Draft agenda

1
Draft agenda

• STEAM overall status
• Science objectives
• Present mission concept
• Reports by participants
• Study activities and future meetings.
• Instrument requirements
• International collaboration
• Other

2
The STEAM spacecraft

• Launch on Start-1
• Ascending node at 600 or 900
• Circular, polar 700 km sun-sync orbit
• 4 year lifetime
• Control and down-link to ESRANGE
• 3-axis stabilised using reaction wheels
• Rear viewing star trackers, sun sensors
• 1 arc minute pitch control accuracy
• 160 kg (54 kg payload)
• 277 W average power

3
STEAM Imaging Radiometer

• Imaging with 8 beams to support tomographic 3-d
  retrievals.
• Improved sensitivity and horizontal resolution,
  no gaps in coverage due to scanning.
• Results in 2 km altitude by 40 km along-track
  grid.
• H2O, O3, and CO in the upper troposphere / lower
  Stratosphere (UT/LS), 5 to 28 km (the 340 GHz
  band).
• O3, N2O, H2O and ClO in the Stratosphere, 15 to
  40 km (the 500 GHz band).
• LO 337.9, IF 5.9-13.9, LSB/USB 324.0-332.0/
  343.8-351.8 GHz
• LO 496.25, IF2.75-6.75, LSB/USB 489.5-493.5/
  499-503 GHz

4
STEAM Radiometer antenna

• Designed, built and tested as Odin.
• CFRP face-sheets on honeycomb.
• Vacuum deposited aluminium.
• 15 micron RMS surface (Odin was 8).
• Simple box-like CFRP support structure.
• Integrates star tracker optical heads and
  receiver front-end parts.
• Back side radiatively coupled to spacecraft.

5
STEAM Radiometer
6
STEAM optics

• One optical axis
• 4 beam building block
• 4 beams in each polarisation, when combined
  overlap at half-power width.
• One redundant drive switch mechanism, calibrating
  one polarisation at a time.
• Few armin nodding motion by spacecraft to fill in
  gaps.

7
STEAM mixers and LO

• Sub-harmonically pumped, planar mixer chips (self
  biased) for both frequency bands.
• LO coupled via waveguide and integrated frequency
  multipliers.
• LO generated either from Gunn sources or low
  frequency source followed by multipliers and
  power amplifiers.
• Standard hybrid mode horns or simplified design.

8
STEAM spectrometers

• Chip set (9x16mm) tested at 1.7 GHz
• Flight production at 2 GHz per chip
• Power down of unused lags (1024)
• Possibility to go to 4 GHz per chip with more
  time multiplex and 0.18 micron process.

9
STEAM optical instrument

• Range 400 800 or 1000 nm.
• 30 km height range.
• wedged slit to equalise signal levels (or
  internal scan).
• Based on OSIRIS.
• Canadian contribution.
• This study assumed OSIRIS properties.

10
STEAM study result

• Relatively well defined.
• Smaller than Odin and much simplified both
  payload and attitude control.
• Substantial (as Odin) payload power. Huge
  technical leap utilised to implement multi-beam
  (16) receivers and large (8 GHz) bandwidth.
• Clearly feasible.
• Payload should be pre-developed (prototype)
• 300 MSEK including 2 years operation
• Swedish-French-Canadian-?