The history of pursuing hydrographic measurement accuracy

Leadline sounding operation.
(Photo: 1928 and 1931, Hydrographic Manual)

From Hydro

The profession of hydrographer is built upon measurement accuracy.
Ever since Lucas Janszoon Waghenaer produced the first true nautical charts in 1584, hydrographers have been working to improve the accuracy of their measurements.
For anyone fortunate enough to have reviewed Waghenaer’s atlas, the 'Spieghel der Zeevaert' (The Mariner’s Mirror), one of the first questions that comes to mind is how accurate are these charts?

As the technology of the times was crude at best, it would be difficult to evaluate his charts by modern standards.
However, two soundings stand out as indicative of both the relative accuracy of his data and Waghenaer’s integrity.

Study of Waghenaer’s charts reveals that there are few soundings deeper than 30 fathoms: one 60-fathom sounding, and one anomalous nearshore sounding of 200 fathoms.
This 200-fathom sounding was the final sounding of a line of soundings that ended with 7, 50, and then 200 fathoms.
Was this a blunder on Waghenaer’s part, an error on the part of the engraver, or indicative of the real configuration of the seafloor?

Comparison with a modern bathymetric map gave the answer.
These two soundings were made at the head of Subetal Canyon – a large canyon incising the Portuguese continental shelf and slope.
The soundings are convincing evidence of Waghenaer’s integrity as a hydrographer and also his commitment to producing charts that were as accurate as the technology of the times permitted.

Waghenaer's Chart No. 17.
It is oriented with North to left.
200 fathom sounding on north wall of Subetal Canyon is to east of Cape Spichel.

 

Cape Spichel with the GeoGarage platform (UKHO nautical chart)

 
For the next 340 years, little was done to improve the accuracy of depth sounding instrumentation.
The hydrographer was constrained to using the lead line.
However, positioning technology began improving in the eighteenth century with the invention of octant, sextant, chronometer and station pointer.
These inventions, coupled with the evolving understanding that depth information had to be placed in the same geographic framework as the shoreline and landmarks shown on charts, led to a quantum leap in the accuracy of charts.
This new understanding was driven by the work of such British hydrographers as Murdoch Mackenzie Senior, Murdoch Mackenzie Junior, Graeme Spence and the incomparable James Cook.

Triangulation Network

In 1747, Mackenzie Senior was the first hydrographer to develop a local triangulation scheme during his survey of the Orkney Islands.
In 1750, he wrote, “The lives and fortunes of sea-faring persons, in great measure, depend on their charts.
Whoever, therefore, publishes any draughts of the sea-coast is bound in conscience, to give a faithful account of the manner and grounds of performance, impartially pointing out what parts are perfect, what are defective, and in what respects each are so….”

He then went on to describe his methodology of measuring a baseline, developing a triangulation network, building “beacons, or landmarks” over prominent points in the network, and then positioning his sounding boat by taking intersecting compass bearings to these points during sounding operations.
The weakest link in this methodology was the use of compass bearings to position the sounding boat.
Murdoch Mackenzie rectified this situation in 1775 with the invention of the station pointer, or as it is known in the United States, the three-arm protractor.
This instrument allowed hydrographers to plot three-point sextant fixes which resulted in horizontal accuracies of less than ten metres within the bounds of the triangulation scheme.
By 1785, George Vancouver was able to report regarding his survey of the Kingston, Jamaica harbour that, “The positive situation of every point and near landmarks as well as the situation and extent of every Shoal has been fixed by intersecting Angles, taken by a sextant and protracted on the Spot, the Compasses only used to determine the Meridian, and observe its Variation.”

Swiss Precision

The United States began making contributions to the sciences of geodesy and hydrography in 1807 with the beginnings of the Survey of the Coast of the United States.
The Swiss immigrant, Ferdinand Hassler, was chosen to head this embryonic organization.
He combined the talents of mathematician, geodesist, metrologist, instrument-maker, linguist, and even legal expert.
Not only had he worked on the trigonometric survey of Switzerland, he had also served as its attorney general in 1798.
Hassler procured books and instruments for the Coast Survey between 1811 and 1815 and then started the field work in 1816.
In 1818, a law was passed forbidding civilians from working on the survey.
Hassler retired to a home in western New York for the next 14 years until recalled to head the survey again.
In 1825, he published Papers on Various Subjects connected with the Survey of the Coast of the United States in the Transactions of the American Philosophical Society.
This document served as the philosophic underpinning of the work and role of the Coast Survey.

NOAA's Ferdinand R.Hassler (S 250) is a coastal mapping vessel.
(Photo: NOAA)

The twin themes of standards and accuracy permeate the ‘Papers’.
The word ‘standard’ is used as either noun or verb over 60 times.
The word ‘accurate’ or its derivative forms have over 120 occurrences throughout the document.
These simple words, combined with the inherent integrity of Ferdinand Hassler, were the foundation of the Survey of the Coast.
Hassler addressed the concept of accuracy in the ‘Papers’ with many practical examples of means to eliminate or reduce error and thus increase the accuracy of the final results of observation and measurement.
But he made a philosophical leap when he stated: “Absolute mathematical accuracy exists only in the mind of man.
All practical applications are mere approximations, more or less successful.
And when all has been done that science and art can unite in practice, the supposition of some defects in the instruments will always be prudent.
It becomes therefore the duty of an observer to combine and invent, upon theoretical principals, methods of systematical observations, by which the influence of any error of his instruments may be neutralized, either by direct means, or more generally by compensation.”

The observer must also counteract those errors “to which he himself is liable in making his observations.
Without such a method, and a regular system in his observations, his mean results will be under the influence of hazard, and may even be rendered useless by adding an observation, which would repeat an error already included in another observation.”

The Law of Human Error

Two surprisingly modern concepts that Hassler addressed were personal bias in the observation of physical phenomena and the effect of personal comfort, in other words ergonomics, upon the observer’s results.
He was among the first to take steps to mitigate various systematic errors and analyse their causes.
Further advances in understanding were made by Benjamin Peirce, head of Coast Survey longitude operations in the 1850s, and Charles Schott, the chief mathematician and geodesist of the Coast Survey.
Their work, like Hassler’s, was related to terrestrial positioning problems but ultimately this led to more accurate nautical charts.

The three-point sextant fix was the most accurate positioning technique for inshore hydrographic surveying for nearly 200 years.
Plotting a three-point sextant fix.

Peirce began with the supposition that with only one observation of a physical quantity, that observation must be adopted as the true value of the constant.
However, “A second observation gives a second determination, which is always found to differ from the first.
The difference of the observations is an indication of the accuracy of each, while the mean of the two determinations is a new determination which may be regarded as more accurate than either.”

As more and more observations are acquired: “The comparison of the mean with the individual determinations has shown, in all cases in which such comparison has been instituted, that the errors of … observation are subject to law, and are not distributed in an arbitrary and capricious manner.
They are the symmetrical and concentrated groupings of a skillful marksman aiming at a target, and not the random scatterings of a blind man, nor even the designed irregularities of the stars in the firmament.
This law of human error is the more remarkable, and worthy of philosophic examination, that it is precisely that which is required to render the arithmetical mean of observations the most probable approach to the exact result.
It has been made the foundation of the method of least squares, and its introduction into astronomy by the illustrious Gauss is the last great era of this science.”

Peirce continued: “If the law of error embodied in the method of least squares were the sole law to which human error is subject, it would happen that by a sufficient accumulation of observations any imagined degree of accuracy would be attainable in the determination of a constant; and the evanescent influence of minute increments of error would have the effect of exalting man’s power of exact observation to an unlimited extent.
I believe that the careful examination of observations reveals another law of error, which is involved in the popular statement that ‘man cannot measure what he cannot see’.
The small errors which are beyond the limits of human perception, are not distributed according to the mode recognized by the method of least squares, but either with the uniformity which is the ordinary characteristic of matters of chance, or more frequently in some arbitrary form dependent upon individual peculiarities – such, for instance, as an habitual inclination to the use of certain numbers.
On this account it is in vain to attempt the comparison of the distribution of errors with the law of least squares to too great a degree of minuteness; and on this account there is in every species of observation an ultimate limit of accuracy beyond which no mass of accumulated observations can ever penetrate.”
Improving the Methods

“A wise observer, when he perceives that he is approaching this limit, will apply his powers to improving the methods, rather than to increasing the number of observations.
This principle will thus serve to stimulate, and not to paralyse effort; and its vivifying influence will prevent science from stagnating into mere mechanical drudgery....”

Peirce’s words are at the heart of modern hydrographic surveying.
With the coming of electronic systems, the need to analyse and understand sources of error and the limits of accuracy of those various systems has been of paramount importance.
From the early twentieth century onward, generations of hydrographers have studied the limitations of and made improvements to their navigation systems and sounding systems.
They have not ‘stagnated’, but instead have concentrated their efforts on ‘improving of methods’.
One wonders what our future ‘ultimate limit of accuracy’ will be.

In the third quarter of the 20th century, several evolutionary concepts were advanced that fundamentally changed the way we map the seafloor.
(Courtesy: NOAA)

Links :

• GeoGarage blog : The hydrography of the former Zuiderzee

ClimaCell, an ambitious private weather firm, plans to launch its own satellites

 Artistic rendering of a ClimaCell satellite. (ClimaCell)

 

From WP by Andrew Fredman

The company would be the first to operate a satellite fleet to improve its own forecasts, rather than selling the data to others

ClimaCell, a growing private weather company based in Boston whose customers include airlines, maritime shipping firms and everyday consumers, plans to spend $150 million during the next few years to launch its own satellite radar constellation.

The goal, company leaders said in an interview, is to make its own forecasts more reliable, thereby benefiting its clients, the public through its weather app and policymakers.

This aim contrasts with the business of most, if not all, space companies today that are pursuing weather applications. 

These firms, such as GeoOptics and Spire, have business models based on selling the data for others to use in forecasting the weather, with customers that include federal agencies.

However, ClimaCell would use its own technology, which already includes proprietary weather modeling, to take advantage of the data it gathers from space.

The end result, if all goes well, would be a vertically integrated weather company whose operations range from generating its own data to sifting through that information using computer models and turning that into products aimed at improving how businesses operate.

According to ClimaCell co-founder and chief executive Shimon Elkabetz, ClimaCell has several dozen scientists and engineers now dedicated to developing and eventually deploying a fleet of small space-based weather radars that could gather real-time data of every location on the globe at any time.

This would be a major leap forward for radar coverage over data-sparse regions, he said, such as Africa, South America and the oceans.

The satellites would carry a Ka-band radar instrument, Elkabetz said, which he compared to a research mission that NASA has carried out known as the Global Precipitation Measurement (GPM) satellite.

GPM consists of a dual-frequency radar that allows it to get a three-dimensional view of precipitation falling within a storm, including by seeing the distribution of different droplet sizes within the clouds, according to Dalia Kirschbaum, who heads NASA’s hydrological sciences lab at the Goddard Space Flight Center in Greenbelt, Md.

The downside to GPM is that it is just one satellite. 

“When you have a single orbiting spacecraft, if you don’t get a good [pass over] a storm, then you just miss it,” she said.

The space agency has also launched small satellites, such as rainCube, which was deployed from the International Space Station, to help solve the challenge of building powerful radars in small boxes, Kirschbaum said.
“The instrument will offer similar capabilities” to the radar aboard GPM, Elkabetz said, “in terms of both resolution and sensitivity, but exceed the swath,” or scan footprint, by a factor of more than two.

To accomplish this, the company is planning to use its own technologies to develop a new radar and antenna. ClimaCell is seeking to lower the costs per satellite by at least half compared with the NASA satellite, which scans a location on Earth only every three days.

The cost savings, Elkabetz said, “will allow us to scale this from a single-satellite mission to a constellation of dozens of satellites that enables global coverage with high revisit rates.”

Rei Goffer, co-founder and chief strategy officer at ClimaCell, said revisit times, the interval between instances when the satellite passes over the same location on Earth, would be one hour in the company’s planned satellite constellation.
“We are not going to space just because it’s cool,” Goffer said in an interview, but instead are trying to solve a data gap that could allow the company to make far more accurate forecasts.

Outside experts, such as Brian Weeden of the Secure World Foundation, questioned whether the new satellites would interfere with other spacecraft also operating within the Ka band of spectrum, including planned 5G satellites and other weather satellites already in low Earth orbit.

Elkabetz said he expects to encounter skepticism from those who may not believe that ClimaCell has solved some of the technical challenges in developing and deploying these satellites.

If he were not involved in the project already, he would not believe it, either, he said.

“I respect anyone who thinks it’s difficult, and as we are able to reveal in the future how it works, hopefully people will be able to witness it themselves,” he said in an interview.

Marshall Shepherd, director of the University of Georgia’s atmospheric sciences program, said he sees this project as a way to better predict weather extremes.
“Precipitation is at the heart of many weather-related extremes ranging from flooding to hurricanes, yet is very difficult to measure on global scales,” Shepherd said in an email.

Estimates of rainfall rates on July 8, 2019, a day that brought flooding to the D.C. region, from NASA's Global Precipitation Measurement Core Observatory. (NASA)

“I am not surprised that scholars are exploring new ways to provide measurements with the accuracy and resolution useful for applications.”

ClimaCell has raised a substantial amount of money for a recent entrant into the weather forecasting business: about $112 million in venture capital funding, with the most recent round closing in July 2020.

Elkabetz noted that most of the world still does not have radar coverage, including in Latin America, Africa, the Middle East and Asia.
“The system’s capabilities will enable new modeling and analytics with precision never before available in the developing world,” he said.

“The data will power applications such as monitoring the conditions favorable for locust reproduction and migrations, as well as conditions that lead to devastating infectious diseases such as malaria, which put millions of lives and livelihoods at risk,” Elkabetz said in a statement.

The satellites could significantly help hurricane forecasts, he said, since they would provide details about the structure and evolution of such storms.

The National Hurricane Center has utilized data from the GPM mission and previous weather satellites for forecasting purposes.

The chief engineer for the program is John Springmann, who has worked with private sector space firms including SpaceFlight industries, which launched the BlackSky constellation.

The team has also been working with Kerri Cahoy, co-director of the small-satellite center at MIT.

ClimaCell is aiming to launch its first radar satellite in the third quarter of 2022.

Through the company’s nonprofit arm known as ClimaCell.org, the satellite data could flow to areas where improved forecasts are desperately needed, mainly in the developing world, Goffer and Elkabetz said.

Links :

• WP : Private weather company ClimaCell to spin off nonprofit to tackle weather forecasting, early warnings in Africa / Meet the ClimaCell weather app. Alerting you when it’s about to rain / NASA launches game-changing satellite for tracking global precipitation / Weather is turning into big business. And that could be trouble for the public.  
• SpaceNews : ClimaCell to launch dozens of radar satellites to improve forecasts
• Spacefligth Now : Russia launches Arctic weather satellite
• NYTimes : How We Can Better Predict Weather Catastrophes  

Brunt Ice Shelf in Antarctica calves

First imageFirst image of the newly calved Brunt Ice Shelf from Sentinel 2!

Taken (26th Feb) at 09:40:19 UTC.

From BAS

A huge iceberg (1270 km²) the size of the county of Bedfordshire has broken off the 150-m thick Brunt Ice Shelf, almost a decade after scientists at British Antarctic Survey (BAS) first detected growth of vast cracks in the ice.

The Brunt Ice Shelf is the location of British Antarctic Survey’s (BAS) Halley Research Station.
BAS glaciologists, who have been expecting a big calving event for at least a decade, say that the research station is unlikely to be affected by the current calving.
The 12-person team working at the station left mid-February by BAS Twin Otter aircraft.
The station is now closed for the Antarctic winter.

North Rift crack photographed by Halley team in January 2021

The first indication that a calving event was imminent came in November 2020 when a new chasm – called North Rift – headed towards another large chasm near the Stancomb-Wills Glacier Tongue 35 km away.
North Rift is the third major crack through the ice shelf to become active in the last decade.

During January, this rift pushed northeast at up to 1 km per day, cutting through the 150-m thick floating ice shelf.
The iceberg was formed when the crack widened several hundred metres in a few hours on the morning of 26th Feb, releasing it from the rest of floating ice shelf.

 

Map of Brunt ice shelf and Halley Research Station

The glaciological structure of this vast floating ice shelf is complex, and the impact of ‘calving’ events is unpredictable.
In 2016, BAS took the precaution of relocating Halley Research Station 32 km inland to avoid the paths of ‘Chasm 1’ and ‘Halloween Crack’.

Since 2017, staff have been deployed to the station only during the Antarctic summer, because during the dark winter months evacuation would be difficult.
‘Chasm 1’ and ‘Halloween Crack’ have not grown in the last 18 months.

Professor Dame Jane Francis, Director of British Antarctic Survey says:
“Our teams at BAS have been prepared for the calving of an iceberg from Brunt Ice Shelf for years.
We monitor the ice shelf daily using an automated network of high-precision GPS instruments that surround the station, these measure how the ice shelf is deforming and moving.
We also use satellite images from ESA, NASA and the German satellite TerraSAR-X.
All the data are sent back to Cambridge for analysis, so we know what’s happening even in the Antarctic winter, when there are no staff on the station, it’s pitch black, and the temperature falls below minus 50 degrees C (or -58F).

Two of our GPS units on the new iceberg show it is just drifting around with the tides at the moment #A74 #BruntIceShelf @BAS_News pic.twitter.com/9c5x0npBUI

— Oliver Marsh (@ojmarsh) February 27, 2021

“Over coming weeks or months, the iceberg may move away; or it could run aground and remain close to Brunt Ice Shelf.
Halley Station is located inland of all the active chasms, on the part of the ice shelf that remains connected to the continent.
Our network of GPS instruments will give us early warning if the calving of this iceberg causes changes in the ice around our station.”

Simon Garrod, Director of Operations at British Antarctic Survey adds:
“This is a dynamic situation. Four years ago we moved Halley Research Station inland to ensure that it would not be carried away when an iceberg eventually formed. That was a wise decision.
Our job now is to keep a close eye on the situation and assess any potential impact of the present calving on the remaining ice shelf.
We continuously review our contingency plans to ensure the safety of our staff, protect our research station, and maintain the delivery of the science we undertake at Halley.”

More information

About Halley VI 

Halley VI Research Station is an internationally important platform for, atmospheric and space weather observation in a climate-sensitive zone.
In 2013, the station attained the World Meteorological Organization (WMO) Global Atmosphere Watch (GAW) Global station status, becoming the 29th in the world and 3rd in Antarctica.

Halley VI Research Station sits on Antarctica’s up to 150–m thick Brunt Ice Shelf.
This floating ice shelf flows at a rate of up to 2 km per year west towards the sea where, at irregular intervals, it calves off as icebergs.

Long-term monitoring of the natural changes that occur in the ice shelf has revealed changes, including growth of a recently-formed chasm, the North Rift.
Halley VI Research Station has been unoccupied during the last four winters because of the complex and unpredictable glaciological situation.

Change in the ice at Halley is a natural process and there is no connection to the calving events seen on Larsen C Ice Shelf, and no evidence that climate change has played a significant role.

During the 2016-17 Antarctic Summer season (Nov-March), in anticipation of calving, the eight station modules were uncoupled and transported by tractor to a safer location upstream of Chasm-1.

Over the summer 18/19, BAS installed an autonomous power generation and management system – Halley Automation project – which provides a suite of scientific instruments with power even when we have no staff at the station.
This system has proved effective in running through more than eight months of darkness, extreme cold, high winds and blowing snow and delivering important data back to UK.

There have been six Halley research stations on the Brunt Ice Shelf since 1956.

About Chasm 1

In 2012, satellite monitoring revealed the first signs of change in a chasm (Chasm 1) that had lain dormant for at least 35 years.  This change had implications for the operation of Halley VI Research Station.
In the 2015/16 field season, glaciologists used ice penetrating radar technologies to ‘ground truth’ satellite images and to calculate the most likely path and speed of Chasm 1.
Chasm 1 grew up until 2019 but has not moved for the past 18 months.
There is now 2 km of ice holding this iceberg in place.

About Halloween Crack

In October 2016, a new crack was detected some 17 km to the north of the research station across the route sometimes used to resupply Halley.  The ‘Halloween Crack’ continues to widen and a second large iceberg may calve to the north’.
The tip of Halloween Crack is also currently static.

About North Rift Crack

In November 2020, a new chasm, known as the North Rift opened and started extending towards Brunt-Stancomb Chasm.
The Brunt Ice Shelf is probably the most closely monitored ice shelf on Earth.
A network of 16 GPS instruments measure the deformation of the ice and report this back on a daily basis.
European Space Agency satellite imagery (Sentinel 2), TerraSAR-X, NASA Worldview satellite images, US Landsat 8 images, ground penetrating radar, and on-site drone footage have been critical in providing the basis for early warning of changes to the Brunt Ice Shelf.
These data have provided science teams with a number of ways to measure the width of Chasm 1 and changes to the Halloween Crack and North Rift crack, with very high precision.
In addition, scientists have used computer models and bathymetric maps to predict how close the ice shelf was to calving.

About Halley science 

 
Ozone measurements that have been made continuously at Halley since 1956 (which led to the discovery of the ozone hole in 1985, and since that time, its slow progress towards recovery)
Monitoring of space weather undertaken at Halley contributes to the Space Environment Impacts Expert Group that provides advice to UK Government on the impact of space weather on UK infrastructure and business.

 

Links :

• The Guardian : Iceberg size of Greater London breaks off Antarctica
• BBC : Brunt Ice Shelf: Big iceberg calves near UK Antarctic base

The Long Leg , Edward Hopper (1935)

Messing about on boats all summer is a holiday lived in the present; that’s the sense of this picture.

The boat remains still; it is the wind and water that move it along.
Hopper’s coolly beautiful painting of a sailboat off the New England shore perfectly expresses this curious fact about sailing.
And in conditions like these – a hot blue day, windless, the sun beating down on the blanched sand – the boat is lying almost motionless to one side, solitary as the characteristic Hopper lighthouse in the background.
Like the water itself, the painting is almost entirely composed in shades of blue.

 

Links :

• GeoGarage blog : Ground swell

Underwater photographer of the year 2021

Renee Capolzzola (USA), for her graceful image: “Shark’s Skylight“.

 
The full set of UPY2021 results is now available to view in the Winners’ gallery, and the complete collection is available to download and keep in the free Yearbook.

The UPY team would like to thank all the talented photographers who supported this year’s competition with their pictures, especially in these challenging times.

We hope that this year’s stunning collection of winning images provides a welcome escape to everyone who enjoys them and a chance to reconnect with the underwater world.

The Titanic disaster and its aftermath

View of the bow of the RMS Titanic photographed in June 2004 by the ROV Hercules during an expedition returning to the shipwreck of the Titanic.
(Courtesy of NOAA/Institute for Exploration/University of Rhode Island)

From Hydro by Albert E. Theberge

Understanding the Unthinkable

In the night of 14 April 1912, the unthinkable happened.
The mightiest ship afloat, the brand new White Star Line ship Titanic, was on its maiden voyage from Southampton, England, to New York.
The ship was advertised as unsinkable.
And, if unsinkable, why should there be adequate lifeboats for all of the passengers and crew? The ship departed from Southampton on 10 April.
Less than five days later, it was at the bottom of the Atlantic Ocean.
More than 1,500 people perished within three hours of striking an iceberg, which ripped the bottom out of the ship.

How this happened is a story told many times.
Human hubris, unswerving trust in the infallibility of technology, and the commercial impetus of fast Atlantic passages all contributed to the loss of the ship and the accompanying loss of life.
Even as the ship was settling in the waters of an icy North Atlantic, some survivors reported that there was a belief among many passengers that the ship was the safer place to be; accordingly, not all the lifeboats were filled to capacity.

This accident shocked the international community.
The British and American governments investigated the accident – the British determined: “That the loss of said ship was due to collision with an iceberg, brought about by the excessive speed at which the ship was being navigated.” Certainly, that was the major factor.
However, like many accidents, there were a number of contributing causes.
These included: watertight bulkheads that were improperly designed; an insufficient number of lifeboats and life rafts; apparent lack of concern by the captain concerning reports of ice prior to collision with the iceberg; little training of crew in emergency procedures including lowering of lifeboats; no radio watches on nearby ships which could have assisted in lifesaving efforts; and, remarkably, not even binoculars for the ship’s lookouts.

Steamship Titanic showing length as compared with highest buildings.

Both the British and American governments arrived at similar conclusions and recommendations following the loss of the Titanic.
The chief recommendation was that all ships be equipped with sufficient lifeboats for passengers and crew, that all ocean-going ships maintain 24-hour radio-telegraph watches, and that bulkheads be designed such that flooding of any two adjacent compartments would not result in sinking of a vessel.
These recommendations and others were adopted by the first International Convention for the Safety of Life at Sea (SOLAS) at a conference held in London in 1914.

Development of Seafloor Mapping Technologies

Commercial concerns saw an opportunity in the Titanic disaster and began searching for a means to determine the presence of icebergs and other unseen or submerged obstructions forward of moving vessels.
European and North American inventors joined the race.
In 1912, Reginald Fessenden, a Canadian inventor and radio pioneer, joined Submarine Signal Company, a forerunner of today’s Raytheon, and began work on an electro-acoustic oscillator similar to a modern transducer.
This oscillator was originally designed for both ship-to-ship communication and to receive reflected sound from an underwater object.
In late April 1914, Fessenden tested this device off the Grand Banks on the US Revenue Cutter Miami and succeeded in reflecting sound off an iceberg at a range of approximately two miles and hearing the return echo.
A second echo was heard that was determined to be from the bottom.

Submarine warfare during World War I accelerated research into the field of acoustics.
By the end of the war, the use of acoustics for both detection of objects in the water and measuring depth had been proven.
In 1922, the USS Stewart, equipped with a Hayes Sonic Depth Finder that utilized a Fessenden oscillator, ran a line of soundings across the Atlantic Ocean taking over 900 individual soundings.
The profile obtained from these soundings was published in the first issue of the International Hydrographic Review.
Piano-wire sounding systems became obsolete overnight.
Although leadline sounding continued for a number of years in shallow water, acoustic sounding systems replaced the leadline for most purposes within two decades.

World War II further accelerated the development of directional sonar systems (called Asdic in England).
Although meant originally for detection of submarines, these systems ultimately developed into modern side-scan sonar systems.
Underwater photography equipment and magnetic anomaly detection (MAD) instruments were in their infancy during this period.
MAD systems were proved effective in detecting submarines.
An early use by hydrographers of the complementary use of sonar, underwater photography and MAD gear was in the charting of ships torpedoed off the United States East Coast.
This was done by Coast and Geodetic Survey (C&GS) officers working off the Coast Guard buoy tender Gentian in 1944.

Following the war, there were further advances, including the development of an early side-scan sonar system called Shadowgraph in 1954 by German scientist Julius Hagemann, who was working at the United States Navy Mine Defense Laboratory.
This system remained classified for many years, but civil use of side-scan began developing shortly after this advance.
In the commercial sector, Harold Edgerton of the Massachusetts Institute of Technology (MIT) and Martin Klein, also of MIT, were early pioneers.
Edgerton turned a bottom-penetration sonar on its side in 1963 and imaged a sunken lightship from a C&GS vessel.
Edgerton was a founder of EG&G and discovered the Civil War era USS Monitor off Cape Hatteras with an EG&G commercial side-scan system.
Martin Klein began his career with EG&G but left to found Klein Associates, a name synonymous with side-scan technology.

Advances in depth measurement technology paralleled the development of side-scan technology.
In April 1961, engineers at General Instruments Corporation developed a proposal for BOMAS, Bottom Mapping Sonar.
Quoting from the proposal: “BOMAS derives bottom profile information from the intersection of the ocean bottom with a vertical plane perpendicular to the heading of a ship.
The sonar data is processed automatically and in real time to provide a depth contour strip map….
A sonar intensity map can be provided simultaneously….” 

Multi-beam sounding with its attendant bottom reflectivity mapping capability was born.
Two years later, the first prototype multi-beam system was installed on the USS Compass Island and subsequent units installed on Navy survey ships.
In the meantime, the acronym had changed to SASS (Sonar Array Sounding System).
By the late 1970s, the technology had migrated to the civil community and has since displaced single beam sounding systems as the standard seafloor mapping tool.

Painting of the Titanic sinking by the bow, with people rowing a lifeboat in the foreground and other people in the water.
Icebergs are visible in the background.
(Engraving by Willy Stöwer: Der Untergang der Titanic) 

Finding Titanic and the Aftermath of the Discovery

In the immediate aftermath of the sinking, proposals to locate the sunken Titanic were discussed and ultimately dismissed because the wreck lay well beyond the limits of technology at that time.
Through the decades, the development of subsea technology finally provided the means to locate the wreck and subsequently to not only investigate it using remote technology, but also to dive to the wreck and conduct a series of investigations that included surveys of the interior of the ship.

In July 1985, the final search began, with Ifremer deploying their newly developed side-scan sonar SAR vehicle on a mission led by Jean-Louis Michel on the research vessel Le Suroit.
That survey covered 70% of a 150 square nautical mile survey box without locating the Titanic.
Picking up the search in August, the WHOI team, led by Robert Ballard aboard the research vessel Knorr, utilized the towed vehicle Argo, with a 100kHz side-scan sonar, and three low-light black and white video cameras.
Ballard’s team relied on the optical system to locate the Titanic, and in the early morning hours of 1 September, the unmistakable form of a boiler made it clear that the search was over.
Titanic’s final resting place had been found.

Since the discovery in 1985, a series of expeditions have visited the Titanic with a variety of goals.
Ballard and Woods Hole returned to the wreck in July 1986 on the WHOI research vessel Atlantis II, with the submersible Alvin, and the ROV Jason Jr.
The 1986 expedition photographed and filmed the wreck, focusing on the largely intact bow section.
Working from the data collected from the 1985 Argo survey as well as 1986 data, WHOI’s William Lange and others assembled a preliminary site map of the Titanic wreck site that delineated the site from the bow to the stern section and plotted a wide range of features scattered on the seabed.
A private venture funded and led by RMS Titanic, Inc., the salvor-in-possession of the wreck (RMST), and technically supported by Ifremer, returned to the wreck in July 1987 and made 32 dives to recover some 1,800 artifacts from the seabed, the first of a series of recovery dives made by RMST until 2004, which ultimately salvaged nearly 5,000 artifacts.

The remotely operated vehicle (ROV) Hercules exploring the bow of the Titanic, 2004.
(Courtesy: Institute for Exploration/University of Rhode Island/NOAA

Dives made by documentary film crews and James Cameron (whose first dives were in 1995) working with the P.P.
Shirsov Institute, captured dramatic images of the wreck as well as additional technical information and a more detailed view of aspects of the wreck site in the Mir submersibles.
In particular, Cameron’s extensive documentation and penetration of the interior of the bow with small ROVs known as ‘bots’ provided incredible insights into the ongoing processes of environmental change and preservation inside the ship, as well as evidence of what had occurred during the sinking of the Titanic.
Cameron’s work has arguably done more to share the Titanic as a wreck site with a greater audience than anyone else.

The scientific products of the various expeditions include a detailed analysis of the microbiological corrosion of the ship’s steel (led by Roy Cullimore), geological studies of the sediments and current studies (by the Shirsov Institute), a detailed sonar survey of the bow where the Titanic struck the iceberg, photo mosaics of the bow section, and forensic studies of the ship’s sinking sequence and break-up.
In addition, RMS Titanic, Inc. commissioned the creation of an ‘archaeological GIS’ map delineating where the 5,000 artifacts had been recovered from between 1987 and 2004.
That GIS, which is being completed by RMST under contract by the Center for Maritime & Underwater Resource Management of Michigan, a private non-profit, is reported to be nearly complete.

The National Oceanic & Atmospheric Administration’s Office of Ocean Exploration conducted two missions to the Titanic in 2003 and 2004.
As the nation’s ocean agency, NOAA has an interest in the scientific and cultural aspects of the Titanic.
NOAA’s focus is to build a baseline of scientific information from which we can measure the processes and deterioration of the Titanic, and apply that knowledge to many other deepwater shipwrecks and submerged cultural resources.
The 2003 mission, with the Shirsov Institute, had several key goals, the first being to catalogue any anthropogenic activities currently impacting the wreck site, or evidence of such activity since its discovery in 1985.
Digital imagery was obtained and a deck-view mosaic of the bow section was created.
Additionally, ongoing bacteriological analysis was conducted as well as basic oceanographic research.

The 2004 Mission, Conducted On Board the NOAA Research Vessel

Ronald H. Brown, working with Robert Ballard, then (and now) with the University of Rhode Island and the Institute of Archaeological Oceanography, utilized an ROV to continue the assessment of the wreck’s ongoing environmental changes and the bacteriological work of Roy Cullimore.
One other key achievement of the 2004 mission was the completion of a topographic map of Titanic Canyon and the surrounding area, including the wreck of the Titanic, with a Seabeam 2112 multi-beam sonar system.
The digital terrain model of this large area of seabed places the Titanic within a larger geological and geographical context.

NOAA also participated, as did Woods Hole, the National Park Service, the Institute of Nautical Archaeology, the Waitt Institute and contracted partners such as Phoenix International, Ltd., in RMS Titanic, Inc.’s last (to date) expedition to the wreck in August 2010.
This mission, with a non-recovery scientific focus, focused on William Lange’s and the WHOI Advanced Imaging and Visualization Laboratory’s work to create a detailed 2D and 3D visual mosaic of the site.
To do so, it made a detailed survey using the Waitt Institute’s REMUS 6000 autonomous underwater vehicles of an approximately ten square nautical mile survey zone around the wreck site, with a series of closer, higher resolution surveys of the area delineated in the 1986 WHOI map of the site and even closer surveys of key features and areas of the site.
That project was successful in generating the mapping data as well as comprehensive visual coverage of the wreck, including detailed photo mosaics of a number of features in the artifact scatter, which included sections of the ship’s hull, machinery and equipment and other artifacts.

This composite image, released by RMS Titanic Inc., and made from sonar and more than 100,000 photos taken in 2010 by unmanned, underwater robots, shows a small portion of a comprehensive map of the 3-by-5-mile debris field surrounding the bow of the Titanic on the bottom of the North Atlantic Ocean (Courtesy: AP Photo/RMS Titanic Inc.)

What is clear in this brief overview is that the last few decades have witnessed a revolutionary expansion of humanity’s capacity to not only locate deep-sea shipwrecks, but increasingly to capture imagery and data that essentially ‘virtually raises’ these wrecks for ongoing research as well as public education.
In many ways, the Titanic and the surrounding area are likely to be the best-studied section of the deep ocean floor.
That status has come because of the iconic nature of the wreck and the potential for profit from the opportunity to connect to this ship and its tragic loss either through a tour of the recovered artifacts or a virtual tour on film or in a photograph.
At the same time, measurable and important science has been conducted, and in that, a way forward for not only this site but others has been demonstrated, especially in the adaptation and adoption of technology to access and learn from sites once thought unreachable.

Links :

• GeoGarage blog : Explorers can take Titanic's Marconi ... / Scientist's theory of climate's Titanic moment ... / Titanic sank due to enormous uncontrollable ... / Challenge to Titanic sinking theory/ Titanic sinks in real time / New images of Titanic wreck revealed / New expedition to Titanic site will create 3D ... / Titanic items to be sold 100 years after sinking / First map of entire Titanic wreck site sheds ... / Vow to “virtually raise the Titanic”: new 3-D ... / Her tale will go on: Titanic survivor's story ... / Titanic threat: why do ships still hit icebergs? / Could a Titanic seawall save this quickly ...

Scientists use nuclear reactor to investigate Amelia Earhart’s mysterious disappearance

Earhart beneath the nose of her Lockheed Model 10-E Electra, March 1937, Oakland, California, before departing on her final round-the-world attempt prior to her disappearance.

Credit: Wikimedia Commons.

From ZMEScience by Tibi Puiu

A metal plate thought to have once belonged to Earhart's plane was probed for hidden secrets using neutron beams.

One of the bravest women of the 20th century, Amelia Earhart, vanished unexpectedly during her attempt to fly around the world.

Now, scientists have turned to nuclear technology to analyze a piece of metal debris that some suspect was part of Earhart’s wrecked plane. In doing so, they hope to piece together the final moments of the pioneering aviator’s final living hours. 

A tragic end to a brave pioneer

Amelia Earhart was the first female pilot to fly across the Atlantic Ocean.

In 1937, Earhart and her navigator, Fred Noonan, were flying their Lockheed Model 10-E Electra on an even more ambitious quest: flying around the world.

On July 2, 1937, they were about six weeks and 20,000 miles into their journey when their plane suddenly crashed en route to Howland Island in the Pacific, which is halfway between Hawaii and Australia. 

 

Howland island with the GeoGraage platform (NGA/NOAA source)

 

The Howland Island is a flat sliver of land about 2,000 meters (6,500 feet) long and 460 meters (1600 feet wide), so it must have been very difficult to distinguish from similar-looking clouds’ shapes from Earhart’s altitude.

Of course, Earhart and Noonan were well aware of the challenges, which is why they had an elaborate plan that involved tracking their routes using celestial navigation and linking to a U.S. Coast Guard vessel stationed off Howland Island using radios.

But despite their well-thought-out contingency plans, the pair were simply flat out of luck.

When they took off, witnesses reported that a radio antenna may have been damaged by the maneuver. On that morning, there were also extensive overcast conditions.

Later investigations also showed that the fliers may have been using outdated, inaccurate maps.
 

 

On the morning of July 2, 1937, at 7:20 AM, Earhart reported her position to the crew at the Coast Guard vessel, placing her plane on a course at 32 kilometers (20 miles) southwest of the Nukumanu Islands.
“We must be on you, but we cannot see you. Fuel is running low. Been unable to reach you by radio. We are flying at 1,000 feet.”

The ship replied but there was no indication that the signal ever reached Earhart’s plane.

The Coast Guard ship released its oil burners in an attempt to signal the flyers, but they weren’t seen by all accounts.

Noonan’s chart of the island’s position was off by about five nautical miles, subsequent investigations showed, and it seems likely that the plane ran out of fuel.

Despite a huge search and rescue mission involving 66 aircraft and nine ships, the fate of the two flyers remains a mystery to this day.

With the years, the mystery only intensified, amplified by countless conspiracy theories surrounding Earhart’s last days.

Neutrons and dirty metal plates

While watching a National Geographic documentary on the disappearance of Earhart, Daniel Beck, a pilot who also manages the engineering program for the Penn State Radiation Science and Engineering Center (RSEC), home to the Breazeale Nuclear Reactor, was shocked by a particular scene discussing an aluminum panel believed to be part of the wrecked airplane.

The documentary ended with the idea that, perhaps, sometime in the future, technology will advance to the point where scientists can elucidate more information from the panel.
“I realized that technology exists. I work with it every day,” Beck said.

The scientist got ahold of Richard “Ric” Gillespie, who leads The International Group for Historic Aircraft Recovery (TIGHAR) and was featured in the documentary, and offered to analyze the metal part using neutron technology at his lab. 

 

Kenan Ünlü, director of the Penn State Radiation Science and Engineering Center, holds a metal patch that might be from Amelia Earhart’s airplane.

Credit: Kenan Ünlü/Penn State.

The metal panel had been recovered in storm debris on Nikumaroro, a Pacific island located about 480 kilometers (300 miles) away from Howland Island.

Some have suggested before that Earhart’s plane made an emergency landing on the reef surrounding the small, uninhabited island.

A human skeleton was even found in 1940, and although the bones were lost, a 2018 study found that the historical records of the bones’ measurements matched Earhart’s closer than 99% 0f the general population.

A skull fragment that may be from the original skeleton was found in a storage facility in a museum on a nearby island and is currently being tested to see if it is a genetic match for any of Earhart’s relatives. Beck’s goal was to perform a similar investigation, only instead of genetics, he wanted to use the reactor’s neutron beams to reveal the history of the metal patch.

Perhaps they could find a long-faded serial number or other marks that might link the debris to the Electra.

Beck and colleagues placed the sample in front of the neutron beam, while a digital imaging place was placed behind the sample.

As the neutron beam passed through the sample and then through the imaging plate, an image was recorded and digitally scanned.

“As the beam passes through, if it were uniform density, we wouldn’t see anything,” Beck said.

“If there’s paint or writing or a serial number, things that have been eroded so we can’t see with the naked eye, we can detect those.”

This investigation revealed that the metal plate had axe marks along the edges, except for one of the edges where the metal must have snapped from whatever it was attached to.

In other words, not much linking it back to Earhart.

“It doesn’t appear that this patch popped off on its own,” Beck said.

“If it was chopped with an axe, we should see peaks for iron or nickel left by the axe along that edge. Neutron activation analysis gives us that detail at a very fine resolution.”

For now, the researchers plan on performing more examinations using more comprehensive experiments, including adjusting the irradiation time and power level of the reactor.

Even if they eventually don’t find anything in connection to Earhart, this inquiry is still valuable.

For one, it disqualifies the object so other people don’t waste time in the future.

Secondly, it sets a precedent that may spur more research with neutron radiography.
“It’s possible we’ll learn something that actually disqualifies this artifact from being part of Earhart’s plane, but I prefer the knowing! It is so exciting to work with scientists who share our passion for getting to the truth, whatever it is,” Gillespie said in a statement.

Links :

• GeoGarage blog : Inside the search for Amelia Earhart's airplane/ Amelia Earhart mystery may finally be solved / Amelia Earhart: sonar image shows what may be ...