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)
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 Shingler, 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. 2)
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) 3)
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. 4)
Figure 2: Photo of the 28 Flock 1 nanosatellites before being sent to the launch site (image credit: Planet Labs) 5)
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. 6)
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.
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. 7)
• 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. 8)
• 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 3).
Figure 3: Image of Cygnus grappling with Canadarm2 and berthing to the ISS (image credit: NASA)
Status of Flock 1 nanosatellite constellation:
• Once the 28 Flock 1 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 J- SSOD). 9)
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. 12)
Figure 4: The Flock 1 nanosatellites are prepared for deployment on board the ISS. The photo shows four NanoRacks SSODs (Small Satellite Orbital Deployers), each containing two Doves (image credit: Astronaut Koichi Wakata)
Figure 5: Deployment of the first two Flock 1 nanosatellites from J-SSOD attached to the Kibo robotic arm (image credit: NASA)
Figure 6: Deployment of the first two Flock 1 nanosatellites from J-SSOD of the ISS (image credit: NASA, Universe Today)
The payload description will be provided when available.
1) “Planet Labs Launches Two More Satellites - Delivers Largest Imaging Fleet to Launch Pad;Company’s Latest Remote-Sensing Satellites Launch from Russia,” Planet Labs Blog, Dec. 11, 2013, URL: http://blog.planet-labs.com/2013/12/11/planet-labs-launches-two-more-satellites-delivers-largest-imaging-fleet-ever-to-launch-pad-companys-latest-remote-sensing-satellites-launch-from-russia/
2) “Planet Labs set to launch largest satellite fleet in history,” Planet Labs, Match 17, 2014, URL: http://www.planet.com/assets/themes/planet/press-releases/2014-03-17-pr.pdf
3) 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
4) “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---delivers-largest-imaging-fleet-to-launch-pad.html
5) “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-largest-imaging-fleet-ever-to-launch-pad-companys-latest-remote-sensing-satellites-launch-from-russia/
6) Trent J. Perrotto, Josh Byerly, “New Science, NASA Cargo Launches to Space Station Aboard Orbital-1 Mission,” NASA, Release 14-009, URL: http://www.nasa.gov/press/2014/january/new-science-nasa-cargo-launches-to-space-station-aboard-orbital-1-mission/#.Us98i_uFf_o
7) 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
10) 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/
11) 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
12) “Saving the Planet One Tiny Satellite at a Time,” Discovery Channel, Jan. 16, 2014, URL: http://news.discovery.com/space/private-spaceflight/saving-the-planet-one-tiny-satellite-at-a-time-140116.htm
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.