Mars Express
Radio Science Team
Stanford University Element
Data Management Plan
Prepared by: _____________________
Richard A. Simpson
Concurrence by: _____________________
David P. Hinson
Approved by: _____________________
G. Leonard Tyler
Version 1.1
18 February 2005
Change Log
|===============================================================|
| Date |Version|Sections Changed| Description |
|==========+=======+================+===========================|
|2003-06-20| 1.0 | All |New document |
|----------+-------+----------------+---------------------------|
|2005-02-18| 1.1 | 1.1 |Updated version information|
|----------+-------+----------------+---------------------------|
|2005-02-18| 1.1 | 2.1 |Updated mission history |
|----------+-------+----------------+---------------------------|
|2005-02-18| 1.1 | 2.2.4 (para 4) |Revised discussion of BSR |
| | | 4.2 |calibration |
|----------+-------+----------------+---------------------------|
|2005-02-18| 1.1 | 2.2.4 (para 5) |Updated requirements for |
| | | |solar wind/corona studies |
|----------+-------+----------------+---------------------------|
|2005-02-18| 1.1 | 2.2.4 (page 9) |Updated Table |
|----------+-------+----------------+---------------------------|
|2005-02-18| 1.1 | 3.1 |Updated information on data|
| | | 3.5 |paths; updated table with |
| | | |better numbers after 1 year|
|----------+-------+----------------+---------------------------|
|2005-02-18| 1.1 | 3.2 |Updated data path info |
| | | 3.4 | |
| | | 3.6 | |
|----------+-------+----------------+---------------------------|
|2005-02-18| 1.1 | 4.6 |Updated status of: |
| | | |EQUALIZ, TNF_READER, |
| | | |MON_READER, BSR Processing,|
| | | |and Two-Way Occultation |
| | | |Processing |
|----------+-------+----------------+---------------------------|
|2005-02-18| 1.1 | 5.1 |Updated Table for MCH, BCK,|
| | | |and BSP. Added BRO, ENB, |
| | | |MFT, MCT, NMC, OPT, SRG, |
| | | |and FRK. Added paragraph |
| | | |about PI requests for |
| | | |alternate formats/labeling |
|----------+-------+----------------+---------------------------|
|2005-02-18| 1.1 | 7 |Updates to figure |
|===============================================================|
TBD Items
|===============================================================|
| Section | Description |
|===========+===================================================|
| 2.2 |Several parameters in the tables (uplink and down- |
| |link 3 dB angles, circuit losses, EIRP) |
|-----------+---------------------------------------------------|
| 2.2.4 |Procedure and configuration for egress occultations|
|-----------+---------------------------------------------------|
| 3.6 |Data formats, contents and volumes of NNO, NNC, ECH|
|===============================================================|
Contents
1 INTRODUCTION 1
1.1 PURPOSE 1
1.2 SCOPE 1
1.3 APPLICABLE DOCUMENTS 2
2 CONTEXT 3
2.1 MARS EXPRESS MISSION OVERVIEW 3
2.2 MARS EXPRESS RADIO SCIENCE OVERVIEW 3
2.2.1 Science Operations 6
2.2.2 Science Objectives 6
2.2.3 Instrument Modes 7
2.2.4 Data Requirements 8
3 DATA ACQUISITION 11
3.1 FILES OBTAINED BY REMOTE QUERY 11
3.2 FILES OBTAINED FROM MULTI-MISSION NAV 11
3.3 FILES OBTAINED FROM THE EIS WEB SITE 12
3.4 FILES OBTAINED FROM A JPL-BASED MEX DOM 12
3.5 FILES OBTAINED FROM NAIF 12
3.6 FILES OBTAINED FROM ESOC 13
4 DATA PROCESSING 14
4.1 QUICK LOOK PROCESSING 14
4.2 CALIBRATION DATA EXTRACTION 15
4.3 DETERMINISTIC FREQUENCY CALCULATION 15
4.4 STEERING AND SIGNAL PARAMETER ESTIMATION 17
4.5 ABEL INVERSION 17
4.6 SOFTWARE STATUS 18
5 ARCHIVING 19
5.1 RAW DATA ARCHIVE 19
5.2 CALIBRATED DATA ARCHIVE 20
5.3 REDUCED DATA ARCHIVE 21
6 ROLES AND RESPONSIBILITIES 22
6.1 G.L. TYLER (SUE PI) 22
6.2 D.P. HINSON (RADIO OCCULTATIONS) 22
6.3 R.A. SIMPSON (SURFACE SCATTERING AND DATA MANAGEMENT) 22
6.4 OTHER PERSONNEL 22
7 FACILITIES AND INSTITUTIONAL SUPPORT 23
8 REFERENCES 25
Abbreviations, Acronyms, and Symbols
a impact parameter
A~ amplitude estimate
APS average power spectra
APS' calibrated average power spectra
ASCII American Standard Code for Information Interchange
AX ASCII extract (from binary file)
B byte
BWG beam waveguide
{c0, ..., c3} frequency coefficients for steering
CD compact disc
CD-R compact disc recordable
chan channel
CLR closed loop reception
d(r) density as a function of radius
D/L downlink
D8W DSN eight-week schedule
dB decibel
dBm decibel with respect to one milliwatt
DC direct current (zero frequency)
deg degree
df~ estimated width of bistatic radar echo signal
DKF DSN keyword file
DOM
DSMS Deep Space Mission System
DSN Deep Space Network
DVD Digital Versatile Disc
DVD-R Digital Versatile Disc - Recordable
e(r) electron density as a function of radius
ECH channelized spacecraft engineering data
ECH_READER program to extract certain channels from ECH data
EIRP effective isotropic radiated power
EIS JPL Information Services
EOP Earth orientation parameters
EQUALIZ program to equalize filter response
ESA European Space Agency
ESOC European Space Operations Centre
f~ frequency estimate
f0 carrier frequency
fg classical frequency correction (from geometry)
FND program to filter and decimate
fr general relativity frequency correction
FY fiscal year
G(a) bending angle as a function of impact parameter
GB gigabyte
Gbs gigabits per second
HEF high efficiency (antenna)
HGA high gain antenna
HIST program to plot histograms of data samples
HSB high-speed beam waveguide (antenna)
Hz hertz
ID identifier
IGM Institut fuer Geophysik und Meteorologie
ION ionosphere media calibration data
JPL Jet Propulsion Laboratory
K kelvin
kHz kilohertz
kw kilowatt
LCP left circular polarization
LIT light time file
LOOK program to compute average power spectra
LSK leap seconds kernel
m meter
MaRS Mars Express Radio Science
Mbs megabits per second
MDOM MEX DOM
MEX mars Express
MHz megahertz
MON DSN monitor data
MON_READER program to extract certain channels from MON data
MRS Mars Express Radio Science
N/A not available; not applicable
n(r) refractive index as a function of radius
NAIF Navigation and Ancillary Information Facility
NASA National Aeronautics and Space Administration
NAV Navigation (team)
NNC New Norcia closed loop data
NNO New Norcia open loop data
ODF orbit data file
OLR open loop reception
ONE-D one-way dual frequency
ONE-S one-way single frequency
OPT orbit propagation and timing generation
OSCARX multi-mission NAV server
p(r) pressure as a function of radius
P~ power estimate
{p0, ..., p3} phase coefficients from RSR
{P0, ..., P4} phase coefficients of simulated oscillator
PCK planetary constants kernel
PDS Planetary Data System
PI principal investigator
POWER program to compute average samples vs time
POWERFIT program to estimate amplitude and frequency
PREPNNO preprocessing program for New Norcia data
PREPRSR preprocessing program for DSN data
PSA Planetary Science Archive (ESA)
Pt spacecraft transmitter power
QS-M RSR_MASTER_QueryServer
QS-R Mgs_CDR_QueryServer
QS-T Trk_trk1_QueryServer
r radius
RCP right circular polarization
RSSG Radio Science Systems Group
RSR radio science receiver
rsr01 output from PREPRSR or EQUALIZ
rsr02 output from FND (same format as rsr01)
rsr03 output format from STEER (sam format as rsr01)
s second
S-Band band centered on approximately 2 GHz
SCK spacecraft clock conversion file
SOE sequence of events
SOPC science operations planning computer
SPK spacecraft/planetary ephemerides
STARLab Space, Telecommunications,
and Radioscience Laboratory
SUE Stanford University Element
T-p(r) temperature-pressure profile vs radius
T(r) temperature profile vs radius
TBD to be determined
TCK spacecraft attitude kernel
TNF tracking and navigation file
TNF_READER program to extract certain channels from TNF data
TRO tropospheric media calibration file
Tsys system temperature
TWO-D two-way dual frequency
TWO-S two-way single frequency
U/L uplink
uso on board oscillator
VPN Virtual Private Network
w watt
WEA DSN meteorological data
X-Band band centered on approximately 8 GHz
1 Introduction
1.1 Purpose
For purposes of proposal and readiness evaluation prior to Mars Express (MEX)
Phase E, the first version (1.0) of this document described plans for data
acquisition, processing, and archiving by the Stanford University Element
(SUE) of the MEX Radio Science (MaRS) Team.
For purposes of data use during and after the mission, later versions of this
document (e.g., 1.1) describe the data acquisition, processing, and archiving
actually performed by the SUE of the MEX MaRS Team.
1.2 Scope
With regard to Mars Express Radio Science and ancillary data originating
within the NASA Deep Space Network (DSN) and Jet Propulsion Laboratory (JPL)
this document describes:
Transfer of radio science and ancillary data from JPL and DSN sources to
Stanford;
Processing of some of those files by the SUE; and
Generation and delivery of archival volumes of both the original data
and partially processed results (calibrated data) to the MaRS Principal
Investigator (PI), Martin Paetzold, Universitaet zu Koeln.
The document also describes:
SUE acquisition of certain data files obtained by the MaRS PI from ESA
sources; and
Processing of those files by the SUE, and delivery of the partially
processed results (calibrated data) to the MaRS PI.
The document does not discuss:
Strategies for maximizing science utility of and detailed planning for
MaRS observations;
Handling of non-JPL/DSN MaRS files that are not germane to Stanford
investigations;
Transfer of data files from the MaRS PI to the European Space Agency
(ESA) Planetary Science Archive (PSA);
Transfer of ESA PSA files to the NASA Planetary Data System (PDS)
1.3 Applicable Documents
[REF1] Paetzold, M., Rosetta, Mars Express, Venus Express Archive Generation,
Validation, and Transfer Plan, MEX-MRS-IGM-IS-3019, Issue 3,
Revision 2, 20 May 2003
[REF2] Tyler, G.L., Proposal to the California Institute of Technology Jet
Propulsion Laboratory for Operations Phase E, Mars Express Radio
Science Experiment, Stanford University Element, 27 May 2003.
[REF3] Planetary Data System Standards Reference, JPL Document D-7669, Part 2,
Version 3.5, 15 October 2002.
[REF4] Planetary Data System Data Dictionary Document, JPL Document D-7116,
Rev. D, 15 July 1996.
[REF5] DSMS Telecommunications Link Design Handbook: 70-m Subnet
Telecommunications Interfaces, Document 810-005, Rev. E, Section
101, Pasadena, CA: Jet Propulsion Labroratory, 30 November 2000.
[REF6] Mars Express Orbiter Radio Science Flight Operations Manual/Experiment
User Manual, MEX-MRS-IGM-MA-3008, Issue 1, Revision 1, 03 March
2003.
[REF7] DSMS Telecommunications Link Design Handbook: 34-m HEF Subnet
Telecommunications Interfaces, Document 810-005, Rev. E, Section
103, Pasadena, CA: Jet Propulsion Laboratory, 30 November 2000.
[REF8] DSMS Telecommunications Link Design Handbook: 34-m BWG Subnet
Telecommunications Interfaces, Document 810-005, Rev. E, Section
104, Pasadena, CA: Jet Propulsion Laboratory, 30 November 2000.
2 Context
Phase E operations of the SUE represent part of the MaRS investigation of the
MEX mission. In order to understand the SUE data management plan, some
context is required.
2.1 Mars Express Mission Overview
The MEX spacecraft was launched on 2 June 2003 from the Baikonur launch
facility in Kazakhstan. After a six-month cruise, the spacecraft separated
from the Beagle 2 lander and went into orbit around Mars. Over a period of
months, the orbit was adjusted to a final inclination of 87 deg, a period
of 6.7 hours, and distances from Mars' surface between 250 km (pericenter)
and 11500 km (apocenter).
Each orbit includes an Observation Phase of 0.5-1.0 hours centered on
pericenter, during which many of the six onboard instruments collect data from
the planet, and a Communications Phase, during which the spacecraft high-gain
antenna (HGA) is aimed toward Earth for transmission of data and reception of
commands.
Objectives of the mission include:
Interaction of the atmosphere with the interplanetary medium
Global atmospheric circulation and high-resolution mapping of
atmospheric composition
Improved understanding of the surface-atmosphere interaction
Global photogeology at 10 m resolution
Global mineralogical mapping of the surface at 100 m resolution
Detection of subsurface structures at km-scale
HGA pointing, instrument panel pointing, and the rotational axis of the solar
panels define three orthogonal axes of a right-hand coordinate system. As
negotiated with mission planners and other instrument teams, MaRS will
interrupt the Communications Phase (and, less often, the Observation Phase) to
gather radio science data.
The work described in this document addresses the first three mission
objectives listed above.
2.2 Mars Express Radio Science Overview
The Mars Express Radio Science instrument includes elements on both the
spacecraft and ground. The spacecraft radio system includes a dual-band (S/X)
transponder and a high-gain antenna with a body-fixed parabola. The ground
element includes an ESA station near New Norcia (Australia) and parts of three
NASA Deep Space Network complexes near Canberra (Australia), Madrid (Spain),
and Barstow (California).
Spacecraft radio system performance is summarized in the table below [REF6]:
|=========================================================|
| | S-Band | X-Band |
|=================================+===========+===========|
|Antenna Diameter (m) | 1.73 | 1.73 |
|Nominal Uplink Frequency (MHz) | 2100. | 7100. |
|Uplink Gain (dB) | 28.60 | 39.18 |
|Uplink 3 dB Angle (deg) | TBD | TBD |
|Receiver System Temperature (K) | 190. | 300. |
|Noise Power Density (dBm/Hz) | -175.81 | -173.83 |
|Nominal Downlink Frequency (MHz) | 2300. | 8400. |
|Downlink Gain (dB) | 29.56 | 41.43 |
|Downlink 3 dB Angle (deg) | TBD | TBD |
|Transmitter Power (w) | 5.0 | 65.0 |
|Circuit Losses (dB) | 5.5 | 3.0 |
|=========================================================|
New Norcia ground station capabilities are summarized in the table below
[REF6]:
|=========================================================|
| | S-Band | X-Band |
|=================================+===========+===========|
|Antenna Diameter (m) | 35. | 35. |
|Nominal Uplink Frequency (MHz) | 2100. | 7100. |
|Uplink Gain (dB) | 53.48 | 64.06 |
|Uplink 3 dB Angle (deg) | 0.31 | 0.09 |
|Transmitter Power (w) | 20000. | 2000. |
|Circuit Losses (dB) | TBD | TBD |
|EIRP (dBm) | TBD | TBD |
|Nominal Downlink Frequency (MHz) | 2300. | 8400. |
|Downlink Gain (dB) | 55.75 | 67.00 |
|Downlink 3 dB Angle (deg) | 0.29 | 0.08 |
|Receiver System Temperature (K) | 71. | 62. |
|Noise Power Density (dBm/Hz) | -180.09 | -180.68 |
|=========================================================|
DSN 34-m high-efficient (HEF) antenna nominal performance is shown in the
table below [REF7]:
|=========================================================|
| | S-Band | X-Band |
|=================================+===========+===========|
|Antenna Diameter (m) | 34. | 34. |
|Nominal Uplink Frequency (MHz) | N/A | 7145. |
|Uplink Gain (dB) | N/A | 67.1 |
|Uplink 3 dB Angle (deg) | N/A | 0.0778|
|Transmitter Power (w) | N/A | 20000. |
|Circuit Losses (dB) | N/A | 0.25 |
|EIRP (dBm) | N/A | 139.9 |
|Nominal Downlink Frequency (MHz) | 2295. | 8420. |
|Downlink Gain (dB) | 56.00 | 68.3 |
|Downlink 3 dB Angle (deg) | 0.242 | 0.0660|
|Receiver System Temperature (K) | 40. | 20. |
|Noise Power Density (dBm/Hz) | N/A | N/A |
|=========================================================|
DSN 34-m beam waveguide (BWG) and high-speed beam waveguide (HSB) antenna
nominal performance is shown in the two tables below [REF8]. The second table
shows differences in frequency coverage among the BWG and HSB systems.
|=========================================================|
| | S-Band | X-Band |
|=================================+===========+===========|
|Antenna Diameter (m) | 34. | 34. |
|Nominal Uplink Frequency (MHz) | 2115. | 7145. |
|Uplink Gain (dB) | 56.1 | 67.1 |
|Uplink 3 dB Angle (deg) | 0.263 | 0.0778|
|Transmitter Power (w) | 20000. | 4000. |
|Circuit Losses (dB) | TBD | TBD |
|EIRP (dBm) | 128.5 | 133.1 |
|Nominal Downlink Frequency (MHz) | 2295. | 8420. |
|Downlink Gain (dB) | 56.8 | 68.2 |
|Downlink 3 dB Angle (deg) | 0.242 | 0.0660|
|Receiver System Temperature (K) | 30. | 25. |
|Noise Power Density (dBm/Hz) | N/A | N/A |
|=========================================================|
In the table below entries in the uplink (U/L) columns give maximum available
uplink transmitter power; no entry means no transmitter for that band.
Entries in the downlink (D/L) columns give the number of low noise amplifiers
and receiver front ends available for the band; no entry means no low noise
receiving capability. Ka-Band entries are included for completeness but are
not relevant for MaRS.
|====================================================|
| | S-Band | X-Band | Ka-Band |
|----------------+-----------+-----------+-----------|
| Antenna | Type | U/L | D/L | U/L | D/L | U/L | D/L |
| | | (kw)| | (kw)| | (kw)| |
|=========+======+=====+=====+=====+=====+=====+=====|
| DSS 24 | BWG | 20 | 1 | | 1 | | |
| DSS 25 | BWG | | | 4 | 1 | 0.8 | 1 |
| DSS 26 | BWG | | | 4 | 2 | | |
| DSS 27 | HSB | 0.2 | 1 | | | | |
| DSS 34 | BWG | 20 | 1 | 4 | 1 | | |
| DSS 54 | BWG | 20 | 1 | 4 | 1 | | |
|====================================================|
DSN 70-m antenna nominal performance is summarized in the table below [REF5]:
|=========================================================|
| | S-Band | X-Band |
|=================================+===========+===========|
|Antenna Diameter (m) | 70. | 70. |
|Nominal Uplink Frequency (MHz) | 2115. | 7145. |
|Uplink Gain (dB) | 62.7 | 72.9 |
|Uplink 3 dB Angle (deg) | 0.128 | 0.0378|
|Transmitter Power (w) | 20000. | 20000. |
|Circuit Losses (dB) | 0.3 | 0.45 |
|EIRP (dBm) | 134.4 | 145.4 |
|Nominal Downlink Frequency (MHz) | 2300. | 8420. |
|Downlink Gain (dB) | 63.34 | 74.16 |
|Downlink 3 dB Angle (deg) | 0.118 | 0.0320|
|Receiver System Temperature (K) | 16. | 19. |
|Noise Power Density (dBm/Hz) | N/A | N/A |
|=========================================================|
2.2.1 Science Operations
The Mars Express radio link to Earth is used for science investigations in two
ways.
2.2.1.1 Radiometric Observation
The distance between and relative velocity of the spacecraft and a tracking
station on Earth can be determined by measuring the propagation time (most
accurately, the two-way round-trip time) and Doppler shift, respectively. For
example, additional gravitational attraction of a mass concentration will
affect the trajectory of the spacecraft, inducing a Doppler shift. The
signature of the Doppler shift, in conjunction with the observational
geometry, allows inference of the location of the mass concentration and its
magnitude.
2.2.1.2 Media Dispersion
The properties of intervening media may be inferred from time and frequency
effects on the propagating signal. Refractivity increases with the density of
a neutral gas; it decreases in a plasma as the electron density increases.
Both positive and negative refractivity can be observed when the radio path
intercepts a planet's atmosphere (including its ionosphere). Propagation
through the (turbulent) solar corona or reflection from a rough planetary
surface both cause Doppler broadening of the signal.
2.2.2 Science Objectives
Science objectives of the MaRS Team are as follows:
(a) Sounding of Mars' neutral and ionized atmosphere by radio occultation
(b) Improvement of the gravity field, especially regarding anomalies
(c) Determination of the mass of Phobos
(d) Measurement of Mars' surface dielectric constant using bistatic radar
(e) Sounding of the solar corona
Among the objectives above, the SUE will address items (a) and (d) directly
and assist the MaRS Team in acquiring DSN data to meet the other objectives.
2.2.3 Instrument Modes
Four instrument 'modes' have been defined for MaRS on the spacecraft [REF6].
In all cases the optimum radio science data are obtained when the spacecraft
modulation index is minimized--except for the ranging subchannel.
One-way single frequency (ONE-S): The spacecraft uses its internal
oscillator and transmits an X-band carrier.
One-way dual frequency (ONE-D): Same as ONE-S except that both X-band
and S-band are transmitted.
Two-way single frequency (TWO-S): An X-band signal is transmitted from
the ground, is echoed by the spacecraft at X-band, and is received on
the ground.
Two-way dual frequency (TWO-D): Same as TWO-S except that the
spacecraft echoes at both X- and S-band. For sounding of the solar
corona, the uplink from the ground may be at S-band.
For each spacecraft mode, there are several options for reception on the
ground. In some cases, more than one may be selected.
Open Loop and Closed Loop Reception: With open loop reception (OLR),
the spacecraft signal is down-converted to a frequency range of a few Hz
to a few tens of kHz, sampled, and stored for later analysis. OLR
effectively preserves all details of the signal within the bandwidth
captured, but at a significant cost in data volume. In closed loop
reception (CLR), a phase lock loop (or equivalent device) tracks the
signal amplitude and frequency; its output is recorded at intervals on
the order of tenths of a second. CLR is very efficient in terms of data
volume, but it works poorly when the signal is dynamic and is of no use
when the signal is spread.
Polarization: The default polarization transmitted by the spacecraft is
right-circular. During interaction with targets en route to Earth, the
signal's polarization may be altered. Randomization from Faraday
rotation is expected during deep probing of the solar corona; both
deterministic (Fresnel) polarization changes and random depolarization
are expected in scattering from Mars' surface. DSN 70-m antennas are
equipped to receive both RCP and LCP at both S- and X-band. DSN 34-m
antennas can receive one polarization at S-band and one polarization at
X-band. New Norcia can receive two signals simultaneously; the user
chooses whether they are two polarizations in the same band or a single
polarization in each of two bands.
2.2.4 Data Requirements
Among the MaRS science objectives above, the SUE will address items (a) and
(d) directly and will assist the MaRS Team in acquiring DSN data to meet the
other objectives. The MaRS PI will, in turn, provide Stanford with New Norcia
data suitable for incorporation into the SUE (a) and (d) investigations.
Atmospheric Occultation Immersion: The spacecraft will be in the TWO-D mode
and open loop receivers on the ground will sample S-RCP and X-RCP receiver
outputs at rates on the order of 2000 16-bit I, 16-bit Q (complex) samples per
second. Receivers will be tuned using two-way closed-loop receiver
predictions; analysis will require the uplink (transmitted) tuning profile.
Atmospheric Occultation Emersion: Details of this operation remain TBD. The
configuration could be identical to that used for Atmospheric Occultation
Immersion. The spacecraft phase lock loop likely will not lock up quickly
enough to allow analysis of the (lower) neutral atmosphere, but the data
should be good for the egress ionosphere. Alternatively, the spacecraft could
be operated in ONE-D mode. In this mode the spacecraft signal frequency is
less stable than when in the TWO-D mode, but there are no data gaps as a
result of the lock-up process.
Surface Dielectric Constant: The spacecraft will be in ONE-D mode and open
loop receivers on the ground will sample S-RCP, S-LCP, X-RCP, and X-LCP at
rates up to 25000 I/Q pairs per second. Each I and each Q will have 8- or 16-
bits, depending on the observation. When four channels cannot be captured (as
at New Norcia, where the limit is two), the spacecraft may operate in ONE-S
mode with corresponding simplification on the ground. Since absolute
amplitude calibration of each channel is required during analysis, system
temperature monitoring through CLR receivers is needed. CLR's are used to
turn noise diodes on and off immediately before and after bistatic
observations, providing calibration of the radiothermal noise background. The
noise diodes themselves and "cold" sky are calibrated against ambient loads in
the pre- and post-pass periods. Only two CLR's are usually available; they
must be switched between S- and X-band in order to control the four noise
diodes.
Non-SUE Investigations: Improved gravity modeling (b), investigation of
gravity anomalies (b), and determination of the mass of Phobos (c) are
preferably based on TWO-D data, though TWO-S may be sufficient in some
circumstances such as when the data collection period is short compared with
expected plasma changes along the propagation path. These investigations
require CLR data from the ground station; one polarization (RCP) is
sufficient. Solar corona data (e) are best when the spacecraft is in TWO-D
mode. Two polarizations in each band and both OLR and CLR operation are
preferred when the resources are available.
The table below summarizes the data needed, the sources (based primarily on
SUE experience with Mars Global Surveyor), and the objectives associated with
each data type. The level of need varies among products. Where the need is
less than a requirement, the column shows '?'.
|===================================================|
| Data Type |Source| Science |
| | | Objectives|
|================================+======+===========|
|Radio Science Receiver (RSR) | QS-R | a d e |
| open loop data records | | |
|--------------------------------+------+-----------|
|Tracking and Navigation (TNF) | QS-T | a b c ? e |
| data (TRK-2-34) | | |
|--------------------------------+------+-----------|
|Orbit Data File (ODF) |OSCARX| b c e |
|--------------------------------+------+-----------|
|DSN Monitor Data (MON) | QS-M | d |
|--------------------------------+------+-----------|
|Ionosphere Calibration (ION) |OSCARX| ? ? ? ? |
|--------------------------------+------+-----------|
|Troposphere Calibration (TRO) |OSCARX| ? ? ? ? |
|--------------------------------+------+-----------|
|DSN Meteorology Data (WEA) |OSCARX| ? ? ? ? |
|--------------------------------+------+-----------|
|Channelized Spacecraft | ESOC | ? |
| Engineering Data (ECH) | | |
|--------------------------------+------+-----------|
|Earth Orientation Parameters | EIS | a ? ? ? |
| (EOP) | | |
|--------------------------------+------+-----------|
|Lighttime Files (LIT) | MDOM | ? |
|--------------------------------+------+-----------|
|Orbit Propagation and Timing | ESOC | ? |
| Generation Files (OPT) | | |
|--------------------------------+------+-----------|
|Sequence of Events Files (SOE) | MDOM | ? d ? |
|--------------------------------+------+-----------|
|DSN Keyword Files (DKF) | MDOM | ? d ? |
|--------------------------------+------+-----------|
|DSN 8-Week Schedule (D8W) | MDOM | b c ? e |
|--------------------------------+------+-----------|
|Spacecraft Attitude Kernels | NAIF | ? ? ? d ? |
| (TCK) | | |
|--------------------------------+------+-----------|
|S-P Kernels (SPK) | NAIF | a d e |
|--------------------------------+------+-----------|
|Spacecraft Clock Conversion File| NAIF | a b c d e |
| (SCK) | | |
|--------------------------------+------+-----------|
|Planetary Constants Kernel (PCK)| NAIF | a b c d e |
|--------------------------------+------+-----------|
|Leap Second Kernels (LSK) | NAIF | a b c d e |
|--------------------------------+------+-----------|
|New Norcia Open Loop (NNO) | ESOC | ? ? |
|--------------------------------+------+-----------|
|New Norcia Closed Loop (NNC) | ESOC | ? ? |
|===================================================|
Sources: QS-R RSR_MASTER_QueryServer (SOPC)
QS-M Mgs_CDR_QueryServer (SOPC)
QS-T Trk_trk1_Query Server (SOPC)
OSCARX Multi-Mission NAV server (SOPC)
ESOC ESOC data system via MaRS PI
EIS eis.jpl.nasa.gov web site (SOPC)
MDOM JPL-supported MEX DOM or
equivalent (SOPC)
NAIF naif.jpl.nasa.gov anonymous ftp
SOPC MGS Science Operations Planning
Computer or equivalent
3 Data Acquisition
3.1 Files Obtained by Remote Query
Files needed for MaRS which have been obtained by query during the MGS era
include the following, where the data type acronym is defined in the table
above. MGS RSR, TNF, and MON data are being transferred over a Virtual
Private Network (VPN). For MaRS it has been more convenient to obtain RSR's
using a remote JPL workstation (rsops2) maintained by the Radio Science
Systems Group (RSSG), then transferring the data to Stanford via sftp over the
Internet. Number of Events and Mission Data Volume are calculated for the
primary mission (2004-2005) only.
|======================================================|
|Data| Science | Data Rate|Chans| Time|Number|Mission|
|Type| Objective | | | per | of | Data |
| | | | |Event|Events| Volume|
| | |(B/chan/s)| | (s) |[REF6]| (GB) |
|====+===========+==========+=====+=====+======+=======|
| RSR| a | 10000. | 2 | 1200| 160 | 4. |
| TNF| a | 1000. | 1 |21600| 160 | 3.5 |
| TNF| c | 1000 | 1 |21600| 2 | 0.04|
| RSR| d | 100000. | 4 | 7200| 20 | 144. |
| TNF| d | 1000. | 1 |21600| 20 | 0.5 |
| MON| d | 400. | 2 |21600| 20 | 0.4 |
| RSR| e | 10000. | 4 | 7200| 60 | 43. |
| TNF| e | 1000. | 1 |21600| 60 | 1.3 |
|======================================================|
B = bytes
3.2 Files Obtained from Multi-Mission NAV
The following files have been collected through the JPL Multi-Mission
Navigation Team server oscarx during MGS. Similar access has been obtained
for MaRS. Data volume is negligible compared with the data types above (e.g.,
RSR). ODF's are typically released five times per week, ION's once per week,
TRO's once per week, and WEA's twice per week.
|=========================================================|
|Data| Science | Number of Files | Typical File Size |
|Type| Objective | in Primary Mission | (MB) |
|====+===========+====================+===================|
| ODF| c e | 700 | 0.1 |
| ION| c e | 100 | 0.05 |
| TRO| c e | 100 | 0.05 |
| WEA| c e | 300 | 0.5 |
|=========================================================|
3.3 Files Obtained from the EIS Web Site
Earth Orientation Parameter files can be downloaded from eis.jpl.nasa.gov.
The files are released at the rate of approximately four per week; their
volume is negligible compared with files such as the RSR.
|=========================================================|
|Data| Science | Number of Files | Typical File Size |
|Type| Objective | in Primary Mission | (MB) |
|====+===========+====================+===================|
| EOP| a c | 400 | 0.5 |
|=========================================================|
3.4 Files Obtained from a JPL-based MEX DOM
The following files are helpful in setting up experiments and in managing
data. For MGS Stanford obtains these from the MGS DOM; the source for MaRS is
the MEX DOM. These files have negligible volume compared to files like the
RSR.
|=========================================================|
|Data| Science | Number of Files | Typical File Size |
|Type| Objective | in Primary Mission | (MB) |
|====+===========+====================+===================|
| LIT| ? | 1 | 1.0 |
| SOE| ? | 300 | 0.5 |
| DKF| d | 300 | 0.1 |
| D8W| a c d e | 100 | 0.01 |
|=========================================================|
3.5 Files Obtained from NAIF
The following files are available through the NAIF anonymous ftp server
naif.jpl.nasa.gov. Files are released on about the 15th of each month
covering ther previous month.
|==========================================|
|Data| Science | Data Rate|Number|Mission|
|Type| Objective | | of | Data |
| | | | Files| Volume|
| | |(MB/month)| | (GB) |
|====+===========+==========+======+=======|
| SPK| a d e | 13. | 24 | 0.3 |
| TCK| a c d ? | 2. | 24 | 0.05 |
| SCK| a c d e | N/A | N/A | <0.01 |
| PCK| a c d e | N/A | N/A | <0.01 |
| LSK| a c d e | N/A | N/A | <0.01 |
|==========================================|
B = bytes
3.6 Files Obtained from ESOC
The following files must be obtained from ESOC. New Norcia data are basic
input to the atmospheric, ionospheric, and surface scattering studies, but
their content, format, and volume are not known at this time. Spacecraft
Engineering Data may be important in bistatic radar if the MEX transmitter
power varies significantly (but this is not expected). The Lighttime File is
used in some predictions, although the same information can be obtained more
laboriously from the OPT. Information in the OPT can be derived from the SPK.
The ESOC SOE presumably would cover the entire mission whereas the SOE listed
above (Section 3.4) is limited to DSN-supported activities.
|=========================================================|
|Data| Science | Number of Files | Typical File Size |
|Type| Objective | in Primary Mission | (MB) |
|====+===========+====================+===================|
| NNO| a d | TBD | TBD |
| NNC| a d | TBD | TBD |
| ECH| ? | TBD | TBD |
| LIT| ? | 1 | TBD |
| OPT| ? | 100 | TBD |
| SOE| ? ? | 100 | TBD |
|=========================================================|
4 Data Processing
The following sections describe the typical steps in processing open loop data
to obtain radio occultation temperature-pressure profiles of Mars' atmosphere,
profiles of electron density for the ionosphere, and reflectivity estimates
from surface scatter. RSR is taken to be the generic input data type; when
more details are known about NNO formats and content, the procedures will be
adapted for that data type.
4.1 Quick Look Processing
Data processing takes place in several steps. For open loop RSR data, a
'quick-look' processing step provides immediate information on data quality.
PREPRSR is a program which converts the RSR integer I/Q samples to a standard
double-precision complex value format; it also saves the distribution of I and
Q values for later plotting as a histogram. EQUALIZ digitally filters the
floating point samples. Input data bandwidth can be reduced, and
'equalization' can be applied to correct for a 'colored' spectrum at the
input. EQUALIZ is used only for bistatic radar data, where the signals are
broad and drift within the passband during the course of the experiment. The
rsr01 output from EQUALIZ (or PREPRSR in occultation processing) can then be
used to calculate plots of average sample power (1 sec averages) versus time
and power spectra typically averaged over 60 seconds.
--------- ------ Histograms
RSR --->| PREPRSR |--->| HIST | of
--------- ------ I/Q Samples
|
| rsr01
v /
--------- / ------- Power
| EQUALIZ |--->| POWER |--> vs
--------- | ------- Time Plot
|
| ------- Average
|->| LOOK |--> Power Spectra
| ------- (APS)
|
v
-----
| FND |
-----
|
v
rsr02 Digitally Filtered
Complex Time Samples
In the bistatic radar analysis, there is usually no reduction in the data
bandwidth, and Average Power Spectra (APS) become the input to later
processing.
It is assumed that a PREPNNO program can be written for New Norcia data that
mimics the functions of PREPRSR and provides output in the standard rsr01
format.
4.2 Calibration Data Extraction
In bistatic radar analysis, Average Power Spectra (APS) are obtained during
pre- and post-calibration periods when the receivers are looking at "cold" sky
(zenith), when they are connected to ambient loads, and when noise diode
energy is injected in both of the previous configurations. The system
temperature of each receiver Tsys can be obtained by comparing the cold sky
power against the ambient load; the value of each noise diode may also be
determined. Immediately before and after the bistatic radar observation, the
noise diodes are turned on; this injects a known amount of additional
background power from which the operating Tsys can be derived. Finally, the
power in the bistatic radar echo signal can be determined by comparison
against the background noise.
Amplitude calibration can be improved with knowledge of the output power Pt
of the spacecraft transmitter, which should be obtainable in the spacecraft
engineering data stream ECH using an ECH_READER tool.
------------
ECH --->| ECH_READER |------------> Pt
------------
Processing of two-way radio occultation data requires knowledge of the uplink
transmitter phase or frequency f0, which is carried in the TNF.
------------
TNF --->| TNF_READER |------------> f0
------------
4.3 Deterministic Frequency Calculation
The apparent frequency of the baseband signal recorded on Earth depends on
several factors. In the simple case (one-way transmissions from the
spacecraft) these include:
frequency of the spacecraft oscillator
position and motion of the spacecraft at transmit time
general relativistic effects (Sun's gravitational field)
position and motion of the antenna on Earth at receive time
tuning and mixing of the Earth based receiver
For two-way observations the position and motion of the transmitting antenna
on Earth, the tuning profile of the uplink signal, and the turn-around ratio
in the spacecraft electronics are substituted for the spacecraft oscillator
frequency.
Each of these contributions can be calculated from information in available
data products. The first four yield sets of polynomial coefficients which can
be used to approximate part of the baseband signal frequency (f = c0 + c1*t
+c2*t^2 + c3*t^3). These coefficients are typically computed at one second
intervals; past experience shows them to be accurate at the millihertz level.
Tuning and mixing of the receiver on Earth are described by offsets and by
sets of coefficients for a phase polynomial computed and carried along in the
RSR data record (p = p0 + p1*t + p2*t^2 + p3*t^3).
uso
|
fg v
---------------------- / ----------
EOP --->| GEOMETRY CALCULATOR: |--->| FREQUENCY|
SPK --->|S/C, RELATIVITY, EARTH| | |<--- RSR
TCK --->| ROTATION, LIGHT TIME |--->|CALCULATOR|
---------------------- \ ----------
| fr |
v v
bsr-g {c0, c1, ...}
In the figure above fg is the frequency correction based on classical
Doppler effects (including motion of the spacecraft and Earth antenna,
including Earth rotation), fr is a general relativistic correction for the
change in the Sun's gravitational potential as the signal propagates from Mars
to Earth, and uso is the current estimate of spacecraft oscillator
frequency, based on previous one-way observations or the two-way uplink tuning
profile (f0, in the previous figure) adjusted appropriately for transmitter
motion and the spacecraft transponder turn-around ratio. RSR, on the right,
denotes the ground receiver tuning information (and, implicitly, the mixing
design of the receiver), stored in the RSR file along with the open loop data
samples. TCK represents spacecraft attitude, a Doppler correction of marginal
significance on MGS where the HGA is at the end of a 3-m boom; the MaRS HGA is
attached to the spacecraft bus, and the Doppler effects are likely to be
insignificant. This correction may be ignored.
In bistatic radar analysis, calculation of the absolute downlink frequency is
not usually required. During the experiment, the receiver bandwidth is chosen
so that both the surface echo and a weak signal reaching Earth directly via
one of the HGA sidelobes are captured. It is sufficient in the great majority
of cases to know frequencies in the echo spectrum relative to the carrier
frequency and not necessary to know either absolutely. Instead, the GEOMETRY
CALCULATOR synthesizes the bistatic viewing geometry (including the HGA
pointing) and provides parameters such as angle of incidence at the specular
reflection point and expected polarization ratio for an assumed dielectric
constant. In a separate step, the frequency difference between the carrier
and echo can be calculated.
4.4 Steering and Signal Parameter Estimation
With the coefficient sets {c0, c1, c2, c3} and {p0, p1, p2, p3} one can
synthesize a 'software' representation of a sinusoid with phase P = P0 + P1*t
+ P2*t^2 + P3*t^3 + P4*t^4 where the frequency contribution {ci} has been
integrated to give phase. The phase function is continuous across time
intervals (as coefficients change), and the accumulating phase can be
subtracted from the (accumulating) phase of the data samples rsr02. If the
coefficients are a perfect match to the data, the result is a constant phasor
(DC). If the match is not perfect (as would be expected when the radio path
passes through Mars' atmosphere), the phasor rsr03 is a measure of the phase
advance or retardation caused by the plasma or neutral gas, respectively. In
radio engineering, this process is known as 'mixing'; at Stanford we have
adopted the term 'steering', since the resultant can be directed to any
frequency by adding a bias to the c0 coefficient.
{c0,c1,...,c3}
{p0,p1,...,p3}
|
v rsr03
------- / ----------
rsr02 --->| STEER |---->| POWERFIT |---> f~, A~
------- ----------
The steered data rsr03 can be Fourier transformed. A sinc function can be
fitted to the carrier using program POWERFIT; the fitting parameters yield
estimates of the carrier amplitude A~ and frequency f~ as a function of
time.
In bistatic radar data processing, steering is rarely used. After removing
the noise baseline from the APS', power in the echo P~ can be calculated
directly from its spectrum, and width of the echo signal df~ can be obtained
using one of several smoothing and/or fitting algorithms. The ratio of the
P~ values from the RCP and LCP channels plus knowledge of the geometry yields
the effective dielectric constant of the surface material [Simpson and Tyler,
2001]. df~ is taken to be proportional to the surface roughness except when
the HGA beamwidth does not fully illuminate the scattering surface.
Calculation of the cross-spectrum (from rsr01 data in two polarizations)
allows estimation of the polarized and unpolarized fractions of the echo
power.
4.5 Abel Inversion
The remaining steps in deriving temperature-pressure profiles for the neutral
atmosphere are based on a procedure developed by Fjeldbo et al. [1971] and
summarized by Tyler et al. [1992]. The frequency or phase estimates f~ are
converted to a measure of bending angle G as a function of impact parameter
a using reasonable assumptions of symmetry and the reconstructed experimental
geometry. An Abel transform of G(a) yields a unique solution for refractive
index n(r) as a function of radius r from the planet's center. If the
composition of the atmosphere and the refractive indices of the major
components are known, n(r) can be converted to d(r), the mass density of
the atmosphere as a function of r. Assuming hydrostatic equilibrium and the
ideal gas law allows inference of p(r) and T(r), the pressure and
temperature profiles of the atmosphere.
For profiles of the ionosphere, n(r) is obtained as above. Then a standard
translation [Yeh and Liu, 1972] can be used to obtain the electron density
profile e(r) from the refractive index.
4.6 Software Status
Most of the software mentioned above exists and is operational for Mars Global
Surveyor. Certain file naming and directory conventions will need to be
adapted for MaRS. The following were identified in the previous version of
this document as needing additional work:
PREPNNO This program does not exist and cannot be designed until
details of the New Norcia formats become available. PREPNNO converts
raw data to a standard format; it is expected to be modeled on the
operational PREPRSR.
EQUALIZE This program has been implemented by adding an "equalizing"
option to the existing FND program
TNF_READER This program extracts a few numbers from a larger file; it
is operational and has been used to process more than 40 MaRS radio
occultations.
MON_READER This program extracts a few numbers from a larger file.
Because of the changes in bistatic radar calibration, it is no longer
needed.
ECH_READER This program extracts a few numbers from a larger file. It
does not exists but is not expected to require much work.
bsr-g Software exists to calculate the bistatic radar observing
geometry, including the boresight pointing of the spacecraft antenna.
But software to calculate the illumination of the surface (the HGA
footprint) does not. Such a program would be useful in interpretation,
but it will take some time to develop. The illumination pattern is not
required for generation of the products described in this document.
BSR Processing The modules for processing bistatic radar data have been
written and used on MaRS bistatic radar data collected in May 2004.
Their use is labor intensive and they have not been organized into a
processing pipeline. The process will be streamlined as efficiencies
are identified during coming months.
Two-Way Occultation Processing: Processing of two-way radio occultation
data is now routine; over 40 temperature-pressure profiles have been
generated using MaRS data.
Registration of Dual-Frequency Profiles: The ability to acquire
profiles of electron density and neutral atmosphere profiles is improved
by having observations at two frequencies--especially in the case of the
former. The procedure for resolving differences is understood but not
being used for MGS, which only operates at X-band. To date no S-band
MaRS data have been processed to Level 2.
5 Archiving
There are three levels of data products suitable for archive from SUE
operations:
raw and ancillary data acquired from JPL/DSN
calibrated data derived from the above and from NNO
reduced data derived from the calibrated data
5.1 Raw Data Archive
The raw data archive will be generated as the files are acquired from JPL/DSN
in formats and on schedules defined in the MaRS Archive Generation,
Validation, and Transfer Plan [REF1]. In general, delivery to the MaRS PI
will be as soon as the volumes have been validated (e.g., 1-2 weeks after data
acquisition). Based on data volume and rate predictions in the "Data
Acquisition" section above, an average of 3 GB of raw data (approximately 5
CD's or one DVD) will be collected and delivered each week.
The table below shows data types expected to be included in the raw data
archive. Formats are ASCII, binary, and ASCII extract (AX) from a binary
original. File names, data set ID, volume ID, and other nomenclature issues
have either been addressed in [REF1] or will be negotiated with the MaRS PI.
All data products will be accompanied by PDS labels and will comply with PDS
standards [REF3, REF4]. The MaRS PI will integrate the Stanford contributions
with other data and submit the full package to the ESA PSA.
|==================================================|
| Data Type |Source|Format(s)|
|=================================+======+=========|
|Radio Science Receiver (RSR) | QS-R | binary |
|---------------------------------+------+---------|
|RSR Browse plots (BRO) | SUE | binary |
|---------------------------------+------+---------|
|Tracking and Navigation (TNF) | QS-T | binary |
|---------------------------------+------+---------|
|Orbit Data File (ODF) |OSCARX| binary |
|---------------------------------+------+---------|
|DSN Monitor Data (MCH) | QS-M | binary |
|---------------------------------+------+---------|
|Monitor Channel Tables (MCT) | SUE | AX |
|---------------------------------+------+---------|
|Ionosphere Calibration (ION) |OSCARX| ASCII |
|---------------------------------+------+---------|
|Troposphere Calibration (TRO) |OSCARX| ASCII |
|---------------------------------+------+---------|
|DSN Meteorology Data (WEA) |OSCARX| ASCII |
|---------------------------------+------+---------|
|Earth Orientation (EOP) | EIS | ASCII |
|---------------------------------+------+---------|
|Spacecraft Engineering (ECH) | ESOC | AX |
|---------------------------------+------+---------|
|Lighttime Files (LIT) | MDOM | ASCII |
|---------------------------------+------+---------|
|Sequence of Events Files (SOE) | MDOM | ASCII |
|---------------------------------+------+---------|
|DSN Keyword Files (DKF) | MDOM | ASCII |
|---------------------------------+------+---------|
|Orbit Propagation/Time (OPT) | MDOM | ASCII |
|---------------------------------+------+---------|
|S-P Kernels (BSP) | NAIF | binary |
|---------------------------------+------+---------|
|Spacecraft Attitude (BCK) | NAIF | binary |
|---------------------------------+------+---------|
|Spacecraft Clock (SCK) | NAIF | ASCII |
|---------------------------------+------+---------|
|Frame Kernel (FRK) | NAIF | ASCII |
|---------------------------------+------+---------|
|Planetary Constants (PCK) | NAIF | ASCII |
|---------------------------------+------+---------|
|Leap Second (LSK) | NAIF | ASCII |
|---------------------------------+------+---------|
|Network Monitor/Control (NMC) | DSN | ASCII |
|---------------------------------+------+---------|
|Experimenter Notebook (ENB) | SUE | ASCII |
|---------------------------------+------+---------|
|Daily Health Report (HEA) | SUE | ASCII |
|---------------------------------+------+---------|
|Surface Reflection Geometry (SRG)| SUE | ASCII |
|---------------------------------+------+---------|
|Manifest - list of files (MFT) | SUE | ASCII |
|==================================================|
In addition, the MaRS PI has requested that we provide files meeting different
naming and aggregation criteria, which will more easily fit into the archiving
system being developed at his home institution. This additional work is in
progress.
5.2 Calibrated Data Archive
The following data products have been identified for the Calibrated Data
Archive. All products will be generated in the form of ASCII tables and will
meet PDS standards [REF3, REF4]. Calibrated data will be delivered to the
MaRS PI within two months of the corresponding data acquisition. The MaRS PI
will integrate the Stanford contributions with other data and submit the full
package to the ESA PSA.
|===========================================================================|
| Data Type | Source |Typical Data Rate|
|=================================+=======================+=================|
|Frequency and amplitude estimates|POWERFIT from | 0.1 MB/week |
| vs time (f~, A~) |occultation analysis | |
|---------------------------------+-----------------------+-----------------|
|Calibrated Average Power Spectra |Modified LOOK step in | 0.1 MB/week |
|(APS'); cross-spectra |Quick-Look processing | |
|===========================================================================|
5.3 Reduced Data Archive
The following data products have been identified for the Reduced Data Archive.
All products will be generated in the form of ASCII tables and will meet PDS
standards [REF3, REF4]. They will be delivered to the MaRS PI within two
months of the corresponding data acquisition.
|===========================================================================|
| Data Type | Source |Typical Data Rate|
|=================================+=======================+=================|
|Temperature-pressure profiles vs |Abel inversion, gas law| 0.1 MB/week |
| radius: T-p(r) |and hydrostatic equilib| |
|---------------------------------+-----------------------+-----------------|
|Electron density profiles vs |Abel inversion; Yeh and| <0.1 MB/week |
| radius: e(r) |Liu conversion | |
|---------------------------------+-----------------------+-----------------|
|Reflectivity and dielectric |Arithmetic operations | <0.1 MB/week |
|constant vs latitude-longitude |on calibrated data | |
|===========================================================================|
6 Roles and Responsibilities
6.1 G.L. Tyler (SUE PI)
G.L. Tyler will serve as leader of the Stanford group of investigators.
During Phase E he will work with MaRS PI Paetzold, Hinson, and Simpson in
detailed operations planning and execution of the MaRS atmospheric occultation
and surface scattering investigations. He will oversee the data processing
and analysis at Stanford, and collaborate on the interpretation of results
from both types of investigations.
6.2 D.P. Hinson (Radio Occultations)
D.P. Hinson has the lead responsibility for investigation of the atmosphere by
radio occultation sounding. He will work with Tyler, Simpson, and Paetzold in
operational implementation and execution of observations, and with the MaRS
Team in interpretation and publication of the results. He will carry
responsibility for production of occultation derived soundings of the
atmosphere and ionosphere, including both calibrated and reduced data as
defined above.
6.3 R.A. Simpson (Surface Scattering and Data Management)
R.A. Simpson has lead responsibility for investigations of the martian surface
by means of oblique (bistatic) surface scattering observations. He will work
with Tyler, Hinson, and Paetzold in planning and carrying out observations,
and with the MaRS Team in interpretation and publication of the results. He
will carry primary responsibility for producing measures of surface parameters
based on scattering results, including both calibrated and reduced data as
defined above. Simpson will also assume primary responsibility for data
organization and management at Stanford, including collection of New Norcia
data (when those become available) from ESA sources and preparation of
archival data records which will eventually, by way of the ESA Planetary
Science Archive, be deposited with the NASA Planetary Data System.
6.4 Other Personnel
Hinson and Simpson will be assisted by a part-time scientific programmer and
one or more part-time graduate students. The scientific programmer is
currently identified as J.D. Twicken.
7 Facilities and Institutional Support
Members of the SUE work in the Space, Telecommunications, and Radioscience
Laboratory (STARLab) of the Department of Electrical Engineering at Stanford
University.
STARLab is housed in the Packard Electrical Engineering Building which has
state-of-the art networking (multiple 100 Mbs to all rooms, 1 Gbs optional).
The facilities supporting Mars Express will be a central work station and file
server, a color laser printer, a Science Operation Planning Computer (SOPC), a
CD copier, and several desktop satellite work stations. There are also
several desktop PC-type machines with peripherals such as scanners available
for word processing, spreadsheet development, and presentations. All
computers are networked; the SOPC is connected to JPL via a 56 kbs data line
and it is protected from the Stanford network by a Cisco router. Most of this
equipment is maintained in a secure room (approximately 600 sq ft) with access
limited to approved individuals.
Most of the equipment listed above has been acquired to support Mars Global
Surveyor. It has been used by other projects such as Mars Express and the
Planetary Data System on a non-interference time-available basis. We expect
that sharing arrangement to continue except that Mars Express will now begin
providing the core components. The Sun Blade 2000 was recently obtained with
funding budgeted for Mars Express Phase C/D; it replaces an MGS Sun Ultra
Enterprise 2. Several of the satellite workstations are scheduled for upgrade
using Phase E funds early in FY04. We expect to add a DVD writer in FY05, as
the volume of bistatic radar (RSR) data begins to increase.
The MaRS SUE processing configuration is shown in the diagram below. The 1 TB
disk system is sized to hold a few months of data; files will be processed,
then off-loaded to tape and CD-R (later, DVD-R). For Mars Express, the RSR
volume from bistatic radar experiments will be largest. Although storing all
of the raw data on line would require a nominal 0.3 TB, the first two stages
of processing (PREPRSR and EQUALIZE) will generate 2.4 TB of output; so not
all data can be maintained on-line in raw, intermediate, and final forms for
the length of the mission. MGS, which will be using the new Sun Blade 2000 on
a non-interference basis, will also have storage requirements.
------ ------
| DELL | | DVD-R|
|----| PC |----|WRITER|
| ------ ------
|
------- ------ | -----
| 72 GB | | CD | | | 1 TB |
| DISK | |WRITER| | | DISK |
------- ------ | ------ --------
| | | | --| TAPE 0 |
------- | | ------- | --------
56 kbs | SUN |----- | | SUN |--- --------
to/fm -->|ULTRA 5| -------- |----| BLADE |------| TAPE 1 |
JPL | SOPC |---| ROUTER |---| | 2000 | --------
------- -------- | -------
| |
----------- | ---------
| HP 4000N | | | COLOR |
| B&W | |---| LASER |
| PRINTER | | | PRINTER |
----------- | ---------
| -------- --------
----------- ---- | | HINSON | | SIMPSON|
| MACINTOSH | | PC | | |COMPUTER| |COMPUTER|
----------- ---- | -------- --------
| | | | |
<---------------------------------------------------------->
Packard Building Net | other
| users
| Stanford Net
V
to/from MaRS
8 References
Fjeldbo, G., A.J. Kliore, and V.R. Eshleman, The neutral atmosphere of Venus
as studied with the Mariner V radio occultation experiments, Astronomical
Journal, 76, 123-140, 1971.
Simpson, R.A., and G.L. Tyler, Mars Global Surveyor bistatic radar probing of
the MPL/DS2 target area, Icarus, 152, 70-74, 2001.
Tyler, G.L., G. Balmino, D.P. Hinson, W.L. Sjogren, D.E. Smith, R. Woo, S.W.
Asmar, M.J. Connally, C.L. Hamilton, and R.A. Simpson, Radio science
investigations with Mars Observer, Journal of Geophysical Research, 97, 7759-
7779, 1992.
Yeh, K.C., and C.H. Liu, Theory of Ionospheric Waves, San Diego: Academic
Press, 464 pp., 1972.