Saturday, December 29, 2007

IX. Dive Series - The Next Phase

Tues 01-Jan - 0032 hrs New Year's Day

"Come, wander with me she said into regions yet untrod. Read with me what is still unread in the manuscript of God." - Longfellow

The words return to me as they did in Louisiana almost a month ago. The assembling swaths of sonar data reveal the seabed to us as if it were a scroll from a mighty manuscript written by a mighty hand. The numerous ROV dives are the Rosetta Stone for reading the great manuscript.

The seabed tells a different tale at every scale of observation. The submarine terrain appears tired, bent, and worn- a stark yet welcomed contrast to our jagged expectations. The seabed is deeply pitted, torn, and scarred. It cryptically cries out in past neglect, ruin, and abandon. Sparkling coral and happy creatures thrive in the shallows blissfully unaware of the decay of their heritage laying just out beyond the reef. The water deepens and color fades to grey where predators roam. Deeper still, the seabed appears lifeless and void. As the ROV touches down onto the deep seafloor, a benthic nephloid cloud erupts, engulfing the remote intruder. As the silt settles in the darkness, polycheate worms withdraw into their delicate burrows. Now under immense pressure, the ROV is in total solitude, stillness, and cold. There is no margin for failure in the ocean. The seafloor speaks of past failure, where grim reminders of the lost and broken abound. It is a relief to be back on board the Persistence in relative safety.

The Persistence is amid uncovering the final planned quadrant of the search area. Once completed and ROV ground-truthed, we will assemble the data and read from the last scroll in this mighty manuscript.

Mon 31-Dec - 1022hrs
The Persistence spent yesterday performing multiple dives with the ROV. The purpose of the dives is for collecting video of each sonar target. Typically, the sonar target is quickly identified and ruled out from the ROV video. The ROV operations lasted until dusk, where we resumed sonar survey operations through the night. Today, we are performing more ROV dives on targets of potential interest.

Sun 29-Dec- 2335 hrs

Dockside, the ROV team went into action this morning on board the Persistence. Before a test dive could be performed, all systems were checked and rechecked. Once the diagnostics were complete, the Persistence and crew went out to a test dive site known to be free of obstructions and major hazards to the ROV. The purpose of testing the ROV was two fold: 1) ensure all systems function perfectly underwater in full operation mode, and 2) prove the Persistence could hold location over the ROV, track the vehicle, and maneuver itself to keep the ROV umbilical cable out of the ship's screws.
During the first test dive, the deployment went smoothly. The ROV motored to the bow of the boat, while the captain kept the stern of the Persistence into the seas. The purpose of this maneuver was to keep the ROV umbilical out of the ship's screws. During this maneuver, the umbilical got temporarily hung up on the ship's hull, but freed itself. The visibility through the water column with the ROV cameras was excellent. When the ROV reached the seafloor we noticed it could not maintain control over it's attitude because of the very strong currents. On the second and third test dive more weight was added to better control the umbilical and ROV. At dusk, the final test was successful and proved we could maintain safe control over both the Persistence and ROV. With a sigh of relief from all, the Persistence and crew resumed survey mode. We will run additional sonar lines into the early morning.

Sat. 29-Dec-1100 hrs
From Tim Miller:

Please allow me to give my sincere appreciation for all the comments supporting our efforts in our search for Natalee. Today is an exciting day as we will now begin working the ROV in hopes of finding a special treasure at the bottom of the sea named Natalee.

Let us keep Natalee, Dave, and Beth in our hearts and prayers. Also, let's not forget all the other families of missing loved ones.

Texas Equusearch has been so very blessed with the support of Underwater Expeditions, the R/V Persistence (Silvetti Group), and their crew - which I think is the best in the world- for all their heartfelt efforts.

May it be His will to bring Natalee home.
-Tim Miller
Texas Equusearch

Wednesday, December 19, 2007

VIII. Side Scan Sonar search

Video: The Search for Natalee Holloway - R/V Persistence Dec 26, 2007

Update: Fri Dec-28 2143 hrs

The USBL calibrations are completed. The Persistence just reached the dock to spend the night and take on fresh water. The ROV test dive will proceed first thing in the morning. If successful, the first dive on a sonar target will follow. It will be difficult getting sleep tonight. Months of planning for some, years of planning for a few have all come down to the next couple days. Although unspoken, the stress is intense. We all seem to cope in our own ways. What stays on the surface is unwavering professionalism and focus. Inside, we all hope and pray tomorrow goes perfectly.

Fri Dec-28 1200 hrs

Last night, most of the crew and search team took a break and had dinner on the island. As much as we love the Persistence, it was a needed separation both of work and surroundings. For most of us, it was the first time off the Persistence in over a week.

Today, the trade winds are steady and strong. Wind surfers and parasails dot the beach as the Persistence completes the primary grid of sonar lines. To clarify, there is more planned grid remaining to be surveyed but the priority area is essentially complete. Within minutes, we will perform a calibration routine for the USBL acoustic tracking system. When successful, the ROV team will bring out the ROV and perform a test dive. The dive ensures the Persistence can maintain position over a fixed point (in 35+kt winds, 3-5ft swells, and strong cross currents) while the ROV safely navigates to a known point and can adequately maneuver in close proximity to the seafloor. For once, the pressure is off the sonar operators as they breath a major sigh of relief. All eyes will now turn toward the ROV pilot and boat captain as they perform this difficult dance among men and machine.

Thurs 26-Dec 1230 hrs
Murphy's Law always applies offshore. After acquiring data all day in sustained 35kt winds and strong cross currents, the night was going rather smooth. In about 450 ft of water and towing 20 ft off the bottom, the magnetometer started to tow differently. The operator (Kent) immediately recognized we had a snag. We brought in the towfish to find a mass of derelict fishing gear snagged on the acoustic beacon. The beacon was fastened to the tow cable above the magnetometer only by two small stainless steel hose clamps. Despite the massive strain on the beacon, it survived without any damage.

Wed 26-Dec -0320 hrs
The sonar search is progressing smoothly and the end is within sight. The ROV team has flown into Aruba and will reunite with the Persistence tomorrow. Below is a 3-D perspective view (looking west) of the bathymetric portion of the search on the NW side of Aruba. The contour interval is 25ft, showing water depth ranging from about 60 ft to almost 900 ft. The search area with bathymetry shown below is 22 square miles (the size of Manhattan).

Tues 25-Dec 1400 hrs

From Tim Miller (TES):
I want to personally thank the entire crew of the Persistence for their dedication and sacrifice they have given for the search for Natalee Holloway. Let us keep Dave, Beth, and all who knew and loved Natalee in our thoughts and prayers.
Every day I believe we are more and more optimistic that we will bring Natalee home to Alabama. We have just finished Christmas dinner on the boat and it's now time to go back to work -God be with us in our efforts.
Laura...I Love and miss you. Your death wasn't in vain.

Merry Christmas to All,
Tim Miller
Texas Equusearch

Tues 25-Dec 0140 hrs
To the family and loved ones of the search team and crew of the Persistence:
Words can not express our longing to be with our families over Christmas and the void we all feel. The contact we receive from loved ones through phone calls and emails does provide a diminutive sense of normalcy and solace. We take comfort in knowing life goes on back home in our absence and that this project will eventually come to an end, returning us safely to our families. We thank you from the bottom of our hearts for your continuous prayers, love, and support throughout this project. Loved ones are always on our minds which helps us maintain an unwavering focus and determination to complete this project with success, knowing that in success we shall return.

From the search team and crew of the Persistence to all:
Thank you dearly for your love, support, and prayers both for the search effort and the Holloway family. We hope that during this Christmas season you will stand witness and understand the true Christmas story which has been told and retold in varies forms throughout history. True love never fails and gracefully proves itself strong through sacrifice. We consider ourselves honored to use our God-given gifts and resources to this cause. From all of us, have a wonderful, safe, and merry Christmas.

The search is amidst perhaps the most difficult phase. The excitement and energy of the beginning has waned, yet the end is still on the horizon. We will persevere and give this wonderful vessel reason for it's namesake.

R/V Persistence - 25-Dec- 1225 hrs Christmas Morning (photo by Tony Fontenot)

Mon 24-Dec- 1452 hrs
After reaching the dock at 0600 hrs, the Persistence rests as her crew perform some routine maintenance and make a supply run. There is no obvious outward adornment that it is Christmas Eve, save a single strand of colored lights hung around the galley ceiling. Inwardly, everyone is filled with the true Christmas spirit. Almost routine now, the gear is in the water scanning away. Inch by inch, mile by mile we are progressing nicely.

Mon 24-Dec- 0045 hrs
The side scan sonar and magnetometer search quietly continues on through the night. Rain begins to fall on the Persistence.

Sun 23-Dec- 1452 hrs
Agitated by stiff trade winds, white caps blur the boundary between sea and sky today. Below the daily skirmish over wind and water's supremacy of the horizon, the search quietly continues in the crushing Aruban depths. Yesterday, we devoted some time testing the magnetometer and side scan sonar sensors over local construction materials likely used in constructing a wire trap. This test provided valuable information, both confirming that the construction materials alone can be detected and what kind of signatures to expect from the materials when on the seabed. In light of the test, we have renewed focus and zeal on our goal, to find Natalee Holloway.

Sun. 23-Dec -0130 hrs
The seas are calm and the moon is brilliant on the last survey line of the night. Murphy's Law always applies offshore. Midway through the survey line, the boat suddenly veers off course to avoid a small ~16ft wooden fishing boat anchored near the line. We hold our breath and bring in the sonar and magnetometer as fast as the winches allow. On the telemetry screens, both sensors suddenly go crazy. We caught the anchor line of the fishing boat with the sonar and magnetometer. The Persistence immediately comes all-stop as we cautiously bring in the gear. Fortunately for us and the fishermen, our reaction time was swift. We didn't give the fishermen much of a ride and no one was hurt. After a careful inspection, we determined that miraculously none of the gear was even slightly damaged in the collision. After the encounter was over, we thanked the fishermen for their patience and the small wooden fishing boat and Persistence went their separate ways into the moonlit night.

Sat. 22-Dec - 2035 hrs
The seas calmed throughout the evening. The progress we're making is satisfying. Once again, we will work through the night. At night, the seas tend to be calmer and it's easier to focus on the work without being able to see the beach. The sunset was beautiful this evening. ROV pilot Brandon Hernandez hurried out to the back deck of the Persistence to take the photo for the blog. At the same instance he snapped the picture, a swell washed across the back deck, soaking him half way up his shins. Brandon, now the world will know you by this noble photographic cause.

We came across another unknown wreck today, an approximately 50ft long catamaran. When a wreck is discovered or rediscovered, it is easy to get excited and often celebrate it's finding with a cheer. However, we must remind ourselves that all wrecks have stories and these stories are attached to lives and often lost lives. The ocean is terrific at keeping the especially solemn stories for itself. Only after great effort is the ocean willing to reveal it's deepest secrets.

Sat. 22-Dec- 1110 hrs
The Persistence awakes after a few hour much-deserved nap. The crew diligently toss the lines and she's free of the dock. Leaving the port facility, the seas are calm and the trade winds are pleasant and tropical. The occasional cumulus cloud appear cartoon-like. One small cloud in the distance is dumping rain on a few unfortunate people. I can just imagine what they're thinking.. "why me". The rain has a tendency of seeking us all out. Today over the Persistence, the sun is shining bright.

"We've gridded a 22 sq. mile area with bathymetry and will cover it again with this sonar system and magnetometer... Yes. We will find her if she's out there." -John Silvetti (1102 hrs, 22-Dec).

The search area we already covered by bathymetry and began surveying with side scan and magnetometer is the size of Manhattan.

"I believe she's been out here for over the last two years but we didn't have the resources and technology to find her until now. We're blessed to have these resources. Now, hopefully we'll have a wonderful Christmas present for Dave and Beth". - Tim Miller (1108 hrs, 22-Dec).

Fri. 21-Dec - 0350 hrs
The sonar search is progressing forward very well, ranging in water depths from shallow to around 900 ft. The data quality is terrific. The seafloor morphology although complicated, is much more accommodating than expected. Once the sonar search is completed, the ROV dives will commence.

Thurs. 20-Dec - 1310 hrs
The search team deploy a Marine Magnetics SeaSpy 'Overhauser' magnetometer to aid in the search. The magnetometer will tow behind the boat approximately 20ft off bottom and detect iron-bearing debris or targets. The mag will be used in conjunction with the side scan sonar.

Thurs. 20-Dec -0430 hrs
The Persistence has completed the first day of the side scan sonar search. The search team is very optimistic about the probability of finding Natalee Holloway. The data quality is excellent and the conditions are sufficient to carry out the detailed search.

The first sonar line is generally the most stressful part of the survey. Since the sonar is towed, it is very easy to collide the towfish with an unknown wreck or obstruction. We chose a starting point free of charted obstructions or known wrecks. Once the crew was ready, the side scan sonar was deployed before we reached the search area to provide a long approach to the first line.
Murphy's Law always applies when working offshore. Minutes after deploying the towfish and without warning, an uncharted shipwreck suddenly appears on the sonar screen. Immediately recognizing the danger, I pull in cable as fast as I could to make the side scan climb high in the water column. It's a near-miss. We missed hitting the wreck by just a few feet. After the adrenaline died down, we came around for another pass to better image the wreck. The image below is a snap-shot of the second pass on the approximately 150ft-long unknown wooden wreck.

To illustrate the quality of the sonar system, the following image is a side scan sonar image of an anchor and chain found during this search (Dec-21, 0130 hrs). Notice the links are clearly imaged.

The Holloway family expressed their deepest appreciation to the search effort, TES, and to all who are behind the scenes praying and helping support this project.

If this project has touched your heart and you would like to help in future missing persons projects, please learn more about Texas EquuSearch. It is a 501 (c) (3) nonprofit organization with over 350 members. They are a highly professional, compassionate, and dedicated group of people who have a passion for finding lost persons.
TES and Tim Miller has been directly involved in over 800 investigations with around 260 persons returned to their families alive!
If you would like to make a donation to help find missing persons:

Monday, December 17, 2007

VII. Beginning the Search

Tuesday, 18-Dec - 1500 hrs:
Aruba authorities and prosecutors close the Holloway case and investigation and said they do not have the evidence to charge anyone. Prosecutors said they will reopen the case "if new serious evidence were to be found." The statute of limitations is six years for involuntary manslaughter and 12 years for homicide, they said. Regardless, this announcement WILL NOT affect the search by the Persistence. This announcement comes the day before the search team will begin the side scan sonar survey of the newly-mapped area.

UPDATE: 18-Dec - 1510 hrs: The Persistence has begun the search. Bathymetric survey nearing completion.

Before the side scan sonar can be safely towed, the seafloor must be accurately characterised in terms of its topography. The R/V Persistence comes all-stop once it reached the survey area. A sound velocity profile (SVP) is performed to measure the speed of sound throughout the water column. Normally, performing a SVP in deep water is nothing exciting to write home about. However, without announcement and in unison the crew gathers on the back deck of the Persistence and takes a silent vigil as the sensor disappears into the depths. This SVP feels somehow different than the rest. We continue to watch as the instrument approaches bottom. Once it reaches bottom, it is slowly retrieved. Again, the crew awaits silently watching and waiting for the return of the instrument. Suddenly, out of the deep it takes shape and it breaks the surface. Although unspoken, I believe the crew felt this SVP to be somewhat symbolic of what lies ahead.

Line by line, the Persistence collects bathymetry data from within the search area as if conducting an interrogation. After a while, a picture slowly emerges. With a geologic history dating back to the Late Cretaceous, the seabed resembles an old living creature, full of character and tales. We know this creature will fight to hold onto its secrets. However, the very nature of the seabed merely fortifies our resolution and renews our vigor knowing that every crevice will soon be exposed in the light of a side scan sonar.

Sunday, December 16, 2007

VI. The Arrival

Friday, Nov-30, 2200 hours: The R/V Persistence departs the Port of New Iberia with seven crew members on board, headed to Isla Mujeres Mexico. The seas and wind are calm, and the visibility is excellent.

Tuesday, Dec-04- 1200 hrs: Dockside Isla Mujeras. The tropical waters are calm and the skies are clear. We take on 1,700 gallons of fuel and head out bound for Jamaica in 2-4ft swells.

Thursday, Dec-06 - 1900 hrs: Slowed down to clutch speed due to weather. We took shelter on the west-side (leeward) of Jamaica.

Tuesday, Dec-11 - 1100 hrs: Leaving Jamaica for Aruba. Tropical Storm Olga is quickly moving towards our location. We head out in 7-10ft seas to stay ahead of the coming storm. Wind E 15-20kts.
1900 hrs: The seas quickly build to 10-12 ft swells. We alter our course to avoid heaving rolling due to running in side-seas. Winds NE 20-25kts.

Wed, Dec 12 - 0900 hrs: Seas 8-10ft, in a moderate squall with heavy rain. Wind NE 30-35kts.

Thurs, Dec 13 - 1900 hrs: Seas building at 10-12ft with E wind 25-30kts. Rain is often heavy.

Friday, Dec-14th - 0600 hrs: Seas 12-14 ft with E wind 25-30kts. 121 miles to Aruba

Saturday, Dec-15 - 1615 hrs: ARRIVED at Aruba pilot station. Port Authorities board and the Persistence is cleared for docking.

Sunday, Dec-16 - 1100 hrs: Taking on fresh water. Crew change.

Friday, December 7, 2007

V. Behind the Effort

Behind the search effort is a team of individuals with a single unified focus and purpose: Find Natalee Holloway.
Perhaps the most common question we receive is "How is this search being supported?"

The answer: The collaboration of a lot of people and numerous companies with the financial support of Louis Schaefer Jr.

The major contributors are as follows (in no particular order):

Tim Miller with Texas EquuSearch

Louis Schaefer Jr. and Tim Trahan

Saturday, December 1, 2007

IV. Background

This post's intention is to provide a technical brief for background on how a search of this kind is possible and how it all works together.

The technical details of any ocean exploration project largely depends on the purpose of the survey. Common purposes include: exploration for science and general mapping, military applications (unexploded ordnance detection), marine construction such as for submarine cables, pipelines, offshore energy infrastructure, offshore wind-farms, offshore Liquefied Natural Gas (LNG) facilities, bridges, tunnels... etc), marine mining and drilling, searching for downed aircraft, lost shipwrecks, marine salvage, and in this case...missing persons.

Typical tools of the trade to image the water column, seafloor, and what's below the seafloor include (but are certainly not limited to) the following:

Side Scan Sonar - A sonar system used to efficiently image large areas of the sea floor in terms of bathymetric features and character, and detection and identification of underwater objects. A side scan sonar emits a fan-shaped wide angle pulse of sound towards the seafloor perpendicular to the path of the sensor through the water. The sound pulses reflect off of relief or objects that are laying on the seafloor. The strength and travel time of those reflected sound pulses are recorded and processed by a sonar computer to produce an image of the seafloor.

Magnetometer - An instrument used to measure the strength and/or direction of the magnetic field in the vicinity of the instrument. A magnetometer is used for detecting iron-bearing debris, cables, and pipelines. We are using a SeaSpy Overhauser marine magnetometer. An Overhauser magnetometer utilizes some interesting quantum physics effects (Nuclear Magnetic Resonance-NMR) that takes advantage of the physical phenomenon based upon the quantum mechanical magnetic properties of the hydrogen atom's nucleus, but probably beyond the scope of this writing.

Echo Sounder - (or fathometer) uses pulses of sound directed from the sea surface vertically down to the seafloor to measure the distance to the bottom. The water depth is measured by multiplying the half-travel time of the outgoing pulse to it's return by the speed of sound in water (about 1,500 meters per second). We commonly use a multi-beam echo sounder (MBES) to produce a high-resolution 3-dimensional map of the seabed.

Subbottom Profiler - An acoustic system used to create cross-sectional images below the seafloor. The relatively low frequency sonar (typically 3.5kHz) penetrates the upper 10s of meters of sediment below the seafloor (penetration dependent upon geology, power, and frequency) and reflects on density contrasts (acoustic impedance contrasts) within the sediment which is recorded and processed to produce a "subbottom profile".

Remotely Operated Vehicle (ROV) - Unoccupied tethered underwater robot. ROVs are typically highly maneuverable, operated by a pilot aboard a vessel to which the ROV is tethered, and are useful for video, sampling, salvage, or construction.

Autonomous Underwater Vehicle (AUV)- Unoccupied, untethered, underwater robot typically used for acquiring high-resolution sonar data (side scan, subbottom, and multi-beam), video, or sampling. AUVs are programmed to fly along a specific route or to perform a set of specific tasks during a dive. They navigate by acoustic beacons referenced to a support ship with GPS along with an internal inertial navigation system and Doppler velocity imaging system.

Human Occupied Vehicle (HOV) - Manned deep-ocean submersibles used for in situ exploration, sampling, and observation. These versatile submersibles are capable at bringing scientists, researchers, and workers to great depths. The submersible Alvin (DSV-2) is perhaps the world's most famous, known for surveying the wreck of the RMS Titanic in 1986. Alvin carries two scientists and a pilot as deep as 4,500 meters (about three miles).

This search will utilize a side scan sonar, echosounder, and a remotely operated vehicle (ROV). Once the R/V Persistence is on site in Aruba, we will perform a sound velocity profile (SVP) to measure the sound velocity of the local sea water. A bathymetric survey will be performed to basically map out the seabed. This will consist of gridding the search area with the echosounder so that we know what to expect during the side scan sonar survey. After the bathymetry throughout the survey is at least roughly known, the side scan sonar search will be performed. After the sonar data is processed and analysed for sonar targets, the ROV will perform a dive series on the sonar targets.

During the side scan survey, the side scan sonar will be towed behind the boat. The height of the towfish will be controlled to stay a fixed height off the bottom. Typically, a side scan sonar is towed 10% of its range per side off the sea floor. For example, if we set the side scan to cover 100m (50m to either side), then we will tow the fish 5m off the bottom. Maintaining this height off bottom can be challenging and stressful in unknown or quickly changing conditions. Flying too high will provide poor data and flying too low also provides poor data and worse... risks a catastrophic collision with the seabed. The towfish depth is only controlled by varying the length of cable out (layback) and varying tow speed with the vessel.

GPS positioning is recorded into the sonar data during acquisition. In shallow water (less than around 300ft) the position of the towfish will be calculated based on the GPS provided position of the boat and the amount of cable out. In deeper water, towfish position (and the ROV when in use) will be tracked acoustically by an ultra-short baseline (USBL) tracking system. A transducer / hydrophone mounted on the R/V Persistence sends a low frequency "ping" into the water column. A transponder beacon mounted on the towfish or ROV submersible hears the ping, then sends two reply pings on different frequencies. The first ping gives range and bearing information, and the second ping gives water depth. This occurs at a regular interval throughout the dive. The information from these acoustic signals are then converted into horizontal distance and bearing points indicating the position of the submersible in relation to the support ship.

The accurate positioning of the side scan sonar towfish is vital to properly locating any sonar targets it detects. At the same time, the ROV must be properly positioned and tracked so it can be guided to those targets. If for example the towfish was positioned 1/2 degree off, with about a mile of cable out (expected layback in the deeper portions of the search), we would mis- locate the sonar target by 50ft. This error would make it difficult and time consuming to find the target with the ROV (if it isn't missed completely).

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