Tuesday, April 19, 2022

Answer: Why water the astroturf?

 It's true!  

This IS a picture of the University of North Carolina very actively watering an artificial turf.  I took this pic one sunny afternoon not long before the field hockey team was about to take the field.  Of course, this struck me as nonsensical, but when you see things that seem truly odd, there's usually an explanation. That's this week's Challenge... 


This week's Challenge: 

1. Why do they water the artificial grass before (and sometimes during) a game?  

In this case, when I was there I spotted the groundskeeper who was actually running the sprinkler and monitoring how well they were doing.  Being a curious sort of fellow, I walked over, struck up a conversation and asked "Why are you watering the artificial grass?"  His reply:  "We do it a couple of hours before the game to make sure the field hockey balls (or lacrosse balls) won't run quite as far when they hit the surface.  If it's dry, they move fast and run off the field too quickly... which is a hassle."  

So, his answer: To increase the drag on the ball.  He helpfully pointed out that on "hot days, we'll water the field during halftime for the same reason."  

That's probably correct, but naturally, I was interested if there was any other reason.  So I started my reading with: 

     [ field hockey water on surface ] 

and found several good results.  The UK's Express sports page says that "The artificial playing surface is actually watered on purpose before each hockey game in order to improve play. GreenFields, an artificial turf systems company, said: 'The pitch is fully irrigated with a layer of water which results in an extremely fast and professional game.'"  

Interesting.  That's not what the groundskeeper said.  He said the reason is to have the balls move more slowly.  

Greenfields goes on to say that "During a hockey match, an average of 6,000 litres of water is used to irrigate the pitch. This is enough drinking water for a 3-person household for 6.5 years!"  (That's enough water to cause this Californian to pause.)  They also go on to say that the reason for watering the field is to "lower the surface temperature" to something more like natural grass.  

Looking around at other results I find that Halloran and Yauch (an irrigation systems company) say that watering an artificial field can: 

a. lubricate the surface to reduce injuries; 

b. cools the surface to reduce rug burns; 

c. stabilize the surface to add to field life; 

d. keeps the surface moist to prevent the synthetic fibers from breaking.  

Similar arguments are made by the TigerTurf company (another artificial field provider).  

On the other hand, searching for: 

     [ water on artificial turf soccer ] 

leads me to several other articles that repeat the "cooling" story, but also to an article (ParksAndRecBusiness) pointing out that for the special case of field hockey, water on the astroturf provides "“Uniform ball bounce and a non-directional roll..."  

Sounds like the PRIMARY reason is for this extravagant field watering is to make the field cooler--that makes sense, especially in places like North Carolina, which can get mighty warm.  There's also probably a more consistent ball rolling behavior with water on the field, which might be slower, might be faster, but certainly more predictable.  

Lest you think this is only an issue in places with lots of water, what kind of water you use on an artificial field matters--it's supposed to be potable water.  So, in LA, the question comes up, does watering an artificial field use less water... or more... than natural grass.  I will leave this as an open question for rabid sports fans to answer.  

Where the stick hits the watery field...

2. In what other sports do they water the field before (and sometimes during) a game?  Why do they water those fields?  

I did a generic search by: 

     [ "spray * on * field" sports ] 

to find all mentions of spraying something (the first *) onto something followed by "field."  I added sports to the query to get rid of results talking about spraying on agricultural fields.    

And, I found what you'd expect: that they spray water on baseball infields (which are usually red clay, which gets mighty dusty), and they spray water for the same reason on horse-racing tracks.  Of course, I also found many articles about spray-painting logos onto artificial turf for both permanent markings (e.g. lines), but temporary markings (e.g., for visiting team logos).  

But the biggest surprise in these results was the observation that sometimes you need to spray artificial grass with weed killer!  This led me to do a special search on: 

     [ spray herbicide on artificial grass ] 

and discover that it's recommended to use a herbicide twice a year to control those pesky weeds that can even grow... on an artificial field.  

SearchResearch Lessons

It's often a really good idea to talk with people in the field when you've got a SearchResearch question.  This is especially true when they're engaged in the activity that's piqued your curiosity.  But as good as that is, there might be a deeper story to discover.  That's why I always: 

1.  Trust, but verify.  The conversation is often a great place to begin your SearchResearch.  But even people who are doing something might not have the full story.  Sometimes they do--but it's a great starting point.  (And who knows, you might make a friend.)  

Search on! 

P.S.  I'll be away for the next two weeks, heading off on an actual vacation.  You can guess that there will be more SearchResearch Challenges in the near future that draw upon what I see there.  Details when I return.  But don't take two weeks of quiet as me being MIA--it's just time for a bit of a break.  The Challenge will return on May 11.


Bula vinaka!  

Wednesday, April 13, 2022

SearchResearch Challenge (4/13/22): Why water the astroturf?

 I couldn't believe my eyes!  

As a native Californian, I'm sensitive to water use and I'm drawn to extravagant displays of water.  Waterfalls attract me, rivers and even creeks capture my attention. (And you know I love the sea.)  

So as you might expect, seeing large fountains of water being sprayed onto an athletic field in midday caused me to watch in admiration as these powerful jets rocketed vast quantities of water onto the field. 

But wait a second... That turf is remarkably green, smooth, and oh-so-perfect.  

Naturally, curiosity made me wonder about the reality of the grassy field.  As I was walking across campus, I had a few extra minutes, so I took a detour and wandered down to the field to see what was going on.  Much to my surprise, I found that it's an artificial field!  Can that be real? Are they really putting a LOT of water onto fake grass?  It didn't add up.  

The question here is obvious... Why water the astroturf?  

A big part of my curiosity engine is to keep asking about what it is I'm seeing. Does what I'm seeing make sense?  Why is the land like that?  Why are people standing in that line?  What's going on with the plants / animals / fish / water... 

As it turned out, a groundskeeper was monitoring the sprinklers, so I was able to walk over and chat with him for a few moments and ask him the question.  His answer surprised me--and perhaps it will surprise you as well.  

As a Californian, I'm still stunned that this university in North Carolina would put so much water onto a surface without any plants, but NC doesn't exist in a state of drought.  In fact, the day before this photo was taken, it was raining very, very hard--one of those hard, tropical rains--which only made the field watering seem weirder.  

This week's Challenge: 

1. Why do they water the artificial grass before (and sometimes during) a game?  

2. In what other sports do they water the field before (and sometimes during) a game?  Why do they water those fields?  

As usual, I'm curious in what you learn in your search... but I'm VERY interested in how you found the answer.  What was your SearchResearch process?  

But most of all... why on earth would you water artificial grass?

Search on!  

Wednesday, April 6, 2022

Answer: Where is the oldest solar observatory in the Americas?

 Watching the sun... 

... is something that humans have done since we noticed that it traces out a pattern in the sky over the course of a year.  Of course, it's much easier to do this if you live on an open plain, where it's obvious that the sun sets and rises in a slightly different place each day.  As mentioned, Stonehenge is famously aligned with the solstices and seems to have been used as a large astronomical calculating device.  (Although how anyone in central England had enough clear and sunny days to make the calculations is actually beyond me.)  

But our curiosity also runs to solar observations made in the Americas.  What about the New World?  When did similar solar observations start here? 

That was the Challenge--can you find out? 

1.  When was the first observatory for sun-watching purposes created in the Americas?  Can you find out who made it?  Where is it?  And what happened to those people?  

I, like many of you, started with a simple, pointed query: 

     [ first solar observatory Americas ]

If you read those stories carefully, you'll find they all point back to an article published in Science (and VERY high reputation journal) Ghezzi, Ivan, and Clive Ruggles. "Chankillo: a 2300-year-old solar observatory in coastal Peru." Science 315.5816 (2007): 1239-1243.  (Link to full-text of the paper.) 

The observatory dates to the 4th century BCE, or about 2300 years ago.  It's 9 miles from the Pacific ocean on the eastern slope of a wide plain that gives a great 360 view of sunrises and sunsets.  It's a place without many trees, a place where you'll learn what the sun does every day of the year.  It's easy how one might come to view the sun as a god-figure.  We know that the Inca revered the sun and built astronomical temples (e.g., Machu Picchu), but learning about this site made me wonder about the relationship between the people who built Chankillo (the Casma/Sechin culture) and the Inca.  

In the above interview with NPR, the first author, Ivan Ghezzi said that: 
"We know that the Incas made powerful political statements based on the relationship between the sun and the king... The Inca claimed to be the offspring of the sun. But now we have a society that is 1,800 years before the Inca that is clearly using the sun as a way to make a political, social and ideological statement."
The Casma/Sechin culture is amazing--they began around 3200 BCE and stopped around 200 BCE.  There's not a lot of information about what followed the Casma/Sechin people; they seemed to be invaded by people from the mountains and just vanished into the mists of time as the Early Horizon (900 – 200 BCE) era ended... right around when Chankillo was built, and then abandoned.  

The Inca, meanwhile, date from 1438-1533, just under 100 years.  How is it possible that I didn't know about a pre-existing culture that lasted for 3 millenia?  I'm sure I'll be reading more about this remarkable culture in the weeks ahead.  (The Incas and Their Ancestor:  The Archaeology of Peru.  Michael Edward Moseley. 2001)

The Chankillo site itself is full of fascinating things.  You can even use Google Maps to get a look at the site from the satellite images.  The 13 pinnacles are arrayed on the back of a low ridge, looking like vertebrae that have been cut out of the stone:   

Closeup view of the observatory ridge.  P/C Google Maps

If you zoom out, you can see that there's evidence of a LOT of other buildings and sites all around the area. 

View from above.  P/C Google Maps

The chankillo ridge with 13 notches, looking towards the mountains in the east. 
P/C Google Maps

Most impressively, there's a large temple/fortress complex just to the west.  This is interpreted as being a temple with defensive capabilities--a suggestion that even 2300 years ago, battles were being fought in this part of Peru.  (There's some debate about whether these were actual battles or ritualized fights--whatever the actual interpretation, building this site was a lot of work in difficult environment.)  

Nearby fortified temple site (P/C Google Maps)

A great shot of the ridge.  P/C Wikimedia, by David Edgar (2013)

As Remmij pointed out, there's a GREAT video tour of the Chakillo site: If you're interested, check it out. 

One of my goals was to quickly get a sense of the surrounding literature about Chankillo.  My favorite way to do that is to find the most authoritative article (in this case, the original article in Science by Ghezzi and Ruggles), and then use Google Scholar to see what other works cite this paper.  That is, I did this--searched for the paper in Scholar, and... 

Which then gives me a list of other publications that cite this original work, usually extending it or giving new interpretations: 

I then just opened a bunch of these papers in parallel ("lateral browsing") and then scanned through them, picking out the ones that were interesting and/or relevant to my interests.  

SearchResearch Summary 

1.  When you're curious about something, take a look!  In this case, Google Maps (or other aerial image sources, as we've discussed) can be a great resource for furthering your curiosity.  

2.  Looking "around" a topic can be done by looking at other works that cite the work that's most like what you're interested in.  I tend to use the "Cited by" link in Google Scholar as a great way to look around.  This won't give you news accounts, but it does link you to some of the surrounding literature that can teach you a great deal.  (In my case, I'm going to start running down the mysterious Casma/Sechin culture!  

Search on!