Nominal Aquarius Operations imposes requirement on Aquarius Data Processing System

1
Aquarius Support Example L0 - L1a
Nominal Aquarius Operations imposes requirement
on Aquarius Data Processing System

• 3 to 5 passes per 24 hours over the Cordoba
  ground station, each pass used for stored
  Aquarius science data and Service Platform
  telemetry.
• 2 passes per 24 hours over Matera ground station,
  each pass used for stored Aquarius science data
  and Service Platform telemetry that are
  transferred to Cordoba after pass.
• 6 - 11 minutes per pass
• Downlink full science memory of 110 MB at 4Mbps
  (just under 4 minutes), repeating throughout pass
• SAC-D Housekeeping telemetry file (format and
  content not yet fully defined) will be available
  for each downlink which covers the period of
  Aquarius science data collection.

2
Aquarius Support Example L0 - L1a

• Each downlink and SAC-D telemetry file will be
  pulled from the CONAE data server to the Aquarius
  Preprocessors (one primary, one spare) which will
  have the storage capacity to hold the ENTIRE
  mission source data (less than 3 terabytes).
• Since open Internet will be used to transfer data
  from Cordoba to NASA/GSFC, it is advantageous to
  reduce the data volume transferred.
• Current scenario would require over 1 gigabyte of
  data per day.
• Proposed solution reduces this by a factor of 2
  to 3.
• The subsequent preprocessed Level-0 files (one
  per downlink) are copied to NASA/GSFC for
  subsequent processing.

3
Aquarius Level-1A Generation

• AQL0gen convert Aquarius frames from native
  frame format to Level-0 and remove duplicate data
  from multiple transmissions during a single
  downlink contact.
• Read in L0 records from downlink file.
• Determine duplicate records.
• Determine "best" record within duplicates.
• Sort unique records by time
• Output to L0 file.

4
Aquarius Level-1A Generation

• AQL1Agen write each full orbit (with 10 minute
  padding on either end) represented within the
  downlink to a time-ordered Level-1A file in HDF
  format. Extract complete set of coincident SAC-D
  spacecraft telemetry data and append to file.
• 1) Find first relevant record in ephemeris file
• 2) Open first output L1A file.
• 3) Determine next open file time. (10 min
  before next orbit beginning)
• 4) Determine next close file time. (10 min after
  next orbit beginning)
• 5) Read L0 record
• 6) Determine whether to open next file.
• 7) Unpack L0 record into L1A record and write to
  open files.
• 8) Determine whether to close open file.
• 9) Determine next open file time. (10 min
  before next orbit beginning)
• 10) Determine next close file time. (10 min
  after next orbit beginning)
• 11) Return to (5) if more records else close
  last file and exit program.

5
Aquarius Level-1A Generation

• AQL1Amerge combine common data from 2 or more
  downlinks to a single Level-1A file
• combine with any Level-1A from previous downlink
  for this orbit
• quality assessment logic same as L1Agen
• output format same as L1Agen

6
Aquarius Data Content at time of first downlink
Aquarius memory content at start of downlink
partial orbit
complete orbits
4
5
6
7
8
9
1
2
3
sample time
tn
Downlink File Content (assume 11 min contact)
data copy 2
partial data copy 3
data copy 1
AOS
LOS
NOTE use of Aquarius memory and possible
overwriting of contents during downlink being
investigated
7
Aquarius Data Contentat time of second downlink
(98 min later)

• No re-initialization after downlink, so data
  wrapped in time

partial orbits
partial orbit
complete orbits
4
5
6
7
8
9
9
2
3
10
sample time
tearliest data
tn
tn
8
Aquarius Data Content Consecutive Downlinks

• Expect 1-2 contacts with CONAE on consecutive
  orbits, twice per day
• Data from particular orbits will be repeated in
  multiple downlinks, with redundant copies per
  downlink

time
0
4
5
6
7
8
1
2
3
9
one orbit between contacts
98m
4
5
6
7
8
9
9
2
3
10
half-day between contacts
12h
13
14
15
16
8
9
11
12
10
9
9
Redundancy in Data CopiesSingle Days Data -
Quality Varies
downlink 1
4
5
6
7
8
1
2
3
9
4
5
6
7
8
1
2
3
9
4
5
6
7
8
1
2
3
downlink 2
4
5
6
7
8
9
9
2
3
10
4
5
6
7
9
2
3
10
downlink 3
13
14
15
16
8
9
11
12
10
9
13
14
15
16
8
9
11
12
10
9
9
10
Corrupt data
10
Level-0 Processing - Done at Cordoba
Original downlink file
4
5
6
7
8
1
2
3
9
4
5
6
7
8
1
2
3
9
4
5
6
7
8
1
2
3
L0Gen
Improved Level-0 downlink file
4
5
6
7
8
9
1
2
3
Corrupt data or dropped packet (1.44 second
increments)
11
Level-1A Processing - Done at NASA/GSFC
Improved Level-0 downlink file
4
5
6
7
8
9
1
2
3
L1Agen
SAC-D Telemetry
AQ2009131017.L1A
AQ2009145017.L1A
Level-1A orbit 1
Level-1A Orbit 9
Level-1A orbit 2
Level-1A orbit 7
SAC-D TLM
SAC-D TLM
SAC-D TLM
SAC-D TLM
12
Level-1A Merge ProcessingOrbit 9, Ascending Half
downlink 1
Level-1A Orbit 9
SAC-D TLM
downlink 2
merged
Level-1A Orbit 9
L1Amerge
Level-1A Orbit 9
SAC-D TLM
SAC-D TLM
Corrupt data