# Evocative Endeavour – Space Shuttle Endeavour 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.

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.

Engines

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.

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.

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.

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.

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

# Jupiter Conjunction with the Moon 21st January 2013

Jupiter this afternoon is moving in for the closest line-of-sight conjunction with the moon you’ll see until the year 2026.

Jupiter is very bright and easily viewable in the daytime – especially with binoculars; the problem is you can never find it.   Because it’s so close to the moon today, that’s no problem: find the moon and you’ve found Jupiter.  This is my first pic of the day.  I’ll update with new ones every few hours as Jupiter moves in to closest approach and the Jovian satellites start to appear.   I have only a reasonable telephoto with me, not a telescope, but we’ll see how it goes.

Get out there now with those binocs!

That’s about as close as it will get: 30 minutes of arc, or a Moon’s diameter.  Some folks in the Southern Hemisphere will see Jupiter completely disappear behind the moon – an occultation.  But that’s me done for the evening.  Happy stargazing!

# Busy Bees

Here are a few shots I took this afternoon of bees feeding on/pollinating one of the many species of Aloe that populate the Huntington Gardens.

The bees burrow and completely disappear inside the tubular orange flowers.

These two shots show the pollen baskets:

# To Catch a Humming Bird

It’s no secret humming birds beat their wings fast, but it’s also nice to catch one in the act.

I snapped this Allen’s Hummingbird (Selaphorus sasin) yesterday at a shutter speed of 1/800th second (0.00125 s) and his wings are still a blur.

Humming birds can beat their wings at up to 200 beats per second – the wing completing its travel in 0.005 s.  I reckon the blurred area above represents about a quarter of a full beat, which is just what we’d expect if this guy were flapping near the max. (i.e. 4 x 0.00125 = 0.005).

Look how the body stays almost perfectly still; it reminds me of those stories about being able to balance a coin on the bonnet of a Rolls-Royce.  There is a slight wobble: if you compare his head to his foot (and the pictures below where he’s settled down) the head shows a slight shimmer.

With the sun catching him like that, we’re also getting a good demonstration of the iridescent color effects humming birds exhibit due to interference of light within the microstructure of their feathers.

Here are a few more pictures of the same bird:

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

# Vesta

The asteroid Vesta is well placed for viewing at the moment in the constellation Taurus.   From Earth, it appears as a mere pinpoint of light; so here’s an image NASA made earlier with the Dawn spacecraft that’s been orbiting Vesta for much of 2011/12:

Just too dim for the naked eye, at Magnitude 6.34, Vesta is easily picked out with binoculars or a digital camera.  I took these snaps on 15, 26, and 29 December in mixed conditions, including a nearly full moon and Christmas lights for the shot on 26th.  So not the best quality you’ll ever see, but satisfying all the same – at least for me – to capture a 326 mile wide lump of rock hurtling against the starry background.

Vesta is presently about one and half times the distance of the Earth to the Sun away from us (1.65 Astronomical Units).

Vesta is easy enough to find with software like Starry Night.  It also shows up on Sky Walk for the iPad, but not with sufficient accuracy to locate it with confidence.  There again, if you simply point your camera at the bright red star Aldebaran in Taurus, and take a couple of one or two second exposures of the area with a few days between them, Vesta will give itself away as the only object moving over time.

# Squirrel Impossible

This squirrel’s been entertaining us today stealing the birds’ supposedly inaccessible food.

# Geminids

Having missed the peak of the Geminid meteor shower this year; or rather experienced it through icy fog in London, it was a bit of a bonus to catch this picture at 3.00 am this morning during a visit to Leicester.

Whatever the meteor shower, this is my favourite bit of sky, so that’s where the camera gets pointed.  This is one of a series of 15 second exposures at IS0 1600, f4, focal length 17mm on my Canon 7D.

What more could you ask for:  Orion with sword, Hyades and Pleiades clusters in Taurus, Jupiter passing through, and a Geminid meteor to top it off.

Just goes to show it’s worth heading out in the dark and the cold for ‘one more go’.

Related Posts

Perseids

# Erasmus Darwin’s Birthday 12th December 1731

We shouldn’t let the day pass without a thought for Erasmus Darwin, whose birthday it is today.

Erasmus was born on 12th December 1731, at Elston Hall in Nottinghamshire.

During his seventy year span, Charles’s illustrious grandfather made more and varied contributions to the world of ideas than many today would guess – if they’ve even heard of him.

Erasmus is also of course the spirit behind Zoonomian; here are a couple of earlier posts that sum up his achievements and involvements:

The Other Darwin Genius

Unweaving the Waterfall – Erasmus Darwin at Vauxhall Gardens  (per my  talk at the Foundling Museum in June)

Erasmus set up his medical practice in Litchfield, where he lived from 1756 to 1781.  His house, now the Erasmus Darwin House Museum, is close to the magnificent cathedral, and well worth a visit.  (Samuel Johnson also lived in Litchfield, so you can visit his house while you’re there.)

Erasmus spent the last two years of his life at Breadsall Priory, where he died on April 18th 1802, aged 70.

To round off, here are three excellent and recent videos on Erasmus courtesy of History West Midlands:

Erasmus Darwin at The Heart of The Litchfield Enlightenment

The Litchfield Enlightenment

Erasmus Darwin The Scientist

# A Ghost of Medicinal Misnomers Past

Aspirin by any other name

Drugs have at least two names: a generic or scientific name, and then any number of manufacturers’ brand names for what is essentially the same thing.

So the generic names for two well-known painkillers are aspirin (acetylsalicyclic acid) and paracetamol (acetaminophen), but on Wikipedia you’ll find at least a hundred alternative brand names for paracetamol alone.  My favourites are the cuddly ‘Panda’ and the bemusing ‘Europain’.

It’s done of course to differentiate a commercial product, or identify a mixture of drugs – like aspirin and caffeine in Anadin.  But it hinders keeping track of particular chemicals that suit you, for a cold or whatever.   Also annoying are brands that list different drugs by application under the same headline brand, especially when the contents vary between countries.

Ghost Sign

As much as I enjoy banging on about how brands can obfuscate choice and cloud rational decision-making – and not just in medicines – this post is really about that photo of a building above, that I took yesterday in Regent Square, London.   It’s an unlikely and incongruous survivor.   A wall covered in early hand-painted advertisements for medicines from a bygone age.  It’s a ghost sign.

Probably Victorian, when salve and laxatives were all the rage, the full spiel for one of the products, ‘King’s Citrate of Magnesia’, made by Bates & Company, reads:

King’s Citrate of Magnesia

Invented in 1844

The Original Safest

& Best

W.W. King was a Liverpool chemist of mixed fortune.   I found him listed twice in sources for 1851.  First as a prize winner in the Catalogue of the Great Exhibition1 – for his ‘effervescent citrate of magnesia’, but also in Charles Dickens’s Household Narrative2 for that year, in his regular round-up of bankrupts.

Citrate of Magnesia induces a Motion

It was no secret that the article was entirely wanting in both citric acid and magnesia3

The Pharmaceutical Journal and Transactions, October 1, 1870

Magnesium Citrate, or Citrate of Magnesia, is still used as a uncontentious  saline laxative and magnesium supplement.  But it has a 19th century history that echos some of today’s complexities around drug names, descriptions, and branding.

We expect boxes and bottles of medicine to contain what the label says.  But by 1870, a situation had developed where products labelled citrate of magnesia were more often than not found to contain a mixture of “tartaric acid, sugar, and carbonate of soda3 .  It made for a nice fizzy summer drink, but little else.

A hapless public bought the mis-named drug in spite of the unrealistically low street price; it wasn’t like they could slip on glasses and read the small print, because compulsory ingredients listing hadn’t been invented.  That some brands, including King’s (of our wall fame), appeared to ship the real deal didn’t simplify the big picture.

All this threatened the reputation of professional pharmacists, so, as reported in the October 1st 1870 edition of the Pharmaceutical Journal and Transactions3 , some of them met to discuss a formal motion that would set things right – they hoped.

What’s in a name?

19th century Britons got their medicines from a variety of sources: via a doctor’s prescription, from an apothecary, chemist, or druggist, but also as commercial articles from the general store or local  grocer.  It’s like us going to the doctor, the pharmacy at Boots or RiteAid, or shopping at Tescos or Walmart.  The difference is we get the same drug wherever we go, while for 19th Century folk it was more of a lottery.  General commercial outlets were especially problematic – where unscrupulous quacks plied their mischievous trade of old.  At worst, the more renegade outlets might be guilty of “applying definite chemical names to articles not having the composition thereby designated3 “.

The pharmacists thought renaming the product might be the answer, but that idea just got them in a mess.  Do you call a thing what it is, or what it should be?   Suggestions included “citrate of magnesia of commerce“, “citrate of magnesia so called” , “citrate of magnesia of pharmacy“, “granular effervescent citrate of magnesia“, or the more vague “granular effervescent salt“.  Also names closer to the common composition, like “granulated tartrate of soda“; or  “citro-tartrate of soda” – whose sponsor claimed special privilege because it was already listed in the British Pharmacopoeia (an early list of approved drug standards published in 1867).

In the end, relative sense prevailed, with options smacking of inaccuracy and deception, however pragmatic, being rejected in favour of scientific purity.

…this Conference, as representing and expressing the highest aims of pharmacy, ought to maintain a scientific purity and exactness in its nomenclature3

The Pharmaceutical Journal and Transactions, October 1, 1870

Not that everyone was behind an honest naming regime.  It would confuse the public, said some, and open a Pandora’s Box of renaming obligations; hundreds of ambiguous favourites would be challenged: from ‘Salt of Lemons’, to ‘Seidlitz Powders’, to ‘Soda Water’.

From this strained conflict of pragmatism with scientific integrity a final motion was passed: a bit lame on specific actions, but a signal that professional pharmacists would not countenance inaccurate naming driven by commerce or tradition.   At least for Citrate of Magnesia that is, by now firmly established as the tip of a misnomer ice-berg.

That this Conference is of opinion that the term ‘citrate of magnesia’ as applied to the ordinary granulated preparation of commerce is a misnomer, and ought to be discouraged as inconsistent with the true interests of pharmacy. (The final form of the motion)

The Pharmaceutical Journal and Transactions, October 1, 1870

Legislation

Motions from professional bodies are all well and good, but they’re not law.  ‘Discouragement’ without legislation is toothless, and laws in this area had been slow in coming and often contested.

Earlier legislation, like the Apothecaries Act of 1815, defined standards and training for licensed apothecaries without actually outlawing unqualified practitioners, druggists, or quacks.   The Medical Act of 18584 was more about regulating doctors, and explicitly excluded from its provision chemists, druggists, etc. involved in the sale of medicines (although it did action the earlier mentioned British Pharmacopoeia).

The Pharmacy Acts of 1852 and 1868, established under the auspices of the pharmacists’ own professional society – the Pharmaceutical Society of Great Britain (est 1841) gave them powers to control drugs, and may explain why this was such an issue in 1870.  But with those acts focused on poisons and dangerous drugs, legal actions against peddlers of mis-named versions of the pedestrian citrate of magnesia were brought under the more generic Food Adulteration Act (1860) or Adulteration of Food and Drugs Act (1872).  Coincidently, these same legislations helped reduce the sawdust content of sausages, and alum and chalk in bread.

In this 1873 case, the defendant was found guilty under the Adulteration of Food and Drugs Act (1872), and fined £10 – about £1000 today – plus the cost of analysing his product:

Gradually things moved along, with further legislation on dangerous and controlled drugs appearing in the 1920s.  The Medicines Act 1968 split drugs into the prescription, pharmacy, and general sales categories we have now.   The naming of medicines in the UK is today administered by the Medicines and Healthcare products Regulatory Agency (MHRA), an agency essentially tasked with resolving the sort of issues our pharmacist friends were facing in 1870.

There’s no doubt controls over the naming and description of medicines has progressed massively since 1870.  But with outstanding issues around the labelling and promotion of homeopathic products, and the classification and control of herbal remedies, the job’s far from over.

References

1. Official Catalogue of the Great Exhibition of the Works of Industry of All Nations 1851, Cambridge University Press, 2011

2. The Household Narrative of 1851, Ed Charles Dickens

3. The Pharmaceutical Journal and Transactions, October 1, 1870, P.275

4. Medical Act of 1858 (here at legislation.gov.uk)

Of Related Interest on Zoonomian

Monkey Brand Comes Clean (re: nineteenth century soap ads.)