A U.S.-developed space surveillance telescope has been assembled at a new facility in Western Australia and is expected to start operating in 2022, the U.S. Space Force Space and Missile Systems Center announced April 2020. The telescope, designed to track and identify debris and satellites more than 22,000 miles above Earth, was developed a decade ago by the Massachusetts Institute of Technology’s Lincoln Laboratory with funding from the Defense Advanced Research Agency. Between 2011 and 2017 the telescope was tested at the Atom Site on White Sands Missile Range in New Mexico. DARPA handed over the telescope to the U.S. Air Force in 2017.
Pentagon’s DARPA (The Defense Advanced Research Projects Agency) has handed over its Space Surveillance Telescope to the United States’ Air Force Space Command (AFSPC) in New Mexico. The AFSPC plans to transfer its Space Surveillance Telescope to Australia as part of an effort to manage the growing amount of satellite traffic in geosynchronous orbit. It has a beneficial vantage point since it provides important space situational awareness information from the southern hemisphere. The southern hemisphere is a geosynchronous belt that has been sparingly observed until now. After the move, SST will be owned by the United States Air Force, but operated and maintained by Australia. It will be a dedicated sensor in the U.S. Space Surveillance Network (SSN).
The volume of space between the Earth’s surface out to geosynchronous orbit is enormous—equivalent to 240,000 times all the Earth’s oceans. Yet the number of objects calling that volume home is growing all the time—not just with satellites but with debris of all kinds, natural and manmade. And keeping track of it all is becoming a real-time, non-trivial challenge. “That is why the U.S. Department of Defense has made space situational awareness a top priority and why few areas of DARPA research are as important to the future of U.S. and global security as helping to secure this most strategic frontier,” said Dr. Steven Walker, DARPA Deputy Director, at the Transition Ceremony for the Space Surveillance Telescope.
The US Space Surveillance Network (SSN) is the principal system used to detect, track and identify objects orbiting earth. It has the best set of SSA capabilities, operating a global network of 30+ ground based radars and optical telescopes and 2 satellites in orbit. It maintains the most complete tracking database of 23,000+ space objects bigger than 10 cm. SSN largely relies on phased array radars that are also used for early missile warning sensors .The data is fed to the Joint Space Operations Center (JSpOC) in California that provides a range of data and services for US government, satellite operators, and public.
The SSN has fewer telescopes, but they are better distributed geographically. The ground based Electro-optical Deep Space Surveillance System (GEODSS) consists of three separate sensor sites located in New Mexico Hawaii and Diego Garcia in the Indian Ocean. Each site operates a cluster of three telescopes, each of which can be operated independently of each other. Along with these sites there is a mobile site with one telescope located in spain. Together they provide global coverage of the GEO belt, although weather can cause gaps. The SSN however, has little or no coverage in the southern hemisphere or in the South America, Africa and Asia.
The United States and Australia signed an agreement to base the telescope in Australia in an effort to fill a fill a gap in the U.S. Space Surveillance Network coverage of the Southern Hemisphere. The United States shares the SSN network of ground-based sensors with key allies, including Australia. SMC said the telescope last month achieved “first light,” meaning that course alignment of the telescope optics with the wide field of view camera has been completed, allowing the first images of objects in orbit to be seen by the telescope. The Australian government built a new dome for the telescope at the Harold E. Holt Naval Communication Station in Western Australia. The facility has a 2-megawatt central power station. The telescope will undergo tests before entering service in 2022. The Royal Australian Air Force will operate the telescope jointly with the U.S. Space Force’s 21st Space Wing.
Space Situational Awareness
Space situational awareness (SSA) is the foundational element of space security, and it entails keeping track of all natural and artificial space objects, energy and particle fluxes and understanding how the space picture is changing over time. SSA is a system of systems dealing with space surveillance, space weather and NEOs. Comprehensive SSA requires a networked system of radars and electro-optical sensors.
Space Fence, currently under construction on Kwajalein Atoll by Lockheed Martin, will revolutionize Space Situational Awareness (SSA) using advanced phased array radar technology in two of the largest phased arrays to ever be constructed. “Once complete, Space Fence will deliver revolutionary capability to the U.S. Air Force with a flexible system capable of adapting to future missions requiring new tracking and coverage approaches.” It would detect, track, and catalog about 200,000 orbital objects in space more than 1.5 million times a day to predict and prevent space-based collisions. That site is expected to be fully operational by the end of 2018.
The shortcomings of radar have to do with the technology itself. Even though radar has excellent capabilities to track objects in space regardless of atmospheric weather and the time of day, the amount of power used and the wavelength of radar limit its ability to see small objects in space. This limit occurs because objects smaller than the wavelength do not affect the returned signal. As a result, radar can only see objects about 0.75 cm or larger. This technological shortcoming holds regardless of whether the radar is looking for space objects from the ground, from the air, or from space.
Optical telescopes provide another SSA capability, but there are environmental shortcomings of optical telescopes. Ground- or air-based telescopes can detect objects when they are sunlit against a dark background. In low earth orbit, only one to two hours of detection are possible during dawn and dusk each day while at higher earth orbits, detection is possible throughout the night. Another environmental limitation of ground and air-based telescopes is the atmospheric weather over the telescope; cloud cover inhibits the telescope effectiveness.
Space Surveillance Telescope program
The Space Surveillance Telescope program aims to enable ground-based, broad-area search, detection, and tracking of faint objects in deep space for purposes such as space mission assurance and asteroid detection. SST offers improvements in determining the orbits of newly discovered objects and provides rapid observations of events that may only occur over a relatively short period of time, like a supernova.
The telescope can view objects in the entire solar system and the universe outside the solar realm apart from observing the Earth. This would help in getting information about any objects or asteroids reaching close to the Earth. It is definitely the need of the day given the fact that there were 2.2 million asteroid sightings in 2014 and 7.2 million in 2015. In 2016, the figure is expected to reach 10 million. The telescope has already identified 3,600 asteroids and 69 objects that are getting closer to Earth. Four of them might hit the Earth.
DARPA designed the telescope to rapidly search for small space objects using a new imaging technology based on curved charge-couple devices. The design greatly reduces the telescope’s size while making it ten times more sensitive than the current state of the art. The telescope’s mount also used advanced servo-control technology that allows the telescope to rapidly search for small objects.
Current deep space telescopes do not provide a comprehensive picture of all objects in orbit around the Earth. Existing search telescopes have relatively narrow fields of view and cannot reliably detect and track faint objects, including small objects in geosynchronous orbits (roughly 22,000 miles high). There may be as many as hundreds of thousands of additional pieces of debris and asteroids that are too faint to track with current sensors.
“Currently we have a ‘soda straw’ view of deep space, where we can only see one narrow segment of space at a time,” Lt. Col. Travis Blake, DARPA’s Space Surveillance Telescope (SST) program manager and an Air Force office said. “The Space Surveillance Telescope should give us a much wider ‘windshield’ view of deep space objects, significantly enhancing our space situational awareness.”
Beyond providing faster data collection, the SST is very sensitive to light, which allows it to see faint objects in deep space that currently are impossible to observe. The detection and tracking of faint objects requires a large aperture and fast optics. The SST uses a 3.5 meter primary mirror, which is large enough to achieve the desired sensitivity.
“The SST will give us in a matter of nights the space surveillance data that current telescopes take weeks or months to provide,” explained Air Force Lt. Col. Travis Blake, DARPA’s Space Surveillance Telescope program manager. Furthermore, it can survey the whole geosynchronous belt not one or two but multiple times in one night. It must be noted that the whole geosynchronous belt is approximately one-quarter of the sky.
While space is increasingly crucial to modern society, it is also increasingly hazardous for satellites. Space is congested with tens of thousands of man-made objects as well as micro-meteors, asteroids and other natural satellites. Space is contested by a range of man-made threats that may have adverse effects on satellites. Some of the missions assigned to the SST include watching for debris in low earth orbit to help avoid satellite collisions, tracking objects in deep space and taking wide-angle pictures of stars and comets for astronomers.
Innovative technologies in DARPA’s Space Surveillance Telescope
The Space Surveillance Telescope is advanced in more than one respect and has given birth to a number of new technologies: its primary mirror has the world’s largest steep curve which allows the telescope to gather more light to view images across a wider field. The SST mirrors are some of the steepest aspherical curvatures ever to be polished and allow the telescope to have the fastest optics of its aperture class. These features combine to provide orders of magnitude improvements in deep space surveillance.
SST’s innovative design allows for a short focal length, wide field of view, and a compact optical train. The system is an f/1.0 optical design, with a large-area mosaic CCD camera constructed from the curved imagers and a high-speed shutter allowing for fast scanning at the high sensitivity.
The Space Surveillance Telescope (SST) uses image-capturing CCD (curved charge coupled device) technology and boasts a wide field-of-view and large-aperture optics. This combination helps the SST to move easily so it can quickly scan the sky – perfect for watching for strange spacecrafts or aliens, of course!
It uses Mersenne-Schmidt design to keep the mirror intact and provide compact construction; as well as being the world’s quickest and most nimble large telescope. In a nutshell, this telescope has revolutionized the way telescopes operate.
The camera of this telescope also boasts numerous inventions. It has the first-ever curved CCD/charge coupled device which ensures that the image is crystal clear no matter how wide the view or field is. Regular digital cameras contain flat CCDs and cannot record distortion-free images from curved mirrors. The telescope’s camera also has the world’s fastest shutter that can take thousands of pictures within one night.
Currently, the SST program is developing enhanced small-object detection algorithms, a new, advanced wide-field camera, and faster search operations in preparation for relocation to Harold E. Holt Naval Communication Station. SST is also leading the community in developing and applying tactical sensor tip-and-cue techniques, as well as applying the vast data archive to refine orbital debris density models.
DARPAs Tactical Technology Office director Brad Tousley stated that
“With its amazing capabilities, SST joins a prestigious list stretching back decades of game-changing space situational awareness programs on which DARPA and AFSPC have collaborated. DARPA looks forward to seeing what the Air Force will do with the SST and we will continue to work with them as DARPA pushes the technological envelope on space situational awareness with our Hallmark and OrbitOutlook programs.”
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