NASA X-ray concept inspired from a roll of Scotch tape

Jul 26, 2012
Principal Investigator Maxim Markevitch is using R&D funding to pursue the feasibility of fashioning a low-cost X-ray mirror from plastic tape and tightly rolling it like the sticky adhesive ubiquitous in most homes and offices. The whiteboard drawing shows the shape of the X-ray mirror roll. Credit: Credit: NASA/D. McCallum

The inspiration behind NASA scientist Maxim Markevitch's quest to build a highly specialized X-ray mirror using a never-before-tried technique comes from an unusual source: a roll of Scotch tape.

Markevitch and a team of X-ray optics experts at NASA's Goddard Space Flight Center in Greenbelt, Md., have begun investigating the feasibility of fashioning a low-cost from plastic tape and tightly rolling it like the sticky adhesive commonly found in most homes and offices.

"I remember looking at a roll of Scotch tape and thinking, 'was it possible to use the same design for capturing hard X-rays,'" Markevitch recalled. "I talked with a few people, and to my surprise, they didn't see any principal reasons why it couldn't be done."

With funding from NASA's Center Innovation Fund, the team now is pursuing Markevitch's "early-stage" idea and has already begun testing candidate materials that could be fashioned into a rolled mirror capable of collecting X-rays — in itself a challenging proposition. To capture these ever-elusive photons, the mirrors must be curved and nested inside a cylindrical optical assembly. The rounded geometry allows the high-energy light to graze their surfaces, much like a stone skimming the surface of a pond.

Motivating Markevitch is the fact that these highly specialized mirrors are time-consuming and expensive to build and assemble, despite efforts to dramatically reduce production costs. Making matters more demanding is the fact that X-ray observatories in the future likely will require much larger collecting areas, therefore requiring an even greater number of individual mirror segments that all must be nested, coated with layers of highly reflective materials, and perfectly coaligned inside their optical assemblies. "It's a lot of work fabricating these rigid shells and making sure they're properly aligned," he said.

The Science

The science Markevitch would like to pursue is one that would require a larger mirror. Over the past few decades, NASA has launched several X-ray observatories sensitive to lower-energy "soft X-rays," including the Chandra X-ray Observatory. They discovered and imaged the faint, diffuse X-ray signal from a variety of astrophysical sources dominated by thermal emission, such as galaxies and clusters of galaxies. Other missions, like NASA's Swift satellite, were sensitive to higher-energy gamma rays, but they lacked imaging capabilities.

"There remains a large and totally unexplored discovery space of faint, diffuse nonthermal astrophysical objects emitting at high X-ray energies," Markevitch said.

One class of objects waiting to be better understood is cosmic rays — highly energetic subatomic particles generated in deep space — that reside in galaxy clusters and other large-scale structure in the universe. Scientists believe that cosmic rays and the magnetic fields between galaxy clusters can alter the physics within galaxy clusters. A better understanding of these physics could reveal more about the birth and evolution of the cosmos, Markevitch said.

To study cosmic rays, however, observatories would have to be tuned to hard X-rays. Although 's recently launched Nuclear Spectroscopic Telescope Array (NuSTAR) and Japan's New X-ray Telescope, also known as Astro-H, are sensitive to hard X-rays, Markevitch said they only "will graze the surface of this discovery space." Because the signal is so faint, only an imaging X-ray telescope with a collecting area 30 times larger than that of NuSTAR, working with current and future radio telescopes, could do the job, Markevitch said.

"However, to our knowledge, nothing of the kind is planned or even proposed in the U.S. or elsewhere because of the cost something like this presents," he said.

The only solution then is developing a new technology that would dramatically reduce the cost of building X-ray optics and increase the size of the light-collecting area. "If we can build a mirror that's big enough, this might be the way to go," he said.

Under his research plan, Markevitch, Takashi Okajima, Will Zhang, and Peter Serlemitsos are acquiring and testing candidate tape that would be coated on one side with a multilayer of reflective material and then wound into a roll, forming a large number of densely packed nested shells that are spaced by the varying thickness of the tape. "The collecting surface is automatic, it's rolled, self-supporting, and already aligned," Markevitch said. Multiple rolls then would be placed in an optical assembly, providing a much larger collecting area, or, in other words, a larger mirror.

"Maxim's idea is in an early stage," Zhang said. "In the next year, we will know whether it has a chance of working."

If it does, it could prove "game-changing for hard X-ray astronomy," Markevitch said. "It could significantly reduce the cost of building large mirrors, bringing within reach the possibility of building a mirror with 10 to 30 times greater effective area than current X-ray telescopes."

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Lurker2358
1 / 5 (3) Jul 26, 2012
How does he plan on converting this to a digital signal for transmission and recovery as a still photo?

Since the photons should be smeared out along the entire surface randomly, it would seem like it may take a lot of work to figure out the formatting needed to turn the signal into a photo, since I gather each roll is going to essentially be one "pixel" in "black and white".

I gave this a 4 because the details of how this is actually going to work are not explained, and they also don't explain what the problems or uses will be for any scattering effect among varying wavelengths as they behave slightly differently in the surfaces.
Eric_B
5 / 5 (1) Jul 26, 2012
hmmm...i was wondering if this article was going to reference the use of scotch tape as an x-ray generator and detail somehow using those properties. however, i was skeptical that this would make sense. so, my skepticism was rewarded as the two things have naught to do with each other.

the other info.http://www.nature...185.html
Bewia
5 / 5 (3) Jul 26, 2012
I gather each roll is going to essentially be one "pixel" in "black and white".

I'd rather say, you didn't gather the principle of X-ray optics at all.
Lurker2358
1 / 5 (2) Jul 26, 2012
I'd rather say, you didn't gather the principle of http://en.wikiped...y_optics at all.


That article is more or less dealing with X-Ray crystallography, and does not address my concerns at all. In fact, the Diffraction section highlights my concern of scattering of different wavelengths.

A spiral curved surface is not going to behave the same as a flat crystal surface. Additionally, for astronomy, he's not trying to gain information about the atoms in the rolls, but rather the galaxies and black holes and other interesting objects "out there," which is a potential problem because scattering modifies the wavelengths.

Additionally, with a spiral, the degree of curvature changes depending on your position on the spiral, which will modify the reflective properties, such as different focal point and different scattering behavior.

My impression was that he wanted to "photograph" these objects in the X-Ray spectrum, i.e. to see structure, not just "detect" X-rays.
pauljpease
5 / 5 (6) Jul 26, 2012

A spiral curved surface is not going to behave the same as a flat crystal surface.


You don't know anything about X-ray lenses, do you? "Flat crystal surfaces", I think you're referring to optical lenses. They work great for optical wavelengths, but X-rays go straight through them, so they don't work as a refractive medium for X-ray optics. X-ray lenses are based on thin layers of material, where each layer bends the X-ray a little bit, so that after many layers it is as if the X-ray had gone through a refractive lens. So, a roll of tape with the right properties would be perfect for this application.
Lurker2358
1 / 5 (2) Jul 26, 2012
You don't know anything about X-ray lenses, do you?


I know what a lense is and I understand the concept. The article bewia linked to had next to nothing to do with this.

"Flat crystal surfaces", I think you're referring to optical lenses.


No, that was in reference to crystallography, sorry for the lack of explanation, but 1000 characters isn't much.

X-ray lenses are based on thin layers of material, where each layer bends the X-ray a little bit, so that after many layers it is as if the X-ray had gone through a refractive lens. So, a roll of tape with the right properties would be perfect for this application.


I think this is going to produce annoying distortions, because the properties of slightly different wavelengths is going to scatter them with a different focal length.

Multiple rolls then would be placed in an optical assembly


I suddenly get the impression of one of those insect eye viewers, only with spiral and color distortions as well
Vendicar_Decarian
not rated yet Jul 26, 2012
X-ray Fresnel lens analogy using very small angle internal reflection rather than refraction.

Shinichi D_
5 / 5 (2) Jul 27, 2012
@Lurker: You can't build a X-ray lense like an optical or infrared lense. X-rays go through materials with small atomic number, and they scatter on high atomic number materials. Such an optical design would only scatter them, or let them through.
In a circular mirror design all layers just barely modify the path of the rays. The mirrors in this design wouldn't be able to reflect x-rays at high angles. It's not possible to buld a 'venice-mirror' for x-rays, just like it's not possible to build a solid optical lense for them. You can't construct a Newton or Gregorian type telescope for x-rays.
Lurker2358
3 / 5 (1) Jul 27, 2012
@Lurker: You can't build a X-ray lense like an optical or infrared lense. X-rays go through materials with small atomic number, and they scatter on high atomic number materials. Such an optical design would only scatter them, or let them through.
In a circular mirror design all layers just barely modify the path of the rays. The mirrors in this design wouldn't be able to reflect x-rays at high angles. It's not possible to buld a 'venice-mirror' for x-rays, just like it's not possible to build a solid optical lense for them. You can't construct a Newton or Gregorian type telescope for x-rays.


I understand that.

I still think there's going to be more time spent calibrating this thing than the actual design and build time.
dnatwork
4.3 / 5 (3) Jul 27, 2012
I still think there's going to be more time spent calibrating this thing than the actual design and build time.


Why? Build it, put a detector on the back, and stick it in front of a set of x-ray sources laid out in a pattern. Use a computer program to match the detected images to the pattern of known sources, and it's calibrated.