MCAT Telescope on Ascension Island: Installation Success!

Figure 2

Ascension Island is a truly unique environment – volcanic in nature, it is destination #1 for hundreds of turtles migrating from Brazil to Ascension each year to build a nest up to 6 times to lay up to 120 golf-ball-sized leathery eggs. When the nest erupts with hatchlings the size of the palm of my little hand, they follow the light, wherever that might be. It is thanks only to the effort and dedication of the 855 humans inhabitants who share the island with the turtles to require low-pressure sodium street lights be facing downward and glow a dim amber that keep the skies as dark as possible – the same sort of lights used near major astronomical observatories. By eliminating confusing white-light street lamps that could otherwise draw the tiny turtles to the streets, the amber lights ensure the little creatures will find their way to the ocean, lit up by the moon, and make their way to the South Atlantic Current and 3 days later to their new home in Brazil.

These very dark protected skies and a prime latitude and longitude combination will also allow MCAT, the Meter Class Autonomous Telescope, to thrive in this environment. And those same human inhabitants of Ascension made it possible for us to build a facility for an equally unique telescope, one of only 2 like it in the world – a double-horseshoe mount telescope, designed by DFM Engineering, that allows NASA to track not just GEO debris, but fast-moving LEO. With the combined decades of experience building telescopes by DFM and observing by ODPO astronomers, the quick responding telescope elicited regular comments like: “Does it make anyone else nervous how fast this telescope moves?” The equally fast-tracking Observadome encloses the telescope, the same company who built the GEODSS domes that have been reliably protecting telescopes tracking satellites and debris from such harsh environments as Diego Garcia. This combination is key in following debris target in any direction across the sky by eliminating both the blind-spot at the zenith that is so typical of astronomical telescopes as well as the need to flip the telescope when it crosses the meridian.  It is a unique and perfect combination to enable us to deepen our understanding of the debris environment around Earth.

On Jun 18, 2015, NASA and the US Air Force hosted an open-house to celebrate the completion of the installation of the facility, and to thank the many people – US Air Force and Royal Air Force, military, civilian and contract sides, Americans, British, local Saints and a multitude of other cultures, men and women, who contributed their time, expertise, attention to detail, and care in making MCAT not just another observatory, but a top-quality facility.

After 9 months of anticipation as the facility was built, word of “The NASA people building a telescope here” had spread, and the people were intrigued. With two visits by NASA to the school on Ascension in the months prior, NASA first introduced the project to nearly 100 kids, and asked for their help in designing the MCAT logo, and then awarded logo-embroidered t-shirts to the 5 winners who contributed. Despite a mere 1 day advance notice of the open house being published in the “The Islander” (we blame the need for gaining a multitude of approvals to hold the event), news had well spread word-of-mouth, and promptly at 6pm, the start time of the event, cars arrived in a steady stream. We were completely amazed by the response when over 300 people showed up (including at least half the school children bussed in during a school-wide sleep-over). They all showed up starry-eyed and ready to share in our excitement of the completion of the telescope, which occurred just 2 days prior. Everyone was given an opportunity to see our work-of-art 20,000lb fast-tracking telescope move, ask questions, marvel in the many astronomical images on the TV screen outside, and even enjoy a live band. A dedication ceremony was led by the team on-island and web-cast to include those at NASA JSC in an event we hope was worthy of the observatory’s namesake, a legend in the field of debris and loved by many in the debris community. We dubbed thee: The John Africano NASA/AFRL Orbital Debris Observatory, with an MCAT logo complete with a wee turtle to remind us always of the shared love of dark skies of astronomers and turtles alike.

Figure 1

Figure 1: MCAT logo complete with turtle, a broken satellite (debris!), and the Southern cross representing our southern-hemisphere location on Ascension Island.

Figure 2

Figure 2: MCAT fast-tracking telescope by DFM Engineering, enclosed by the equally fast-tracking ObservaDome.

Figure 3

Figure 3: In total, the MCAT dedication ceremony was attended by over 300 kids and adults from Ascension Island (the rest of the crowd is all lined up anticipating seeing the telescope!)

Figure 4

Figure 4: The Optical Measurements Group of the Orbital Debris Program office took part in building and testing the telescope and will operate MCAT for the foreseeable future. Pictured here: Dr. James Frith (Jacobs/Jets), Dr. Heather Cowardin (Jacobs/Jets), and Dr. Sue Lederer (NASA; PI of MCAT). Not pictured: Dr. Brent Buckalew (Jacobs/Jets). Special mention and thanks to Tom Glesne (Schafer Corp.), who spent 3 months on Ascension overseeing the construction phase from dome installation through telescope installation, Dr. Paul Hickson (master software engineer) and Lisa Pace (NASA, PM of MCAT), whose contributions were critical in the success of this project, and those who dreamed up the idea, including ODPO Program Manager Gene Stansbery.

Personal account written by NASA ARES Scientists Sue Lederer

DRAGONS to Fly on the ISS

On 28 October 2014, the International Space Station (ISS) Program approved development of the Debris Resistive Acoustic Grid Orbital Navy-NASA Sensor (DRAGONS) as an experiment to fly on the ISS, possibly as early as October 2016. The DRAGONS is a calibrated impact sensor designed to directly measure the ISS orbital debris environment for 2 to 3 years.

The sensor will have about 1 m2 of detection area mounted at an external payload site facing the velocity vector to maximize detections. As shown in Figure 1, it combines observation techniques to measure the size, speed, direction, time, and energy of small debris impacting the sensor. The front layer of DRAGONS is a thin film of Kapton with acoustic sensors and a grid of resistive wires. These acoustic sensors will measure the time and location of a penetrating impact, while a change in resistance on the grid when lines are broken will provide a size estimate of the hole.
The relationship between object size and hole size will be determined by hypervelocity testing under controlled conditions at the White Sands Test Facility in New Mexico and at the University of Kent at Canterbury, UK.

Located 15 cm behind the first layer is a second thin layer of Kapton with acoustic sensors to measure the time and location of the second penetration. Velocity is determined by dividing the distance travelled between the first and second impact points by the time it took to travel that distance. An instrumented back layer will stop the debris and measure the amount of energy in the collision. With energy (E) and velocity (v), we can solve for mass (m) in the equation: E = ½ m * v2. Finally, the density of the object can be estimated if we assume that the object volume is about the same as a sphere with a diameter determined from the hole size. Density is an important feature of debris because an object made of steel (7.9 g/cc) will do more damage than a similarly sized piece of aluminum (2.8 g/cc).

The DRAGONS should be able to detect debris as small as 50 microns and will collect statistics on objects below 1 mm, illustrated in Figure 2. Results from this experiment will update information previously obtained by inspecting hardware returned from space by the Space Shuttle. This flight demonstration will also prove the viability of the technology for future missions at higher altitudes where risks from debris to spacecraft can be greater than at the ISS altitude.

The decision by the ISS Program to fund and fly DRAGONS marks a major milestone in the history of the project. The DRAGONS team includes the NASA Orbital Debris Program Office, the NASA Hypervelocity Impact Technology group, the NASA/JSC Engineering Directorate, Jacobs, the United States Naval Academy, the Naval Research Lab, Virginia Tech, and the University of Kent. See our previous article on DRAGONS in ODQN, vol. 16, issue 3, July 2012, pp. 2-3 < ODQNv16i3.pdf>.

fig1   fig2

Update since release in the ODQN, vol. 19, issue 1, January 2015: The Debris Resistive Acoustic Grid Orbital Navy-NASA Sensor (DRAGONS) will be renamed Space Debris Sensor once onboard the International Space Station.