01
Side view of the eruption
Coronal mass ejections are tracked in profile, so speed and direction are measured instead of inferred. Arrival-time error drops from eighteen hours to under four.
Mission ISH-04 · Lagrange point L5
Five days
before the
storm
From a vantage point 60 degrees behind Earth in its orbit, SENTINELLE L5 watches the side of the Sun that nobody else can see — and tells Europe what is coming before it arrives.
Scroll
Orbit insertion countdown
Arrival at station
The cruise phase ends when the observatory settles into its halo orbit around L5 and opens the coronagraph door.
000
Days
00
Hours
00
Minutes
00
Seconds
Space weather index
Today over Europe
G0 Quiet
G1 Unsettled
G2 Active
G3 Minor
G4 Severe
Current geomagnetic condition — Active
Why L5
A point in space
nobody was using
Every operational solar monitor sits on the Sun–Earth line. From there, an eruption heading our way is a fuzzy halo. From L5, the same eruption is seen from the side — measurable, and five days early.
02
The Sun before it turns
L5 sees solar longitudes that will rotate towards Earth in the coming week. Active regions are catalogued before they ever face us.
03
Warning that is useful
Grid operators need eight hours to reconfigure a network. Airlines need twelve to reroute polar traffic. Five days changes a warning into a plan.
150M
km from the Sun
60°
Behind Earth in orbit
6
Scientific instruments
1 082
°C on the shield face
The observatory
Built in Switzerland,
pointed at the Sun
A 1 240 kg three-axis stabilised platform carrying a coronagraph, a magnetograph, a spectrometer and an in-situ particle suite behind a ceramic shield that never stops facing the light.
- Launch mass
- 1 240 kg
- Payload mass
- 318 kg
- Power
- 1 380 W end of life
- Downlink
- 512 kbit/s Ka-band
- Pointing stability
- 0.2 arcsec / 10 min
Bulletin 244
Five-day outlook
Published every morning at 06:00 UTC and distributed to grid operators, airlines, satellite fleets and national weather services in eleven countries.
Day 1
Quiet
Day 2
Quiet
Day 3
Active
Day 4
Storm
Day 5
Active
Live from the spacecraft
Telemetry
Simulated downlink for public display. Operational data is served to member states through the ISH secure channel.
Solar wind speed
412
km/s
Proton density
5.8
particles / cm³
Magnetic field Bz
-3.4
nanotesla
Shield temperature
-68
°C rear face
X-ray flux, last 2 hours
Mission log
Ground segment
Davos, and two
antennas in the north
Operations run from the institute above Davos, with tracking passes shared between a 15-metre dish in the Grisons and partner stations in Lapland and the Canary Islands.
People
The flight and
science team
Ninety-four people in Davos and Bern, plus instrument teams in six partner institutes across Europe.
Dr Nadia Brunner
Principal investigator
Coronal physicist, twenty-two years at the institute, led the L5 proposal from a two-page note to a funded mission.
Prof. Marc Lüthi
Instrument scientist
Responsible for the coronagraph optical chain and for the calibration campaign carried out at Davos in 2026.
Elin Roth
Lead forecaster
Writes the morning bulletin and keeps the phone that grid operators call when the index climbs past G3.
Latest
From the institute
Mission updates, science results and forecast notes, published without an embargo.
2028-04-02
Coronagraph door opens on schedule
First light from the white-light channel arrived eleven minutes after the command, showing streamers already resolved at 1.8 solar radii.
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2028-03-11
Cruise phase trajectory correction completed
A 3.4 m/s burn refined the approach to the halo orbit and used sixty per cent less propellant than the allocation.
Read →
2028-01-27
Eleven states sign the forecast distribution accord
National grid and aviation authorities will receive the five-day bulletin directly from Davos from the first day of science operations.
Read →
Stay with the mission
Get the bulletin
before the storm
before the storm