Marine Mapping Midpoint and Venus

Halfway through the R/V Falkor expedition to map the Papahānaumokuākea Marine National Monument, we have traveled nearly 4000 km and mapped many areas, including the Rogatien Ridge and the Gardner Pinnacles. Along the way, we have to take turns keeping watch for whales and diverting the ship away from them if necessary in order to maintain a safe distance due to the ship's active sonar. My turn taking watch is usually the hour before and after dinner out on the ship's upper deck, which means I get to witness many spectacular sunsets and moonrises.

My colleagues on the sunrise whale watches have remarked at how bright Venus can be. This got me thinking about just how similar mapping the seafloor is to mapping the surface of Venus. Can you tell which of the two pictures below is from Earth's seafloor and which is from Venus?

Both are backscatter images. One is produced by radar and the other by sonar, but the principle is the same. You send a pulse of energy down and record how much of it bounces back along the same track to you.  Backscatter tells you primarily about surface roughness, helping one determine the texture and type of soil reflecting the signal. The biologists and geologists on board like this type of data because it helps them discern marine habitats, debris flows, and potential future dive sites for submersibles to collect samples.

Most of what we know about the surface of Venus comes from the Magellan mission (1989-1994), which used synthetic aperture radar (SAR) to peer through the planet's dense atmosphere.  Coincidentally, one of my first jobs in college was mapping remote parts of the Arctic and Antarctic with SAR, which today is also used to view land deformation due to earthquakes in near real time.  This week scientists have gathered in Houston for a Workshop on Venus Exploration Targets to identify and evaluate key locations for future exploration of this enigmatic planet.  Why the climate of Venus is so different from Earth's remains a mystery that only further missions can help answer.

The atmosphere of Venus is 90 times thicker than the Earth's, giving it a pressure equivalent to being at a depth of 900 meters (3000 feet) in the Earth's ocean.  With the loss of the Nereus submersible last week in the Kermadec Trench, we are reminded of the great difficulties associated with deep ocean exploration. Technologies we develop to survive crushing pressures in Earth's ocean may be the ones needed to survive Venus as well. The synergies between ocean and space exploration are many. I'll leave you with an excerpt from John Steinbeck's 1966 letter in Popular Science:

I know enough about the sea to know how pitifully little we know about it. We have not, as a nation and a world, been alert to the absolute necessity of going back to the sea for our survival.

I do not think $21 billion, or a hundred of the same, is too high a price for a round-trip ticket to the moon. But it does seem unrealistic, unreasonable, romantic, and very human that we indulge in these passionate pyrotechnics when, under the seas, three-fifths of our own world and over three-fifths of our world's treasure is unknown, undiscovered, and unclaimed.

... My passion for the world's seas and underseas does not lessen my interest in our space probes. When the astronauts go up in their beautiful skyrockets, my stomach goes up with them until it collides with my lungs and pushes them against my throat.

... Experiments are going on all over the world. Cousteau has men living undersea, and so has the American Navy. Men are learning the techniques of changing pressures. Whereas the astronauts must become accustomed to weightlessness and vacuum, the undersea men must learn to endure the opposites. They receive little official encouragement.

... There is something for everyone in the sea—incredible beauty for the artist, the excitement and danger of exploration for the brave and restless, an open door for the ingenuity and inventiveness of the clever, a new world for the bored, food for the hungry, and incalculable material wealth for the acquisitive—and all of these in addition to the pure clean wonder of increasing knowledge.


The magnetic personalities of seamounts

The Papahānaumokuākea Marine National Monument encompasses a vast area larger than all U.S. national parks combined. As I mentioned last time, We came here on the R/V Falkor to map the seafloor around the islands, atolls, reefs, and seamounts that comprise the Northwestern Hawaiian Island chain within the monument. Ultimately, we want to gain a better understanding of the geological processes that helped shape this part of the world.

As the ship cruises along at around 10 knots, we operate three different data collection systems. First, we have a multibeam sonar that pings the seafloor with sound to give us a picture of what the ocean bottom looks like. Then, we have a gravimeter, which detects minute gravity variations that tell us what is beneath the seafloor surface. Finally, our magnetometer measures the Earth’s magnetic field along our path and provides information on the relative ages of seafloor features.

On this cruise, we are using a Geometrics G-882 magnetometer provided by the University of Hawai‘i. It's towed about 170 meters behind the ship in order to avoid magnetic interference from the metal vessel itself. The torpedo-shaped instrument glides along about 10 meters beneath the surface, logging the magnetic field intensity every tenth of a second. We can then subtract the Earth’s background magnetic field to create a map of local variations, which we call a magnetic anomaly map. This gives us an idea of the relative ages of different portions of the seafloor.

When oceanic crust forms in the fiery furnace of a mid-ocean ridge, its rocks contain tiny iron atoms that align themselves with the local magnetic field. As the rock cools to a solid, these atoms freeze in place, preserving a record of the direction and intensity of the magnetic field at that time. That field tends to fade over time, so the intensity of the signals we measure is one indicator of age.

As it happens, the Earth’s outer core is a dynamic place, and this causes the north and south magnetic poles to trade places every few hundred thousand years. When Navy ships combed the oceans with magnetometers in the 1950s looking for ways to detect submarines, they unexpectedly discovered alternating bands of magnetizations in the seafloor, which was one of the strongest pieces of evidence that gave birth to the theory of plate tectonics.

Now that we know the plates move, we think we have a good idea how the Hawaiian Island chain formed and the lifecycle of a Hawaiian island. A hotspot in the mantle beneath the central Pacific plate causes rocks to melt and rise up to form volcanoes, which eventually break the surface to form islands. These volcanoes eventually die as the plate moves past the hotspot. Over time, the island sinks into the sea, transforming into an atoll and eventually a subsurface mountain called a seamount. These Hawaiian seamounts coexist with other older seamounts that pepper the bottom of the ocean.

How can we tell them apart? Remember that when volcanic rocks solidify, they lock in the magnetic field of the time and place where they form. That means that we can tell at what latitude rocks formed based on their magnetic signature. Plus, the minerals within the rock alter over time, and the little iron atoms lose their alignment. The intensity of magnetization within the rock decreases as a result. Thus, we would expect to see lower magnetic anomalies with our magnetometer when we pass over older non-Hawaiian seamounts compared with the younger Hawaiian ones. The seafloor in this area is Cretaceous in age about 80-100 million years old, so we’re trying to use magnetic data to discriminate between Cretaceous vs. Hawaiian seamounts, which are only about 5-45 million years old.

As a geophysicist with mostly a seismology background, I am excited by this hands-on opportunity to learn about marine magnetics. I hope to fold this into my dissertation involving other geophysical exploration methods on the Earth and planets. Mahalo nui loa to everyone on the R/V Falkor team for a superb cruise so far!

Note: A version of this post was originally published on the Schmidt Ocean Institute website.


Falkor's Neverending Story

What if we could explore far off corners of the world just like the famous luck dragon Falkor in the classic book and movie The Neverending Story?

The Schmidt Ocean Institute launched the R/V Falkor to do just that. Funded by Google's deep pockets, this private research ship is charged with exploring uncharted depths of the sea and offers scientists competitive opportunities to conduct their own research expeditions along the way. Since we know more about the surface of the Moon and Mars than we do our own ocean, this is a very timely mission. All data collected on the Falkor is made freely available to the public in order to best advance knowledge about the regions it explores.

I have had the good fortune to take part in two cruises aboard the Falkor. Last month, I participated in a short 3-day training cruise to the Maui Nui area, and now I am one week into a 36-day cruise to map the Papahānaumokuākea Marine National Monument (PMNM) (aka: Northwestern Hawaiian Islands). The World Heritage Site, which is larger than all U.S. national parks combined, encompasses unique biological, geological, and cultural wonders that have barely been explored. The vast area is triple the length of the main Hawaiian Island chain, and would stretch from New Orleans to Los Angeles if you overlaid it across the U.S.

Very few high resolution multibeam mapping surveys have been undertaken in the PMNM, leaving gaps in our knowledge about the seafloor there. We are here to fill in as many of the blank areas as we can using the Falkor's state-of-the-art multibeam sonar mapping systems. Follow us on journey here.

Besides advancing scientific knowledge, Google's interest in the project is to use the newly collected data to enhance its Google Ocean features within Google Earth. To achieve this objective they partnered with the University of Hawaii to plan and carry out the mapping operation to optimize science return. We took the opportunity to also bring a gravimeter and magnetometer to collect geophysical data along with the mapping information. This provides an unprecedented opportunity to help unravel the geologic history of the region by helping us understand what is beneath the surface.

The eleven scientists and students on the cruise have broken up the day into three 8-hour blocks, during which we serve as watchstanders to ensure the mapping and geophysical systems are all operating properly. We continuously plan the ship's route and modify the plan as we go depending on where the holes in existing data are, what subsurface targets are of most interest, weather conditions, and how much time we have. It requires a balancing of priorities and making decisions on the fly to achieve the expedition's goals. Since this is a national monument, we must be extra careful not to interfere with wildlife, so we take turns standing watch on the ship's upper "monkey deck" from sunrise to sunset to watch out for marine mammals. We have already seen pilot whales, sperm whales, and bottlenose dolphins.

Life on the Falkor is very nice. It’s stylish and homey, with a decor that looks like something out of an IKEA catalog. There are several amenities like a gym, sauna, and outdoor lounge. The crew is very friendly, and we have had several social get-togethers like barbeques, movie nights, and a ping pong tournament. The scientists also give seminars on various topics twice per week; I'll be giving one about tsunami warning later in the cruise. By far, the best thing about life on board is the food. Every meal is cooked by gourmet chefs and is among the best food I have ever eaten. You can see for yourself by touring the ship virtually via Google Street View on the Falkor’s website.

The Falkor is similar in many respects to the NOAA Ship Okeanos Explorer, where I participated in a 15-day mapping cruise from Guam to Hawaii back in 2010. The two ships have similar exploration missions and capabilities. For example, they both use the Kongsberg EM302 multibeam mapping system, although the Falkor also has a high resolution EM710 system too. Both ships share the same spirit of discovery to unravel the mysteries of the deep. I am honored to have had the privilege to sail on both of them.


Gaining InSight on Mars

I just returned from California where I participated in a NASA InSight Science Team meeting. InSight (Interior Exploration using Seismic Investigations, Geodesy and Heat Transport) is NASA’s first dedicated geophysical mission to Mars. Keep reading to learn more!

A key goal of planetary science is to understand the formation and evolution of the planets, which means we need to know what they are made of. Geology, geochemistry, geodesy, and geophysics are tools that we can use to get at questions associated with the structure and composition of planetary interiors. Previous and current Mars missions have utilized all of these approaches except geophysics, which is the only technique that can give direct measurements about what is beneath the surface. InSight will help us determine the size, composition, and state of the crust, mantle, and core while also measuring the thermal state of the interior and level of seismic activity on Mars. Watch the video below to learn more about this exciting mission.


Sailing on the HI-SEAS

Do you dream of being an astronaut and exploring Mars? Have you always wanted to visit Hawaiʻi, or do you live in Hawaiʻi but just want to get away from your regular life for a while? Do you have a burning desire to carry out research to advance our understanding of long duration space missions? If you answered yes to any of these questions, then I highly recommend you apply to be a crewmember on an upcoming HI-SEAS mission!

HI-SEAS stands for "Hawaiʻi Space Exploration Analog and Simulation." It's a NASA-funded study led by researchers from the University of Hawaiʻi at Mānoa. The goal of the program is to study aspects of crew cohesion and performance in the context of three simulated Mars surface missions of 4, 8, and 12 month durations in 2014-2016.  You can read all about it and learn about the application details on the HI-SEAS website or in the UH press release. The application deadline is November 1, 2013.

While the study pertains primarily to human social factors, it also presents an opportunity for many other add-on research projects ranging from microbiology to robotics and geology.  These activities provide realistic tasks that astronaut crews will likely carry out on a Mars mission. NASA wants to understand how teams of astronauts will perform on long-duration space exploration missions while doing relevant scientific and operational tasks. HI-SEAS will also provide recommended strategies for crew composition and how best to support crews while they are working in space.

I am fortunate to be one of the researchers involved with the HI-SEAS program in the areas of geology, crew selection, and mission support. The first HI-SEAS mission focused on food and lasted four months, ending in August 2013. During that mission, I coordinated an international group of mission support volunteers who helped facilitate the mission and presented on this work at the ICES 2013 Conference. I also helped prepare the crew for their mission the week before their mission began and was there to greet them when they emerged after four months of isolation. Below are some pictures of me at the HI-SEAS site last August. I'm going back there next week with the HI-SEAS science team to help plan the upcoming three missions.

It is fitting that we are announcing this opportunity during World Space Week, whose theme this year is "Exploring Mars, Discovering Earth." I can think of no better way to accomplish both of those goals than to get involved with Mars analog research activities. In addition to HI-SEAS, there are other planned long duration Mars analog missions on the horizon. For example, the Mars Society will launch its Mars Arctic 365 mission next summer at the Flashline Mars Arctic Research Station on Devon Island, Canada - a place I know well. In China, the Research Group of Advanced Life Support Technology at Beihang University will simulate a Mars mission in a habitat sporting a high fidelity biogenerative life support system that provides closed loop recycling of consumables like air and water for the crewmembers living inside. This is indeed an exciting time for Mars analog mission research!