VRSS-1 (Venezuelan Remote Sensing Satellite-1) / Francesco de Miranda
VRSS-1 is Venezuela's first remote sensing satellite. The goal of the VRSS-1 mission is to provide resource studies (high-resolution land and vegetation observations - to assess Venezuela's soil and water resources, collect images to help urban planners, monitor illegal mining and drug activities, and strengthen national defense), support of disaster monitoring.
On May 26, 2011, a contract for the manufacture and launch of the VRSS-1 spacecraft was signed in Caracas, Venezuela, between the government of Venezuela (the Ministry of People’s Power for Science, Technology and Intermediate Industries) and CGWIC (China Great Wall Industry Corporation), a subsidiary of CASC (China Aerospace Science & Technology Corporation). 1)
After launch, the VRSS-1 satellite was renamed in honor of Sebastián Francisco de Miranda (1750-1816), a Venezuelan revolutionary hero, known as ‘Generalissimo’ Francisco de Miranda, who had planned the independence of the Spanish colonies in South America.
Partner organizations in the VRSS-1 program: ABAE is the Space Agency of Venezuela, subordinated and funded by the Venezuelan Ministry of People’s Power for Science, Technology and Innovation (MPPCTI). ABAE is in charge of in-orbit operations, management and application of the VRSS-1 satellite mission. Prior to signing the cooperation agreement of VRSS-1, CGWIC Ltd. had launched Venezuela's first communication satellite, VeneSat-1 on Oct. 29, 2008. VeneSat-1 was renamed to Simón Bolívar-1, in honor of Simón Bolívar, who successfully liberated a vast portion of South America from the Spanish domain. 2)
Note: ABAE (Agencia Bolivariana para Actividades Espaciales) or in English, the “Bolivarian Agency for Space Activities”, the name of ABAE signifies the importance of Simón Bolívar to Venezuela) is responsible for developing and carrying out the policies of the National Executive of Venezuela, regarding the peaceful use of outer space. The organization was originally designated as 'Venezuelan Space Center (CEV)', created on November 28, 2005. Later, the requirements grew and the body was renamed to ABAE (Bolivarian Agency for Space Activities). The objective of the ABAE is to design, coordinate and implement the policies of the National Executive, related to the peaceful use of outer space, and to act as a decentralized entity, specializing in aerospace in the country. Since its inception, ABAE has been working on the launch of the first communication satellite of Venezuela, the Simon Bolivar Satellite (VeneSat-1), which was launched on October 29, 2008, and the VRSS-1 satellite, launched September 29, 2012. 3)
Figure 1: Artist's view of the deployed VRSS-1 spacecraft (image credit: CAST) 4)
The spacecraft was designed and developed by DFH Satellite Co. Ltd. of CAST (China Academy of Space Technology) of Beijing, also a subsidiary of CASC, and is being operated by the Venezuela Ministry of People’s Power for Science, Technology and Intermediate Industries. The spacecraft is based on the CAST-2000 satellite bus, a compact satellite platform developed for high performance payloads, providing flexibility to host a number of payloads for different applications including remote sensing, communications, and navigation payloads. 5) 6)
The expandable minisatellite bus has a mass of 200 - 400 kg and supports payloads of up to 600 kg. In total, VRSS-1 has a liftoff mass of 880 kg, and the satellite is 1.53 m x 1.65 m x 1.87 m in size (without solar arrays). The spacecraft has two deployable solar arrays for power generation of ~1 k W at the beginning of the mission and ~900 W at EOL (End of Mission). The platform is three-axis stabilized offering a highly precise pointing control; in addition, the CAST-2000 bus provides a large sway maneuver capability. The satellite bus can support different communications systems, including S-band, C-band and X-band or a combination of those. VRSS-1 has an on-orbit design life of 3 years (the service life is estimated to be 5 years).
The VRSS-1 satellite consists of two main parts: payload and platform (Figure 2).
The PSS (Power Supply Subsystem) stores, distributes and manages electrical power for all electrical equipment, controlled by the PCU (Power Control Unit) and the PDU (Power Distribution Unit). The GaInP2/GaAs/Ge solar arrays take the job for generating electrical power. In the sunlight, the output power of solar array will meet the satellite operation requirements at first, then meet 55Ah NiCd (Nickel-Cadmium) battery charge power requirement. While in umbra, the battery will discharge and provide power to the equipment.
The SMS (Structure & Mechanism Subsystem) is designed based on the CAST-2000 platform. The satellite consists of three modules: propulsion module, platform module and payloads module. The propulsion module totally inherits the design of the previous CAST-2000 satellites, being composed of the shell, the bracket of the propellant tank, and the bracket pole. The platform and the payload modules are composed of several horizontal and vertical panels to mount the onboard instruments and sustain the load. Each panel features a honeycomb sandwich structure. Two solar arrays are mounted with a biased angle of -10º along the ±Y axis. During flight and after separation, both solar arrays deploy and rotate to follow the sunshine direction.
Table 1: Overview of spacecraft parameters
Figure 2: Schematic of platform and payload subsystems (DFH Satellite Co.)
Figure 3: Schematic view of the VRSS-1 spacecraft elements (image credit: DFH Satellite Co. Ltd., Ref. 6)
RF communications for VRSS-1 employs an S-band system for TT&C support and an X-band system for data transmissions, the X-band data rate is 190 Mbit/s.
Figure 4: Photo of the VRSS-1 spacecraft (image credit: CAST)
Operational modes: A duty cycle of 10% is used for payload observations. There are four operation modes defined:
- Real-time imaging mode: PMCs and WMCs images when the satellite keeps normal attitude pointing to the ground. In the meantime, DTS may transmit data in real-time.
- Quasi real-time imaging mode: PMCs and WMCs images when the satellite keeps normal attitude pointing to the ground. In the meantime, DTS may transmit data in real-time and records into SSM (Solid State Memory).
- Recording mode: PMCs and WMCs are imaging and the DTS records data, when satellite is inaccessible to any X-band ground station or in roll maneuver status.
- Replay mode: DTS transmits data recorded into the SSM through the X-band antenna to a ground station.
Table 2: Payloads operation modes without rolling maneuver
Launch: The VRSS-1 satellite ‘Francisco de Miranda’ was launched on Sept. 29, 2012 (at 04:12 hours UTC) on a Chinese Long March 2D vehicle (CZ-2D) from the Jiuquan Satellite Launch Center in China. 7)
Orbit: Sun-synchronous near circular orbit, altitude of 625.7 x 662 km (mean altitude of 640 km), inclination = 98º, period = 97.5 minutes, LTDN (Local Time on Descending Node) at 10:30 hours. The revisit time is 4 days.
Status of the mission:
• In early September 2013, China has delivered full control of the Chinese-built Miranda satellite over to Venezuela. 8)
• On May 31, 2013, VRSS-1 has been on-orbit for more than 8 months; all the subsystems are operating nominally (Ref. 6).
In May 2013, an analysis of the spacecraft health was performed by the DFH project covering the period of the last 8 months. According to the analysis, all equipment was in nominal status.
- All equipment temperatures are stable and maintain a nominal range within bounds.
- The battery can still endure discharge/charge action for the next 5 years.
- No degradation can be detected on the performance of the rotation equipment.
- The thermistor telemetry data from the four cameras remains very stable, which means the quality of the imagery is ensured.
• On October 1, 2012, the two PMC and the two WMC cameras started to take their first images.
Figure 5: PMC MS image of the BCIA (Beijing Capital International Airport) at 10 m resolution acquired in Oct. 2012 (image credit: DFH Satellite Co. Ltd.)
Figure 6: WMC MS image of BCIA at 16 m resolution acquired in October 2012 (image credit: DFH Satellite Co. Ltd.)
Figure 7: PMC PAN image of BCIA at 2.5 m resolution acquired in October 2012 (image credit: DFH Satellite Co. Ltd.)
Sensor complement: (PMC, WMC)
VRSS-1 is the first Chinese satellite with both high-resolution cameras and wide-swath cameras. There are four cameras, including 18 CCDs, and four X-band data transmission antennae implemented on VRSS-1.
PMC (PAN and Multispectral Camera)
PMC is a high-resolution pushbroom imager (2 cameras) with TDI (Time Delay Integration) capability observing in the visible range at a resolution of 2.5 m in PAN, and of 10 m in MS (Multispectral)mode.
Table 3: Parameters of the PMC instrument
WMC (Wide-swath Multispectral Camera)
WMC is a medium-resolution pushbroom camera set (2 cameras) with TDI (Time Delay Integration) capability observing in the visible range at a spatial resolution of 16 m in MS mode.
Table 4: Parameters of the WMC instrumentation
According to contract, the China Satellite Launch and Control Systems Division is responsible for the development of the Ba Mali station in Venezuela along with a ground control OMS (Operations Management System), the system includes the master control station, an alternate (backup) control station, and the SCC (Satellite Control Center). The SCC is responsible for the monitoring and control of the spacecraft, for the acquisition, archiving and processing of the payload data, and for the preparation of the satellite operations and control schedules at OMS. 11)
Figure 8: Overview of the VRSS-1 ground segment elements (image credit: CGWIC)
3) “Agencia Bolivariana para Actividades Espaciales,” Wikipedia, URL: http://en.wikipedia.org/wiki/Agencia_Bolivariana_para_Actividades_Espaciales
5) “China launches first Venezuelan Remote Sensing Satellite via CZ-2D,” Spaceflight 101, Sept. 29, 2012, URL: http://www.spaceflight101.com/long-march-2d-vrss-1-launch.html
6) Yan Cheng, Zhizhuang Li , Hongzhi Zhao, Shuyan Wang, Yufu Cui, Jian Zhao, “VRSS-1 Satellite Summary,” Proceedings of the 64th International Astronautical Congress (IAC 2013), Beijing, China, Sept. 23-27, 2013, paper: IAC-13-B4.1.7
7) Rui C. Barbosa, “Chinese Long March 2D launches Venezuela’s VRSS-1 satellite,” NASA Spaceflight.com, Sept. 28, 2012, URL: http://www.nasaspaceflight.com/2012/09/chinese-long-march-2d-launches-vrss-1/
8) “China delivers control of satellite to Venezuela,” Space Daily, Sept. 09, 2013, URL: http://www.spacedaily.com/reports/China_delivers_control_of_satellite_to_Venezuela_999.html
9) Information received from Romina Acevedo, Chief coordinator, Department of International Affairs of ABAE, Caracas, Venezuela.
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.