark matter, dark energy and the possibility of higher dimensions in the context of string, brane and M-theory, where he underlines the mutuality of physics and cosmology in understanding the bang, whimper, crunch or (somewhat depressing) rip possibilities of an uncertain multiverse.

Looking to the future, Halpern suggests the fate of particle physics itself is less certain than current LHC excitement might lead us to believe. If the Higgs Boson, higher dimensions, or mini-blackholes show up, then fine; but if they don’t – where do we go next?’. Larger machines might be an answer, but with costs that were never pocket money now truly enormous, stakeholders, including the physics community, will need to look to their priorities. And as if to say ‘don’t say it will never happen’, Halpern dedicates a whole chapter to the last, some would say terminal, back-step in American particle physics: the 1992 cancellation of the Reagan era Superconducting Super Collider (SSC).

Something Collider really brought home for me is how the nature of particle physics as a discipline and a career has changed. Individual pioneers have been replaced by research groups working on projects staffed by thousands. As Halpern says, if the Higgs were discovered, they’d be no obvious single candidate for the inevitable Nobel prize (except Higgs himself of course). Data filtration and computation as disciplines have become as important as the collider itself: the LHC is served by a global network of computers. That creates the opportunity for remote distributed working and facilitates multi-national involvement, but also means young researchers need to think about the kind of experience, and resume, they’re building. At PhD level already, Halpern says the slow pace of fundamental revelations has required a force-put change in the definition of what qualifies for the degree in particle physics [we can’t all split the atom for the first time, right?].

I’ve one critical note on the history, and maybe I’ve just been reading too many Cold War biographies of late, but I felt Halpern’s analysis underplayed the military motivation and sponsorship behind the adolescent years of particle physics. Given that the topic’s already well covered in works like Gregg Herken’s Brotherhood of the Bomb, and that I walked away from Collider feeling inspired rather than cynical, it’s a choice of emphasis I’m inclined to forgive.

So quibbles aside, Collider is a bit of a page turner – which by the timbre of my opening statements isn’t a bad endorsement. By presenting the obscure realities of particle physics in the context of the machines and people that revealed them, Halpern has for sure made an unfamiliar pill easier to swallow.

computing, education, Engineering, Experiments

Out of the Archives – Calculators, Computers….and Stuff

July 19, 2010 Tim Jones 3 Comments

sinclair scientific calculator — Sinclair Scientific Calculator (Photo:Tim Jones)

This picture of a Sinclair Scientific is the latest recovered image from the 30 year archive of negatives I’m dutifully working through.

The reflections in this post are also prompted by this recent post on Andrew Maynard’s blog, (2020science), describing the sophisticated graphing calculator his children are required to have for school.

A pass-me-down from my brother, the Sinclair Scientific was my first electronic calculator. Built from a kit in 1975, I used it to prep for the UK O-Levels when I was 14 or 15; in the O-Level exams themselves we only had log tables :-P. By the A-Levels (16-18), I’d upgraded to a Casio fx-39.

John_Napier — John Napier, father of logarithms (Image: Wikicommons)

As it turns out, the calculator my nephews require for today’s GCSE syllabus is a Casio; but costing around £5, against the £75 or so for Andrew’s Texas Instruments machine.

An interesting feature of the Sinclair Scientific was its use of Reverse Polish Notation (RPN): an unusual but logical way to express calculations. Under RPN, the operator (+,- x, / etc) comes after the operands (the numbers); so the more well known Infix representation of 7+8 , in RPN becomes 7 8 +. RPN is more memory efficient for computers – a bigger deal once than it is now. Today, modern computers just translate into RPN without us seeing it.

You might think getting to grips with RPN was an awkward distraction for a 15 year old, but it proved handy background when it came to writing programs for this:

I guess this was our graphing calculator. Not exactly pocket size.

If memory serves, my school, named the ‘The Gateway’, acquired the 1958 Stantec Zebra from the local university; before that it was with the Post Office.

A small team of students operated and maintained the machine which, filled with hot valves, would frequently catch fire and give the occasional electric shock. This could never happen today of course, on safety grounds alone. But at the time, the teachers and students took it all in their stride, seizing the opportunity to build a short extra-curricular programming course into the timetable.

Programming lessons involved: writing code on cards with pencil and paper, encryption onto punched cards that the Stantec Zebra could read optically, then receiving line-printer output of the results. Looking back, it’s amazing any of this happened – a great opportunistic use of a rare resource.

powertran1 — Powertran Comp 80 (Photo:Tim Jones)

Pupils who later built their own computers, like the Science of Cambridge MK14, a basic kit machine launched in 1977 with about 2k of memory, or the Sinclair ZX-80, were doubtless inspired by the presence on site of their valve-driven (but still significantly more powerful) ancestor.

An interest in computers in this era meant just that: an interest in the information structure, solution algorithms, programming and hardware. High level programming languages, like BASIC even, were too memory inefficient to exist, and ‘games’ typically comprised simple models around the laws of motion; moon lander simulations were popular.

Our household variously hosted a home-built Powertran Comp 80, a Sharp MZ-80A (including some early green dot graphical capability), a Sinclair Spectrum and Sinclair QL. I’ve put pics of these and various other devices I’ve owned in the gallery at the end of the post – minus the obvious PCs that started with a Viglen P90 in 1995. Also our Creed 75 teleprinter – the only one I’ve seen outside the London Science Museum, this true electro-mechanical wonder was brought to good working order save for the chassis occasionally running live with mains voltage.

Are there any world-changing messages to be drawn from all this nostalgia? Possibly not. But I’m reminded how very hands on we were in just about everything. And that’s relevant given the buzz today about how kids might not be getting enough practical science and engineering experience in schools (I’m thinking of comments most recently made by Martin Rees in the Reith Lectures).

No one is arguing kids need a nuts and bolts knowledge of all modern gadgetry, but I do think off-syllabus projects like the Stantec Zebra (but perhaps less dangerous) are a good thing in schools. They show how diverse academic subjects come together in an application, making the theory real. This is pretty much my mantra in this earlier post about the Young Scientists of the Year competition. I would have thought such projects give a school a sense of identity and foster a bit of team spirit?

But it’s really an area I’m out of touch with. Does this type of stuff happen in lunchtime science clubs? Is there time in the curriculum? Do teachers have the time and/or skills? Or has our health & safety culture, however worthy, killed off anything interesting?

Also of interest

Kids Today Need a License to Tinker (Guardian 28/8/2011)

astronomy, Engineering, technology

Out Of The Archives – Telescope Tales

July 6, 2010 Tim Jones 2 Comments

I’ve been amusing myself this evening scanning old black & white negatives and colour slides into the computer: strips of film that have languished in negative files on top of cupboards for years. It’s a boring process, but punctuated with the reward of finding something I thought was lost, or a negative that was never printed.

developing tank developer fixer darkroom — Home developing. This is how we did it….

developing trays darkroom — when I were a lad…..

Some of the pictures go back to 1973, and are an unwelcome reminder of my antediluvian origins. But they’re also revealing of the state of technology at the time, and what I was doing with it. All the black and white pictures in this post are from the archive.

zenith enlarger — This is not a telescope

The photographic process itself is a prime example: the relative time and cost of developing and printing my own films being one reason many pictures haven’t been properly seen until now.

Things sure have moved on. I asked my 15 year old nephew if he’d ever used film, and after clarifying I didn’t mean video tape, he confirmed he’d never touched the stuff. Silly of me to ask really.

Regrettably, some of the more fun, not to say embarrassing, pictures from the archive are not suitable for public display. But I’m happy to inflict the sci-tech oriented discoveries – starting today with these pics of my first serious astronomical telescope.

fullerscopes six inch reflecting telescope — Same paint job as the 200″ on Mount Palomar

The main components were bought in 1977, and this photo of the telescope in its observatory is probably from 1979. The instrument is a classic Newtonian reflector of a design that hasn’t changed in hundreds of years. It has a 6″ primary mirror, and was built by Fullerscopes of London, the same company that made Patrick Moore’s fork-mounted 15″. The mount is a Fullerscopes Mk III German Type equatorial. The ancillaries: motor drives, plinth, finder, camera attachments, and the observatory itself are home built.

To be accurate, this was my second telescope, the first being an entirely home-built open-tube reflector in an altazimuth type cradle. Constructed almost entirely from sturdy aluminium bar stock – largely because that’s what I had – it all proved a little unwieldy. No photos survive – probably for the best.

Reflecting telescope made by Isaac Newton (Photo:Tim Jones, taken at the Royal Society) — Made by Newton (Photo:Tim Jones, taken at Royal Society)

The 6″ was mainly used for visual observations. I later added an improved synchronous motor drive to the Right Ascension (RA) axis to make the instrument more suited to astrophotography, but as that happened in 1980, just before I left home for university and ever on, that feature was little used.

Warning – Telescope building aficionados, engineers, (and all other interested readers….!) only

Assembling, augmenting, or building a telescope from scratch is an excellent engineering, as well as scientific, training. To save money, I purchased only the RA axis worm drive from Fullerscopes, with a view to reverse engineering it and building a copy for the declination axis. Operations to do that included aluminium casting, worm screw cutting, and making my own integrated roller ball-bearings on the worm shaft (to remove any trace of play, and hence instrument movement). Thankfully, my brother was building a model steam engine at the time, so a good selection of machine tools were available around the home.

lathe_ml7_1 — Myford ML7 lathe. Every home should have one (here operated by my brother).

I realise now that some of these operations were quite sophisticated engineering tasks, particularly for a 15 year old – probably why things didn’t always turn out as planned. I struggled to reproduce the 4.5″ phosphor bronze worm wheel (although the trick for cutting a worm wheel, by winding a tool-post mounted wheel into a spinning tap mounted between lathe centres, I find fascinating and elegant), and instead adapted an ex-military gun-sight for the declination axis. That said, the worm unit I’d made was better than the original, and eventually replaced it.

screw-cut worm in ball-races / cradle — Great British engineering….

The RA motor connected to the drive worm via a gearbox, also homemade using mecano gears mounted in a solid block of steel, the centre of which had been milled out on the lathe and fitted with individually turned and reamed phosphor-bronze bushes. The whole drive assembly was bolted to the plinth and linked to the final worm gear on a universal joint. This all worked fine, unless the telescope was incorrectly counter-balanced, when teeth would expensively shear off the little mecano gear wheels.

Despite these set-backs, or perhaps because of them, it’s my firm belief that this activity set me up well to tackle life’s later challenges: like building my own research equipment and mending the car.

The telescope’s plinth and observatory have their own stories. I’d read somewhere that telescopes need a rock-solid mount, and that plinths mounted in concrete are superior to tripods. In the photo, you can just see the top of a 5ft x 5″ x 1/4″ steel tube, 2 ft of which is buried in a 3ft square cube of concrete. The base of the observatory is covered in paving stones laid on sand, with a gap around the central concrete block to prevent footstep vibrations reaching the plinth. The plinth was capped by a 7″ square x 3/8″ thick oxy-acetylene welded plate. I remember this well, as the welder had to commission an unusually large nozzle for the job. This was of course total overkill for a 6″ reflector; but I suspect I harbored secret fantasies of some day owning a more substantial instrument.

The observatory was made from resin bonded plywood on a pine frame. Originally designed as a run-off shed, I switched to the fold-off roof idea when the weight of the structure dictated a need for major railroad-type work adjacent to the observing area – effectively doubling the project’s footprint. In practice, a south-facing aspect and relatively low observatory walls meant the compromise solution made little impact on sky visibility. A telescope mounted permanently out of doors is always ready for action – an important consideration with UK weather – with no need to wait for thermal stabilisation of the optics or to spend time aligning the equatorial mount. It goes without saying that, like all the world’s great observatories, it was painted white.

I keep saying ‘was’, because Mount Tim was decommissioned in the early nineties, such that you’d never know the paved area had ever been anything other than a regular garden patio. Amusingly, the plinth proved immovable, save for the use of explosives, so was instead ceremoniously tipped on its side in a shallow grave. I sometimes wonder what a future Tony Robinson might make of it.

Coming back to Fullerscopes. Buying a telescope in 1976 was not like popping down the road to Curry’s and carrying it home under your arm. When my father and I first visited Telescope House on the Farringdon Road, we were greeted by Dudley Fuller in person. He’d formed the company a few years earlier by buying out the historic but failing maker of optical instruments – Broadhurst & Clarkson Ltd.

We talked about my telescope-making efforts to date, and what I needed from Fullerscopes. He was wary of my plans to attach one of his diagonal mirrors to my homemade spider using glue (EvoStick No.2 – if I must!), but we agreed a package – including a Fullerscopes spider – and placed the order. (The spider sits in the top of the telescope tube and holds a diagonally placed mirror that diverts light into the eye-piece.) A month later, I returned to man-handle this tribute to Sir Isaac through the streets of London and back to Leicester – by train.

etx90 — What I’m using today: Meade ETX-90.

Telescope building was still being done in a traditional way. Fuller explained that all the brass tube-work on his telescopes was hand made using Broadhurst & Clarkson’s original equipment. That meant the brass sheet was rolled on an antique mill by hand, then soldered along the seam. On my telescope, the solder seam is visible on the brass focusing mount and Barlow lens adapter tube. The economics of this, particularly on parts destined for smaller instruments like my 6″, and at a time when Japan was starting to export mass-produced alternatives, must have been unsupportable. I’m guessing that’s the reason the Farringdon road shop closed down in 2005 and Telescope House moved out of town. It looks like they’re still trading though, with Patrick Moore’s endorsement into the bargain. (Telescope House website). But they don’t seem to be making their own instruments any more – please correct me if you know different.

There’s a related and slightly surreal twist to the story here, concerning my move to London in 2000. Needing a more portable telescope for out of city viewing, I visited Fullerscopes, now the UK agent for Meade Instruments Corp. of the USA, makers of the compact Cassegrain-Maksutov telescope I was after. The odd thing was, when I got chatting to the guy who handed over the box, it turned out he had personally been involved in making the brass-work for my 6 inch reflector 24 years earlier! It’s a nice story.

Anyhow, I hope that wasn’t completely boring and self-absorbed. If nothing else, it may have given you an insight into what I was getting up to in my formative years. You know, when I should have been out doing drugs, smashing up cars, and getting my underage girlfriend pregnant – like a normal teenager 🙂

Don’t forget to check back for the next exciting edition of Out Of The Archives……

Communicate Science