Thursday, September 14, 2017

A Salute to Cassini-Huygens and the Team Who Successfully Explored Saturn for More Than a Decade

Amid the stupidity emanating from Washington D.C. these days, depression can be a real impediment to a happy life. Other events unrelated to politics give me some sense of hope about the future of humanity, and one of those things is drawing to a close this week: the Cassini-Huygens mission to Saturn. It is one of humanity's greatest accomplishments, the extended exploration of another planet in our Solar System. I want to offer my congratulations and appreciation to the team that made this mission possible.
Source: https://nasa.tumblr.com/post/165331742919/cassini-spacecraft-top-discoveries
Have a look at this summary of discoveries from NASA; it has some astounding images.
This incredible mission resonates with me in a special way. I was a child of the 1950s, and the world and the Universe were different places in so many ways for a kid who was fascinated by astronomy. In particular, we barely knew more about our own Solar System than we did a hundred years earlier. We had made larger telescopes, but their effectiveness was limited by the disturbances in the upper atmosphere that distorted high magnification images. In those primitive years before the Hubble Space Telescope and the Voyager satellites, the science of astronomy was an exercise in frustration. I would head to the library week after week, checking out every astronomy book in the stacks, hungering to understand our own Solar System. 

Source: Unknown

How little we knew! Venus was shrouded in clouds. Mars had visible features, but they were unidentifiable from earthbound telescopes. Jupiter and Saturn had some visible cloud bands, but their moons were simple points of light. Only Saturn had rings, and maybe three divisions were visible. Neptune and Uranus were small disks, and diminutive Pluto was a dot of light. I wanted to know more!
The advances came so slowly (at least to this young growing child). The first satellite missions to Mars in the 1960s revealed surface features (and a lack of alien civilizations). Pioneer swept past Jupiter, but the camera on board was relatively primitive by modern standards. In the late 1970s, the two Voyagers began the grand tour of the outer gaseous planets. It was an excruciating wait as the small satellites passed first Jupiter, then Saturn, followed by Uranus and Neptune (years passed between each visit). Then, knowing the satellites had arrived, there was the excruciating wait for the pictures to be downloaded and processed. It was worth the wait. The pictures and data were astounding, revealing worlds never imagined by humans. The child in me was absolutely enchanted. But something still seemed to be missing.

The missions were all fly-bys. The trajectory was carefully planned to glean as much information as possible, but the satellites flew past their targets fast, and the numbers of pictures were limited by both time and technology. What was really needed was to insert a satellite in orbit, and that is a daunting challenge. The Cassini-Huygens mission accomplished that task in a spectacular manner. Check out the "ball of yarn" below...satellites can only maneuver to a very limited degree because of fuel requirements, so the crew had to aim the craft with an extreme degree of accuracy.
A computer-generated representation of all Cassini’s Saturn orbits -affectionately called the “ball of yarn” by mission planners. The time frame spans Saturn Orbit Insertion on July 1, 2004 to the end of mission on Sept. 15, 2017. Credit: NASA/JPL-Caltech

The pictures of the clouds and bands of Saturn are spectacular enough, but the real adventure of the Cassini-Huygens mission has been the exploration of the rings and moons of Saturn. Six new moons were discovered and named, bringing the total of known moons to 62, second only to Jupiter's 69. In essence, Saturn is a planetary system with one "planet" that is larger than Mercury.
This picture is not showing Mars, Venus and Earth orbiting Saturn. It's actually a view towards the inner Solar System from behind Saturn (which is hiding the Sun)
 George Lucas could barely come up with stranger moons for his Star Wars movies than the very real moons we have in our Solar System. More than enough of them are somewhat like our own Moon, cratered and "dead" (i.e. geologically inactive). But some are...very different. It turns out that Titan, the largest, has a thick atmosphere complete with rivers and streams, lakes and even a few seas. It rains and snows. That might seem a bit odd, since the surface temperature is hundreds of degrees below zero, but the liquid isn't water. It is made of hydrocarbons that on Earth would exist as gases like methane.
Saturn's moon Titan, complete with atmosphere, and shallow seas reflecting the sun.
Another major moon of Saturn, Enceladus, is even stranger, if that is possible. It's the brightest object in the Solar System aside from the Sun itself. The reason is ice. The entire crust of the "planet" is made of water ice, and it covers a "molten" layer below of salty water that may be four or five times deeper than Earth's oceans (Enceladus is much smaller than Earth, only about 310 miles in diameter).
Enceladus, the ice moon of Saturn. An incredibly deep ocean lies hidden beneath the icy crust.
The fractures and cracks in the surface, along with a relative lack of craters suggests the surface of Enceladus is tectonically active. It is simply one of the most fascinating "worlds" in our Solar System. And when I was growing up, all it was to us on Earth was a barely visible dot of light in our most powerful telescopes.
Enceladus and Saturn. Enceladus is the brightest object in the Solar System besides the Sun itself.
 Saturn is full of wonders and mysteries that are now becoming apparent to human beings for the first time in all our existence as a species. What a privilege to be living in a time when things like this can happen! And what a privilege and honor it must be to be part of the team that made the entire mission possible. And what competence! The Cassini-Huygens satellite left Earth nearly twenty years ago, and the moment it left, no repairs would ever be possible. When I consider how often my laptops and smartphones have to be replaced or repaired, just think what it means to be the inventor and maker of a complex piece of technology that has operated for twenty years with barely a glitch in performance.
Mima and Saturn
So what now? It's going to take years to interpret and present the scientific discoveries concerning Saturn, and the data will inform the objectives of future missions to the planet. But what to do in the meantime? Well, there's another really big planet out there, and a new satellite just arrived and started its explorations. It's called Juno, and the planet it is exploring is Jupiter. Jupiter has now had a number of fly-bys (Pioneer 10 and 11, and Voyager 1 and 2), and it also had an orbiter mission (Galileo). Galileo provided a treasure trove of information, and the Juno will be able to build on that (it also has a more polar orbit, providing views that the other missions could not). In other words, this very wonderful human adventure continues.
Titan and Dione with Saturn as a backdrop.
So thank you, and congratulations to the team that gifted us with the Cassini-Huygens mission to Saturn. Tomorrow, the Cassini satellite will plunge into atmosphere of Saturn at a ludicrous speed (echoes of "Spaceballs") of about 75,000 miles per hour and go out in a literal blaze of glory after 13 years of collecting data. It will be transmitting information right up to the final seconds of its existence. It was a job well done.

Friday, September 8, 2017

The Worst Natural Disaster in U.S. History: It wasn't last week, and it won't be this week either

Source: National Weather Service

I was doing a quick search for information on the United State's worst ever natural disaster, and found almost immediately that today is the anniversary of that event. That might sound a bit strange, since the media is describing the devastation of Hurricane Harvey as the worst U.S. disaster ever, and the possibility that Hurricane Irma could surpass it in a few days. And to be sure, these are horrible events, and before I started writing this post I made a number of donations to relief organizations in the south Texas region (I recommend charitynavigator.org to guide your choices). But we can have a strange measure of "worst": we tend to think of monetary damages. And by that measure, the 2017 hurricane season is practically apocalyptic, and one of the hurricanes hasn't even hit U.S. soil yet (islands in the Caribbean have been devastated). But there is of course the other measure of disaster: lives lost. Lives have been lost, and every life lost is a tragedy, but these hurricanes are far from the worst in American history.
Galveston, 1900. Source: https://en.wikipedia.org/wiki/1900_Galveston_hurricane
Hurricane Katrina in 2005 is high on the list, despite having taken place in the modern era with a population given advance warning (botched evacuation efforts and the unexpected failure of poorly reinforced levees led to the increased flooding that killed 1,836 people). But wasn't the worst. The San Francisco Earthquake of 1906 is an obvious candidate, and indeed more than 3,000 people were killed in that tragedy. But was number two. What event was the worst?

You know, the year of 1900, children,
Many years ago
Death came howling on the ocean
Death calls, you got to go
Now Galveston had a seawall
To keep the water down,
And a high tide from the ocean
Spread the water all over the town.

In 1900, weather forecasting was a science hampered by a lack of data. Entire hurricanes could remain undetected in the Atlantic, and limited telegraph networks meant that storms that made landfall might still not be publicized. That was the situation in the days leading up to Sept. 8 of that year. The storm had been reported by weather watchers in Cuba, and the Weather Bureau office in Washington sent storm warnings to coastal areas in Louisiana and Texas. Few heeded the warnings. Storms had come and gone in Galveston over the years without serious damage, so why would this one be any different?
Source: https://en.wikipedia.org/wiki/1900_Galveston_hurricane
Galveston was a town of 36,000 people. It was an economic powerhouse, situated on an excellent natural harbor. But geologically, it was a disaster waiting to happen. The town was built on a barrier island, a long sand island that paralleled the Texas coastline. Such islands are unstable locations for human development due to the lack of solid foundations for buildings, and the low elevation. The island sat no more than 8 feet above sea level, and despite the song lyrics above, there was no seawall.

You know the trumpets give them warning
You'd better leave this place
Now, no one thought of leaving
'til death stared them in the face
And the trains they all were loaded
The people were all leaving town
The trestle gave way to the water
And the trains they went on down.

Winds, as we have been learning these last few weeks, are not the worst aspect of hurricanes. The winds can certainly produce extensive damage, but nothing quite compares to the storm surge of a major hurricane. The extreme low pressure at the eye of the hurricane acts to raise sea level, and as the storm makes landfall, the seawater surges inland. The storm surge of the Galveston hurricane was 15 feet, more than enough to sweep over the entire island, and too deep to stand in. Many people trying to swim were crushed by debris from the 3,600 buildings that had been demolished. Bridges and trestles that would have allowed people to escape the island were washed away. They were trapped.
Source: https://en.wikipedia.org/wiki/1900_Galveston_hurricane

Rain it was a-falling
thunder began to roll
Lightning flashed like hellfire
The wind began to blow
Death, the cruel master
When the wind began to blow
Rode in on a team of horses
I cried, "Death, won't you let me go"

We can never know just how many people died that night. 6,000 is the low estimate. 12,000 is the high-end guess. There were too many corpses for burial, so an attempt was made to dispose of them at sea. Many floated back and accumulated on the beaches. Eventually funeral pyres were constructed, and the bodies were burned. I can hardly comprehend the horror, although ghastly pictures from the 2004 tsunami in Indonesia provided a stark example. And as we all know, pictures cannot convey the sound and odor of death.

Hey, now trees fell on the island
And the houses give away
Some they strained and drowned
Some died in most every way
And the sea began to rolling
And the ships they could not stand
And I heard a captain crying
"God save a drowning man."
This photo was labeled "Seeking valuables in the wreckage". What would they call it in the present day? Source: https://en.wikipedia.org/wiki/1900_Galveston_hurricane
This weekend our country faces what might be the most powerful Atlantic hurricane ever recorded. Many people will die (indeed several dozen already have in the Caribbean), and the property damage will be devastating. It will be a tragedy for all in the path. But imagine how different it would be were it not for the climate scientists who labor to understand the formation and pathways of hurricanes and other violent storms. Imagine not knowing the end of your world is just over the horizon, only hours away, coming with no warning. Tens of thousands of people will owe their lives to the work done by these scientists.

Politicians and pundits on one side of the aisle in Washington have a shocking lack of respect for climate scientists, and have denigrated their efforts to understand and analyze the changes taking place in our atmosphere due to warming caused by greenhouse gases. With their college degrees in political science or business administration, or in the case of some media personalities, their high school diplomas, a number of people have declared themselves to be experts in climate science, and deny the effects of climate change that are happening around them. Some accuse scientists of being hoaxers. It's ironic that they evacuate when the scientists give a warning about an imminent threat, but ignore the mountain of evidence for long-term changes in the environment that sustains us.

Climate scientists are heroes and they deserve both respect and support. This is not the time that our government should be cutting funding for climate research, but that is what is happening. This must be stopped. Our very lives, and the lives of our children and grandchildren depend on it.

The ghosts of Galveston are watching...

Death, your hands are clammy
You got them on my knee
You come and took my mother
Won't you come back after me
And the flood it took my neighbor
Took my brother, too
I thought I heard my father calling
And I watched my mother go.

You know, the year of 1900, children,
Many years ago
Death came howling on the ocean
Death calls, you got to go

The song is a folk anthem called Wasn't That a Mighty Storm. Learn more about it here.





Sunday, September 3, 2017

Time Heals All Wounds. Or Does it Just Hide Them? The Ghosts of Nelder Grove (Reposted)

According to news reports, the Railroad Fire in the Sierra Nevada has reached the Nelder Grove of Sequoia Trees. It's uncertain what the outcome will be, as the trees are adapted to wildfires, but less so when the forest surrounding the trees is overgrown and stressed by five years of drought. Nelder is kind of a special grove, having been logged a century ago, and left out of the boundaries of Yosemite National Park. Abused, but precious. I wrote about Nelder when I visited for the first time a couple of years ago. Since it has been in the news, I thought you would like to learn of its threatened beauty. The original post follows...
It's a beautiful place, really. It was one of the most serene places I've been in my travels, away from busy roads, cities, tourist traps, and most of all, crowds. We were only 10 miles from Yosemite National Park on a Sunday afternoon, yet we shared the place today with just six other people, all of whom were quietly looking up as if in a a medieval cathedral.
Sequoia groves are like that. The ancient trees are so big and so tall, so grand, that they seem to inhabit a different universe than "normal" trees. They tower above, like placid gods looking down on their earthly domain. They are the only species in their genus,  Sequoiadendron giganteum. The species, or species very much like it, once grew across the northern hemisphere. Through habitat loss, perhaps related to the ice ages, they disappeared from most of their range. Only on the western slopes of the Sierra Nevada have they survived, living in 68 isolated groves, and numbering only in the few tens of thousands (the more widespread Coast Redwoods of northwest California are related, but are classed in a different genus).
We were walking through a mountain cathedral, marveling at the beauty and size of the incredible trees, but I realized there were ghosts all around us. There were only 16 mature Sequoia trees along the trail we were following, but there were dozens of gigantic stumps. This serene forest was a shadow of its former glory. Someone had cut down these forest giants. According to the Friends of Nelder Grove, the entire grove includes just over 100 mature trees spread over 1,540 acres (2.4 square miles). There are 277 stumps hidden in the shadows. Three quarters of the trees that had survived for 2,000 years or more were cut down in a few decades, between the 1890s and 1920s.
The sad part is that the wood, though resistant to rot, is brittle and was rarely used for anything more substantial than grape stakes and shakes, even toothpicks. As much as 75% of the wood went to waste, as most of the trees shattered when they hit the ground. Loggers would build trenches filled with tree branches for the trees to have a soft landing, but to no avail.
The remaining trees have been protected since the 1920s, but they still face some serious threats. The trees are adapted to fire. Their trunks are very thick and do not readily burn, so the wildfires that would burn through the grove every decade or so would kill off saplings of other trees and clear the forest duff, but would rarely kill the Sequoia trees. The nature of the fires has been changing. The policy of the Forest Service for decades was to suppress fires at all cost, allowing the other conifers like White Fir and Sugar Pine to grow very tall, reaching the lowest branches of the giant Sequoia trees.
Sugar Pines are especially susceptible to catching fire, and the fire rises up the trunk into the crown. Crown fires can kill the Sequoia trees by destroying their foliage. So by protecting the trees from fire, we've made it easier for fire to destroy them. The situation has not been helped by the growing effects of global warming. Ongoing drought has led to super wildfires on a scale never before seen in the Sierra Nevada. Several recent fires burned through 200,000 acres or more.
The deep conifer forests threaten the Sequoia trees in a different way. The seedlings need bare soil and sunny conditions to germinate, but the thick forest instead provides shade and thick forest duff. The remaining ancient giants are not being replaced by young trees, not at a rate fast enough to guarantee the future of the grove.
At least we've reached a point where we know what many of the problems are, and steps (sometimes baby steps) are being made to preserve the future of these incredible trees. In the meantime, the Nelder Grove is a quiet treasure, a beautiful place for meditation.
The Nelder Grove is off of Sky Ranch Road, about 8 miles off of Highway 140 north of Oakhurst, just a few miles from the south entrance of Yosemite National Park. The last two miles of road are unpaved, but the gravel is well-graded. Our walk was along the Shadows of the Giants trail, but there is a network of trails throughout the grove. The Mariposa Grove in Yosemite is presently closed to visitation as the site is being renovated to improve the visitation experience and protect the trees. Of course when it is finished, the grove will still be visited by hundreds of thousands of people yearly. If you want to see a Sequoia grove the way it should be, quiet and uncrowded, check out Nelder. For more information, check out the web pages of the Friends of Nelder Grove, or this Sierra Nevada Geotourism site.