HEMERA balloon flight

admin FORUM Field Campaigns

The FIRMOS team is spending most of August in Timmins, Ontario, Canada, to carry out a measurement campaign aboard a high-altitude balloon system.

The FIRMOS-B instrument will measure the Earth’s infrared emission from an altitude of about 30km. This will provide valuable data and experience for the preparation and Cal/Val activities of the FORUM mission.

FIRMOS-B is able to contribute unique far-infrared stratospheric nadir-looking data for testing of cloud parameters databases (e.g. single scattering databases) and spectroscopic databases, as well as for testing FORUM retrievals.

More info:

Post-flight update

Despite the vibration-induced noise degradation encountered during the flight, an in-depth analysis of the FIRMOS-B measurements was successfully carried out. A subset of 235 calibrated spectra, collected across seven measurement sequences (two in clear sky, five in cloudy sky), was used to retrieve cloud optical depth, particle effective size, cloud top height, and the vertical profiles of water vapour and temperature, together with the surface temperature and spectral emissivity. The retrieved cloud optical depth and cloud top height were obtained with good accuracy – despite the elevated measurement noise – and the atmospheric profiles showed good agreement with co-located radiosonde measurements and ERA-5 data. These results are a promising step toward the retrieval algorithms that will be used to analyse the FORUM mission’s spectral measurements.

Di Natale, G., Belotti, C., Barucci, M., Ridolfi, M., Viciani, S., D’Amato, F., Del Bianco, S., Dinelli, B. M., and Palchetti, L.: Retrieval of Cloud, Atmospheric, and Surface Properties from Far-Infrared Spectral Radiances Measured by FIRMOS-B During the 2022 HEMERA Stratospheric Balloon Campaign, Remote Sensing, 17(14), 2458, 2025. https://doi.org/10.3390/rs17142458

Below is the day-by-day diary of the campaign as it unfolded, from instrument preparation to launch and recovery.

FIRMOS-B preparation

10 August – Unpacking and first instrument verification
  • Workplace setup, unpack container / boxes
  • Set up local network
  • The instrument arrived without any damage
  • It was installed and switched on for operation
  • Tested the latest release of Pyroelectric detectors electronics
  • Characterization of the detector response in the final configuration
11 August – Instrument preparation
  • Beam Splitters mounting and optical alignment
  • Characterisation of the calibration function and NESR
12 – 13 August – Optimisation
  • Final interferometric alignment
  • Characterisation of the calibration function and the NESR in the final configuration
14 August – Gondola integration
  • The instrument is mounted on the gondola
  • Cable dressing
  • Integration and testing of electrical and communication interfaces
15 August – Line of sight optimisation
  • Line of sight verification
  • Flight program testing
  • Mounting of the mechanical protection shield
16 August – Flight program optimisation
  • Pointing angles are defined
  • Flight program is decided and tested
  • New characterisation of the instrument performance
17 August – Co-alignment with GLORIA-B++
  • Set-up of the VIS camera
  • FOV co-alignment between the camera and FIRMOS-B using a horizontal beam and a 45° mirror below the nadir views of both instruments (alternatively moving the gondola).
  • Test of attitude sensors on FIRMOS-PI (Raspberry-PI with Sense HAT)
18 August – Other tests on the integrated system
  • Co-alignment of on-board VIS camera and the FIRMOS-B FOV
  • Test of the gondola PASTIS telecommunication system
19 August – Gondola balancing and end-to-end test
  • Set up of the date synchronisation
  • Test of power consumption
  • Balancing of the gondola
  • Full CNES end to end test with all instruments
20 August – Final preparation and tests on-board
  • Mounting of the superinsulation shield
  • Preparing the recovery procedure
21-22 August – Waiting for the flight opportunity
23 August – Launch day
  • The countdown started at 9:00 LT (13:00 UTC)
  • The CARMEN gondola was rolled out at 11:10 LT (15:10 UTC)
  • Launch pad was reached at 11:20 LT
  • The main balloon was inflated at 12:39 LT
  • Final payload preparation
  • Launch at 14:02 LT (18:02 UTC)
HEMERA 3 CNES flight at the CSA-ASC Stratospheric Balloon Base, Timmins (CAN)
24 August – Landing
  • End of flight 24/8/2022 at 9:15 UTC
  • Balloon flight duration: 15 h 10 m
  • Landing site: Near Val Paradis, Quebec, Canada
25 August – Recovery
  • FIRMOS-B was recovered apparently without damages. A tree entered inside the gondola but no instrument was damaged.
  • Unfortunately, data seems degraded by unexpected vibration which disturb the acquisition of the path difference
  • An in-depth analysis is necessary to evaluate the quality of the measurements.