NASA’s Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer (OSIRIS-Rex) spacecraft launched on September 8 to the near-Earth asteroid Bennu to harvest a sample of surface material and return it to Earth for study. But before the science team selects a sample site, they can find out a bit about Bennu’s elemental make-up.

PolyCam (center), MapCam (left), and SamCam (right) make up the OSIRIS-REx Camera Suite, responsible for most of the visible light images that will be taken by the spacecraft. (University of Arizona/Symeon Platts)

To deter mine the composition of Bennu’s surface, the team equipped the spacecraft with the OSIRIS-REx Camera Suite (OCAMS), developed by the University of Arizona. OCAMS consists of three cameras: PolyCam, MapCam, and SamCam. These cameras will “see” the asteroid as the spacecraft first approaches it. OCAMS will then provide global image mapping and sample site imaging and characterization. Finally, OCAMS will record the entire sampling event during the touch-and-go (TAG) maneuver.

PolyCam is an 8" long-range telescope that will first locate the asteroid from 2 million kilometers away. It identifies hazardous areas and performs high-resolution imaging of Bennu’s surface at short range.

MapCam is a medium-range camera that searches for satellites and outgassing plumes around Bennu. It maps the asteroid in color, and provides images to construct topographic maps. Its filter wheel and five-element lens system allow both panchromatic (clear) and wideband spectral imaging in the blue, green, red, and near-infrared.

Sam Cam is a close-range camera that verifies both the act of acquiring the sample during the TAG sampling maneuver, and images the sampling mechanism after attempting sample collection.

A Brain View from the Inside

To operate on the brain, doctors need to see fine details on a small scale. A tiny camera that could produce 3D images from inside the brain would help surgeons see more intricacies of the tissue they are handling, and lead to faster, safer procedures. An endoscope with such a camera is being developed at NASA’s Jet Propulsion Laboratory in Pasadena, CA.

MARVEL (Multi Angle Rear Viewing Endoscopic tooL) features a camera that is 0.2" (4 millimeters) in diameter and about 0.6" (15 millimeters) long. It is attached to a bendable “neck” that can sweep left or right, looking around corners with up to a 120-degree arc. This allows for a highly maneuverable endoscope.

Operations with the small c amera would not require the traditional open craniotomy, a procedure in which surgeons take out large parts of the skull. Craniotomies result in higher costs and longer stays in hospitals than surgery using an endoscope.

A laboratory prototype of MARVEL, one of the world’s smallest 3D cameras. MARVEL is in the foreground. On the display is a 3D image taken by MARVEL of the interior of a walnut, which has characteristics similar to that of a brain. (NASA/JPL-Caltech/Skull Base Institute)

Stereo imaging endoscopes that employ traditional dual-camera systems are already in use for minimally invasive surgeries elsewhere in the body. But surgery on the brain requires even more miniaturization. That’s why, instead of two, MARVEL has only one camera lens. To generate 3D images , MARVEL’s camera has two apertures — akin to the pupil of the eye — each with its own color filter. Each filter transmits distinct wavelengths of red, green, and blue light, while blocking the bands to which the other filter is sensitive. The system includes a light source that produces all six colors of light to which the filters are attuned. Images from each of the two sets are then merged to create the 3D effect.

Now that researchers have demonstrated a laboratory prototype, the next step is a clinical prototype that meets the requirements of the U.S. Food and Drug Administration. The researchers will refine the engineering of the tool to make it suitable for use in real-world medical settings. In the future, the MARVEL camera technology could also have applications for space exploration. A miniature camera such as this could be put on small robots that explore other worlds, delivering intricate 3D views of geological features of interest.

Dynamic Propulsion Data

NASA’s High Dynamic Range Stereo X (HiDyRS-X) high-speed, high-dynamic-range camera was used to film the full-scale test of the Space Launch System (SLS) booster, recording propulsion video data in detail never seen before.

The HiDyRS-X project originated from a problem that exists when trying to film rocket motor tests. Rocket motor plumes, in addition to being extremely loud, are also extremely bright, making them difficult to record without drastically cutting down the exposure settings on the camera. Doing so, however, darkens the rest of the image, obscuring other important components on the motor. Traditionally, video cameras record using one exposure at a time, but HiDyRS-X records multiple, slowmotion video exposures at once, combining them into a high dynamic range (HDR) video that perfectly exposes all areas of the video image.

(Top) Image of the Space Launch System test without using the HiDyRS-X camera, and (bottom) with the HiDyRS-X camera.

The massive booster test served as a rare opportunity to test the HiDyRS-X hardware in a full-scale environment. Unlike smaller-scale rocket engine tests, boosters are extremely powerful and, once ignited, cannot be turned off or restarted. The HiDyRS-X team had one shot at getting good footage. When the team reviewed the camera footage, they saw a level of detail on par with the other successful HiDyRSX tests. The team saw several elements never before caught on film in an engine test, including the exhaust plume, nozzle, and the nozzle fabric going through gimbaling patterns — an expected condition, but usually unobservable at slow motion or normal playback rates.

A Jump in Resolution

It’s an age-old astronomical truth: To resolve smaller and smaller physical details of distant celestial objects, scientists need larger and larger light-collecting mirrors. This challenge is not easily overcome given the high cost and impracticality of building and — in the case of space observatories — launching large-aperture telescopes.

However, a team of scientists and engineers at NASA’s Goddard Space Flight Center in Greenbelt, MD has begun testing a potentially more affordable alternative called the photon sieve. This telescope optic could give scientists the resolution they need to see finer details still invisible with current observing tools — a jump in resolution that could help answer a 50- year-old question about the physical processes heating the Sun’s million-degree corona.

Although potentially useful at all wavelengths, the team specifically is developing the photon sieve for studies of the Sun in the ultraviolet — the wavelength needed to disentangle the coronal heating mystery. The team has fabricated three sieves and plans to begin testing to see if they can withstand the rigors of operating in space.

This image shows how the photon sieve brings red laser light to a pinpoint focus on its optical axis, but produces exotic diffraction patterns when viewed from the side. (NASA/W. Hrybyk)

The optic is a variant of a Fresnel zone plate. Rather than focusing light as most telescopes do through refraction or reflection, Fresnel plates cause light to diffract — a phenomenon that happens when light travels through a thin opening and then spreads out. This causes the light waves on the other side to reinforce or cancel each other out in precise patterns.

Fresnel plates consist of a tightly spaced set of rings, alternatingly transparent or opaque. Light travels through the spaces between the opaque zones, which are precisely spaced so that the diffracted light overlaps and focuses at a specific point, creating an image that can be recorded by a solid-state sensor. The photon sieve operates largely the same. However, the sieve is dotted with millions of holes precisely placed on silicon in a circular pattern that takes the place of conventional Fresnel zones.

The team wants to build a photon sieve at least three feet in diameter — a size they think could achieve up to 100 times better angular resolution in the ultraviolet than NASA’s high-resolution space telescope, the Solar Dynamics Observatory.

RESOURCES

www.nasa.gov/osiris-rex 

www.asteroidmission.org 

microdevices.jpl.nasa.gov 

www.nasa.gov/exploration/systems/slsgsfctechnology.gsfc.nasa.gov/newsletter/Current.pdf 

WATCH ON TECH BRIEFS TV

SLS rocket booster from the HiDyRS-X camera.

Behind the design of the OSIRIS-REx Camera Suite.


NASA Tech Briefs Magazine

This article first appeared in the October, 2016 issue of NASA Tech Briefs Magazine.

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