The Space Force is expected to shift investments from large satellites like the Space Based Infrared System, which the Air Force acquired around 20 years ago to smaller spacecraft.

According to the the head of military space acquisitions, the era of massive satellites needs to be a thing of the past for the Department of Defense and he told the government and industry executives about this a week ago.

Frank Calvelli, assistant secretary of the Air Force for space acquisition and integration, since taking office has been insistent that reforms are needed in satellite procurements, including the transition to smaller satellites that can be built and launched within a three-year period, compared to a decade or longer for traditional large satellites. 

Calvelli spoke at the National Security Space Association’s defense and intelligence conference in a fireside chat with former DoD official Doug Loverro.

Echoing points he made in previous public appearances, Calvelli called for DoD to break from the past and embrace more agile ways to buy satellites in order to make United States of America systems more resilient to threats. Most space-based systems the U.S. military needs — for communications, space domain awareness, missile detection and tracking, navigation, weather and other applications — can be accomplished using small satellites, Calvelli said. 

“We are transforming from what’s been called ‘big juicy targets’ of the past to a more proliferated and more resilient architecture that can be counted on during times of crisis and conflict,” he said. 

Using commercially available satellite buses and components, DoD can build smaller spacecraft for operations in low, medium or geostationary Earth orbits, Calvelli said. “I see us building small satellites everywhere, regardless of whether it’s LEO MEO or GEO.”

Calvelli made the case that the traditional “big structures with lots of payloads on them” can be broken down into smaller satellites which would be harder for an enemy to target. That concept, also known as “disaggregation,” was advocated by some Air Force officials a decade ago but was largely rejected in favor of big satellites that, although expensive, can operate in orbit for decades. 

In light of recent advances in anti-satellite weapons developed by China and Russia, the Pentagon has to pivot to more resilient systems, Calvelli stressed. “I do believe that we can break apart the big behemoths in GEO and break them into smaller bite-sized chunks which is going to diversify the architecture and protect us more.”

‘Do not design new buses’

Since taking office seven months ago, Calvelli has noticed that Space Force program offices tend to design bespoke satellite buses, another practice that he wants to end. 

“If you need some new tech, that’s okay. But keep that development focused on the payload. Do not create new buses,” he said. 

There are plenty of commercially available buses to choose from, he said. “We love building new buses. We love building new bus components. We love doing new things that are already out there,” he said. “If you need to do some tech development, keep it minimal.”

Meteorologists are eager to protect the spectrum from radio frequency interference coming from satellite mega-constellations threat.

At the American Meteorological Society (AMS) annual meeting in Denver, meteorologists and spectrum experts expressed concern about proposals for SpaceX’s second-generation Starlink broadband constellations and acknowledged that other proposed mega-constellations could create interference as well.

SpaceX enquired to the U.S. Federal Communications Commission for a license to transmit signals from gateway stations to nearly 30,000 Starlink second-generation constellations in the 81 to 86 gigahertz band.

“The sheer number of potential gateway uplink stations around the world could contribute to adjacent band contamination and further due diligence would be needed,” said David Lubar, Aerospace Corp. senior project leader, said at the AMS meeting. “We do not know if their out-of-band emissions will be an area of concern.”

Meteorologists pick up faint signals indicating humidity over land in the 86 to 92 gigahertz band, adjacent to the bands Starlink has proposed for uplinks.

It’s not yet clear whether the Starlink uplinks would pose any danger to the meteorological observations, but weather forecasts rely on passive radiometers to pick up faint signals to identify water vapor, precipitation and atmospheric temperature in various spectral bands.

“These bands are established by the fundamental laws of physics,” Tony McNally, principal scientist in the European Centre for Medium-Range Weather Forecasts Research Department, said at the AMS meeting.

Complicating the matter is the fact that “the signals that we are looking for with our passive satellites are much smaller than the interference patterns created by some of the other uses of the spectrum,” McNally added. “I would liken it to trying to gaze up at the stars at night when someone puts an incredibly bright flashlight in your eyes.”

Meteorologists sought protection from unwanted emissions in the 81-86 gigahertz band at the 2019 World Radiocommunications Conference in Egypt. At the time, the International Telecommunications Union body of delegates declined to take up the matter.

As a result, the FCC has no current regulations that would limit SpaceX’s use of the band.

“Any new international rules are unlikely to be enacted until after 2027,” Lubar said.

This is just one example of the whack-a-mole predicament meteorologists face in trying to safeguard atmospheric measurements and weather data relays from RF interference.

Another potential problem relates to the passive measurements meteorologists make from 50.2 to 50.4 gigahertz. Careful observation of that band reveals temperatures at various levels of the atmosphere. That data, paired with humidity measurements in the 180 to 184 gigahertz band, are key elements of weather forecasts.

Existing regulations protect the 50.2 to 50.4 gigahertz band from interference, but the signals are so weak they could be drowned out by noise emitted in adjacent bands.

“These systems in space are measuring extremely sensitive bits of energy,” said Beau Backus, Johns Hopkins Applied Physics Laboratory senior spectrum manager. “That makes it essential that this be in protected areas.”

Tens of thousands of satellites are expected to launch in the next decade. Many satellite operators are proposing transmitting data to spacecraft in bands immediately above and below the 50.2 to 50.4 gigahertz band.

“The industry is moving faster than our scientific development,” Michael Farrar, director of the National Centers for Environmental Prediction at the National Weather Service, said at the AMS meeting. “This problem is going to accelerate. We should build a process that can rapidly respond to these scenarios.”

The American Meteorological Society’s RF Allocation Committee also is concerned about potential interference in the 23 to 24-gigahertz band, where the Advanced Technology Microwave Sounder on the National Oceanic and Atmospheric Administration’s Joint Polar Satellite System collects passive measurements of atmospheric water vapor. Those observations combined with data from other active and passive sensors on U.S. and international satellites help meteorologists predict storm tracks and rainfall levels.

“Our systems are making very good use of combinations of channels,” McNally said. “The problem with it is that if you then have a losing battle [to protect] one channel, you can effectively wipe out the value of channels which are not contaminated because you don’t have this corroborating piece of evidence from the channel that you’ve lost. The quality of forecasts that we enjoy in our society are a result of this very sophisticated multichannel usage in data simulation systems.”

Lockheed Martin has developed a satellite-based augmentation system that leverages both GPS and Europe’s Galileo

Lockheed Martin’s vice president of navigation systems, Andre Trotter said that the availability of a new GPS navigation signal for civilian users is creating market opportunities in so-called satellite-based augmentation systems (SBAS) that countries around the world are developing or upgrading to support transportation and other industries.

Six GPS 3 satellites that broadcast the L1C signal have been launched since 2018, the most recent one last week. GPS 3 is a modernized version of the U.S. military’s Global Positioning System satellites that broadcast positioning, navigation and timing signals. Compared to earlier generations, the GPS 3 satellites provide military users extra protection from jamming attacks but one of its most significant features is the L1C signal for civilian users that is interoperable with Europe’s Galileo navigation satellites.

Lockheed Martin has built 10 GPS 3 satellites under a 2008 contract from the U.S. Air Force, and will produce at least 10 more GPS 3F, a more advanced version.

“The company developed what it calls a 2nd generation SBAS that takes advantage of both GPS L1/L5 and Galileo E1/E5 signals to provide more accurate navigation and positioning, and reduce dependence on any one system,” Trotter told SpaceNews.

Lockheed Martin in September won a $1.18 billion 19-year contract to develop and operate the Southern Positioning Augmentation Network (SouthPAN) for the governments of Australia and New Zealand. The system is expected to be operational by 2028. “There is a significant amount of testing that must go on in order for the signals to be certified for different types of use, whether that be safety-of-life or commercial aircraft operations,” Trotter said.

Lockheed Martin’s SBAS broadcasts on two frequencies to augment signals from GPS and Galileo. 

“We are currently broadcasting the dual-frequency multiple constellation SBAS signal as part of SouthPAN,” Trotter said. “As additional GPS 3 and GPS 3F satellites are launched, service will improve even further.”

Winning the SouthPAN contract “could lead to more opportunities, as we have the ability to expand this enabling technology globally,” he said. “We are having discussions with other potential international customers. We also expect that more benefits will be realized as we bring in users and learn about new applications of the technology.” 

The SouthPAN system, for example, will improve accuracy from the current 5 to 10 meters, to about 10 centimeters, he said. More precise navigation and positioning data, Trotter said, is in high demand for commercial aviation, precision agriculture, maritime tracking, and the operation of drones and unmanned vehicles.

The U.S. SBAS is known as the Wide Area Augmentation System (WAAS). Europe’s is called EGNOS, or European Geostationary Navigation Overlay Service. Several countries have implemented SBAS systems, including Japan and India, and more are in development. 

In the SouthPAN system, an SBAS payload is hosted on an Inmarsat geostationary Earth orbit communications satellite, which rebroadcasts the augmentation messages to user receivers. Lockheed Martin operates a tracking, telemetry and control ground station in Uralla, New South Wales. Spain-based GMV will develop SouthPAN’s data processing and control centers.

According to research, combining satellite technology with machine learning may allow scientists to better track and prepare for climate-induced natural hazards.

During the past century, many natural phenomena like hurricanes, snowstorms, floods and wildfires have grown in intensity and frequency.

While humans can’t prevent these disasters from occurring, the rapidly increasing number of satellites that orbit the Earth from space offers a greater opportunity to monitor their evolution, said C.K Shum, co-author of the study and a professor at the Byrd Polar Research Center and in earth sciences at The Ohio State University. He said that potentially allowing people in the area to make informed decisions could improve the effectiveness of local disaster response and management.

“Predicting the future is a pretty difficult task, but by using remote sensing and machine learning, our research aims to help create a system that will be able to monitor these climate-induced hazards in a manner that enables a timely and informed disaster response,” said Shum.

Shum’s research uses geodesy—the science of measuring the planet’s size, shape and orientation in space—to study phenomena related to global climate change.

Using geodetic data gathered from various space agency satellites, researchers conducted several case studies to test whether a mix of remote sensing and deep machine learning analytics could accurately monitor abrupt weather episodes, including floods, droughts and storm surges in some areas of the world.

In one experiment, the team used these methods to determine if radar signals from Earth’s Global Navigation Satellite System (GNSS), which were reflected over the ocean and received by GNSS receivers located at towns offshore in the Gulf of Mexico, could be used to track hurricane evolution by measuring rising sea levels after landfall. Between 2020 and 2021, the team studied how seven storms, such as Hurricane Hana and Hurricane Delta, affected coastal sea levels before they made landfall in the Gulf of Mexico. By monitoring these complex changes, they found a positive correlation between higher sea levels and how intense the storm surges were.

The data they used was collected by NASA and the German Aerospace Center’s Gravity Recovery And Climate Experiment (GRACE) mission, and its successor, GRACE Follow-On. Both satellites have been used to monitor changes in Earth’s mass over the past two decades, but so far, have only been able to view the planet from a little more than 400 miles up. But using deep machine learning analytics, Shum’s team was able to reduce this resolution to about 15 miles, effectively improving society’s ability to monitor natural hazards.

“Taking advantage of deep machine learning means having to condition the algorithm to continuously learn from various data inputs to achieve the goal you want to accomplish,” Shum said. In this instance, satellites allowed researchers to quantify the path and evolution of two Category 4 Atlantic hurricane-induced storm surges during their landfalls over Texas and Louisiana, Hurricane Harvey in August 2017 and Hurricane Laura in August 2020, respectively.

Accurate measurements of these natural hazards could one day help improve hurricane forecasting, said Shum. But in the short term, Shum would like to see countries and organizations make their satellite data more readily available to scientists, as projects that rely on deep machine learning often need large amounts of wide-ranging data to help make accurate forecasts.

“Many of these novel satellite techniques require time and effort to process massive amounts of accurate data,” said Shum. “If researchers have access to more resources, we’ll be able to potentially develop technologies to better prepare people to adapt, as well as allow disaster management agencies to improve their response to intense and frequent climate-induced natural hazards.”