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INSTRUMENT ARCHITECTURE:

MARSCHALS

MILLIMETRE WAVE LIMB SOUNDER

Brian Moyna

Millimetre Technology Group, RAL Space

Rutherford Appleton Laboratory, UK

Outline

• Definition

• History

• Original instrument

• SCOUT-O3

• UAMS

• PREMIER-Ex, ESSenCe

• Future: NSTP, SHIRM, Spectrometer, Pointing,

Future campaigns

MARSCHALS

– Millimetre-wave Airborne Receiver for Spectroscopic

CHaracterisation of Atmospheric Limb-Sounding

– Conceived as an airborne simulator of the MASTER1 instrument, onboard

the proposed ACECHEM2 Earth Explorer Core mission. Funded by ESA

– Now deployed as a demonstrator for STEAMR onboard PREMIER, an

Earth Explorer 7 candidate mission

1 Millimetre- wave Acquisitions for Stratosphere Troposphere Exchange Research

2 Atmospheric Composition Explorer for CHEMistry and climate interactions

CEOI PM Workshop Nov ‘12

MARSCHALS Development

SCOUT-O3 Campaign

Darwin

UAMS MARSCHALS Upgrades

ESSenCeCampaign,

Kiruna

PREMIER-Ex Campaign,

Kiruna

NSTPMARSCHALS Upgrades

PREMIER/STEAMREarth Explorer Phase A

MASTER/ACECHEMPREMIER/STEAMR

Earth Explorer Phase 0

1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016

Asian Monsoon Campaign

PREMIER/STEAMREarth Explorer Phase B/C/D

CEOI SHIRM Development

Key Performance Specifications

– Instrument Type Total Power Single Sideband Radiometer

– RF target bands

– Band B 294 – 305.5 GHz (O3)

– Band C 316.5 – 325.5 GHz (H2O)

– Band D 342.2 – 348.8 GHz (CO)

– Instantaneous bandwidth 12 GHz @ 200 MHz resolution

– NET (250ms)

– Target 1K

– Sideband Rejection > 30dB

– Beam Width 0.34° HPBW (2 km at 10 km tangent height)

– Beam Pointing <<0.0025 deg. rms knowledge during scan,

bias excepted

– Scan range Tangent heights from –2km to platform altitude

(21km on aircraft) in 1 km steps with +20° “space view”

PREMIER – Limb Imaging of UTLS The global structure

of the troposphere

and lower

stratosphere.

(P. Preusse)

Comparison of limb transparency in PREMIER

12µm infrared (left) and 1mm mm-wave (right)

atmospheric windows.

Annual-mean probabilities of transmittance >20%

calculated from ECMWF analyses.

White dashed line indicates tropopause.

(R. Siddans, RAL)

From PREMIER report for Mission Selection CEOI PM Workshop Nov ‘12

Limb vs Nadir Sounding

Instrument Configuration



- aircraft



- aircraft (& balloon)


Key Elements

Cold Calibration

Load @ 86K Ambient Calibration

Load @ 300K

Quasi-Optics Module

- SSB heterodyne receivers

- (ambient, Schottky diode)

Switching Mirror

50ms switching,

0.1° repeatability

235mm scanning

Antenna

(LoS corrected by

Onboard IMU)

0.34° HPBW (2 km at 10 km tangent height)

NIR (850nm)

Optical Cloud Monitor


Instrument Schematic

Optional High-res

Spectrometer

Antenna/calibration Mm-wave Receivers

IF Spectrometers


Quasioptics Module

FSS

Sideband Filter

Subharmonic

Mixer

Frequency

Doubler

MARSCHALS Receiver Technology

(Original layout c 2005)

Beam Path within QO Module

Band B

Band C

Results from 1st Science Flight

SCOUT O3 Darwin Dec 5th 2005

Mean

Measured

Mean

Simulated OCM


Upgrades identified post-Darwin

Analysis of spectra from Scout-O3 flights identified several

high priority improvements:

Performance

• Improve receiver noise temperature – reduce NEDT

• Improve antenna pointing accuracy during dynamic flight

• Improve thermal stability

• Improve Cold load – reduce standing waves in spectra

Characterisation

• Finer resolution antenna pattern knowledge

• Finer resolution channel shape knowledge


Upgrades identified post-Darwin

Analysis of spectra from Scout-O3 flights identified several

high priority improvements:

Performance

• Improve receiver noise temperature – reduce NEDT

• Improve antenna pointing accuracy during dynamic flight

• Improve thermal stability

• Improve Cold load – reduce standing waves in spectra

Characterisation

• Finer resolution antenna pattern knowledge

• Finer resolution channel shape knowledge

UAMS – ESA funded programme to upgrade MARSCHALS


QON Pre-Upgrade

Band B

Receiver RAL

Band D

Receiver

RAL

Band C

Receiver


QON following Upgrade

Band B

Receiver All new

components

Band D New mixer

New doubler

New SSB filter

Band C

Receiver New mixer

New doubler

New SSB filter


Component upgrades

Band B IF Response

(Before (Blue) After (Red)

Band C FSS Response


Flatter IF Response in new Band B

Receiver – improved dynamic range

Much lower insertion Loss of Band C & D

Sideband Filters – better NEDT

(Queen’s University, Belfast)

New blackbody target for

Cold Calibration Load

- Higher return loss

- Lower standing waves

- Cleaner calibrated spectra CEOI PM Workshop Nov ‘12

Component upgrades

Band B IF Response


Band C FSS Response


Flatter IF Response in new Band B

Receiver – improved dynamic range

Much lower insertion Loss of Band C & D

Sideband Filters – better NEDT

(Queen’s University, Belfast)

New blackbody target for

Cold Calibration Load

- Higher return loss

- Lower standing waves

- Cleaner calibrated spectra CEOI PM Workshop Nov ‘12

Much improved sensitivity in all bands

Reduced Standing Waves

(PREMIER Ex 2010)

Cold Load

Upgrade


Improvements in Measurement

Performance after UAMS Upgrade

• Lower receiver noise temperatures leads to reduced ΔNEBT,

and therefore lower measurement noise.

• Improved blackbody termination of the cold calibration target

mitigates calibration errors and standing wave pattern in cold

sky spectra.

• More frequent and more reliable pointing bias corrections mean

less observation time is lost after aircraft turns (or other

pointing problems).

• Upgraded computer stacks, power supplies and thermal

stability improve operational reliability.


Future upgrades

UK National funding secured for 2 year programme of major

upgrades to MARSCHALS:

• Context : UK support for STEAMR

– Replacement of Band D receiver with one based on

sideband separating mixer (SHIRM) technology

– (being developed with CEOI support)

– Addition of high resolution spectrometer – digital

autocorrelator or Fourier Transform type (TBC)

– UK spectrometer development being supported by

CEOI

– Additional flights (further collaborative proposals to e.g.

FP7, ESA are in preparation)


STEAMR Technology at RAL

• Sideband-separating mixers for STEAMR

Incorporates 2x sub-harmonic mixers

Removes need for optical sideband filtering

RAL/Astrium development with CEOI funding

340 GHz Sideband Separating Mixer


Planned Receiver Configuration

12-16 GHz

BPF

16-20 GHz

BPF

20-24 GHz

BPF

MXR

MXR

MXR

2nd

LO

2nd

LO

2nd

LO

8.0 GHz

12.0 GHz

16.0 GHz

IF = 4.0 - 8.0 GHz

CHANNELISER 1

IF = 4.0 - 8.0 GHzCHANNELISER 2

IF = 4.0 - 8.0 GHz

CHANNELISER 3CRYOGENIC

BLACKBODY

CALIBRATION

TARGET

AMBIENT

BLACKBODY

CALIBRATION

TARGET

MXR

LO

MXR

LO

MXR

LO

SWITCHQUASI-

OPTICAL

NETWORK

ATMOSPHERIC

LIMB

(SCANNING ANTENNA

NOT SHOWN)

294 - 305.5 GHz

342.2 - 348.8 GHz

316.5 - 325.5 GHz

BAND B

BAND C

BAND D

EXISTING MARSCHALS RECEIVERS

DSB MIXERS + QUASI-OPTICAL SIDEBAND FILTERINGCHANNELISER SPECTROMETER

12GHZ @ 200MHZ RESOLUTION


Planned Receiver Configuration


12-16 GHz

BPF

16-20 GHz

BPF

20-24 GHz

BPF

MXR

MXR

MXR

2nd

LO

2nd

LO

2nd

LO

8.0 GHz

12.0 GHz

16.0 GHz

IF = 4.0 - 8.0 GHz

CHANNELISER 1

IF = 4.0 - 8.0 GHzCHANNELISER 2

IF = 4.0 - 8.0 GHz

CHANNELISER 3CRYOGENIC

BLACKBODY

CALIBRATION

TARGET

AMBIENT

BLACKBODY

CALIBRATION

TARGET

MXR

LO

MXR

LO

SWITCHQUASI-

OPTICAL

NETWORK

ATMOSPHERIC

LIMB

(SCANNING ANTENNA

NOT SHOWN)

294 - 305.5 GHz

316.5 - 325.5 GHz

BAND B

BAND C

EXISTING MARSCHALS RECEIVERS

DSB MIXERS + QUASI-OPTICAL SIDEBAND FILTERING

CHANNELISER SPECTROMETER

12GHZ @ 200MHZ RESOLUTION

LO

324 - 336 GHz (LSB)

324.25 - 355.25 GHz (USB)

BAND D

SHIRMHIGH RESOLUTION

SPECTROMETER

NEW RECEIVER (REPLACES BAND D)

- SHIRM SIDEBAND SEPARATING MIXER

HIGH RESOLUTION SPECTROMETER

12GHZ @ ~10MHZ RESOLUTION

Performance Summary Instrument Type Total Power Single Sideband Radiometer

RF target bands Band B 294 – 305.5 GHz

Band C 316.5 – 325.5 GHz

Band D 342.2 – 348.8 GHz

Instantaneous bandwidth 12 GHz

Spectral Resolution 200 MHz (with provision for addition of high resolution spectrometer with up

to12 GHz bandwidth)

NEΔT (4 scans) 2K (Band B), 1K (Band C,D)

Sideband Rejection > 30dB

Beam Width 0.34° HPBW (2 km at 10 km tangent height)

Beam Pointing <<0.0025 deg. rms pointing knowledge during scan, bias excepted

Scan range Tangent heights from –2km to platform altitude (21km on aircraft) in 1 km

steps with +20° “space view”

Mass 330kg

Dimensions 1.55 x 0.76 x 0.56m


Summary

• MARSCHALS – into its 2nd decade

• Continuous upgrades keep it relevant as an airborne

demonstrator of planned spaceborne mm-wave limb

sounders

• Next upgrades will enable closest simulation yet of

PREMIER, operating alongside GLORIA-AB IR Limb

imaging spectrometer


Summary

• MARSCHALS – into its 2nd decade

• Continuous upgrades keep it relevant as an airborne

demonstrator of planned spaceborne mm-wave limb

sounders

• Next upgrades will enable closest simulation yet of

PREMIER, operating alongside GLORIA-AB IR Limb

imaging spectrometer – time & place TBD!


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