Q. How have NASA’s recent financial woes impacted your research?
A. That’s a big question. The research budget has shrunk over the years, so we have limitations. But what we are good at is, I believe, really getting the maximum out of the funds we have. It’s amazing how research, in a sense, is cheap. The outcome you get in the long term for basic projects, like understanding the property of matter in space, is pushing the frontiers of knowledge. We are fortunate to have a very special environment at NASA Ames, because we are [involved] with the space missions and we have direct interaction with all of the work going on. So this synergy helps optimize the interaction between the sciences.
At Ames, you recently recreated stardust. What is space dust, and why recreate it?
Dust is a very broad term that we applied to the materials that are in interstellar or planetary space. It can be in a gas phase or a solid phase. Small molecules, larger particles like nanoparticles, and micrometer-sized grains are all considered dust. It’s material that obscures the light that you see coming from the stars and absorbs or emits that light. It’s basically like a thin veil between the light [coming from stars] and you, the observer. Think of it like a lamp. If you put something between you and the lamp it will attenuate the light from it - and to understand it, knowing what’s between you and the lamp is very important.
One of the reasons we want to understand stardust is to be able to correctly read the messages we get from the stars. It has many other important controls - it is involved in the physics and the chemistry of those huge [cosmic] clouds when they condense and coalesce, and when planetary bodies are being formed. The physics are being affected by the nature of the material, so people have been trying to understand what type of dust is out there. Is it compact? Is it fluffy? How do you form dust in space? One of the [sources] is from the ejection of materials from dying carbon stars. There are many models and theories and laboratory work is being done to try to test some of those different pathways and get some quantitative information, because it’s all about what properties we can measure.
To recreate stardust, you used a machine called “COSmIC,” or the Cosmic Simulation Chamber. What does it do?
The whole nature of the game is ‘how can you simulate on earth what happens in space,’ and of course, conditions are widely different in terms of pressure, vacuum, temperature, and energy. So you try to get all of the elements you can control, to come as close as you can to the conditions, and run those elements in a sealed chamber and measure what happens. You evacuate all of the air, go to high vacuum using pumps, and then you can control what you inject into the environment. You can shine light and you begin to have energy sources and products. Once you detect and measure them, you can compare their properties against what you measured from the space telescope and space missions. So that is why “COSmIC” stands for Cosmic Simulation Chamber. You can simulate a circumstellar (near star) environment - an interstellar cloud, or in a planetary atmosphere.
What elements do you input in order to ultimately produce stardust?
We input very basic hydrocarbon material [based on] the models and scientific proposals about the way this material is being formed when a star is dying. For example, in nuclear reactions you end up with the formation of filamental carbon which reacts with hydrogen to create very small molecules like methane (CH4).
These reactions happen naturally over many millions of years. How do you account for the time variable in a laboratory setting?
The challenge you have is a time scale over thousands of millions of years against to the time you have on earth, in a lab, to run an experiment. But you also have the flux. For example, if you are in the lab you can use a light source - it can be a laser, it can be a lamp, or it can be a discharge from plasma as opposed to the light or energy you would have in space. So the idea is that you have shorter time at higher exposure, as opposed to longer at lower exposure. You cannot do an experiment that would run for the exact amount of time, so the approach we always follow is by using the best tools available and [figuring out] how to best apply them to your problem. The time factor you try to calibrate from the flux - how much energy you put in. If you have a certain material hanging there over a few million years, you can calculate how many photons they will see, and you can scale that in a lab by showing more photons in a much shorter time, without changing the fundamental property of whatever you’re looking at. So thats a big challenge, it’s a difficult process.
If you were to look inside of the Cosmic Simulation Chamber while this experiment was being run, what would you see?
What you would see is a beautiful, what we call, planar expansion and the color would be mostly bluish. It might be a stretch, but it would look a little bit like the blue material you see in the beautiful hubble space telescope images of clouds, of nebula, of gases flowing. You would see something similar because you have a gas that has been excited by some sort of energy - photons or electrons - so it irradiates some light. The basic principles are the same. What you would also see is the end product, which is a solid that would look like soot.
Originally published June 27, 2014.
Dr. Farid Salama
Dr. Farid Salama is a Senior Research Scientist at NASA Ames Research Center, and a founding member of Ames’ Astrophysics and Astrochemistry laboratory. Dr. Salama is an expert in molecular spectroscopy and does extensive work in the areas of laboratory astrophysics and astrochemistry in conjunction with ultraviolet, optical and infrared astronomy (ground-based, space-based and airborne). He was awarded the NASA Medal for Exceptional Scientific Achievement developing a unique experimental facility in laboratory astrophysics and recognizing innovative research on the diffuse interstellar bands. Most recently, Dr. Salama’s team recreated “space dust” in a laboratory setting.