ESA's Proba-3 Dual Satellites to Pave the Way for Unprecedented Solar Observations

ESA's Proba-3 Dual Satellites to Pave the Way for Unprecedented Solar Observations

Ahead of the ESA's Proba-3 pair launching together later this year, the scientists who will make use of Proba-3 observations were able to see the satellites with their own eyes. Members of this team will test hardware developed for the mission during an actual terrestrial solar eclipse over Northern America next April.

The two satellites are currently undergoing final integration in the premises of Redwire near Antwerp in Belgium. They were paid a visit by the Proba-3 Science Working Team, a 45-strong group of solar physicists coming from all across Europe and the wider world.

Many of these experts are regular visitors to terrestrial solar eclipse around the globe but are looking forward to the new perspective Proba-3 will open up on the faint solar corona. This mysterious region is important as the place where coronal mass ejections are created – vast eruptions of charged particles that trigger solar storms – as well as influencing the velocity of the solar wind, which is central to determining space weather.

The satellite hardware was quite something in close up,” explains Joe Zender, ESA’s Proba-3 project scientist. “I was particularly struck by how close the camera head on the Coronagraph spacecraft is to the solar array, less than a meter away. While the array relies on high solar illumination, the camera has to remain in complete darkness, with no stray light whatsoever. It really brings it home how precisely that small shadow cast by the Occulter will need to be maintained in place. We also got a peek at the carefully machined edge of the Occulter spacecraft’s disc – normally kept under protective cover before launch. The curve of this edge has been specially designed to minimize any spillover of diffracted sunlight that would otherwise impact imaging performance.

Russell Howard with Proba-3

Also present was noted US astrophysicist Russell Howard of the John Hopkins University Applied Physics Lab, who played a leading role in NASA’s Parker Solar Probe and the ESA-NASA SOHO mission: “The spacecraft are smaller than the ones that I have been involved with – primarily because this is a single solar viewing instrument with two much smaller instruments. But the mission concept is so unique: placing an occulter 150 meters from the telescope to allow imaging extremely close to the limb of the Sun has never been done before, as though the Occulter spacecraft is a mini-Moon. We won’t see quite as close to the solar limb as during a terrestrial eclipse, but having such images for hours on end compared to the 5-10 minutes duration of an eclipse event will be spectacular.”

Progressing on to the Royal Observatory of Belgium in Brussels, the team went on to discuss preparations for the mission in Brussels, including plans to process and distribute its data, plan co-observations with other space missions and assess Proba-3’s relative performance compared to existing ‘coronagraph’ instruments employed for coronal observations.

These are telescopes that incorporate internal occulting discs to obscure the solar disc. The problem is that these internal occulters still experience light spilling around their edges, known as diffraction, blotting out the extremely faint signals of interest.

Covered edge of Occulter disc

Damien Galano, ESA’s Proba-3 project manager notes: “The best way to reduce diffraction is to increase the distance between the occulter and the coronagraph, which is precisely what Proba-3 is going to do. We are flying our Coronagraph and Occulter on separate platforms for the first time, flying 150 m apart for up to six hours per orbit, applying an array of positioning technologies to keep them rigidly in place.”

By definition, the full-scale end-to-end testing of Proba-3 is impossible here on Earth. But the meeting heard how the same set of filter wheels developed for Proba-3’s ASPIICS (Association of Spacecraft for Polarimetric and Imaging Investigation of the Corona of the Sun) will be used to observe the solar eclipse over Northern America on 8 April 2024, along with a parallel liquid crystal imaging technology.

The filter wheels allow observation of the corona in different polarisation angles, like switching between different polarised sunglasses,” adds Joe. “The nice about observing during an actual eclipse is we won’t need any occulter, to gain insight of exactly the kind of results we are going to get back from Proba-3.”

The Science Working Team also discussed Proba-3’s second instrument, the Digital Absolute Radiometer, DARA, which will measure the total solar irradiance – exactly how much energy the Sun is putting out at any one time. 

Assuming the Sun’s output’s influences Earth’s climate, it’s important to measure any variations as precisely as we can,” notes Joe.

Proba-3 is due for launch in September this year, by PSLV launcher from India.

Click here to learn more about ESA's Proba-3 Mission.

Publisher: SatNow
Tags:-  SatelliteLaunch

GNSS Constellations - A list of all GNSS satellites by constellations


Satellite NameOrbit Date
BeiDou-3 G4Geostationary Orbit (GEO)17 May, 2023
BeiDou-3 G2Geostationary Orbit (GEO)09 Mar, 2020
Compass-IGSO7Inclined Geosynchronous Orbit (IGSO)09 Feb, 2020
BeiDou-3 M19Medium Earth Orbit (MEO)16 Dec, 2019
BeiDou-3 M20Medium Earth Orbit (MEO)16 Dec, 2019
BeiDou-3 M21Medium Earth Orbit (MEO)23 Nov, 2019
BeiDou-3 M22Medium Earth Orbit (MEO)23 Nov, 2019
BeiDou-3 I3Inclined Geosynchronous Orbit (IGSO)04 Nov, 2019
BeiDou-3 M23Medium Earth Orbit (MEO)22 Sep, 2019
BeiDou-3 M24Medium Earth Orbit (MEO)22 Sep, 2019


Satellite NameOrbit Date
GSAT0223MEO - Near-Circular05 Dec, 2021
GSAT0224MEO - Near-Circular05 Dec, 2021
GSAT0219MEO - Near-Circular25 Jul, 2018
GSAT0220MEO - Near-Circular25 Jul, 2018
GSAT0221MEO - Near-Circular25 Jul, 2018
GSAT0222MEO - Near-Circular25 Jul, 2018
GSAT0215MEO - Near-Circular12 Dec, 2017
GSAT0216MEO - Near-Circular12 Dec, 2017
GSAT0217MEO - Near-Circular12 Dec, 2017
GSAT0218MEO - Near-Circular12 Dec, 2017


Satellite NameOrbit Date
Kosmos 2569--07 Aug, 2023
Kosmos 2564--28 Nov, 2022
Kosmos 2559--10 Oct, 2022
Kosmos 2557--07 Jul, 2022
Kosmos 2547--25 Oct, 2020
Kosmos 2545--16 Mar, 2020
Kosmos 2544--11 Dec, 2019
Kosmos 2534--27 May, 2019
Kosmos 2529--03 Nov, 2018
Kosmos 2527--16 Jun, 2018


Satellite NameOrbit Date
Navstar 82Medium Earth Orbit19 Jan, 2023
Navstar 81Medium Earth Orbit17 Jun, 2021
Navstar 78Medium Earth Orbit22 Aug, 2019
Navstar 77Medium Earth Orbit23 Dec, 2018
Navstar 76Medium Earth Orbit05 Feb, 2016
Navstar 75Medium Earth Orbit31 Oct, 2015
Navstar 74Medium Earth Orbit15 Jul, 2015
Navstar 73Medium Earth Orbit25 Mar, 2015
Navstar 72Medium Earth Orbit29 Oct, 2014
Navstar 71Medium Earth Orbit02 Aug, 2014


Satellite NameOrbit Date
NVS-01Geostationary Orbit (GEO)29 May, 2023
IRNSS-1IInclined Geosynchronous Orbit (IGSO)12 Apr, 2018
IRNSS-1HSub Geosynchronous Transfer Orbit (Sub-GTO)31 Aug, 2017
IRNSS-1GGeostationary Orbit (GEO)28 Apr, 2016
IRNSS-1FGeostationary Orbit (GEO)10 Mar, 2016
IRNSS-1EGeosynchronous Orbit (IGSO)20 Jan, 2016
IRNSS-1DInclined Geosynchronous Orbit (IGSO)28 Mar, 2015
IRNSS-1CGeostationary Orbit (GEO)16 Oct, 2014
IRNSS-1BInclined Geosynchronous Orbit (IGSO)04 Apr, 2014
IRNSS-1AInclined Geosynchronous Orbit (IGSO)01 Jul, 2013