In most of the electromagnetic spectrum, a star composed of normal matter and a star composed of antimatter (anti-star) will look the same to an observer on Earth. Their visible spectra will be indistinguishable. A key difference in behavior may be observable in the gamma ray spectrum, where high-energy gamma rays characteristic of matter-antimatter annihilation (i.e., baryon-antibaryon reactions) may reveal the identity of an antimatter star within our galaxy or an antimatter star cluster outside our galaxy. Luigi Foschini provides a good introduction to this subject in his 2000 paper at the following link: https://cds.cern.ch/record/447091/files/0007180.pdf
NASA’s Alpha Magnetic Spectrometer (AMS) has developed into an important tool in the search for anti-stars. The prototype, AMS-01 flew on the STS-91 Space Shuttle mission from 2 to 12 June 1998 and was successfully tested in orbit. The full-scale AMS-2 was launched aboard the STS-134 Space Shuttle mission on 16 May 2011. Since it was installed on the International Space Station (ISS) and activated on 19 May 2011, this 18,739 pound (8,500 kg), 2,250 cu. ft (64 cu meter) instrument has collected and analyzed more than 165 billion cosmic ray events (as of April 2021), and identified 9 million of these as antimatter, including the possible detection of antihelium nuclei.
Another important source of data related to antimatter in our universe is NASA’s Fermi Gamma-ray Space Telescope, which was launched into a low Earth orbit on June 11, 2008. NASA’s website for the ongoing Fermi mission is here: https://fermi.gsfc.nasa.gov
In an 8 February 2021 article, astrophysicist Paul Sutter postulates the existence of antimatter star clusters that escaped the primordial matter-antimatter annihilations and now exist in relative isolation, for example, as an antimatter star cluster orbiting our Milky Way galaxy.
The antimatter stars in the cluster would continuously shed antimatter into the cosmos, leading to subsequent matter-antimatter interactions that produce high-energy particles that may be detectable from Earth.
Sutter commented, “…if astronomers are able to pinpoint a globular cluster as a particularly strong source of anti-particles, it would be like opening a time capsule, giving us a window into the physics that dominated the universe when it was only a second old.”
In a 20 April 2021 paper, authors Dupourqué, Tibaldo, and von Ballmoos report the possible detection of 14 anti-stars within our Milky Way galaxy. They used 10 years of data on 5,800 gamma-ray sources in Fermi’s data catalog to develop an estimate of the possible abundance of anti-stars. The authors report: “We identify in the catalog 14 anti-star candidates not associated with any objects belonging to established gamma-ray source classes and with a spectrum compatible with baryon-antibaryon annihilation.”
The 14 anti-star candidates await further analysis to confirm or refute their existence. If confirmed, they represent only a small fraction of the population of all gamma-ray sources observed by the Fermi Gamma-ray Space Telescope. Nonetheless, even one confirmed anti-star would be a remarkable achievement.
For more information:
Steve Naftilan, “How do we know that distant galaxies are composed of matter rather than anti-matter? If equal quantities of each were produced in the big bang, might not some parts of the universe contain primarily matter and other parts primarily anti-matter?” Scientific American, 21 October 1999: https://www.scientificamerican.com/article/how-do-we-know-that-dista/
Simon Dupourqué, Luigi Tibaldo, and Peter von Ballmoos, “Constraints on the antistar fraction in the Solar System neighborhood from the 10-year Fermi Large Area Telescope gamma-ray source catalog,” Phys. Rev. D 103, 083016, 20 April 2021 (abstract only without subscription): https://journals.aps.org/prd/abstract/10.1103/PhysRevD.103.083016
NASA’s Perseverance rover landed on Mars on 18 February 2021 carrying an impressive suite of scientific instruments and another vehicle, the autonomous Mars helicopter Ingenuity. The Perseverance rover joins the Curiosity rover and the InSight lander, as active NASA missions on the surface of Mars. The Perseverance mission website here: https://mars.nasa.gov/mars2020/
One of the important objectives of this mission is to demonstrate that the solar-powered Ingenuity helicopter can fly in the thin atmosphere of Mars. On Earth, our standard sea level air pressure is 1,013 millibars. On Mars, the surface atmospheric pressure varies during the year, but averages between 6 to 7 millibars. That’s equivalent to an Earth pressure altitude of 88,000 to 90,600 ft (27,127 to 27,615 m). On Earth, the helicopter altitude record is 40,820 ft (12,442 m). During development, Ingenuity’s rotor system was tested in a high-altitude chamber to validate its expected performance.
Ingenuity was carried under the rover and was deployed on 3 April 2021, about six weeks after landing.
After system checkouts and software updates, Ingenuity flew for the first time on 19 April 2021, becoming the first aircraft ever to fly on Mars. The first flight took place in Jezero Crater, lasted 39 seconds, and covered a vertical distance of about 10 feet (3 m), with Ingenuity landing back at the takeoff point. For this first flight, the Perseverance rover was parked about 211 feet (64.3 meters) away and chronicled the flight operations with its cameras.
A longer (47:20 minute) video from NASA Mission Control is here:
The Mars helicopter was conceived as a 30-day technology demonstration. To meet the weight and space budgets allocated for the Mars Helicopter, Ingenuity had to be a very compact, lightweight flying machine. The 1.8 kg (4.0 lb) mini-copter flies with two electric motor driven, counter-rotating, coaxial rotors about 1.1 m (3 ft 7 in) in diameter. The rotors are powered from a rechargeable 2 Ah (Amp-hour) lithium-ion battery. This is similar to the battery capacity of many cell phones. The general arrangement of the Ingenuity Mars helicopter is shown in the following diagram.
In March 2021, the National Aeronautics and Space Administration (NASA) announced that its orbiting Chandra X-ray Observatory had made the first ever detection of X-rays coming from the ice giant planet Uranus. Recent analysis of Chandra observations from 2002 and 2017 resulted in this discovery.
X-rays coming from other planets have been detected in the past. NASA reported, “Like Jupiter and Saturn, Uranus and its rings appear to mainly produce X-rays by scattering solar X-rays, but some may also come from auroras…… The X-rays from auroras on Jupiter come from two sources: electrons traveling down magnetic field lines, as on Earth, and positively charged atoms and molecules raining down at Jupiter’s polar regions. However, scientists are less certain about what causes auroras on Uranus.”
Another possible X-ray source could be from an interaction between Uranus’ rings and the near-space charged particle environment around the planet. This phenomenon has been observed at Saturn.
In connection with the discovery of X-rays coming from Uranus, NASA released two spectacular composite (multi-messenger) images of the planet created by combining images from two different parts of the electromagnetic spectrum: optical / near-infrared and X-ray.
Visible light has a wavelength in the range from about 350 to 750 nanometers (nm, 10-9meters) or 3,500 to 7,500 Angstroms. Near-infrared light is the part of the infrared spectrum that is closest to the visible light spectrum, but at a longer wavelength, from about 800 to 2,500 nm. X-rays have a much shorter wavelength, from about 20 to 0.001 nm. In the following chart, you can see the relative placement of visible and near-infrared light and X-rays in the electromagnetic spectrum.
The components of the first composite image are described below:
Near-infrared image: This was taken in July 2004 with the 10-meter (32-foot 10-inch) Keck-1 telescope located at an altitude of 4,145 meters (13,599 ft) on Maunakea, Hawaii. Image credit: Heidi B. Hammel, Space Science Institute; Lawrence Sromovsky, University of Wisconsin-Madison / W. M. Keck Observatory
The X-ray image: This was produced with 7 August 2002 data from the Advanced CCD Imaging Spectrometer (ACIS) aboard Chandra, which has a spatial resolution of 0.5” (seconds). The angular size of Uranus for the observation was 3.7”. The X-rays were in the 0.6 to 1.1 keV (2.1 to 1.1 nm) spectral range, which is consistent with X-ray emissions from Jupiter and Saturn. Image credit: NASA/CXO/University College London/W. Dunn et al.
The second 2021 composite image, shown below, was created from a Keck optical image and X-ray images made with Chandra’s High Resolution Camera (HRC) during observations on 11 and 12 November 2017. The HRC is sensitive to softer X-ray emissions (down to 0.06 keV, 20.7 nm) than ACIS, enabling it to collect more photons in the 0.1–1.2 keV (12.4 to 0.1 nm) range most important for planetary studies. The authors report, ”These fluxes exceed expectations from scattered solar emission alone, suggesting either a larger X-ray albedo than Jupiter/Saturn or the possibility of additional X-ray production processes at Uranus.”
The authors conclude by noting that, “Further, and longer, observations with Chandra would help to produce a map of X-ray emission across Uranus and to identify, with better signal-to-noise, the source locations for the X-rays, constraining possible contributions from the rings and aurora…… However, the current generation of X-ray observatories does not provide sufficient sensitivity to spectrally characterize the short interval temporal fluctuation observed in the November 12, 2017 observation.”
New space-based X-ray observational capabilities are being developed by NASA and the European Space Agency (ESA), but won’t be operational for a decade or more:
Japan’s Hayabusa2 (Japanese for Peregrine falcon 2) spacecraft returned from its six-year mission to asteroid 162173 Ryugu for a high-speed fly-by of Earth on 5 December 2020, during which it released a reentry capsule containing the material collected during two separate sampling visits to the asteroid’s surface. The capsule successfully reentered Earth’s atmosphere, landed in the planned target area in Australia’s Woomera Range and was recovered intact. The sample return capsule is known as the “tamatebako” (treasure box).
The first asteroid sample return mission was Japan’s Hayabusa1, which was launched on 9 May 2003 and rendezvoused with S-type asteroid 25143 Itokawa in mid-September 2005. A small sample was retrieved from the surface on 25 November 2005. The sample, comprised of tiny grains of asteroidal material, was returned to Earth on 13 June 2010, with a landing in the Woomera Range.
Japan’s Hayabusa2 and the US OSIRIS-Rex asteroid sample return missions overlap, with Hayabusa2 launching about two years earlier and returning its surface samples almost three years earlier. Both spacecraft were orbiting their respective asteroids from 31 December 2018 to 12 November 2019.
You’ll find a great deal of information and current news on the Hayabusa2 and OSIRIS-REx asteroid sample return missions on their respective project website:
An extended mission to explore additional asteroids was made possible by the excellent health of the Hayabusa2 spacecraft and the economic use of fuel during the basic mission. Hayabusa2 still has 30 kg (66 lb) of xenon propellant for its ion engines, about half of its initial load of 66 kg (146 lb).
As of September 2020, JAXA’s plans are is to target the Hayabusa2 spacecraft for the following two asteroid encounters:
Conduct a high-speed fly-by of L-type asteroid (98943) 2001 CC21 in July 2026. This asteroid has a diameter between 3.47 to 15.52 kilometers (2.2 to 9.6 miles).
Continue on a rendezvous with asteroid 1998 KY26 in July 2031. This is a 30-meter (98-foot) diameter asteroid, potentially X-type (metallic), and rotating rapidly with a period of only 10.7 minutes.
On 20 April 2020, the U.S. Geological Survey (USGS) released the first-ever comprehensive digital geologic map of the Moon. The USGS described this high-resolution map as follows:
“The lunar map, called the ‘Unified Geologic Map of the Moon,’ will serve as the definitive blueprint of the moon’s surface geology for future human missions and will be invaluable for the international scientific community, educators and the public-at-large.”
This remarkable mapping product is the culmination of a decades-long project that started with the synthesis of six Apollo-era (late 1960s – 1970s) regional geologic maps that had been individually digitized and released in 2013 but not integrated into a single, consistent lunar map.
This intermediate mapping product was updated based on data from the following more recent lunar satellite missions:
The Lunar Reconnaissance Orbiter Camera (LROC) is a system of three cameras that capture high resolution black and white images and moderate resolution multi-spectral images of the lunar surface: http://lroc.sese.asu.edu
Topography for the north and south poles was supplemented with Lunar Orbiter Laser Altimeter (LOLA) data: https://lola.gsfc.nasa.gov
The final product is a seamless, globally consistent map that is available in several formats: geographic information system (GIS) format at 1:5,000,000-scale, PDF format at 1:10,000,000-scale, and jpeg format.
At the following link, you can download a large zip file (310 Mb) that contains a jpeg file (>24 Mb) with a Mercator projection of the lunar surface between 57°N and 57°S latitude, two polar stereographic projections of the polar regions from 55°N and 55°S latitudes to the poles, and a description of the symbols and color coding used in the maps.
These high-resolution maps are great for exploring the lunar surface in detail. A low-resolution copy (not suitable for browsing) is reproduced below.
For more information on the Unified Geologic Map of the Moon, refer to the paper by C. M. Fortezzo, et al., “Release of the digital Unified Global Geologic Map of the Moon at 1:5,000,000-scale,” which is available here: https://www.hou.usra.edu/meetings/lpsc2020/pdf/2760.pdf
On July 16th, 1969, 13:32:00 UTC, the Saturn V launch vehicle, SA-506, lifted off from Launch Pad 39-A at Kennedy Space Center, Florida on the Apollo 11 mission with astronauts Neil Armstrong (Mission commander), Michael Collins (Command Module pilot) and Edwin (Buzz) Aldrin (Lunar Module pilot).
The Apollo spacecraft consisted of three modules:
The three-person Command Module (CM), named Columbia, was the living quarters for the three-person crew during most of the lunar landing mission.
The Service Module (SM) contained the propulsion system, electrical fuel cells, consumables storage tanks (oxygen, hydrogen) and various service / support systems.
The two-person, two-stage Lunar Module (LM), named Eagle, would make the Moon landing with two astronauts and return them to the CM.
The LM’s descent stage (bottom part of the LM with the landing legs) remained on the lunar surface and served as the launch pad for the ascent stage (upper part of the LM with the crew compartment). Only the 4.9 ton CM was designed to withstand Earth reentry conditions and return the astronauts safely to Earth.
From its initial low Earth parking orbit, Apollo 11 flew a direct trans-lunar trajectory to the Moon, inserting into lunar orbit about 76 hours after liftoff. The Apollo 11 mission profile to and from the Moon is shown in the following diagram, and is described in detail here: https://www.mpoweruk.com/Apollo_Moon_Shot.htm
Neil Armstrong and Buzz Aldrin landed the Eagle LM in the Sea of Tranquility on 20 July 1969, at 20:17 UTC (about 103 hours elapsed time since launch), while Michael Collins remained in a near-circular lunar orbit aboard the CSM. Neil Armstrong characterized the lunar surface at the Tranquility Base landing site with the observation, “it has a stark beauty all its own.”
In the two and a half hours they spent on the lunar surface, Armstrong and Aldrin collected 21.55 kg (47.51 lb) of rock samples, took photographs and set up the Passive Seismic Experiment Package (PSEP) and the Laser Ranging RetroReflector (LRRR), which would be left behind on the Moon. The PSEP provided the first lunar seismic data, returning data for three weeks after the astronauts left, and the LRRR allows precise distance measurements to be collected to this day. Neil Armstrong made an unscheduled jaunt to Little West crater, about 50 m (164 feet) east of the LM, and provided the first view into a lunar crater.
Armstrong and Aldrin departed the Moon on 21 July 1969 at 17:54 UTC in the ascent stage of the Eagle LM and then rendezvoused and docked with Collins in the CSM about 3-1/2 hours later.
After discarding the ascent stage, the CSM main engine was fired and Apollo 11 left lunar orbit on 22 July 1969 at 04:55:42 UTC and began its trans-Earth trajectory. As the Apollo spacecraft approached Earth, the SM was jettisoned.
The CM reentered the Earth’s atmosphere and landed in the North Pacific on 24 July 1969 at 16:50:35 UTC. The astronauts and the Apollo 11 spacecraft were recovered by the aircraft carrier USS Hornet. President Nixon personally visited and congratulated the astronauts while they were still in quarantine aboard the USS Hornet. You can watch a video of this meeting here:
Mankind’s first lunar landing mission was a great success.
Postscript to the first Moon landing
A month after returning to Earth, the Apollo 11 astronauts were given a ticker tape parade in New York City, then termed as the largest such parade in the city’s history.
There were a total of six Apollo lunar landings (Apollo 11, 12, 14, 15, 16, and 17), with the last mission, Apollo 17, returning to Earth on 19 December 1972. Their landing sites are shown in the following graphic.
In the past 46+ years since Apollo 17, there have been no manned missions to the Moon by the U.S. or any other nation.
Along with astronaut John Glenn, the first American to fly in Earth orbit, the three Apollo 11 astronauts were awarded the New Frontier Congressional Gold Medal in the Capitol Rotunda on 16 November 2011. This is the Congress’ highest civilian award and expression of national appreciation for distinguished achievements and contributions.
Neil Armstrong died on 25 August 2012 at the age of 82.
The Apollo 11 command module Columbia was physically transferred to the Smithsonian Institution in 1971 and has been on display for decades at the National Air and Space Museum on the mall in Washington D.C. For the 50th anniversary of the Apollo 11 mission, Columbia will be on display at The Museum of Flight in Seattle, as the star of the Smithsonian Institution’s traveling exhibition, “Destination Moon: The Apollo 11 Mission.” You can get a look at this exhibit at the following link: http://www.collectspace.com/news/news-041319a-destination-moon-seattle-apollo.html
After years of changing priorities under the Bush and Obama administrations, NASA’s current vision for the next U.S. manned lunar landing mission is named Artemis, after the Greek goddess of hunting and twin sister of Apollo. NASA currently is developing the following spaceflight systems for the Artemis mission:
The Space Launch System (SLS) heavy launch vehicle.
A manned “Gateway” station that will be placed in lunar orbit, where it will serve as a transportation node for lunar landing vehicles and manned spacecraft for deep space missions.
The Orion multi-purpose manned spacecraft, which will deliver astronauts from Earth to the Gateway, and also can be configured for deep space missions.
Lunar landing vehicles, which will shuttle between the Gateway and destinations on the lunar surface.
While NASA has a tentative goal of returning humans to the Moon by 2024, the development schedules for the necessary Artemis systems may not be able to meet this ambitious schedule. The landing site for the Artemis mission will be in the Moon’s south polar region. NASA administrator Jim Bridenstine has stated that Artemis will deliver the first woman to the Moon.
After the failure of Israel’s Beresheet spacecraft to execute a soft landing on the Moon in April 2019, India is the next new contender for lunar soft landing honors with their Chandrayaan-2 spacecraft. We’ll take a look at the Chandrayaan-2 mission in this post.
1. Background: India’s Chandrayaan-1 mission to the Moon
India’s first mission to the Moon, Chandrayaan-1, was a mapping mission designed to operate in a circular (selenocentric) polar orbit at an altitude of 100 km (62 mi). The Chandrayaan-1 spacecraft, which had an initial mass of 1,380 kg (3,040 lb), consisted of two modules, an orbiter and a Moon Impact Probe (MIP). Chandrayaan-1 carried 11 scientific instruments for chemical, mineralogical and photo-geologic mapping of the Moon. The spacecraft was built in India by the Indian Space Research Organization (ISRO), and included instruments from the USA, UK, Germany, Sweden and Bulgaria.
Chandrayaan-1 was launched on 22 October 2008 from the Satish Dhawan Space Center (SDSC) in Sriharikota on an “extended” version of the indigenous Polar Satellite Launch Vehicle designated PSLV-XL. Initially, the spacecraft was placed into a highly elliptical geostationary transfer orbit (GTO), and was sent to the Moon in a series of orbit-increasing maneuvers around the Earth over a period of 21 days. A lunar transfer maneuver enabled the Chandrayaan-1 spacecraft to be captured by lunar gravity and then maneuvered to the intended lunar mapping orbit. This is similar to the five-week orbital transfer process used by Israel’s Bersheet lunar spacecraft to move from an initial GTO to a lunar circular orbit.
The goal of MIP was to make detailed measurements during descent using three instruments: a radar altimeter, a visible imaging camera, and a mass spectrometer known as Chandra’s Altitudinal Composition Explorer (CHACE), which directly sampled the Moon’s tenuous gaseous atmosphere throughout the descent. On 14 November 2008, the 34 kg (75 lb) MIP separated from the orbiter and descended for 25 minutes while transmitting data back to the orbiter. MIP’s mission ended with the expected hard landing in the South Pole region near Shackelton crater at 85 degrees south latitude.
In May 2009, controllers raised the orbit to 200 km (124 miles) and the orbiter mission continued until 28 August 2009, when communications with Earth ground stations were lost. The spacecraft was “found” in 2017 by NASA ground-based radar, still in its 200 km orbit.
Numerous reports have been published describing the detection by the Chandrayaan-1 mission of water in the top layers of the lunar regolith. The data from CHACE produced a lunar atmosphere profile from orbit down to the surface, and may have detected trace quantities of water in the atmosphere. You’ll find more information on the Chandrayaan-1 mission at the following links:
2. India’s upcoming Chandrayaan-2 mission to the Moon
Chandrayaan-2 was launched on 22 July 2019. After achieving a 100 km (62 mile) circular polar orbit around the Moon, a lander module will separate from the orbiting spacecraft and descend to the lunar surface for a soft landing, which currently is expected to occur in September 2019, after a seven-week journey to the Moon. The target landing area is in the Moon’s southern polar region, where no lunar lander has operated before. A small rover vehicle will be deployed from the lander to conduct a 14-day mission on the lunar surface. The orbiting spacecraft is designed to conduct a one-year mapping mission.
The launch vehicle
India will launch Chandrayaan-2 using the medium-lift Geosynchronous Satellite Launch Vehicle Mark III (GSLV Mk III) developed and manufactured by ISRO. As its name implies, GSLV Mk III was developed primarily to launch communication satellites into geostationary orbit. Variants of this launch vehicle also are used for science missions and a human-rated version is being developed to serve as the launch vehicle for the Indian Human Spaceflight Program.
The GSLV III launch vehicle will place the Chandrayaan-2 spacecraft into an elliptical parking orbit (EPO) from which the spacecraft will execute orbital transfer maneuvers comparable to those successfully executed by Chandrayaan-1 on its way to lunar orbit in 2008. The Chandrayaan-2 mission profile is shown in the following graphic. You’ll find more information on the GSLV Mk III on the ISRO website at the following link: https://www.isro.gov.in/launchers/gslv-mk-iii
Chandrayaan-2 builds on the design and operating experience from the previous Chandrayaan-1 mission. The new spacecraft developed by ISRO has an initial mass of 3,877 kg (8,547 lb). It consists of three modules: an Orbiter Craft (OC) module, the Vikram Lander Craft (LC) module, and the small Pragyan rover vehicle, which is carried by the LC. The three modules are shown in the following diagram.
Chandrayaan-2 carries 13 Indian payloads — eight on the orbiter, three on the lander and two on the rover. In addition, the lander carries a passive Laser Retroreflector Array (LRA) provided by NASA.
The OC and the LC are stacked together within the payload fairing of the launch vehicle and remain stacked until the LC separates in lunar orbit and starts its descent to the lunar surface.
The solar-powered orbiter is designed for a one-year mission to map lunar surface characteristics (chemical, mineralogical, topographical), probe the lunar surface for water ice, and map the lunar exosphere using the CHACE-2 mass spectrometer. The orbiter also will relay communication between Earth and Vikram lander.
The solar-powered Vikram lander weighs 1,471 kg (3,243 lb). The scientific instruments on the lander will measure lunar seismicity, measure thermal properties of the lunar regolith in the polar region, and measure near-surface plasma density and its changes with time.
The 27 kg (59.5 lb) six-wheeled Pragyan rover, whose name means “wisdom” in Sanskrit, is solar-powered and capable of traveling up to 500 meters (1,640 feet) on the lunar surface. The rover can communicate only with the Vikram lander. It is designed for a 14-day mission on the lunar surface. It is equipped with cameras and two spectroscopes to study the elemental composition of lunar soil.
You’ll find more information on the spacecraft in the 2018 article by V. Sundararajan, “Overview and Technical Architecture of India’s Chandrayaan-2 Mission to the Moon,” at the following link:
1. Overview of US military optical reconnaissance satellite programs
The National Reconnaissance Office (NRO) is responsible for developing and operating space reconnaissance systems and conducting intelligence-related activities for US national security. NRO developed several generations of classified Keyhole (KH) military optical reconnaissance satellites that have been the primary sources of Earth imagery for the US Department of Defense (DoD) and intelligence agencies. NRO’s website is here:
NRO’s early generations of Keyhole satellites were placed in low Earth orbits, acquired the desired photographic images on film during relatively short-duration missions, and then returned the film to Earth in small reentry capsules for airborne recovery. After recovery, the film was processed and analyzed. The first US military optical reconnaissance satellite program, code named CORONA, pioneered the development and refinement of the technologies, equipment and systems needed to deploy an operational orbital optical reconnaissance capability. The first successful CORONA film recovery occurred on 19 August 1960.
Keyhole satellites are identified by a code word and a “KH” designator, as summarized in the following table.
In 1976, NRO deployed its first electronic imaging optical reconnaissance satellite known as KENNEN KH-11 (renamed CRYSTAL in 1982), which eventually replaced the KH-9, and brought an end to reconnaissance satellite missions requiring film return. The KH-11 flies long-duration missions and returns its digital images in near real time to ground stations for processing and analysis. The KH-11, or an advanced version sometimes referred to as the KH-12, is operational today.
Geospatial intelligence, or GEOINT, is the exploitation and analysis of imagery and geospatial information to describe, assess and visually depict physical features and geographically referenced activities on the Earth. GEOINT consists of imagery, imagery intelligence and geospatial information. Satellite imagery from Keyhole reconnaissance satellites is an important information source for national security-related GEOINT activities.
The National Geospatial-Intelligence Agency (NGA), which was formed in 2003, has the primary mission of collecting, analyzing, and distributing GEOINT in support of national security. NGA’s predecessor agencies, with comparable missions, were:
National Imagery and Mapping Agency (NIMA), 1996 – 2003
National Photographic Interpretation Center (NPIC), a joint project of the Central Intelligence Agency (CIA) and DoD, 1961 – 1996
2. The advent of the US civilian Earth observation programs
Collecting Earth imagery from orbit became an operational US military capability more than a decade before the start of the joint National Aeronautics & Space Administration (NASA) / US Geological Survey (USGS) civilian Landsat Earth observation program. The first Landsat satellite was launched on 23 July 1972 with two electronic observing systems, both of which had a spatial resolution of about 80 meters (262 feet).
Since 1972, Landsat satellites have continuously acquired low-to-moderate resolution digital images of the Earth’s land surface, providing long-term data about the status of natural resources and the environment. Resolution of the current generation multi-spectral scanner on Landsat 9 is 30 meters (98 feet) in visible light bands.
3. Declassification of certain military reconnaissance satellite imagery
All military reconnaissance satellite imagery was highly classified until 1995, when some imagery from early defense reconnaissance satellite programs was declassified. The USGS explains:
“The images were originally used for reconnaissance and to produce maps for U.S. intelligence agencies. In 1992, an Environmental Task Force evaluated the application of early satellite data for environmental studies. Since the CORONA, ARGON, and LANYARD data were no longer critical to national security and could be of historical value for global change research, the images were declassified by Executive Order 12951 in 1995”
Additional sets of military reconnaissance satellite imagery were declassified in 2002 and 2011 based on extensions of Executive Order 12951.
The declassified imagery is held by the following two organizations:
The original film is held by the National Archives and Records Administration (NARA).
Duplicate film held in the USGS Earth Resources Observation and Science (EROS) Center archive is used to produce digital copies of the imagery for distribution to users.
The declassified military satellite imagery available in the EROS archive is summarized below:
USGS EROS Archive – Declassified Satellite Imagery – 1 (1960 to 1972)
This set of photos, declassified in 1995, consists of more than 860,000 images of the Earth’s surface from the CORONA, ARGON, and LANYARD satellite systems.
CORONA image resolution improved from 40 feet (12.2 meters) for the KH-1 to about 6 feet (1.8 meters) for the KH-4B.
KH-5 ARGON image resolution was about 460 feet (140 meters).
KH-6 LANYARD image resolution was about 6 feet (1.8 meters).
USGS EROS Archive – Declassified Satellite Imagery – 2 (1963 to 1980)
This set of photos, declassified in 2002, consists of photographs from the KH-7 GAMBIT surveillance system and KH-9 HEXAGON mapping program.
KH-7 image resolution is 2 to 4 feet (0.6 to 1.2 meters). About 18,000 black-and-white images and 230 color images are available.
The KH-9 mapping camera was designed to support mapping requirements and exact positioning of geographical points. Not all KH-9 satellite missions included a mapping camera. Image resolution is 20 to 30 feet (6 to 9 meters); significantly better than the 98 feet (30 meter) resolution of LANDSAT imagery. About 29,000 mapping images are available.
USGS EROS Archive – Declassified Satellite Imagery – 3 (1971 to 1984)
This set of photos, declassified in 2011, consists of more photographs from the KH-9 HEXAGON mapping program. Image resolution is 20 to 30 feet (6 to 9 meters).
4. Example applications of declassified military reconnaissance satellite imagery
The declassified military reconnaissance satellite imagery provides views of the Earth starting in the early 1960s, more than a decade before civilian Earth observation satellites became operational. The military reconnaissance satellite imagery, except from ARGON KH-5, is higher resolution than is available today from Landsat civilian earth observation satellites. The declassified imagery is an important supplement to other Earth imagery sources. Several examples applications of the declassified imagery are described below.
Assessing Aral Sea depletion:
USGS reports: “The Aral Sea once covered about 68,000 square kilometers, a little bigger than the U.S. state of West Virginia. It was the 4th largest lake in the world. It is now only about 10% of the size it was in 1960…..In the 1990s, a dam was built to prevent North Aral water from flowing into the South Aral. It was rebuilt in 2005 and named the Kok-Aral Dam…..The North Aral has stabilized but the South Aral has continued to shrink and become saltier. Up until the 1960s, Aral Sea salinity was around 10 grams per liter, less than one-third the salinity of the ocean. The salinity level now exceeds 100 grams per liter in the South Aral, which is about three times saltier than the ocean.”
On the USGS website, the “Earthshots: Satellite Images of Environmental Change” webpages show the visible changes at many locations on Earth over a 50+ year time period. The table of contents to the Earthshots webpages is shown below and is at the following link: http:// https://earthshots.usgs.gov/earthshots/
For the Aral Sea region, the Earthshots photo sequences start with ARGON KH-5 photos taken in 1964. Below are three screenshots of the USGS Earthshots pages showing the KH-5 images for the whole the Aral Sea, the North Aral Sea region and the South Aral Sea region. You can explore the Aral Sea Earthshots photo sequences at the following link: https://earthshots.usgs.gov/earthshots/node/91#ad-image-0-0
Assessing Antarctic ice shelf condition:
In a 7 June 2016 article entitled, ”Spy satellites reveal early start to Antarctic ice shelf collapse,” Thomas Sumner reported:
“Analyzing declassified images from spy satellites, researchers discovered that the downhill flow of ice on Antarctica’s Larsen B ice shelf was already accelerating as early as the 1960s and ’70s. By the late 1980s, the average ice velocity at the front of the shelf was around 20 percent faster than in the preceding decades,….”
In a 19 June 2019 paper “Acceleration of ice loss across the Himalayas over the past 40 years,” the authors, reported on the use of HEXAGON KH-9 mapping camera imagery to improve their understanding of trends affecting the Himalayan glaciers from 1975 to 2016:
“Himalayan glaciers supply meltwater to densely populated catchments in South Asia, and regional observations of glacier change over multiple decades are needed to understand climate drivers and assess resulting impacts on glacier-fed rivers. Here, we quantify changes in ice thickness during the intervals 1975–2000 and 2000–2016 across the Himalayas, using a set of digital elevation models derived from cold war–era spy satellite film and modern stereo satellite imagery.”
“The majority of the KH-9 images here were acquired within a 3-year interval (1973–1976), and we processed a total of 42 images to provide sufficient spatial coverage.”
“We observe consistent ice loss along the entire 2000-km transect for both intervals and find a doubling of the average loss rate during 2000–2016.”
“Our compilation includes glaciers comprising approximately 34% of the total glacierized area in the region, which represents roughly 55% of the total ice volume based on recent ice thickness estimates.”
The Center for Advanced Spatial Technologies, a University of Arkansas / U.S. Geological Survey collaboration, has undertaken the CORONA Atlas Project using military reconnaissance satellite imagery to create the “CORONA Atlas & Referencing System”. The current Atlas focuses on the Middle East and a small area of Peru, and is derived from 1,024 CORONA images taken on 50 missions. The Atlas contains 833 archaeological sites.
“In regions like the Middle East, CORONA imagery is particularly important for archaeology because urban development, agricultural intensification, and reservoir construction over the past several decades have obscured or destroyed countless archaeological sites and other ancient features such as roads and canals. These sites are often clearly visible on CORONA imagery, enabling researchers to map sites that have been lost and to discover many that have never before been documented. However, the unique imaging geometry of the CORONA satellite cameras, which produced long, narrow film strips, makes correcting spatial distortions in the images very challenging and has therefore limited their use by researchers.”
CAST reports that they have “developed methods for efficient
orthorectification of CORONA imagery and now provides free public access to our imagery database for non-commercial use. Images can be viewed online and full resolution images can be downloaded in NITF format.”
Conducting commercial geospatial analytics over a broader period of time:
The firm Orbital Insight, founded in 2013, is an example of commercial firms that are mining geospatial data and developing valuable information products for a wide range of customers. Orbital Insight reports:
“Orbital Insight turns millions of images into a big-picture understanding of Earth. Not only does this create unprecedented transparency, but it also empowers business and policy decision makers with new insights and unbiased knowledge of socio-economic trends. As the number of Earth-observing devices grows and their data output expands, Orbital Insight’s geospatial analytics platform finds observational truth in an interconnected world. We map out and quantify the world’s complexities so that organizations can make more informed decisions.”
“By applying artificial intelligence to satellite, UAV, and other geospatial data sources, we seek to discover and quantify societal and economic trends on Earth that are indistinguishable to the human eye. Combining this information with terrestrial data, such as mobile and location-based data, unlocks new sources of intelligence.”
The National Aeronautics and Space Administration’s (NASA) durable New Horizon spacecraft made its close flyby of Pluto on 14 July 2015, passing 7,800 mi (12,500 km) above the surface of that dwarf planet and returning a remarkable trove of photos and data. Since then, the spacecraft has been continuing its journey out of our solar system and now is flying through the Kuiper Belt, which is a very large, diffuse region beyond the orbit of Neptune containing millions of small bodies in distant orbits around the Sun. These Kuiper Belt Objects (KBOs) are believed to be “leftovers” (i.e., they never coalesced into planets) from the formation of the early solar system. You can read more about the Kuiper Belt on the NASA website here:
On 28 August 2015, NASA announced that it had selected the next destination for New Horizons after the Pluto flyby: a small KBO designated 2014 MU69, originally named Ultima Thule, about 1 billion miles (1.6 billion km) beyond Pluto. The spacecraft’s trajectory from Earth to Ultima Thule is shown in the following NASA diagram.
On 1 January 2019, the New Horizons spacecraft made a close flyby of 2014 MU69, at a range of 2,200 miles (3,500 km) and a relative speed of 14 kilometers per second (31,317 mph). At a distance of 4.1 billion miles (6.6 billion km) from the Earth, radio signals took 6 hours and 6 minutes traveling at the speed of light to traverse the distance between the spacecraft and Earth during the encounter. On 1 January 2019, NASA released the following blurry image, which was taken at long range.
NASA reported: “At left is a composite of two images taken by New Horizons’ high-resolution Long-Range Reconnaissance Imager (LORRI), which provides the best indication of Ultima Thule’s size and shape so far. Preliminary measurements of this Kuiper Belt object suggest it is approximately 20 miles long by 10 miles wide (32 kilometers by 16 kilometers). An artist’s impression at right illustrates one possible appearance of Ultima Thule, based on the actual image at left. The direction of Ultima’s spin axis is indicated by the arrows. “
In the weeks following the flyby, New Horizons will be downloading all of the higher-resolution photos and data acquired during its close encounter with 2014 MU69 and we’ll be getting a much more detailed understanding of this KBO.
It appears that NASA has the opportunity to target one or more additional KBOs for future New Horizons flybys in the 2020s. The spacecraft’s electric power source, a plutonium (Pu-238)-fueled radioisotope thermoelectric generator (RTG), is capable of providing power well into the 2030s, albeit at gradually reducing power levels. In addition, the spacecraft has significant hydrazine fuel remaining for course correction and attitude control en route to a future KBO flyby.
On 2 January 2019, NASA released the following photo taken on the inbound leg of the flyby, still 18,000 miles (28,000 km) from 2014 MU69.
You’ll find more information on NASA’s New Horizons mission here:
24 January 2019 Update: Latest photo shows 2014 MU69 surface to be unusually smooth
Today, NASA released the following photo of 2014 MU69, taken at a distance of 4,200 miles (6,700 kilometers) on 1 January 2019, just seven minutes before closest approach. Principal Investigator Alan Stern, of the Southwest Research Institute, reported, “Over the next month there will be better color and better resolution images that we hope will help unravel the many mysteries of Ultima Thule.”
12 November 2019: 2014 MU69 renamed
NASA announced that 2014 MU69 was formally renamed “Arrokoth”, which NASA says “means ‘sky’ in the language of the Powhatan people, a Native American tribe indigenous to Maryland. The state is home to New Horizons mission control at the Johns Hopkins University Applied Physics Laboratory in Laurel.” Here’s a colorized view of Arrokoth.
It seems that every week or two there is a news article about another small asteroid that soon will pass relatively close to the Earth. Most were detected while they were still approaching Earth. Some were first detected very shortly before or after their closest approach to Earth. That must have made the U.S. Planetary Defense Officer a bit nervous, but then, what could he do about it? (See my 21 January 2016 post, “Relax, the Planetary Defense Officer has the watch”).
While we currently can’t do anything to defend against NEOs, extensive worldwide programs are in place to identify and track NEOs and predict which NEOs may present a future hazard to the Earth. Here’s a brief overview of the following programs.
NASA Wide-field Infrared Survey Explorer (WISE)
International Astronomical Union’s (IAU’s) Minor Planet Center (MPC)
NASA’s Center for Near Earth Object Studies (CNEOS)
National Optical Astronomy Observatory (NOAO) NEO sky survey
University of Arizona Lunar and Planetary Laboratory
NASA’s Wide-field Infrared Survey Explorer (WISE)
WISE was an Earth orbiting infrared-wavelength astronomical space telescope with a 40 cm (16 in) diameter primary mirror. WISE operated from December 2009 to February 2011 and performed an “all-sky” astronomical imaging survey in the 3.4, 4.6, 12.0 and 22.0 μm wavelength bands. NASA’s home page for the WISE / NEOWISE mission is at the following link:
NEOWISE is the continuing NASA project to mine the WISE data set. An important data mining tool is the WISE Moving Object Processing System (WMOPS), which has been optimized to enable extraction of moving objects at lower signal-to-noise levels. A comet detection is shown in the following multiple images that have been combined to show the comet in four different positions relative to the fixed background stars.
To date, the NEOWISE data mining effort has resulted in the following:
Detection of ~158,000 asteroids at thermal infrared wavelengths, including ~700 near-Earth objects (NEOs) and ~34,000 new asteroids, 135 of which are NEOs.
Detection of more than 155 comets, including 21 new discoveries.
Determination of preliminary physical properties such as diameter and visible albedo for nearly all of these objects.
Estimation of the numbers, sizes, and orbital elements of NEOs, including potentially hazardous asteroids
Results have been published, enabling a range of other studies of the origins and evolution of the small bodies in our solar system.
The output from NEOWISE is delivered to NASA’s Planetary Data System (PDS), which NASA describes as follows:
“The PDS archives and distributes scientific data from NASA planetary missions, astronomical observations, and laboratory measurements. The PDS is sponsored by NASA’s Science Mission Directorate. Its purpose is to ensure the long-term usability of NASA data and to stimulate advanced research. All PDS data are publicly available and may be exported outside of United States under ‘Technology and Software Publicly Available’ (TSPA) classification.”
The link to the NASA Planetary Data System is here:
International Astronomical Union’s (IAU’s) Minor Planet Center (MPC)
The MPC describes itself as the “single worldwide location for receipt and distribution of positional measurements of minor planets, comets and other irregular natural satellites of the major planets. The MPC is responsible for the identification, designation and orbit computation for all of these objects.”
On this website, MPC lists the following 2017 summary statistics:
The MPC website offers several short videos that explain the NEO hazard and the challenges of detecting these small objects and determining their orbital parameters with high precision. Key points made in the MPC videos include:
The Earth’s cross-section represents only 1/10,000th of the area of the near-Earth region. Earth is a relatively small target area for a NEO.
To determine if a NEO is a potential hazard, its orbital parameters must be established with a precision of greater than 1/100th of 1%.
There is a “zone of discoverability” (green area in the following diagram) that varies primarily by the size of the object and the aspect of its lighted side to observers on Earth. If an object is outside this rather small zone, then current sky survey instruments cannot detect the object. An example is the 15 February 2013 atmospheric blast that occurred near Chelyabinsk, Russia. This event was caused by a previously undetected NEO that approached Earth at a high relative velocity from the direction of the Sun and vaporized in the Earth’s atmosphere.
Zone of discoverability (green area). Source: screenshot from MPC video “Asteroid Hazards, Part 2: The Challenge of Detection”
NASA’s Center for Near Earth Object Studies (CNEOS)
CNEOS is NASA’s center for computing asteroid and comet orbits with high precision and estimating the probability of a future Earth impact. CNEOS is operated by the California Institute of Technology (Caltech) Jet Propulsion Laboratory (JPL) and supports NASA’s Planetary Defense Coordination Office.
CNEOS is the home of JPL’s Sentry and Scout programs:
The Sentryimpact monitoring system performs long-term analyses of possible future orbits of hazardous asteroids, searching for impact possibilities over the next century.
TheScout system monitors the IAU’s MPC database for new potential asteroid discoveries and computes the possible range of future motions even before these objects have been confirmed as discoveries.
The average distance between the Earth and the moon is about 238,855 miles (384,400 km), which equals 1 LD. On the CNEOS website, you can view data on NEO close approaches to Earth at the following link:
By adjusting the table settings and sorting by a specific column heading, you can create customized views of the close approach data. Just looking at data from the past year for NEOs that passed Earth within 1 LD yielded the following results:
48 NEOs passed within 1 LD of Earth.
For these NEOs, object diameters were in the range from 1.8 to 83 meters (5.9 to 272 feet). The NEO that caused the 2013 Chelyabinsk blast was estimated to have a diameter of 10 to 20 meters (32.8 to 65.6 feet).
Their relative velocities were in the range from 4.02 to 23.97 km/s (8,992 to 53,620 mph). The NEO that caused the 2013 Chelyabinsk blast was estimated to have a relative velocity of 19.16 km/s (45,860 mph).
In the past year, the closest approach was by object 2017 GM, which had a “CA Distance Minimum” (3-signa estimate, measured from Earth center to NEO center) of 0.04 LD, or 15,376 km (9,554 miles). After subtracting Earth’s radius of 6,371 km (3,959 miles), object 2017 GM cleared the Earth’s surface by 9,005 km (5,595 miles).
Looking into the future, the CNEOS close approach data shows two objects that currently have values of “CA Distance Minimum” that are less than the radius of the Earth, indicating that impact is possible:
Object 2012 HG2: close approach date on 13 February 2047; modest size of 11 – 24 meters (36 – 79 feet); low relative velocity of 4.36 km/sec (9,753 mph)
Object 2010 RF12: close approach date of 6 September 2095; modest size of 6.4 – 14 meters (21 to 46 feet); modest relative velocity of 7.65 km/sec (17,112 mph)
So it looks like we have less than 30 years to refine the orbital data on object 2012 HG2, determine if it will impact Earth, and, if so, determine where the impact will occur and what mitigating actions can be taken. Hopefully, the U.S. Planetary Defense Officer is on top of this matter.
National Optical Astronomy Observatory (NOAO) NEO sky survey
On 30 August 2017, NOAO issued a press release summarizing the results of a survey of NEOs conducted using the Dark Energy Camera (DECam) on the 4 meter (157.5 inch) Blanco telescope at the Cerro Tololo Inter-American Observatory in northern Chile.
“Lori Allen, Director of the Kitt Peak National Observatory and the lead investigator on the study, explained, ‘There are around 3.5 million NEOs larger than 10 meters, a population ten times smaller than inferred in previous studies. About 90% of these NEOs are in the Chelyabinsk size range of 10-20 meters.’”
“David Trilling, the first author of the study,…explained…..‘If house-sized NEOs are responsible for Chelyabinsk-like events, our results seem to say that the average impact probability of a house-sized NEO is actually ten times greater than the average impact probability of a large NEO.’”
As a “quasi-satellite,” 2016 HO3 is not gravitationally bound to Earth, but its solar orbit keeps 2016 HO3 in relatively close proximity to Earth, but in a slightly different orbital plane. As both bodies orbit the Sun, the motion of 2016 HO3 relative to the Earth gives the appearance that 2016 HO3 is in a distant halo orbit around Earth. The approximate geometry of this three body system is shown in the following diagram, with 2016 HO3’s solar orbit represented in red and the halo orbit as seen from Earth represented in yellow.
You’ll find a video showing the dynamics of 2016 HO3’s halo orbit on the EarthSky website at the following link:
Key parameters for 2016 HO3 are: diameter: 100 meters (330 feet); distance from Earth: 38 to 100 LD; composition appears to be the same material as other asteroid NEOs. With its stable halo orbit, there is no risk that 2016 HO3 will collide with Earth.
For additional reading on NEO discovery:
Myhrvold, “Comparing NEO Search Telescopes,” Astronomical Society of the Pacific, April 2016
“I use simple physical principles to estimate basic performance metrics for the ground-based Large Synoptic Survey Telescope and three space-based instruments— Sentinel, NEOCam, and a Cubesat constellation.”
S.R. Chesley & P. Vereš, “Projected Near-Earth Object Discovery Performance of the Large Synoptic Survey Telescope,” JPL Publication 16-11, CNEOS, April 2017
“LSST is designed for rapid, wide-field, faint surveying of the night sky ….The baseline LSST survey approach is designed to make two visits to a given field in a given night, leading to two possible NEO detections per night. These nightly pairs must be linked across nights to derive orbits of moving objects…… Our simulations revealed that in 10 years LSST would catalog 60% of NEOs with absolute magnitude H < 22, which is a proxy for 140 m and larger objects.”