Minimize Dove

Dove-1 and Dove-2 Nanosatellites

Dove-1 is a technology demonstration mission of Cosmogia Inc. (Sunnyvale, CA, USA) with the objectives to: 1)

• test the basic capabilities of the low-cost bus built from non-space, COTS (Commercial Off-the-Shelf) components

• show that a bus constrained to the 3U CubeSat form factor can host a small payload

• demonstrate the ability to design, produce and operate satellites on short schedules and low cost.

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Figure 1: Illustration of the Dove-1 nanosatellite (image credit: Cosmogia)

Spacecraft:

Cosmogia, a NASA spin-out company in Silicon Valley, is using the PhoneSat spacecraft engineering approach to produce the Dove-1 nanosatellite. Dove-1 conforms to the 3U CubeSat form factor with a size of 10 cm x 10 cm x 30 cm and a mass of ~ 5.8 kg.

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.

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Figure 2: Photo of the Dove 2 nanosatellite (image credit: Planet Labs Inc.)

 

Launch: The Dove-1 nanosatellite was launched on April 21, 2013 as a secondary payload on the maiden flight of the Antares-110 (formerly Taurus II) launch vehicle of OSC. The launch site was MARS (Mid-Atlantic Regional Spaceport) on Wallops Island, VA.

The primary payload on this test flight is a Cygnus capsule mass simulator of ~3800 kg (of Orbital Sciences/NASA), a heavily instrumented payload to gather data on the launch environment aboard Antares. - In addition, four small satellites were deployed from two dispensers that will be integrated with the mass simulator. The launch was funded under the NASA COTS (Commercial Orbital Transportation Services) program. 2)

Orbit: Near circular orbit, target altitude of ~ 241 km x 257 km, inclination = 51.6º.

Secondary payloads on Antares 110 demonstration flight: 3)

• 2 PhoneSat-1, technology demonstration mission of two 1U CubeSats of NASA/ARC (Ames Research Center)

• PhoneSat-2, 1U CubeSat technology demonstration mission of NASA/ARC

• Dove-1, a nanosatellite (3U CubeSat, ~ 5.5 kg) technology demonstration mission of Cosmogia Inc. (Sunnyvale, CA, USA).

Ten minutes after liftoff, the rocket released its payload, a simulated Cygnus spacecraft and several smallsats, into low Earth orbit, ending a successful mission.

The launch was a major success for both Orbital and NASA. For Orbital, Antares represented not only the largest rocket the company had ever built, but also a major bet on the company’s future. Orbital hopes Antares can launch not just Cygnus cargo missions, but other satellites, for the US government in particular, that previously flew on the Delta II, a medium-class rocket that will be retired in the next few years. Antares will provide “right-size and right-price” launch services, as the company terms it, for such payloads, a subtle reference to the fact that such satellites now have to use the larger, and more expensive, EELV-class Atlas V and Delta IV. - For NASA, the launch was another vindication of its approach to turn to the commercial sector to launch cargo and, eventually, crews to the ISS. 4)

The Antares picture perfect liftoff marked the first step in a PPP (Public/Private Partnership) between NASA and Orbital Sciences to restart cargo delivery services to the ISS that were lost following the forced retirement of NASA’s space shuttle orbiters.

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Figure 3: Antares rocket configuration – privately developed by Orbital Sciences Corp. (image credit: OSC)

 


 

Mission status:

• On June 26, 2013, the former company Cosmogia announced it had changed its name to Planet Labs Inc., located in San Francisco, CA. The company was founded by former NASA/ARC scientists (Chris Boshuizen, Will Marshall, Robbie Schingler) and includes a team of leading venture capital investors, including Draper Fisher Jurvetson (DFJ), O’Reilly Alpha Tech Ventures (OATV), Capricorn Investment Group, Founders Fund Angel, Data Collective, First Round Capital, and Innovation Endeavors. 5) 6) 7)

The following announcements were provided along with the name change of the company in the press lease of June 26:

1) Planet Labs announced its plans to launch a fleet of 28 nanosatellites, called Doves, into orbit as secondary payloads in 2014. The company’s goal is to operate “the world’s largest fleet of Earth imaging satellites to image the changing planet and provide open access to that information. Planet Labs wants to image the Earth on a regular and expansive basis so that people, including farmers, weather professionals and more, can use this data to take actions.

2) A selection of images from the company’s first two demonstration satellites, Dove-1 (launch April 21, 2013), and Dove- 2 (launch April 19, 2013), are available on the link: http://planet-labs.com/

The Dove-2 nanosatellite was launched on April 19, 2013 as a secondary payload on the primary spacecraft Bion-M1 (with biological and medical payloads of Russia and an international community) with a Soyuz-2.1b rocket. The launch site was the Baikonur launch facility, Kazakhstan. 8) 9)

Orbit: Initial elliptical orbit with an altitude of ~300 km x 575 km, inclination = 64.9º. After separation from the launch vehicle, the Bion-M1 spacecraft circularizes its orbit to the altitude of 575 km x 575 km. The secondary payloads will be deployed from Bion-M1 after the target orbit is reached (~2 days after launch).

The secondary payloads on Bion M-1 spacecraft are:

• BEESAT-2, a 1U CubeSat of TU Berlin

• BEESAT-3, a 1U CubeSat of TU Berlin

• SOMP (Students' Oxygen Measurement Project) of TU (Technische Universität) Dresden, or Dresden University of Technology, Germany.

• OSSI-1 (Open Source Satellite Initiative), an amateur radio CubeSat initiated by the Korean artist Song Hojun. The satellite will carry a 145 Mhz beacon as well as a data communications transceiver in the 435 MHz (UHF) band. It will also carry a 44 W LED (Light-Emitting Diode) array to flash Morse code messages to observers on Earth.

• Dove-2 , a nanosatellite (3U CubeSat, ~ 5.8 kg) technology demonstration mission of Cosmogia Inc. (Sunnyvale, CA, USA).

• AIST-2 is a Russian microsatellite project, a technology demonstration, developed and designed by students, postgraduates and scientists of the Samara Aerospace University in cooperation with TsSKB Progress of Samara, Russia. The microsatellite with a mass of 39 kg will perform a 3 year mission dedicated to measurements of the geomagnetic field and to test methods to compensate low-frequency microaccelerations. Also, the spacecraft will study high-speed mechanical particles of natural and artificial origin.

Table 1: Dove-2 launch information 8) 9)

• The project used separate designs, one was called “high-risk” and the other “ultra-high-risk”. Both satellites, Dove-1 and Dove-2, worked out of the box, straight away (Ref. 7).

The fleet of Dove satellites, to be launched in 2014, will operate in a relatively low orbit of only 450 km. The operational satellites will be similar to Dove-1 and -2, capable of taking images with resolutions of 3-5 m/pixel.

 

Dove-1 mission: 10)

Due to the low orbital altitude at deployment (241 km x 257 km), the Dove-1 nanosatellite reentered the atmosphere on April 27, 2013 (6 day mission).

• Commissioning:

- Manual ops using the SRI antenna dish

- Automated telemetry downlink at HMB (CA) and UK (Chilbolton facility) using mission control system

• Operations:

- Downloading of pictures at Chilbolton facility

- Routine software updates.

• Dove-1 results (satellite goals achieved):

- Nominal health status of all key subsystems

- TT%C over UHF radio

- Attitude stabilization using magnetometers

- On orbit firmware and software upgrades

- 4 Mbit/s payload downlink

- Fine attitude pointing using reaction wheels.

• Ground segment goals achieved:

- 5 locations deployed and remotely coordinated from HQ in San Francisco

- Operations with 2 satellites in 2 different orbits

- Major progress in mission control software and automated operations

- Mission operations lessons learned.

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Figure 4: Sample image of Dove-1 observed on April 24, 2013 (image credit: Planet Labs)

 

Dove-2 mission (Ref. 10):

• The higher insertion orbit of 575 km x 575 km will provide a much longer mission life.

• Commissioning:

- Manual operations using the SRI antenna dish

- Automated downlink at HMB and UK (Chilbolton) using the mission control system

• Operations:

- Downloading of pictures at the MSU (Morehead State University) antenna dish (Morehead, Kentucky)

- Routine software operations.

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Figure 5: Sample image of Dove-2 of Shizuoka, Japan acquired on May 1, 2013 (image credit: Planet Labs)

• Dove-2 results (on-going in the fall of 2013):

- Nominal health status of all key subsystems

- TT&C over UHF radio

- Attitude stabilization using magnetometers

- On orbit firmware and software upgrades

- 30 kbit/s payload uplink over 2.4 GHz radio

• Ground segment goals achieved:

- 5 locations deployed and remotely coordinated from mission HQs in San Francisco

- Operations with 2 satellites in different orbits

- Extremely rapid commissioning phase

- Major progress in mission control software and automated operations

- Mission operation lessons learned.

 


 

Sensor complement:

Dove-1 carries an optical telescope payload (90 mm aperture) and a high-resolution camera. When nadir pointing, the instrument can be used for Earth surface imaging; when pointing upwards, Dove-1 can provide debris tracking services in support of SSA (Space Situational Awareness).

Dove-2 is using the same optics/camera system as Dove-1 providing a GSD (Ground Sample Distance) of 4.4 m.


1) “Dove 1 Satellite Technical Description,” Cosmogia, URL: https://apps.fcc.gov/els/GetAtt.html?id=121393&x=.

2) Chris Bergin, “Flight of the Antares – Orbital closing in on long-awaited debut,” NASA Spaceflight.com, Jan. 22, 2013, URL: http://www.nasaspaceflight.com/2013/01/flight-antares-orbital-long-awaited-debut/

3) “Antares-110 Amateur Radio CubeSat Integration Completed,” AMSAT-UK, Feb. 28, 2013, URL: http://amsat-uk.org/2013/02/28/antares-110-amateur-radio-cubesat-integration-completed/

4) Jeff Faust, “Antares rising,” April 22, 2013, URL: http://www.thespacereview.com/article/2282/1

5) “Planet Labs Reveals First Images from Space; Announces Plans to Launch Fleet of Satellites to Understand the Changing Planet,” June 26, 2013, URL: http://planet-labs.com/downloads/Planet_Labs_Press_Kit.pdf

6) http://planet-labs.com/

7) Jeff Foust, “Smallsat constellations: the killer app?,” The Space Review, July 1, 2013, URL: http://www.thespacereview.com/article/2322/1

8) Patrick Blau, “Soyuz Launch Success - Bion-M1 & various Passengers safely in Orbit,” Spaceflight 101, April 19, 2013, URL: http://www.spaceflight101.com/bion-m1-mission-updates.html

9) “Five Spacecraft Launched By Two Launch Vehicles From Two Continents,” Space Daily, April 23, 2013, URL: http://www.spacedaily.com/.../Five_Spacecraft_Launched_By_Two_Launch_Vehicles
_From_Two_Continents

10) “Planet Labs' Remote Sensing Satellite System,” CubeSat Developers Workshop, Logan Utah, Aug. 30, 2013, URL: http://digitalcommons.usu.edu/cgi/viewcontent.cgi?filename=0&article=2872&context=smallsat&type=additional


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.