Author: thegreenalgae

About thegreenalgae

I am currently a staff scientist at Caltech/IPAC. Before that I worked at Draper Lab for two years preceded by a postdoc at the University of Michigan. I am most interested in high contrast imaging & interferometry of young stars, wavefront sensing, and star & planet formation. I'm originally from the Bronx, NY, I spent my PhD years in Baltimore, and have hopped around between Ann Arbor, Boston, and now Pasadena. I care a lot about STEM education on all levels and showcasing the human side of scientific research.

Yom HaShoah and the Science March

Today is Yom HaShoah, holocaust remembrance day in the Jewish calendar, the day to remember all the lives taken and the generations that never came to exist. Saturday, across the country many people took to their city streets to march for science, as I did here in Ann Arbor. How are these two things related? As the official March for Science organization struggled to find its message, the connection between these two things is more important than ever. Leading up to the march I was conflicted, along with many of my colleagues, about whether to march when the official movement seemed to shy away from getting too political, emphasizing a “celebration of science.” In the process they alienated some of the most vulnerable members of the community, and many of those with the most experience in protesting and political movements — many scientists of color, in particular, refused to march. And I don’t blame them.

On this Yom HaShoah especially, I cannot take a stance of unconditionally celebrating science. Many people pointed out leading up to the march that universal objective truths should not be confused with science, the human-led discipline. Science has been the justification for many terrible atrocities, and still is. It was not a new notion during the holocaust that drove the classification of  people as sub-human because they didn’t fit a biological, scientific (some surely argued objective) standard. Nazi doctors in concentration camps experimented on prisoners for medical research just as American doctors did to prisoners, and mentally ill patients. Speakers at the Ann Arbor march rightly pointed out uncomfortable truths about science, imploring us to demand a better, more ethical science.

Progress in ethical standards and guidelines for best practices did not just come from a group of people celebrating science. This progress largely came from those close to or affected by the horrible things science had justified. Science is not the thing we need to march for. Careful and thoughtful reasoning that considers all the evidence, the historical context, and ethical consequences of decision making — that is what we need to emphasize. We must march for a future science discipline that properly represents all voices (which it definitely does not).

Today I take a special moment to remember my grandparents, whose lives were surely shortened by what they endured, who worked to provide a comfortable and privileged life for me. I would not be a scientist without their perseverance. Today I remember over 10 million slaughtered, through cold, calculated, and scientific means. Science, the human-led discipline MUST go hand in hand with ethics. It MUST not ignore its history. It MUST represent all voices. We still have a lot of work to do.

Life in our backyard?

Last week NASA made an announcement about possible life-supporting conditions on two solar system moons, Enceladus (One of Saturn’s moons) and Europa (One of Jupiter’s moons). While the two gas giants in our solar system are likely not capable of hosting life as we know it, some of their moons make good candidates. Life needs the right chemistry to start and be sustained. The common requirement of all life on earth is liquid water, energy, and a cocktail of ingredients including carbon, oxygen, nitrogen, hydrogen, and other elements. The energy can come from anywhere — up at the surface from the sun, or from hydrothermal vents deep in the ocean, for example. On moons of giant planets, energy can even come from the push and pull  from the parent planet as it orbits. Habitability is definitely not limited to planets!


Hydrothermal vents on Earth’s ocean floor provide a food source for deep sea microbes and support an sun-less ecosystem. Credit: Wikipedia/NOAA

The Cassini mission, famous for many gorgeous views of saturn and its rings, was able to fly nearby Saturn’s moon Enceladus, to try to catch a whiff of what might be coming off the moon using its Ion and Neutral Mass Spectrometer (INMS). To scientists’ delight, they discovered hydrogen gas coming off the surface of Enceladus, indicating hydrothermal vents injecting hydrogen into the subsurface ocean. The findings suggest an environment not unlike the deep sea vents supporting parts of Earth’s ocean ecosystem.


An illustration of the Cassini flyby of Enceladus detecting plumes of hydrogen gas. Credit: NASA/JPL-Caltech

Meanwhile, using our old pal Hubble, a team of astronomers found evidence for water plumes on Europa. An earlier study discovered Europa’s saline liquid water ocean by measuring the magnetic field changes with the Galileo spacecraft as it flew by in 2000. The latest study describes ultraviolet observation’s with HST/STIS that show absorption at a location consistent between two observations on Europa. The possible plumes lie right on top of a hot spot previously discovered on the surface. The plumes could be the result of an eruptive disruption to the surrounding ice shell. How the ice shell gets disrupted is still unknown but has implications on either its thickness or other physical processes on Europa.


Evidence of plumes coming off the surface of Europa in two different observations. High resolution images of Europa are overlaid on top of the Hubble data to more clearly show the location of the plumes. Credit: NASA/ESA/STScI/USGS

Both these latest finds come on top of many previous missions and observations studying these solar system bodies. Learning about the compositions and structures of solar system moons allows scientists to interpret new exciting discoveries like these, and importantly, know what to look for when designing new missions and pointing our favorite telescopes.

Cyanobacteria and Friends!

Recently, I got to see something pretty cool — I saw a good friend defend her PhD thesis in a totally different field than my own, and she rocked it! In December I flew to Boston to watch her defense at Harvard.

When we were in college we shared many interests, an apartment, and many late night conversations about science and philosophy. We would talk about the second law of thermodynamics and how she would build dragons one day (engineering functional single-celled organisms is a good start). We had talked throughout our PhDs too, sharing our discomfort and uncertainty. And it was wonderful to watch her defense (alongside our other very smart and talented college housemates and friends), completing what I know was a challenging journey in many ways.


Steph and her niece talking about single-celled all the way up to dinosaur-scale organisms (I presume). Photo by Alina Chan.

Steph presented on 5.5 years of not just growing cells, but engineering their functions –and friendships! She worked on creating co-inhabiting environments of multiple species that benefit from each other’s presence and more effectively perform some function (e.g., photosynthesis and growth). She gave an excellent and clear presentation that even I, a non-biologist, could understand. I learned that in bioengineering many single-species cells (monocultures) are engineered for specific functions all the time (for example, to achieve high yields of biofuels), by introducing triggers of gene expression or new enzymes. I learned how much complexity can be present in co-cultures of more than one type of cell, how they can affect each other directly (interaction, competition) or indirectly (by changing the environment). The point is that while synthetic biologists can engineer specific cell functions in isolation, this does not necessarily reflect the interactions found in nature. Only by understanding interactions between different organisms in a shared environment can we hope to engineer communities in a more natural setting. One step closer to building dragons!


Two very different petri dishes. Left: One species of cyanobacteria, Right: A neighborhood of diverse organisms collected from the Connecticut River in New Hampshire. Sample collected by Joe Negri, grown and photographed by Stephanie Hays.

A biology PhD is different beast (pun intended) than one in observational astronomy in some obvious ways, but there are similarities too. Steph had to create her experiments; mine were already created and just needed to be observed. 12-hour “time points” for her cell cultures meant she could be found in lab in the middle of the night. My observing nights meant that occasionally we were both up at strange hours and could talk from our respective hemispheres. In both cases we were exposed to the very human component of scientific research. We might like to think of the scientific approach as the petri dish on the left, straightforward and well defined, but we live in the world more like the petri dish on the right. We hope that some symbiosis in the field means that we all benefit and can make the world a better place, greater than the sum of its parts. I think we both learned a great deal beyond our disciplines — about ourselves, about the other imperfect humans we interacted with, about uncomfortable truths in academia… And also statistics.

Thanks to Dr. Hays for reviewing this post, and also for being her kind, intelligent, and engaging self. 

Just arrived at Las Campanas Observatory

After dragging my heels, sleep deprived, through the Santiago airport onto my connecting flight, into the shuttle pickup for LCO HQ, and eventually down into La Serena for dinner and back, I slept very well. This morning I hopped on the shuttle to the observatory, admiring the view of ocean to the left, mountains to the right. And of course, I fell asleep in the van not long after admiring the view. I woke up shortly before we hit the dirt road, a view of the ocean now completely gone. The vigorous rumbling of the van driving on the uneven surface was oddly satisfying, especially as we approached the mountains. I saw the familiar glint of a large telescope dome on one mountain peak, then another. The first one I caught was from ESO’s La Silla Observatory, one large dome immediately obvious followed by the trail of smaller domes. Then to my left I caught the glint from LCO telescopes. I suspected the view to my left was LCO by the twin Magellan telescopes, recognizable from a distance and an impressive sight up close.


La Silla from afar. Can you see the dome?


So I was pretty content with myself when we took the turn towards Las Campanas, in the direction affirming my suspicions. At this point I was wide awake while climbed mountain, catching glimpses of the glinting LCO domes getting closer and closer, until we finally arrived.


Now I am enjoying some down time, catching up on emails and a little bit of work before we get to go “observe” other observers tonight. We came early to learn from more experienced observers and connect with the MagAO team before our observing night on Monday. It’s both calming and thrilling to be up here breathing in the crisp dry air, enjoying a fantastic view of the Andes, and getting ready to take advantage of a cutting-edge instrument! I’m thankful for the clear skies and looking forward to the rest of our stay!

First MagAO Visit

I’m gearing up for my first visit to Las Campanas Observatory where I’ll get to learn how to use Magellan AO, a specialized adaptive optics instrument on one of the Magellan telescopes. I’ve been a long time fan of MagAO, following the various cool results the team has put out as they’ve commissioned the instrument. For this run, I’ll be conducting observations on behalf of my research group Formation and Evolution of Planetary Systems at University of Michigan, using the infrared imager on MagAO. The infrared capabilities of MagAO are matched by few other facilities around the world; these are very challenging observations to make from the ground because everything (telescope, sky, etc) is so warm — good for humans, bad for infrared astronomy. I have also been impressed by the visible light imager performance and capabilities and I hope I’ll have the chance to use both soon for my own research projects.

So off I go, through Houston and Santiago to eventually land in La Serena Chile for the night before heading up to the observatory the next morning. I’m looking forward to meeting all the LCO staff and talking with the MagAO team members who will be running operating the AO.

I’m also excited for empanadas.

Wavefront sensing with a non-redundant mask

I recently completed a study I’m very excited about using a non-redundant mask like the one on JWST’s NIRISS instrument for wavefront sensing. Our method could help measure misalignments in the primary and secondary mirrors on JWST. While NIRISS’s mask will help to study the evolution of protoplanetary systems, how AGN fuel their central engines, and other exciting astrophysical phenomena, it can also be used to measure misalignments of the optics on JWST.


A little bit of background:

The James Webb Space Telescope has a segmented primary mirror and each segment can be controlled in several ways — up and down, side to side, tilted, and curved. When JWST begins setting up, before any science can begin, these mirrors must be aligned. There is a suite of dedicated wavefront sensing hardware in the JWST instrument NIRCam (the Near InfraRed Camera). NIRCam aligns the mirror segments first in big steps, then in small steps. But to make sure the whole field is well corrected (that the secondary mirror is also aligned) requires the use of JWST’s other instruments at different locations in the field.

The problem with phase retrieval:

An image alone is not necessarily enough to retrieve the wavefront in the pupil since features in image intensity do not all map uniquely to phases in the pupil. Successful methods must introduce some “diversity” to solve the problem uniquely.

What did we do?

Diversity is often accomplished by introducing defocus (as with NIRCam’s weak lenses, or moves of the secondary mirror for other instruments). In my study, instead, we use images from a non-redundant mask to first estimate the phase in the pupil. This phase estimate can move a phase retrieval algorithm using a full pupil image in the right direction. In the end the wavefront is measured with just two in-focus images, one with the NRM, one with the full pupil. No moving mirrors or extra hardware necessary.

You can find our published paper here:

Off to the UK

I have one last trip before seriously sitting down to write my thesis. The SPIE conference for astronomical telescopes and instrumentation starts next week and I’ll be advertising my new study on a wavefront sensing method that could serve as a back-up for fine phasing JWST. Lucky for me the conference this year is a city I’ve never been to — Edinburgh! I’m very excited for the trip.

I’m making a few days stop in London first to visit Oxford University and talk a bit about my work with GPI and NIRISS, and what’s to come in the very near future for exoplanet science at small inner working angles! The only time I’ve ever been to the UK was for a 12 hour layover, so I’m really looking forward to spending a week+ with friends and colleagues, not to mention talking technology and hearing about the latest news for all things space telescopes, adaptive optics, and extreme contrasts.

One good thing about summer…

I’m not the biggest fan of summer, especially in the Mid-Atlantic with its hot and humid climate. But there’s one thing that gets me very excited about summer now — swimming outdoors. The working life of an astronomy grad student is often spent indoors on the computer, whether that’s on the east coast of the U.S. or on a mountain in Chile.

I finally joined a swim club last summer that practices in an outdoor pool during summer months. They hold an annual open water swim in one member’s “backyard” to kick off the summer. So this Saturday I enjoyed a very pleasant 2-mile swim with other swimmers from various walks of life.


It’s really nice to get together with other Maryland swimmers of all ages from a range of backgrounds. Swimming is my favorite way to detach from work and clear my head. And in the summer I know I won’t be missing my vitamin D.

It’s back!

Who likes to feel small? Well sometimes I like to remember how small I am in the context of our solar system — our galaxy — neighbors to the Milky Way — even beyond, you get the point. One of my favorite exhibits is back up at STScI – the huge panorama of the Andromeda galaxy.


My cell phone photo does not do it justice.

Through 16 days worth of exposures Hubble was able to see down to individual stars across Andromeda in multiple filters, as a part of the Panchromatic Hubble Andromeda Treasury (PHAT) program.

I like to pick a spot on this poster and get very close to see the individual points of light. I like the the reminder of how vast our universe is, something that can be easy to forget on day-to-day routine, even if you’re studying it. Beyond the awesome science coming out of these observations, it’s a fantastic example of not only what we are capable of doing, but what excites us, scientist or otherwise. If you see the exhibit, I’d definitely recommend taking a few minutes to admire.

More info about the project:

LIGO Announcement: Gravitational Waves!

10:30AM (EST) on February 11, 2016: We gathered into one of the conference rooms in the JHU Physics and Astronomy Department to stream the National Science Foundation Press release from the LIGO collaboration. Over the last week the whole community has been hearing rumors of a big announcement from LIGO, the instrument designed to measure distortions of spacetime due to gravitational waves. At the start David Reitze announced that they had indeed detected the long sought after gravitational waves!

Physicists all the way back to Einstein have considered the existence of gravitational waves and merging black holes became a strong candidate for their production — except that merging black holes had never been observed, until now. Gabriela Gonzalez, Spokesperson for the LIGO science team, took the podium to describe the first gravitational wave detection at LIGO — 29 and 36 solar mass black holes merged to produce a 62 mass black hole. 3 solar masses were radiated away.

At 11am EST Astronomy Picture of the Day updated with a related image representing the numerical simulations matching the signal measured at the two LIGO sites (which are over 2000 miles apart):



The excitement among the team members was obvious. Decades of work and research (and money) have gone into the development of LIGO. NSF director France Córdova gently joked about the relief of institutions like the NSF that have supported this long-term project for many years to see a positive detection.

Locally, it was exciting to see a mix of astronomers and particle physicists gather together to listen in, chew on some bagels, and share reactions. I think this press release reflects one of my favorite parts of the academic world and one the reasons I decided to join it — a shared excitement for new discoveries. Somewhat regardless of individual science interests, everyone is talking about it! And those working more directly on the subject are happy to elaborate and engage with colleagues. Many feel that in time, this will be considered an important historical event.

You can find the discovery paper here.

More on LIGO’s detector