Tuesday, April 26, 2016

The Discovery Program Series: VERITAS (PI: Sue Smrekar, Managed by Jet Propulsion Laboratory)

This post is part of a series discussing the recent NASA Discovery Program mission selections for further refinement. From the 27 proposals submitted in November of 2014, NASA has selected 5 missions for further refinement in the next year. Part 1 of the series focused on the overview of the Discovery refinement selections and an interview with the Lead Program Scientist for the Discovery Program, Dr. Michael New. Part II focussed on the Psyche Mission (PI: Linda Elkins-Tanton, Arizona State University, Managed by JPL). Part III will focus on the NEOCam Mission (PI: Amy Mainzer, Jet Propulsion Laboratory, Managed by JPL). Part IV will focus on the Lucy Mission (PI: Hal Levison, Southwest Research Institute, Managed by NASA Goddard Space Flight Center). Part V will focus on the DAVINCI Mission (PI: Lori Glaze, Managed by NASA Goddard Space Flight Center). Part VI will focus on the VERITAS Mission (PI: Sue Smrekar, Managed by Jet Propulsion Laboratory).

Mission Overview: VERITAS

 VERITAS (Venus Emissivity, Radio Science, InSAR, Topography And Spectroscopy) is aimed at understanding one of the most fundamental questions in planetary evolution: Why are the twin planets Earth and Venus so different? Venus and Earth are nearly the same size and bulk compositions. Yet Earth ended up supremely habitable and Venus a sulfurous hell, where the surface temperature is hot enough to melt lead. Understanding how these two planets arrived at their present state is essential to understanding the evolution of rocky planets like Earth, and thus for predicting whether the Earth-sized planets in other solar systems are likely to be habitable. VERITAS will investigate Venus’ geologic evolution by obtaining global maps of high-resolution radar imaging, topography, and near infrared spectroscopy to constrain surface composition. This wealth of data will provide rich opportunities for discovery and inquiry for the next generation of planetary scientists and bring the information available for Venus on par with that for Mars, Mercury, and the Moon. 

The Magellan mission to Venus in the early 1990s revealed a young, spectacularly diverse surface, with intense deformation and voluminous volcanism. But many mysteries remain unsolved. How active is it today? Without plate tectonics, how does an Earth-sized planet loose its heat and outgas its volatiles? Are the processes operating on Venus today good analogs to those on early Earth? More recently, the European Space Agency’s Venus Express mission was able to pierce the cloud layer at windows near 1 micron and provide evidence of multiple centers of recent and current volcanism as well ancient, evolved (iron-poor) crust.

Why did Venus evolve so differently? A planet’s geology defines the interface between a planet’s interior heat engine and its atmosphere, controlling the timing and style of volatile loss from the interior and possible recycling back into the interior. So far Earth is the only planet that has a system of plate tectonics, which provides long term cycling of volatiles via volcanism and the formation of new plates (outgassing) and recycling and sequestering of volatiles via subduction. Plate tectonics may be a key process for developing and maintaining a habitable planet. The hypothesis that Venus had a catastrophic resurfacing event led to the idea that it may have episodic plate tectonics. But the evidence for catastrophic resurfacing is controversial – VERITAS will test this hypothesis, as well as the hypothesis that Venus has limited subduction and/or delamination (without full plate tectonics) today. The initiation of plate tectonics on Earth happened billions of years ago, obscuring its origin. But we may be able to study the initiation of subduction – the gateway to plate tectonics – on Venus. I think that we are going to find out that Venus is a very dynamic planet with lots of lessons for early Earth and exoplanet evolution.

How active is Venus today? The small number of impact craters put the resurfacing age at 300-1000 m.y. But most of the craters have smooth floors. If they are volcanically flooded, the average surface age would be just 150 m.y. VERITAS will follow up on Venus Express discoveries of present day volcanism using a variety of approaches to search for present day activity, including the first use of interferometry on another planet to reveal tectonic and cm-scale volcanic surface deformation, the thermal or chemical signature of recent or active volcanism, topographic or surface roughness changes, and comparisons to prior mission data sets. The comparison to Magellan data provides a baseline of several decades to look for surface change. 

Does Venus preserve the fingerprints of past or present water? Our understanding of volatiles in the solar system has evolved dramatically in the last decade. Volatiles are everywhere we look! Prior to the acquisition of cometary D:H ratios, comets were thought to be a planet’s primary source of volatiles. But cometary signatures don’t match those of Earth. A rocky planet’s volatiles are released from the interior via geologic processes – volcanism and tectonism. On Earth, continents preserve the earliest record of geologic processes. Earth’s continents form when the primary basaltic crust remelts in the presence of water. The low density, iron-poor rock cannot readily be subducted back into the mantle, so continents float at the surface, recording billions of years of geologic history. Venus may be the only other body in our solar system to have continents. If the high plateaus are different in composition from the basaltic plains they will tell us a lot about the history of volatiles on Venus. There are further hints that volatiles are leaking from active volcanoes today. Venus Express saw SO2 increase dramatically over the last decade. Although it is hard to outgas water under the high surface pressure on Venus, the detection of such present day outgassing would clearly demonstrate that the interior remains volatile rich despite the scalding surface temperature.

About the Mission PI (Sue Smrekar):

Sue Smrekar is a geophysicist with a specialty in the tectonics and geodynamics of Venus and Mars. She is especially interested in what causes planets to evolve to different convective (and thus geologic and atmospheric) states. One focus is on how Venus and Earth evolved so differently, as well as the lessons for understanding exoplanet evolution. She approaches these questions using data analysis (e.g. gravity, topography, radar and visual imaging) and modeling (volcanism, tectonism and convection). She got her Bc.S. in Geophysics/Applied Math at Brown University, and her Ph.D. in Geophysics at Southern Methodist University. She did her postdoc at MIT before coming to JPL during the Magellan mission. Since then she has balanced research with project responsibilities (see below), and is now a Senior Research Scientist. She was inducted into the International Aeronautics Academy this year (along w/Elon Musk at Space X!), and has received both NASA’s Exceptional Scientific and Technical Achievement Medals. Recent work includes the discovery of current volcanism on Venus using Venus Express and Magellan data, along with modeling of the formation of mantle plumes from the interior that fit the observations of recent volcanism.

About the Mission Deputy PI (Melinda 'Darby' Dyar):

Melinda (Darby) Dyar is the Chair and Kennedy-Schelkunoff Professor of Astronomy at Mount Holyoke College and a member of the graduate faculty at the University of Massachusetts in Amherst. She received her B.A. in geology from Wellesley College and her Ph.D. in geochemistry from MIT, followed by a Caltech postdoc and faculty positions at the University of Oregon and West Chester University. She is a Fellow of the Mineralogical Society of America and the author of two textbooks: Mineralogy and Optical Mineralogy and Geostatistics Explained. She has been part of the Mars Science Laboratory science team. Her research uses spectroscopy to understand the distribution of hydrogen and oxygen on terrestrial bodies through laboratory, in situ, and orbital studies that employ novel machine learning tools for data processing and interpretation. She has worked on diverse topics such as alteration of volcanic rocks, mantle evolution, redox changes during metamorphism, minerals in acid mine drainages, and microbial reduction of minerals at mid-ocean ridges – and she’s never met a mineral she didn’t like. She can’t wait to see VNIR spectra of the Venus surface!

About the Mission Project Scientist (Scott Hensley):

Scott Hensley received his BS degrees in Mathematics and Physics from UC Irvine and Ph.D. in Mathematics from Stony Brook University. In 1992, Dr. Hensley joined the staff of JPL where he is a Senior Research Scientist studying advanced radar techniques for geophysical applications. He has worked on most of the SAR systems developed at JPL over the past two decades including the Magellan and Cassini radars. He was the GeoSAR Project Scientist, a simultaneous X-band and P-band airborne radar interferometer. He lead the SRTM Interferometric Processor Development Team for a shuttle based interferometric radar used to map the Earth's topography. He was PI and is currently the Project Scientist for the NASA UAVSAR program which is an L-band fully polarimetric radar designed for repeat pass applications. His worked has spanned solid earth, cryosphere, ecosystem and planetary applications. 

Interview with the PI (Sue Smrekar):

What previous mission experience do you have?
Wow – lots. I think I’ve done every science job there is on a project. I first helped develop mission requirements by doing modeling in support of the gravity science investigation for the Magellan mission to Venus while a graduate student. During my postdoc working on Magellan I analyzed raw data to create usable data products and interpretations. After coming to JPL, I decided to work on developing instrumentation to measure planetary heat flow. I started working with an engineering team to write grants, and going out to the Mojave to throw penetrators from airplanes- really hard to locate amongst the sagebrush! That work led to several instrument grants, including a current PICCASO grant to develop a heat flow instrument for Venus, and to being the Project Scientist on Deep Space 2 Mission to Mars. Deep Space 2 was a small technology development mission. My role was to lead the science team and assure that we developed the right technology for future missions as well as get as much science as possible. After that I had a brief stint as the study scientist for an early version of the Curiosity rover. I’ve been involved in numerous mission formulation teams: MSL, Mars Reconnaissance Orbiter (MRO), the International Lunar Network, to name a few. I was the Deputy Project Scientist for the Mars Reconnaissance Orbiter for about 10 years, where I focused on mission operations. MRO has 6 instrument teams competing for data volume and spacecraft operations, so it was a constant challenge to maximize science. Currently I’m the Deputy PI and Project Scientist on InSight, a Discovery mission to Mars. I am also the DPI for the heat flow probe on InSight. On InSight, I have a range of responsibilities: managing the data archiving, organizing the science working groups, and generally managing the science team activities.

What has been your career steps to this point? Had you always wanted to be a mission scientist?
I’ve always had two ambitions: to do great research and make groundbreaking missions happen. During my postdoc at MIT I got to spend time at JPL working with an amazing science team as they saw new data arrive for a fantastically complex and enigmatic planet: Venus! It was such a thrill to be part of new discoveries about the nature of our twin planet and to brainstorm interpretations with some of the best geoscientists in the world. It was a complete intellectual rush – I was hooked on exploring the solar system! Soon after coming to JPL I started I became the Project Scientist on the Deep Space 2. So, yes, I saw that value of being the science lead for missions quite early in my career. However I’ve been equally hooked on doing the research that informs our understanding of rocky planet evolution. For me the theoretical exploration of the processes shaping planetary bodies is equally fascinating, and is what lead me to being a geophysicist. What I love most are studies that constrain how planets work by linking theory and observations. Like missions and research, one can’t really advance without the other.

What are your next steps and main challenges moving forward?
The next step is to write a compelling Concept Study Report and get selected to explore Venus! The main challenges are the same ones we face throughout the mission: cost and schedule. The decisions the team makes as we work through trades and refine our concepts mirror those of later mission phases. Every decision balances the value to the science versus risks to cost, schedule, and implementation. We are building relationships based on trust, respect, comradeship, and excitement for exploring Venus that will serve us throughout the lifetime of the mission. 

What advice would you give to a new comer in the field looking to go into mission work?
First and foremost has to be to follow your intellectual passion. Sure, you should consider current trends in science. But there are a lot of ups and downs for any scientist. You will need to have a burning desire to advance science to keep you pushing past setbacks. I’ve continued to study Venus despite the lack of new data and thus diminished interest in the community because I am enthralled by its mysteries. Second is to try to get some hardware or mission experience. With the current access to CubeSats, this is a lot easier to come by. This will give you a better appreciation for what it takes to make an instrument or a mission successful. What I’ve noticed at JPL is that not as many women get involved in the hardware side of things. Developing hardware is great experience for being an instrument or mission PI, so especially encourage women to look for these opportunities.
What makes you uniquely qualified to be the VERITAS PI?: 
1. My Dad was born in Venus PA! 2. The first Venus flyby occurred the year I was born! 3. I’ve published more papers/book chapters on Venus than the answer to the meaning of life

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