Kommunikation i rymden

Mats HolmströmInstitutet för rymdfysik (IRF)

SUNET TREFpunktKiruna

30 mars 2004

Översikt

● ASPERA-3 på Mars Express– Vetenskapliga mål och bakgrund

– Nuläge

● Mars Express dataflöden

– Fysiskt

– Format

● Framgångar och problem

Solar System Physics: Scientific Goals

Comparative research on the evolution and dynamics of the solar systemobjects (planets, asteroids, comets, meteoroids) and their interactionwith the solar wind.

• How does the interplanetary medium affect and shape the bodies in theinner solar system?

• What plasma physical processes determine the structure of the interactionregions?

• How do the solar system dust population evolve and interact with planetarybodies?

1

Instrument Development and Construction

The detectors measure characteristic properties such as energy, mass and/ordistribution of the particles (electrons, ions or energetic neutral atoms (ENAs))

• Nozomi (PI). ISAS Mars orbiter. IMI: Ion detector.

• Rosetta (PI). ESA comet orbiter. ICA: Ion detector.

• Mars Express (PI). ESA Mars orbiter.ASPERA-3: ENA, electron and ion detectors.

• Venus Express (PI). ASPERA-4: ENA and ion detectors.

• SMART-1 (CoI). ESA Moon orbiter. D-CIXS: X-ray imager.

Future: Bepi-Colombo (ESA Mercury orbiter), Planet-C (ISAS Venus orbiter).

3

2003-01-22

The Solar Wind

[Parker, 1963]

A collisionless plasma

2

2003-01-22

Magnetized Planets

[Kivelson & Russell, 1995]

Mercury, Earth, Jupiter, Saturn, Uranus, Neptune

4

2003-01-22

Non-Magnetized Planets

[Luhmann, 1986]

Venus, Mars

5

OH +

HO+

ENA Production by Charge-Exchange

ASPERA-3

On ESA’s Mars Express missionLaunch June 2003 on Russian Soyuz/Fregat

Arrives in December 2003

9

ASPERA-3 Delivered June 2002

7

Neutral Particle Imager (NPI)

Neutral Particle Detector (NPD)

Three-dimensional view of the NPD principal components

Cut-away view of the NPD sensor

July 3, 3 Million Kilometers

July 3, 8 Million Kilometers

Rymden - En tuff miljö

● Uppskjutning● Temperatur● Strålning (Single Event Effects)

Planeternas positioner...

Geometri● Fri sikt. 5-10 grader över horisonten.

● Avstånd

– Bandbredden avtar som 1/d2

– Latency: Ljustiden (OWLT)

● Riktning (tre-axel stabiliserad)

– Markstation: Banbestämmning (centimetrar)

– Satellit● Bestämmning: Gyron. Star trackers. Sun sensors● Ändring: Reaktion wheels. Thrusters

Markstationer

ESA (NNO), NASA (DSN)

Satellit

1.6 m HGA (0.4 m LGA) X-band (7.1 GHZ) till Jorden

S-band (2.1 GHZ) från Jorden

Avståndet Mars-Jorden

1/d2

Bandbreddkbps

Händelser idag

PERICENTRE_PASSAGE_0254_/_SSP_(155.68,-43.34)_/_SZA_050 L34T 303 P 04-090T09:40:17.000Z 0 CAN_LOS_10 KMAS 1013 P 04-090T09:50:57.000Z 0 800_KM_ASCEND KMAS 1014 P 04-090T09:55:50.000Z 0 1200_KM_ASCEND L34H 303 P 04-090T10:04:11.000Z 0 CAN_LOS_06 KMAS 1015 P 04-090T10:04:19.000Z 0 2000_KM_ASCEND KMAS 1016 P 04-090T10:24:53.000Z 0 4000_KM_ASCEND L74T 303 P 04-090T12:06:01.000Z 0 NNO_LOS_10 L74H 303 P 04-090T12:54:07.000Z 0 NNO_LOS_01 A75H 303 P 04-090T13:15:37.000Z 43164 KOU_AOS_02 MAPO 255 P 04-090T13:25:10.000Z 0 APOCENTRE_PASSAGE_0255 A75T 303 P 04-090T13:48:06.000Z 39005 KOU_AOS_10 MO2S 6 P 04-090T15:16:27.000Z 2032 OCC_MARS_200KM_START_/_RA_063.81_/_DE_022.41_/_OMP_(331.04,014.80)_/_SZA_113 MOCS 2 P 04-090T15:28:00.000Z 626 OCC_MARS_START_/_RA_063.82_/_DE_022.41_/_OMP_(325.94,-00.10)_/_SZA_118 PENS 154 P 04-090T15:28:34.000Z 3852 MAR_PENUMBRA_START UMBS 151 P 04-090T15:29:23.000Z 3772 MAR_UMBRA_START MOCE 2 P 04-090T15:38:26.000Z 0 OCC_MARS_END_/_RA_063.82_/_DE_022.41_/_OMP_(321.21,-14.32)_/_SZA_121 MO2E 6 P 04-090T15:50:19.000Z 0 OCC_MARS_200KM_END_/_RA_063.83_/_DE_022.41_/_OMP_(315.61,-29.62)_/_SZA_121 KMDS 1017 P 04-090T16:25:16.000Z 5661 4000_KM_DESCEND UMBE 151 P 04-090T16:32:15.000Z 0 MAR_UMBRA_END PENE 154 P 04-090T16:32:46.000Z 0 MAR_PENUMBRA_END KMDS 1018 P 04-090T16:46:02.000Z 3181 2000_KM_DESCEND A24H 303 P 04-090T16:54:06.000Z 47424 GDS_AOS_06

Resursbehov

Sensor-Mode Bit rate [bps] IMA Mode 24 2400IMA Mode 26 600ELS Low 68ELS Normal 260ELS High 1029ELS Burst 4100NPI Normal, High, Burst 265NPD Low 424NPD Normal, High 1576NPD Burst 12328NPD Raw 34000

Power consumption: 16.8 W without scanner 23.4 W with scanner

Dataformat

● Till satelliten:

– Telecommands (TC)

● Från satelliten:

– Telemetri (Payload data, temperaturer, strömmar, ...)

● Datapaket

– CCSDS standard (ESA, NASA,...)

– Felkorrigerande kodning. Komprimering

● 100 Mbit databuss. 12 Gbit massminne

Dataflödet

Mars Express

ESOCDarmstadt

Markstation

IRFKiruna

Commanding

KommandofilerPOR_ 00085 04-086T14:57:34.000Z04-091T00:21:16.000Z 04-091T01:48:12.000Z 0079H1AASF01A2 SH2I UTC T P 000H3 H4 H5 S1 MPER 0000000256 -00:25:00 S204-086T14:57:34Z matsh@irf.seH1AASF03A1 SH2I UTC T P 010H3 H4 H5 S1 MPER 0000000256 -00:23:17 S204-086T14:57:34Z matsh@irf.sePVASD6501 E D ON PVASD6502 E D OFF PVASD6503 E D ON PVASD6504 E D OFF PVAS00026 R A D 0 PVAS01026 R A D 0 PVAS01126 R A D 0 PVAS01226 R A D 0 PVAS01326 R A D 0 PVAS01426 R A D 0

...

SIEMENSHRSC

SIEMENSOMEGA: Water on Mars

Note: Mars (and Venus) are planets lacking a strong intrinsic magnetic field (umbrella) => dehydration.

Solar wind scavenging of the martian atmospherePlanetary wind = Outflow of atmosphere and ionosphere

(cometary interaction)ASPERA will do global imaging and in-situmeasurements of:

Inflow — solar wind

Outflow — planetary wind

using:

Energetic neutral atom cameras and plasma (ion+electron)spectrometers

Solarwind

Planetary wind100 ton/day

ASPERA-3 — Preliminary results (IMA)

Planetary wind (O+)

QuickTime och enTIFF (okomprimerat)-dekomprimerare

krävs för att kunna se bilden.

Solar wind/sheath (H+, He++)

Planetary wind (O+)Solar wind

MEX orbit

Solar wind/sheath Tail/planetary windClosestapproach

Confirmation of the planetary wind - O+ and molecular ions