ESA's Proba Missions

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Proba-2: Extending ESA’s commitment to technological innovation

Proba-2: Artist's impression of internal structure - view 1

Credits: ESA

30 May 2006
Proba-2, currently under development and due for launch in September 2007, is the second in ESA’s series of small, low-cost satellites that are being used to validate new spacecraft technologies while also carrying scientific instruments.

The Proba satellites are part of ESA’s In-Orbit Technology Demonstration Programme, funded through the General Support Technology Programme (GSTP).
The first satellite in the series, Proba-1, was launched in October 2001. Its primary payload is an imaging spectrometer that exploits the spacecraft’s high-performance attitude control and pointing capabilities. Originally designed for a two-year mission, Proba-1 is now in its fifth year of operations.

Proba-2 is being developed a by European consortium lead by the Prime Contractor, Verhaert Design and Development NV of Belgium, a subsidiary of QinetiQ (UK).

Technology demonstrations

The spacecraft infrastructure technologies are:

• a new type of lithium-ion battery
• an advanced data and power management system, containing many new component technologies
• combined carbon-fibre and aluminium structural panels
• new models of reaction wheels, star trackers and GPS receivers
• an upgraded telecommand system with a decoder largely implemented in software

The passenger technologies are:

• a digital Sun-sensor
• a dual-frequency GPS receiver
• a fibre-sensor system for monitoring temperatures and pressures around the spacecraft
• a new star-tracker development being test-flown before use on the BepiColombo mission
• a very high precision flux-gate magnetometer
• an experimental solar panel with a solar flux concentrator
• a xenon gas propulsion system using resistojet thrusters and a solid-state nitrogen gas generator to pressurise the propellant tanks
• an exploration micro-camera (X-CAM) with panoramic optics

Science payload


Proba-2: Artist's impression of internal structure - view 2

Credits: ESA

Four experiments are being flown: two for solar observations and two for space weather measurements.
The solar observations will be performed by a Lyman-Alpha radiometer (LYRA) and an extreme-ultraviolet telescope using new active pixel sensor (APS) technology - the Sun Watcher using AP-sensors and image Processing (SWAP) experiment.

LYRA will monitor four bands in a very wide ultraviolet spectrum while SWAP will make measurements of the solar corona in a very narrow band. Both experiments are collaborations between the Royal Observatory of Belgium, the Centre Spatiale de Liege, Belgium, and the World Radiation Centre in Davos, Switzerland.

The space weather experiments are Dual Segmented Langmuir Probes (DSLP) and a thermal plasma measurement unit (TPMU). DSLP will measure electron density and temperature in the background plasma of the Earth’s magnetosphere. TPMU will measure ion densities and composition. Both experiments are provided by the Institute of Atmospheric Physics at the Czech Academy of Sciences.

Source: ESA - News

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Proba-3: ESA’s first step towards formation flying

Preliminary design for a Proba-3 spacecraft carrying an instrument for observing the solar corona

8 August 2006
Proba-3 is the third in ESA’s series of missions for validating developments in space systems while carrying an ‘added value’ user payload which can directly benefit from the innovations under test.

Proba-3 will demonstrate the technologies required for formation flying of multiple spacecraft. An instrument to observe the solar corona is being used for the ongoing design phase.
During the ESA Council at Ministerial Level held in December 2005, new activities were proposed to cover the design, development and in-flight operation of a set of small satellites for the full-scale testing and validation of formation flying missions.

Formation flying technologies will make new types of missions possible and provide a leap in the performance of future science, Earth observation and application missions.


Preliminary design for the smaller of the two Proba-3 spacecraft

Mastering formation flying missions requires the development of specific technologies well beyond the present state-of-the-art in fields such as metrology and spacecraft guidance, navigation, and control.

Proba-3, currently in its preparatory study phase, will comprise two independent, three-axis stabilised spacecraft flying close to one another with the ability to accurately control the attitude and separation of the two craft.

Utilising either cold-gas or electrical thrusters for agile manoeuvring, and both radio-frequency and optical (laser-based) metrology techniques for accurate position measurement and control, the combined system is expected to achieve a relative positioning accuracy of the order of 100 microns over a separation range of 25 to 250 metres.

Other Proba spacecraft

Proba spacecraft are part of ESA’s technology demonstration initiatives, funded through the General Support Technology Programme (GSTP). They are series of small, low-cost satellites that are being used to validate new spacecraft technologies, research techniques and development approaches, while also carrying scientific payloads.

The first satellite in the series, Proba-1, was launched in October 2001. Its primary payload is an imaging spectrometer for Earth observation. This instrument exploits the spacecraft’s autonomy and high-performance attitude control and pointing capabilities. Originally designed for a two-year mission, Proba-1 is now in its fifth year of operations.

Proba-2 is currently under development and due for launch in September 2007. Seventeen new technological developments will be flown on Proba-2. Eight items form part of the spacecraft infrastructure, while the other nine are being carried as passenger technologies to gain flight heritage and experience before committing them to the infrastructure of other missions. Proba-2 will carry four experiments: two for solar observations and two for space weather measurements.

Source: ESA - News Edited October 23, 2006 by Waspie_Dwarf

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ESA’s small Proba satellite celebrates five years in space

23 October 2006
On 22 October 2001, Proba was launched as a technology demonstrator within ESA’s General Support Technology Programme. Once in orbit, however, the small satellite’s unique capabilities and performance made it evident that it could make big contributions to science and so its nominal lifetime was extended to serve as an Earth Observation mission.

Although Proba (Project for On Board Autonomy) was originally built for a two-year mission, the superb performance of its platform has allowed it to remain fully functional and scientifically productive proving small satellites can be used both to test new technologies at low cost and to conduct space missions.

Measuring just 60 x 60 x 80 cm, Proba performs autonomous guidance, navigation, control, onboard scheduling and payload resources management. Its two imaging instruments – the Compact High Resolution Imaging Spectrometer (CHRIS) and the panchromatic High Resolution Camera (HRC) – have provided more than 10 000 images of more than 1 000 sites. Its two Earth environment intruments, Standard Radiation Environment Monitor (SREM) and Debris Evaluator (DEBIE) have also returned significant results.

Contributions to technology


Proba, Project for On Board Autonomy, demonstrates the potential and
feasibility of small satellites for advanced scientific and Earth Observation
missions.

Credits: ESA

The continued excellent performance of all the new technologies, for example the lithium-ion battery and autonomous navigation system, and the accuracy of the attitude control, which has been further improved during the life of the mission by in-flight software upgrades have provided the basis for the extended Earth Observation mission. Although some of the FDIR (Failure Detection, Isolation and Recovery) actions automatically switch over to redundant units to mitigate transitory radiation effects, none of the primary units have actually failed and the spacecraft remains operational on all primary systems at this time.

“We are very satisfied with the mission performance and efforts of the ESA/industrial teams involved.”, said Frederic Teston, Proba Project Manager.

Contributions to science


This image of Mont St. Michel, France, was acquired by ESA’s Proba satellite with its
Compact High Resolution Imaging Spectrometer (CHRIS)

Credits: ESA

Weighing just 14 kg, CHRIS is the smallest hyperspectral imager ever flown in space and can see down to a resolution of 17 metres and acquire up to five images at a time, at up to 62 spectral channels. CHRIS also exploits the platform agility to obtain views of the same area from several directions, which allows extraction of additional angular information. CHRIS data are used by ESA projects and in support of the International Charter for Space and Major Disasters – an agreement to make space resources available to civil protection agencies responding to natural disasters. CHRIS images are also being used by individual research teams for various scientific applications including:

• assessing the effects of different land use strategies on vegetation types in Central Nambia’s savannahs
• evaluating aerosol retrieval in Hong Kong
• identifying ancient Roman buildings
• helping map and measure alpine snow cover in the Swiss National Park
• monitoring waste landfill operations
• studying the role of woodland as sinks and sources of carbon dioxide.

Proba’s other imager, HRC, is a small-scale monochromatic camera, taking 25-km square images to a resolution of five metres. To date, CHRIS and HRC data support the research of 100 EO projects from nearly 30 countries worldwide.

The Future


The Niau atoll, located in the central South Pacific Ocean, is highlighted in this image,
acquired by ESA’s Proba satellite on 6 October 2005 with its Compact High Resolution
Imaging Spectrometer (CHRIS). Niau is one of nearly 80 coral reef atolls that forms
the Tuamotu Archipelago in French Polynesia.

Credits: SSTL through ESA

The recent successes of small satellite missions signal that the sector has come to maturity in recent years, and the development of these low-cost satellites looks set to take on great importance. “The Proba user community has expressed hope that the spacecraft’s mission will last well beyond its five-year anniversary”, said Bianca Hoersch, ESA Third Party Mission manager.

Note:

Proba is a micro-satellite developed by ESA's General Support Technology Programme (GSTP) and built by an industrial consortium led by the Belgian company Verhaert, launched from India on 22 October 2001 and operated from ESA's Redu Ground Station in Belgium. Its CHRIS instrument, funded by the British National Space Centre (BNSC), has been built by the UK company SIRA Space. Since 2004 it has been operating as an ESA Earth Observation Third Party Mission.

Source: ESA - News