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Exoplanet Instrument Coming Together

SOCORRO, N.M. August 15, 2013– The pieces are all coming together for New Mexico Tech’s new exoplanet instrument.

The New Mexico Extrasolar Spectroscopic Survey Instrument, known as NESSI, is nearly set to be delivered and assembled at the Magdalena Ridge Observatory’s 2.4-meter telescope.

The device is among the very few instruments specifically built to characterize exoplanets – planets in orbit around other stars. A dedicated team of faculty, staff engineers and students have been working for nearly four years to design and build the new instrument. The final testing phase is under way in WorkmanCenter, with delivery expected to happen within the few weeks.

Once testing is complete, the instrument will be disassembled, trucked to the top of Magdalena Ridge and re-assembled inside the dome of the 2.4-meter telescope.

“A lot of work has been done searching for exoplanets,” said Dr. Michelle Creech-Eakman, who is the project scientist for the MRO Interferometer and the principal investigator for NESSI. “Spitzer and Hubble [space telescopes] have looked at exoplanet atmospheres. Now we can do it from the ground by being more clever. This will allow us to do exciting science that is difficult. The lessons we learned from space telescopes will allow us to take those techniques to the next level.”

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The New Mexico Tech instrument includes a rotating K mirror, that lets observers maintain the image orientation as the telescope tracks across the sky, custom masks for each exoplanet target and a series of other optics in a cryogenic Dewar. When in use, the instrument will attach to the side of the 2.4-meter telescope. 

At right, doctoral student Heather Bloemhard inspects a few of the optics that will be at the heart of NESSI.  Among her tasks, Bloemhard will determine which exoplanets the Tech researchers will study first.

Creech-Eakman has applied for a NASA grant to fund observing time. Team members at the Jet Propulsion Lab in California have also submitted internal proposals to fund more observing time.

The optics – more than 20 filters, lenses and grisms – were designed at Tech and manufactured in Albuquerque, California and Colorado. Many of the electronics were purchased off the shelf – and manipulated to serve the purpose of the instrument.

Project engineer Rob Selina was tasked with getting the array readout electronics working. Physics undergraduate Matt Napolitano designed much of the basic operations   software, along with computer science student Tyler Cecil.

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Dr. Luke Schmidt (right) tests NESSI's detector as engineer Rob Selina looks on.

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Project scientist Dr. Michelle Creech-Eakman explains the finer points of exoplanet spectroscopy to reporter Bob Martin of KRQE.

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Schmidt refills NESSI's Dewar with liquid nitrogen. The optics within the Dewar function optimally at 77 Kelvin (-196 C).

Photos by Thomas Guengerich/New Mexico Tech

The optics chamber is cooled by liquid nitrogen to 77 Kelvin (-196 C). Operators will be able to select from multiple masks, filters and grisms to observe various planets and study key aspects of exoplanet atmospheres. Thanks to the meticulous efforts of the software team, operators will be able to select optics, point and track with the K mirror and auto-guiding camera and gather data – all with a press of a few buttons.

The workhorse of the instrument is a Hawaii 2RG Array. Made by Teledyne, the $350,000 array is the end point of the infrared light – the detector that will gather the spectral photons. The same infrared detector will be used on the James Webb Space Telescope, currently scheduled for launch in 2018.

Dr. Luke Schmidt, a recent graduate of Tech, is now a post-doc working on NESSI. His dissertation involved systems that are similar to NESSI, so he joined the team to do a little bit of everything – software, optics, cryogenics, detector optimization and electronics.

“It’s very satisfying to get to this point,” Schmidt said. “You look at drawings or 3D models for so long. Then we start getting the pieces and see them fit together. We’re on the verge and it’s really exciting.”

The specialized optics and the detector essentially comprise a spectrometer – an instrument that can determine the signature wavelengths of various molecules elements and temperatures on the exoplanets.

NESSI prime capabilities involve examining the temperature/pressure, chemical composition and, with enough observations, the weather patterns of exoplanets.

Several observatories around the world are doing similar work, but NESSI will be the first infrared spectrometer was purpose-built for characterizing exoplanets. The NESSI team has high hopes that they will be able to gather new and useful data that will greatly expand the knowledge base about these far-off worlds.

Physics doctoral candidate Heather Bloemhard has been tasked with selecting the planets that will be observed.

“Heather has a huge, crazy Excel spreadsheet of potential targets,” Creech-Eakman said. “About 80 exoplanets transit their stars and are visible in the northern hemisphere. Some of these ‘hot Jupiters’ orbit every two or three days, so there are a lot of opportunities.”

Initially, Bloemhard expects to train NESSI’s “eye” on so-called “Hot Jupiters” – planets roughly the size of Jupiter that orbit extremely close to their stars – closer even than Mercury is to our Sun.

She said that Hot Jupiters are easier to track because of their size and their short orbits. Timing will be key. Observations must be done at night when the weather is agreeable, when the telescope is available and when a target planet is transiting – or eclipsing – its star.

Eight exoplanets have been characterized by other observatories. The Tech team will start by examining some of those worlds as proof of concept – to see if NESSI’s results agree with previous observations. After that, they hope to break ground on exoplanets that have yet to be described. 

Once NESSI proves adept at correctly characterizing Hot Jupiters, Bloemhard hopes scientists will be able to do the same with rocky terrestrial planets, which admittedly will be more difficult.

The search for exoplanets – and now the study of those bodies – captures the imagination of the general population and the scientists who are working on NESSI.

“This field is one that puts everyone’s imagination on fire,” Bloemhard said. “We know a lot about the objects in our solar system. Now, we’ll be trying to learn all the same things about other solar systems.”

Creech-Eakman said she grew up with science fiction, particularly Star Trek. Now, she’s examining other planets. Among her goals is to help people begin to think of these celestial bodies as new worlds instead of just places-out-there.

Bloemhard agreed, saying she hopes to be an educator as much as a scientist. Scientists have found about eight different types of exoplanets.

“We hope to contribute to the understanding of those worlds,” Bloemhard said. “We build up a spectrum of exoplanets. Then the theorists will take our data and speculate further.”

 “I didn’t have any exoplanet experience until college,” said Bloemhard, who earned her bachelor’s at GeorgeMasonUniversity in Virginia. “Until then, very few people believed that there could be life beyond the solar system. But as we become aware of more and more planets in our galaxy, it makes it seem likely that there is life out there. That’s not the goal of my research – finding life – but the possibility that it exists is exciting.”

– NMT –

By Thomas Guengerich/New Mexico Tech