Planet - Flock 1 Imaging Constellation
On Nov. 26, 2013, Planet Labs, a private start-up company of San Francisco, CA, announced that it successfully launched its most recent nanosatellites, Dove 3 and Dove 4, into orbit on a Dnepr vehicle (launch on Nov. 21, 2013 from the Yasny Cosmodrome, Russia), completing a series of four prototype nanosatellites in 2013. Those proved successful, enabling the company to quickly follow up with the production of a 28-member network. The launch of Planet Labs' "Flock 1" fleet of 28 nanosatellites in December/January, which will be the largest constellation of Earth-imaging satellites ever launched. 1) 2)
The latest additions to the Planet Labs fleet offer improvements in the capability provided by the firm's first nanosatellites launched in April, Dove 1 and Dove 2, which also were 3U CubeSats. Dove 3 and Dove 4 will demonstrate the firm's latest technology, including upgraded communications, attitude control and observation technology.
Background: Planet Labs was founded in 2010 by Chris Boshuizen, Will Marshall and Robbie Schingler, three NASA alumni interested in altering the space industry. Their "Dove" nanosatellites are meant to be low-cost and rapidly deployable, and capable of taking pictures of Earth that provide a spatial resolution of 3-5 m. — On March 17, 2014, Planet Labs announced that it has confirmed launches for more than 100 satellites over the next 12 months. This full constellation of nanosatellites will allow Planet Labs to image the entire Earth every day. 3)
The Flock 1 constellation nanosatellites (all 3U CubeSats) were designed and built by Planet Labs Inc. They feature mostly COTS (Commercial-off-the-Shelf) components, including their imagers. Each nanosatellite has a mass of ~5 kg and a size of 10 cm x 10 cm x 34 cm.
Figure 1: Photo of the proud developers and a close-up view of a Flock 1 nanosatellite (image credit: Planet Labs) 4)
It can be expected, that the Flock 1 nanosatellite design corresponds closely to the design of the prototype Dove series, which demonstrated that the company's engineers can accurately position the orbiters and capture a continuous stream of imagery with a resolution of 3-5 m.
ADCS (Attitude Determination and Control Subsystem): The attitude is sensed by magnetometers, gyros and photodiodes. The attitude is being controlled by magnetorquers and reaction wheels. The B-dot controller makes use of the B field to reduce the angular rate of the satellite. In this control mode, Dove-1 therefore behaves as a permanent magnet, remaining locked and axis-aligned to the Earth's magnetic field. - Dove-1 will be nadir pointing twice per orbit. The alignment of the magnetic field is known to about 1º at any point.
EPS (Electrical Power Subsystem): The bus provides central power control through a power supply to the camera, the flight computer and the magnetorquers. The power supply regulates the voltages and ensures a stable power supply to each component. Power storage is provided by 8 Lithium-ion cells, providing 20 Ah of charge at full capacity. The batteries will be recharged by body-mounted TASCs (Triangular Advanced Solar Cells).
C&DH (Command & Data Handling) subsystem: C&DH is controlled by the single board computer. Additionally there will be a discrete watchdog board that will be able to reboot the flight computer in the event of errors.
RF communications: The communication subsystem consists of a VHF radio beacon for transmitting telemetry and an S-band frequency hopping spread spectrum modem for two-way communication and as the primary radio for data downloading. After powering up, the first mission event is to transmit telemetry data over the VHF beacon. The beacon will transmit health packets (including temp/power supply/current/RSSI/solar vector/acceleration) at 1200 baud AFSK approximately every 30 seconds (AX.25 protocol, 145.825 MHz). The beacon can transmit at up to 1 W and will use a quarter wave monopole antenna cut from tape measure.
The S-band radio will operate in the 2.4 GHz half-duplex ISM (Industrial, Scientific and Medical) band at a wireless link rate of 115 kbit/s using a patch antenna.
In Nov. 2013, Planet Labs' Flock 1 nanosatellites were delivered to NASA's Wallops Flight Facility in Virginia for launch on board an Antares rocket in December 2013. These satellites were built in production at the Planet Labs headquarter offices in San Francisco. Planet Labs is on track to launch 32 satellites on four different launches in 2013. 5)
Figure 2: Photo of the 28 Flock 1 nanosatellites before being sent to the launch site (image credit: Planet Labs) 6)
Figure 3: Planet Dove nanosatellite in operational configuration with solar panels deployed and communications antenna flap opened (image credit: Planet)
Launch: The Cygnus CRS-1 logistics flight of Orbital Sciences to the ISS was launched on Jan. 09, 2014 on an Antares-120 Vehicle of OSC from MARS (Mid-Atlantic Regional Spaceport), Wallops Island, VA. 7)
Cygnus CRS-1 (Commercial Resupply Services) Orb-1 logistics flight of Orbital Sciences is the second Cygnus flight to the ISS (International Space Station) and the third launch of the company's Antares launch vehicle from MARS (Mid-Atlantic Regional Spaceport), Wallops Island, VA. The flight is the first of 8 under the CRS (Commercial Resupply Services) contract to NASA. The mission is scheduled to launch on December 18, 2013. Cygnus is expected to deliver 550 kg of cargo to ISS and dispose of about 1,000 kg through destructive reentry.
Orbit: Near-circular orbit of the ISS, altitude between 370-430 km, inclination = 51.6º. — Planet refers to a group of Doves deployed simultaneously into a single orbit as a flock.
Secondary payloads: commercial payloads of Orbital Sciences.
Part of the Cygnus payload consists of 33 CubeSats which will be deployed in early 2014 with the NanoRacks Smallsat Deployment Program using the J-SSOD (JEM-Small Satellite Orbital Deployer), located in the airlock of the JEM/Kibo module of JAXA.
The CubeSats are:
• 28 Flock 1 3U CubeSats, the first generation of an Earth observation constellation of Planet Labs. They will be placed into 400 km circular orbits (inclination of ~52º), providing imagery with a resolution of 3-5 m. 8)
• LituanicaSAT-1, a CubeSat which will carry a VGA camera, a GPS receiver and a voice transponder. The satellite has been developed at the Vilnius University (Lithuania) and has been named after the aircraft named Lituanica that flew across the Atlantic Ocean 80 years ago.
• LitSat, a 1U CubeSat developed by the Lithuanian Space Federation. The satellite will carry an onboard VGA camera and a GPS receiver.
• UAPSAT, a 1U CubeSat developed by UAP (Universidad Alas Peruanas), Lima, Peru, as a student educational project. Once in orbit the satellite can be accessed by radio amateurs; UAPSAT will test the behavior of electronic design communication, orientation and stabilization and verify the implementation of the technology and methodology used in the manufacture of the satellite.
• SkyCube, a 1U CubeSat developed by the Southern Stars Group LLC (San Francisco, CA) and funded by thousands of sponsors and mobile app users around the world (crowd funding). Its objective is to facilitate global grassroots public outreach and educational effort whose purpose is to make space exploration accessible as never before by allowing participants to send simple broadcasts - "tweets from space". The satellite is also fitted with a camera for on-demand pictures of Earth. At the end of the 90 days mission, SkyCube will inflate an onboard balloon that will make it visible to the unaided eyes and assist in de-orbiting the satellite cleanly through atmospheric drag. 9)
• Ardusat-2, developed by Nanosatisfi LLC, which is similar to the Ardusats that were sent to ISS earlier this year.
On January 12, 2014, the Cygnus CRS-1 spacecraft arrived at the ISS where Expedition 38 astronauts grappled the spacecraft and berthed it in a flawless operation (Figure 4).
Figure 4: Image of Cygnus grappling with Canadarm2 and berthing to the ISS (image credit: NASA)
Status of the Planet Flock 1 nanosatellite constellation — and the fleet acquisitions:
• The Geological Remote Sensing Group (GRSG) has expanded its membership once again with the recent news that Planet — the owners and operators of the world's largest commercially-operated fleet of satellites — has joined as the Group's latest corporate member. 10)
- Founded in 2010 by a team of ex-NASA scientists, Planet has designed, built and launched fleets of smallsats to make images of the Earth from space, affordable and widely available, in pursuit of their Mission 1 — to image the entire Earth, every day. With an agile approach to satellite development and Planet's acquisition of BlackBridge's fleet of five RapidEye satellites (in October 2015) and recently, TerraBella's seven high-resolution SkySat satellites, the company has grown their presence in the geospatial industry incredibly quickly.
- Blanca Payas, Planet Sales Director for Europe, Russia and Central Asia explained why Planet decided to join the GRSG by stating that, in a very short time, Planet has become a global company with offices in Europe and the US. More and more, we are finding that our capabilities are supporting projects in the domain of geology. The companies hope to develop new initiatives and activities together.
- GRSG Chairman, Charlotte Bishop, added that Planet's data and access model starts to challenge the way we in the industry think about and use satellite data in a way not done before.
• April 19, 2017: As Planet of San Francisco announced, it has completed its acquisition of rival satellite imaging company Terra Bella April 18, it confirmed that Google is now a shareholder in Planet as part of that deal. 11)
- Planet announced on February 3 that it had reached an agreement with Google to acquire Terra Bella. Google had purchased Terra Bella, then known as Skybox Imaging, in 2014 for an estimated $500 million. At the time, both Planet and Google declined to disclose the terms of the deal other than that Google signed a multi-year deal to purchase imagery from Planet.
- The deal, though, was rumored to include Google taking a stake in Planet. In an April 18 blog post announcing that the deal had closed, Planet co-founder and chief executive Will Marshall confirmed that. "We're also delighted to welcome Google as a shareholder and customer," he wrote.
- Planet spokesperson Rachel Holm said in an April 18 email that Google took an equity stake in Planet, in addition to the previously announced multi-year imagery contract. Neither company, though, has said how much of Planet that Google now owns.
- The deal closed after receiving regulatory approvals from several federal agencies. "Over the last several weeks, we received all necessary regulatory approvals from NOAA (National Oceanic and Atmospheric Administration), FTC (Federal Trade Commission) and FCC (Federal Communications Commission)," Holm said. The NOAA licenses commercial remote sensing systems in the United States, while the FCC licenses satellite communications.
- The FTC, with the Department of Justice, reviews large acquisitions under the 'Hart-Scott-Rodino Act' for any antitrust issues, setting a waiting period for that review before such deals can close. The FTC issued "early termination" notices March 16 for Planet's acquisition of Terra Bella and Google's acquisition of part of Planet, ending that waiting period early and allowing the deal to proceed.
- Planet will now work to integrate the high-resolution imagery from Terra Bella's fleet of seven SkySat satellites with Planet's own constellation of nearly 150 satellites that provide medium-resolution images. That fleet includes 88 satellites launched in February on an Indian Polar Satellite Launch Vehicle.
- "This ‘close' is also the beginning—the beginning of a new chapter at Planet, and of a lot of work across our organization over the next year to make SkySat imagery available on the Planet platform," Marshall said in his statement. - Holm said that a "significant portion" of Terra Bella's employees will remain with Planet. The company, headquartered in San Francisco, will maintain an office in Mountain View, California, where Terra Bella was based.
Figure 5: An illustration of four of the SkySat high-resolution imagery satellites developed by Terra Bella. Planet announced April 18 it has completed its deal announced in February to acquire Terra Bella from Google (image credit: Space Systems Loral)
• March 5, 2017: Located at the gateway to the Sahara desert, within the confines of the fertile zone of the Sudan and in an exceptionally propitious site near to the river Niger, Timbuktu (also spelled Timbuctoo) is one of the cities of Africa whose name is the most heavily charged with history. It is an UNESCO World Heritage Site. - The town is the capital of the Timbuktu Region, one of the eight administrative regions of Mali with a current population of about 55,000. 12)
- Founded in the 5th century, the economic and cultural apogee of Timbuktu came about during the15th and 16th centuries. It was an important center for the diffusion of Islamic culture with the University of Sankore, with 180 Koranic schools and 25,000 students. It was also a crossroads and an important market place where the trading of manuscripts was negotiated, and salt from Teghaza in the north, gold was sold, and cattle and grain from the south.
- The three big Mosques of Djingareyber, Sankore and Sidi Yahia, sixteen mausoleums and holy public places, still bear witness to this prestigious past. The mosques are exceptional examples of earthen architecture and of traditional maintenance techniques, which continue to the present time.
Figure 6: The Flock constellation acquired this view of the famous city of Timbuktu on March 5, 2017 (image credit: Planet)
• Feb. 23, 2017: The 88 nanosatellites of Planet, launched on Feb. 15, 2017, joined dozens already in orbit, bringing the constellation of "Doves," as these tiny imaging satellites are known, to 144. Six months from now, once the Doves have settled into their prescribed orbits, the company says it will have reached its primary goal: being able to image every point on Earth's landmass at intervals of 24 hours or less, at resolutions as high as 3.7 meters — good enough to single out large trees. It's not the resolution that's so impressive, though. It's getting a whole Earth selfie every day. 13)
- The news has already sparked excitement in the business world, which is willing to pay a premium for daily updates of telltale industrial and agricultural data like shipping in the South China Sea and corn yields in Mexico. But scientists are realizing that they, too, can take advantage of the daily data—timescales that sparser observations from other satellites and aircraft could not provide.
- "This is a game changer," says Douglas McCauley, an ecologist at the University of California, Santa Barbara, who wants to use Planet imagery to map coral bleaching events as they unfold. At present, coral researchers often rely on infrequent, costly reconnaissance airplane flights. "The previous state of the science was, for me, like taking a family photo album and shaking out all the photos on the floor and then being asked to haphazardly pick up three images and tell the story of the family."
- McCauley is participating in Planet's Ambassadors Program, which provides free satellite imagery to researchers as it is collected, with no lag time, under an agreement that prohibits them from reselling the data. Joe Mascaro, a tropical ecologist who runs the program, says it was created in the fall of 2015 in response to queries from scientists yearning for access to the company's growing archive of data. Over the course of 2016, Planet approved the applications of about 160 researchers across a range of fields. "We anticipate there will be many new applications of our data that we didn't anticipate," Mascaro says. The company intends to expand the program in the months ahead, and says it is looking for projects that have social, humanitarian, and environmental impacts—and that have the potential for rapid publication in peer-reviewed journals.
Figure 7: With the launch of 88 tiny Doves on Feb. 15, 2017, the satellite company Planet now has 144 at work, which will permit daily images of the entire Earth (image credit: Jonathan McDowell, Harvard-Smithsonian CfA)
- Andreas Kääb, a geoscientist at the University of Oslo, applied to the program to obtain additional data for his work on glaciers, including an investigation into a massive glacial avalanche in Tibet last July that killed nine herders and hundreds of sheep and yaks. Kääb already had before-and-after imagery from Landsat and Sentinel-2, U.S. government and European Space Agency satellites that have, respectively, 30 m and 10 m resolution and revisit intervals of 16 and 10 days. But higher resolution Planet images provided Kääb with valuable, timely clues. The appearance of large crevasses before the avalanche indicated the glacier was "surging," although surges, typically somewhat slow, don't usually lead to avalanches. But Kääb also saw water pooling on the surface of the glacier—a sign of heavy rainfall or unusually high temperatures. That water might have seeped through the crevasses, soaking the sediments below the glacial bed and creating a lubricant that triggered the sudden slip. When he saw a second nearby glacier with similar patterns, "We warned Chinese authorities, but when our warning arrived the glacier had already collapsed," Kääb says (no people, or yaks, were hurt).
- Kääb also used Planet images to study surface displacements along fault lines in New Zealand following the country's 7.8-magnitude earthquake last November. Though high-resolution GPS ground stations are typically used for this, not all faults have dense GPS networks monitoring them. He used Planet images to determine that two fault lines had slipped between 6 and 9 m — showing that medium-resolution optical satellites can fill the gap.
- Dave Petley, who studies landslides at the University of Sheffield in the United Kingdom, has not joined the Ambassadors Program yet, but says that access to the images would be "transformational" for his research. Orbital imagery has revealed some 80,000 landslides in the wake of the New Zealand earthquake. Aftershocks are likely responsible for many of them. But because available images can be weeks apart, "we just have to assume that everything happened in the main shock," Petley says. Daily images during the sequence of aftershocks would show how the landscape responds to different amounts of shaking, Petley says, and help with disaster response. "You want to know how many of your roads are damaged, how many valleys might be blocked."
- Planet's images are also finding a niche among researchers who deal with human-caused calamities, like deforestation. Matt Finer, a researcher at the Amazon Conservation Association in Washington, D.C., gets weekly deforestation alerts based on Landsat images, but says they are too course to determine whether the damage is natural or human-caused. He now turns to Planet data to decide whether an event is concerning. He recalls one incident when his group spotted 11 hectares of forest loss in Peru, accompanied by extensive dredging—signs of an illegal gold mining operation. "The Peruvian government was on the ground within 24 to 48 hours, kicking the miners out," he says. In previous years, Finer says, hundreds of hectares might be lost before anyone acted.
- Micah Farfour, a special adviser on remote sensing at Amnesty International in New York City, is using Planet images to monitor humanitarian crises as they unfold. Timely images can help her corroborate witness testimony or pinpoint emerging refugee crises. "It's a really, really amazing tool for narrowing down time frames," Farfour says. Still, images acquired from other private satellite companies, like DigitalGlobe, remain crucial to Amnesty's work, because they can offer the 30 cm resolution needed to, say, identify mass graves or count the buildings destroyed in a village that's been burned to the ground.
- Another limitation of Planet's Doves is that they only have four spectral bands—red, green, blue, and near-infrared—compared with Landsat's 11 bands. "Planet's daily observation frequencies are incredibly useful," says David Roy, a remote sensing scientist at South Dakota State University in Brookings and co-leader of the Landsat science team. "But there are lots of things .... that are probably not doable with Planet labs data." A major missing component, he says, are thermal bands in the far infrared, which enable Landsat to monitor the evaporation of water from plants. That's "quite important if you're looking at drought monitoring or water consumption, particularly in agriculture," Roy says. The Doves also lack a shortwave infrared band, which on Landsat can distinguish between different types of vegetation.
- These concerns have not slowed the juggernaut of Planet. In early February, it made two major announcements: It had folded Landsat-8 and Sentinel-2 data into its archive and it had initiated a deal to acquire Google's Terra Bella satellite imaging division and its seven SkySats, which have the capability to image at 0.7 m resolution. However, a spokesperson for Planet declined to say whether scientists will have access to those higher resolution images once the deal is completed.
- In the meantime, as more scientists publish their papers using Planet imagery, word is getting around. Mascaro says he was at a meeting of the American Geophysical Union in December 2016 when Kääb showed how Planet data were enabling the monitoring of glaciers. "Not surprisingly, I got a few Ambassadors applications from people who were in the room."
Table 1: Planet Launches Satellite Constellation to Image the Whole Planet Daily 14)
• On February 15, 2017 (UTC), ISRO (Indian Space Research Organization) launched the CartoSat-2D primary mission from SDSC (Satish Dhawan Space Center) on the east cost of India on the PSLV-C37 vehicle, along with a record number of 103 secondary payloads, among them 88 3U CubeSats, (Doves, 4.7 kg each) of Planet (formerly Planet Labs), San Francisco. The Dutch nanosatellite company ISIS (Innovative Solutions In Space), Delft, The Netherlands, provided the integration service for 101 nanosatellites on this flight. The total launch mass was 1378 kg into a sun-synchronous orbit of 506 km altitude. 15)
- Less than a minute after reaching orbit, the fourth stage released the CartoSat-2D environmental satellite — the mission's primary payload — about 17.5 minutes into the mission. Ten seconds later, two experimental Indian nanosatellites separated to test new types of sensors to observe Earth's surface, atmosphere and the conditions in the harsh environment of space. 16)
- Then came a carefully-choreographed deployment sequence for the remaining 101 payloads stowed inside 25 Dutch-built "QuadPacks" for the ride into orbit.
- The QuadPacks opened two at a time to eject their CubeSat passengers. Most of the CubeSats separated while the PSLV was flying over a remote stretch of the Indian Ocean between ground stations in Mauritius and Antarctica. Once the PSLV passed in range of the receiving antenna in Troll, Antarctica, launch controllers at the Satish Dhawan Space Center confirmed all 104 satellites separated as planned.
- The launch of 88 Dove satellites came less than two weeks after Planet announced the acquisition of Terra Bella from Google, which has a constellation of seven higher-resolution spacecraft capable of recording high-definition video during passes over ground targets.
Figure 8: A view of the 25 "QuadPacks" holding 101 CubeSats preparing for launch on the PSL-C37 mission (image credit: Innovative Solutions in Space)
Figure 9: The SDSC (Satish Dhawan Space Center) in Sriharikota, India, imaged by the in-orbit Dove constellation on Feb. 13, 2017, two days prior to the launch of the PSLV-C37 vehicle with 88 Doves onboard (image credit: Planet) 17)
Figure 10: A clear view amid California's rainy winter of Planet's Headquarters, reveals more than just expanse of the Golden Gate Bridge, Park, and Bay Bridge, but the dramatic sediment pulled from the 11900 km2 of the San Francisco Bay watershed. The image was acquired on Feb. 11, 2017 (image credit: Planet)
• September 29, 2016: The U.S. NGA (National Geospatial-Intelligence Agency) continues to expand its use of commercial satellite imagery, exemplified by the agency's recent contract award to Silicon Valley's startup firm Planet, according to Robert Cardillo, the head of NGA. An "introductory" seven-month, $20 million contract to San Francisco-based Planet, formerly Planet Labs, will give defense and intelligence agencies access to the company's global imagery content. This allows NGA to obtain imagery of at least 85% of the Earth's landmass every 15 days from Planet. The imagery has many operational uses, including environmental monitoring, augmenting higher resolution capabilities, change detection, and answering intelligence questions. 18) 19)
- NGA has partnered with other "NewSpace" providers over the last year, including BlackSky Global and the Google subsidiary Terra Bella. In addition, NGA and the NRO (National Reconnaissance Office) recently created the joint CGA (Commercial GEOINT Activity) to evaluate new commercial GEOINT data and services.
- NGA is also working with the GSA (General Services Administration) to set up the CIBORG (Commercial Initiative to Buy Operationally Responsive GEOINT) program, which will use GSA schedules and other government-wide contracts "to provide efficient, rapid access" to new commercial imagery, data, analysis and services, Cardillo said. CIBORG is slated to begin executing in early 2017.
- The "centerpiece" of NGA's commercial imagery program remains EnhancedView, which longtime industry partner DigitalGlobe supports.
• September 2016: The Flock-1 constellation acquired the snow covered Old Crow Flats, deep inside the Arctic Circle, a vast wetland residing within Canada's Vunut National Park (Figure 11). From caribou to grizzly bears, the remote and unspoiled national park plays temporary host to different migratory animals, including waterfowl. 20)
Figure 11: The meandering Yukon River is seen in this Flock-1 image from 19 September 2016. Notice in particular how the September snows cover the landscape, but the various bodies of water are still free of ice (image credit: Planet Labs, eoPortal team)
• July 14, 2016: Off the north-eastern coast of Australia, you'll find one of the seven natural wonders of the world, nearly 1,500 miles long, the Great Barrier Reef (Figure 12). One can see from this image the long veins that look like underwater rivers streaming down, giant avenues for all manner of wildlife (and divers) to explore and navigate – established over thousands of years from the seabed up. 21)
Figure 12: This Flock 1 image, acquired on 8 July 2016, shows the Great Barrier Reef in Australia (image credit: Planet Labs)
• June 17, 2016: The Nazza Lines in Peru are man-made lines and figures in the desert, which are estimated to be between 1500 and 2500 years old. The hundreds of figures vary in form, some of them are simple lines as featured in this image, while others form the shape of animals, people and other life. 22)
- These lines were created by digging shallow trenches in the desert, and removing the red-brown pebbles that coat the Nazca Desert. This made the clear white clay underneath stand out in stark contrast against the ground around the lines. Due to the desert's remote location and arid and windless climate - the Nazca Desert is one of the driest places on Earth - the lines have remarkably been mostly undisturbed in the centuries following their creation.
- The purpose behind the formation of the lines and figures is unknown, leaving scholars with many theories, ranging from astronomical to religious.
Figure 13: This Flock 1 image, acquired on 8 June 2016, shows the enormous Nazca Lines etched into the arid coastal desert in southern Peru (image credit: Planet Labs) 23)
• April 14, 2016: The Saint Lawrence River is one of North America's major shipping channels. The river flows from the Great Lakes Basin into Lake Saint Pierre (Figure 14) — a protected biosphere, home to unique waterfowl — before draining into the Northern Atlantic's Gulf of Saint Lawrence. 24)
- The cities of Trois-Rivières and Sorel-Tracy sit at either end of the lake, where it rejoins the Saint Lawrence River, and part of Trois-Rivières is visible on the mouth of the river here. Lake Saint Pierre is also a Ramsar site, recognized biosphere reserve and wildlife and bird sanctuary, which is an important area for migrating birds.
Figure 14: Lake Saint Pierre in Quebec, Canada, is pictured in this Flock-1 image, acquired on 14 April 2016 (image credit: Planet Labs Inc.)
• Feb. 2016: Figure 15 of the Flock-1 constellation shows a winter scene in the Sumy Oblast region of the Ukraine. This region is known for its rich earth and agriculture. Come summertime, these fields will produce grains, sunflowers, sugar beets, and potatoes. 25)
Figure 15: This Flock-1 image, acquired on 17 February 2016, shows icy fields during winter in Sumy Oblast, Ukraine (image credit: Planet Labs)
• October 26, 2015: Niagara Falls is a famous collection of three waterfalls on the border between the United States and Canada and is situated in the Canadian province of Ontario and the American state of New York. The three individual waterfalls are the Horseshoe, American and Bridal Veil Falls. 26)
- The waterfalls pour forth from the Niagara River, which flows North from the United States into Canada. The river splits into three waterfalls as the water flows around Goat Island (in the center of Figure 16) and a series of smaller islands on its north side. Niagara Falls has become a popular tourist destination over the past 150 years. Some visit the location to witness the power of the torrent of water and enjoy its nearby parks, while others take a more active (and risky) interest, notably including daredevils who have gone over the waterfalls in barrels or crossed the gorge on wires.
- Horseshoe Falls is the widest and deepest of the three waterfalls, and water drops 57 m here. Due to the strength of the current at the waterfalls, this natural source of energy has been harnessed over the years. Power plants have been constructed on or near the falls to take advantage of this, though a treaty was signed in 1950 to limit the use of the falls for this purpose out of concern for conservation of the site.
Figure 16: The Flock 1 constellation acquired this image of Niagara Falls on 26 October 2015. — Niagara Falls is a 12,000-year-old relic of the last Ice Age. Since then, the falls have moved more than 6 miles upstream from their original location near Lake Ontario.
• October 15, 2015: The acquisition of the BlackBridge RapidEye constellation by Planet Labs is now complete. Our energy is now focused on going to market as one team, under a common brand and executing a single global strategy. Over the coming months we'll role out incremental changes, which will improve our product offerings, service levels and empower our partners and customers to do even more. 27)
• March 1, 2015: The area shown in Figure 17 is in Jeollanam-do, the southernmost province on the Korean Peninsula. This region has some of the most favorable weather for farming, which has resulted in the area producing large amounts of crops. In the small town of Hanja Ri, patchwork grain fields line the shore of an inlet, while intricate rows of seaweed are farmed in the protected waters of the Myeongnyang Strait. 28)
Figure 17: This Flock 1 image, acquired on 01 March 2015, shows aquaculture off the coast of South Korea (image credit: Planet Labs)
Legend to Figure 18: Massive tankers are berthed in an oil terminal in the port of Fujairah, a major logistical hub for the United Arab Emirates. It sits on the Gulf of Oman, giving cargo ships easy access to major shipping lanes leading to China and India—two of the world's largest petroleum importers.
Figure 19: Illustration of a fully deployed Flock 1 nanosatellite (image credit: Planet Labs)
• Feb. 2015: The Chinese city of Ordos (Figure 20), located in Inner Mongolia of China (39°36'N 109°47'E), has gained a reputation for being a "ghost town" due to the small population currently living in the city. Built with the capacity to house over a million people when construction began in 2003, this brand new city was expected to reach that total by 2010, but currently only hosts a population of approximately 20,000 instead. 31)
Due to a variety of reasons, the city was never completely finished, leaving a dichotomous mix of new construction and abandoned sections of the city which were left uncompleted. The price of homes in the city was so high when the construction began that few people could afford it. It is estimated that 98% of the city is either still under construction or completely uninhabited. 32) 33)
Figure 20: This Flock 1 image, acquired 24 January 2015, shows the city of Ordos in Inner Mongolia, China (image credit: Planet Labs)
Legend to Figure 20: In this image one can see tall apartment buildings and frozen lakes in the Kangbashi New Area, located close to the Ordos Desert.
Figure 21: Irrigated fields in Pinal County, Arizona captured by Flock 1 nanosatellites in August 2014 (image credit: Planet Labs) 34)
• Once the 28 Flock 1A nanosatellites are operational, Planet Labs will have the largest fleet of orbiting commercial imaging systems on orbit capable of imaging the entire Earth at least once per week.
• Gradually the 28 Flock 1 Earth imaging satellite that were sent to ISS on January 9, 2014 have been deployed from the Kibo module in batches of two over the period Feb. 11-28, 2014 (all were deployed using the NanoRacks deployer system with the JEMRMS (JEM-Remote Manipulator System).
Built and operated by Planet Labs of San Francisco, the Flock 1 small satellites will capture imagery of Earth for use in humanitarian, environmental and commercial applications.
• The Flock1-27 and -28 nanosatellites were deployed on Feb. 28, 2014 (04:20 UTC)
• The Flock1-25 and -26 nanosatellites were deployed on Feb. 27, 2014 (07:40 UTC)
• The Flock1-23 and -24 nanosatellites were deployed on Feb. 27, 2014 (01:50 UTC)
• The Flock1-19 and -20 nanosatellites were deployed on Feb. 26, 2014 (07:35 UTC)
• The Flock1-21 and -22 nanosatellites were deployed on Feb. 26, 2014 (04:20 UTC)
• The Flock1-17 and -18 nanosatellites were deployed on Feb. 25, 2014 (17:00 UTC)
• The Flock1-9 and -10 nanosatellites were deployed on Feb. 15, 2014 (10:55 UTC)
• The Flock1-7 and -8 nanosatellites were deployed on Feb. 15, 2014 (07:00 UTC)
• The Flock1-15 and -16 nanosatellites were deployed on Feb. 14, 2014 (11:45 UTC)
• The Flock1-13 and -14 nanosatellites were deployed on Feb. 14, 2014 (04:15 UTC)
• The Flock1-11 and -12 nanosatellites were deployed on Feb. 13, 2014 (08:20 UTC)
• The Flock1-5 and -6 nanosatellites were deployed on Feb. 12, 2014 (08:30 UTC)
• The Flock1-3 and -4 nanosatellites were deployed on Feb. 11, 2014 (12:41 UTC)
The Flock 1 nanosatellites will be released, two at time, over a span of one to two weeks early this year. Flock 1 will orbit beneath the station's ~400 km altitude to prevent any potential collisions. Like the station, the satellites will circle Earth in an orbit inclined by ~51.6º north and south of the equator, flying over most of the planet at some point. From this altitude, the Flock 1 nanosatellites provide imagery with a spatial resolution of 3-5 m. 37)
Figure 22: The Flock 1 nanosatellites are prepared for deployment on board the ISS. The photo shows four NRCSDs (NanoRacks CubeSat Deployers), each containing two Doves (image credit: Astronaut Koichi Wakata)
Figure 23: Deployment of the first two Flock 1 nanosatellites from the NanoRacks deployer system attached to the Kibo robotic arm (image credit: NASA)
Figure 24: Deployment of the first two Flock 1 nanosatellites from the NanoRacks deployer system of the ISS (image credit: NASA, Universe Today)
News update: In November 2014, the FCC (Federal Communications Commission) cleared Planet Labs' request to launch and operate nongeostationary orbit (NGSO) Earth Exploration Satellite Service satellites. The company plans to launch up to 500 additional NGSO satellites from the ISS (International Space Station) that are physically and technically identical to those previously authorized. 38)
Planet Labs has deployed more than 30 such satellites from the ISS, all of which operate under Call Sign S2912, into circular orbits at altitudes between 380 km and 410 km and an inclination of 51.6º.
The additional satellites were authorized to transmit remote sensing and telemetry data to fixed Earth stations in the 8025-8400 MHz frequency band, receive command signals in the 2025-2110 MHz band, and may use the 401-402 MHz and 449.75-450.25 MHz bands for early phase and emergency-backup telemetry, tracking and command operations.
Payload design: Planet satellites each carry a telescope and a frame CCD camera equipped with Bayer-mask filter. The CCD sensor converts filtered photons into electrons, which are then amplified in order to produce a digital number corresponding to each pixel in each color band. 39)
Figure 25: Planet Optical System and Camera (image credit: Planet)
Planet has flown three generations of optical instruments: Planet Scope 0 (PS0), Planet Scope 1 (PS1), and Planet Scope 2 (PS2). Images have different attributes depending on satellite altitude and instrument type.
PS0 features a 2 element Maksutov Cassegrain optical system paired with an 11MP CCD detector. Optical elements are mounted relative to the structure of the spacecraft.
PS2 features a five element optical system that provides a wider field of view and superior image quality. This optical system is paired with a 29MP CCD detector.
Table 3: Spectral band and FOV (Field of View) information for PS0, PS1 and PS2 instruments flown at various altitudes
PS0 and PS1 optical systems are designed to collect data in the visible portion (red, blue and green) of the electromagnetic spectrum. The following figures show the expected RGB spectral characteristics of the PS0 and PS1 systems:
Figure 26: RGB spectral bands for PS0/1 (image credit: Planet)
Figure 27: RGB spectral bands for PS2 (image credit: Planet)
Figure 28: Expected spectral response for PS2 (with NIR capability), image credit: Planet
Table 4: Orbit, constellation and satellite specifications
Throughout 2014 and the first half of 2016, Planet focused collection capacity on North America, Asia, and South America. Focusing on these areas allowed Planet to establish initial imagery archive to develop and refine imagery processing, imagery quality, imagery mosaic, and API capabilities.
Figure 29: Heat map as of June 2015, showing percent of quad tiles covered by Planet's imagery (image credit: Planet)
Figure 30: Percent of quad covered (image credit: Planet)
Ground Stations and Network
Planet has developed its own global network of ground stations to support both spacecraft mission operations and image data downlink. Each ground station consists of an antenna and a Radio Frequency (RF) system, coupled with a local computer server, connected via secured VPN (Virtual Private Network) access to centralized services. Downlinked image files are transferred from local ground station servers to Planet's cloud infrastructure for ingestion into Planet's data processing and distribution pipeline.
Figure 31: End-to-end data flow (image credit: Planet)
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2) Christopher R. Boshuizen, James Mason, Pete Klupar, Shannon Spanhake, "Results from the Planet Labs Flock Constellation," Proceedings of the AIAA/USU Conference on Small Satellites, Logan, Utah, USA, August 2-7, 2014, paper: SSC14-I-1, URL: http://digitalcommons.usu.edu/cgi/viewcontent.cgi?article=3016&context=smallsat
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4) Quentin Hardy, Nick Bilton, "Start-Ups Aim to Conquer Space Market," The New York Times, March 16, 2014, URL: http://www.nytimes.com/2014/03/17/technology/start-ups-aim-to-conquer-space-market.html?_r=0
5) "Planet Labs Launches Two More Satellites - Delivers Largest Imaging Fleet to Launch Pad," SpaceRef, Nov. 26, 2013, URL: http://spaceref.biz/2013/11/planet-labs-launches-two-more-satellites
6) "Planet Labs Launches Two More Satellites; Delivers Largest Imaging Fleet Ever To Launch Pad; Company's Latest Remote-Sensing Satellites Launch from Russia," Planet Labs, Dec. 11, 2013, URL: http://blog.planet-labs.com/2013/12/11/planet-labs-launches-two-more-satellites-delivers-
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8) Laura Niles, "Largest Flock of Earth-Imaging Satellites Launch into Orbit From Space Station," Feb. 11, 2014, URL: http://www.nasa.gov/mission_pages/station/research/news/flock_1/#.UxHvwc7ihqM
11) Jeff Foust, "Planet confirms Google stake as Terra Bella deal closes," Space News, April 19, 2017, URL: http://spacenews.com/planet-confirms-google-stake-as-terra-bella-deal-closes/
13) Markus Strauss, "Flotilla of tiny satellites will photograph the entire Earth every day," Science Magazine, Feb. 23, 2017, URL: http://www.sciencemag.org/news/2017/02/flotilla-tiny-
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15) "PSLV-C37 / CartoSat -2 Series Satellite," ISRO, Feb. 15, 2017, URL: http://www.isro.gov.in/launcher/pslv-c37-cartosat-2-series-satellite
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17) Gallery of Planet, acsessed on March 1, 2017, URL: https://www.planet.com/gallery/san-francisco-20170211/
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19) "SmallSats In The White House — Harnessing the Small Satellite Revolution to Promote Innovation and Entrepreneurship in Space ," Satnews Daily, Oct. 24, 2016, URL: http://www.satnews.com/story.php?number=1949829205
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35) Elizabeth Howell, "When Doves Fly: Swarm Of Tiny Satellites Shot From Space Station," Universe Today, Feb. 13, 2014, URL: http://www.universetoday.com/109317/when-doves-fly-swarm-of-tiny-satellites-shot-from-space-station/
36) Patrick Blau, "Flock-1 CubeSat Constellation begins Deployment from Space Station," Spaceflight 101, Feb. 11, 2014, URL: http://www.spaceflight101.com/flock-1-cubesat-constellation-begins-deployment-from-iss.html
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39) "Planet Spacecraft Operations and Ground Control," Version 1.2 , Last updated September 2015, Planet, URL: https://www.planet.com/docs/spec-sheets/spacecraft-ops/
The information compiled and edited in this article was provided by Herbert J. Kramer from his documentation of: "Observation of the Earth and Its Environment: Survey of Missions and Sensors" (Springer Verlag) as well as many other sources after the publication of the 4th edition in 2002. - Comments and corrections to this article are always welcome for further updates (email@example.com).