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RØMER

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Political Boundaries

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Industrial Boundaries

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Financial Boundaries

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Ansøgt beløb – detailed design fasen

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Totalt budget – RØMER

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Saml. Ørsted

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AAU budget

RØMER BUDGET - AUC - DRAFT15-08-2001 22:55Version 3.0

WORK PACKAGE NAME WP ID WP MGR LABOR LABOR LABOR TRAVEL PROC TOTAL Incl 20% ovhMonths Hours Kkr Kkr Kkr Kkr

ACS Detailed Design 3620 AUC 4,1 607 174 50 8 232Attitude Determination 3621 AUC 17,3 2553 733 10 36 779Attitude Control 3622 AUC 22,3 3300 948 15 60 1023ACS Algorithms 3620 43,7 6460 1856 75 104 2035 2442

ACS Ephemeris Models 3625 TEB 2,5 370 106 5 0 111ACS Property Estimators 3226 AUC 2,5 370 106 0 0 106ACS Test Environment 3670 TEB 8 1184 340 15 30 385ACS System Verification 3680 TEB 4,5 666 191 39 0 230ACS AUC System Support 3610 17,5 2590 744 59 30 833 1000

AUC TOTAL 61 9050 2600 134 134 2868 UNIVERSITY OVERHEAD 20% 574TOTAL 3441 3441

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AAU budget – 2

COST PROFILERØMER

jun-01 jul-01 aug-01 sep-01 okt-01 nov-01 dec-01 jan-02 feb-02 mar-02 apr-02 maj-02 jun-02 jul-02LABOR

PHD1 (from 01.08.01) 30 30 30 30 30 30 30 30 32 32 32 32FA1 (MMQ) 33 33 33 33 FA2 32 32 32 32 32 32 32 32 32 33 33 33FA3 32 33 33 33FA 30 40 40 40 30 30 30 30 30 30 20 20 20 20

LABOR TOTAL

TRAVEL 24 4 4 4 8 8 24 4 4 4 4 3 24 3PROCUREMENT 70 8 4 4 4 4 40

TOTAL W/O UNI OVH 157 85 139 143 100 104 116 100 96 100 119 120 181 120

UNI OVERHEAD (20%) 31 17 28 29 20 21 23 20 19 20 24 24 36 24TOTAL W UNI OVH 189 102 167 172 120 125 139 120 115 120 142 144 218 144ACC. TOTAL W. OVH. 189 291 458 630 750 875 1014 1134 1249 1368 1511 1655 1873 2017

1587

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AAU budget - 3

aug-02 sep-02 okt-02 nov-02 dec-02 jan-03 feb-03 mar-03 apr-03 maj-03 jun-03 jul-03 aug-03 sep-03 okt-03 nov-03 dec-03 jan-04 feb-04 mar-04 apr-04 maj-04 jun-04 jul-04

32 32 32 32 32 32 32 32 33 33 33 33 33 33 33 33 33 33 33 33 34 34 34 34 1150133383

33 33 33 33 33 33 33 36120 20 10 10 10 10 10 10 20 20 23 573

2600

3 3 3 3 134134

87 87 77 77 74 74 75 42 53 53 56 33 33 33 33 33 33 33 33 33 34 34 34 34 2868

17 17 15 15 15 15 15 8 11 11 11 7 7 7 7 7 7 7 7 7 7 7 7 7 574105 105 93 93 89 89 89 50 63 63 67 39 39 39 39 39 39 39 39 39 41 41 41 41 3441

2122 2227 2320 2412 2502 2591 2680 2730 2794 2857 2924 2963 3002 3042 3081 3120 3160 3199 3238 3278 3319 3359 3400 3441 3441

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Participants

- Science:- Institute of Physics and Astronomy, Aarhus University- Danish Space Research Institute, Copenhagen- Copenhagen University

- Technology:- Institute of Electronic Systems, Aalborg University- Ørsted.DTU, Technical University of Denmark, Lyngby

- Industry:- TERMA A/S, Lystrup- Alcatel Space Denmark, Ballerup- Copenhagen Optical Company, Copenhagen- Patria Finavitec, Tampere, Finland- Auspace, Canberra, Australia- Prime Optics, Eumundi, Australia

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Organization - Organization Chart

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Milestones

- April 1999 Kick-off of Feasibility Study of Rømer- May 2000 Funding for System Definition Phase approved- May 2000 Kick-off of System Definition Phase (SDP)- Oct. 2000 Mid-Term Review- Nov. 2000 Decision to eliminate the Ballerina PL and re-focus

mission- Nov. 2000 Decision to design Rømer as a single-string

mission- April 2001 System Definition Review- May 2001 Complete Report and Documentation for SDP- June 2001 Start of Detailed Design Phase- Dec. 2001 Preliminary Design Review- Dec. 2002 Satellite Critical Design Review- May 2003 Satellite Integration and Test Review- May 2004 Launch (tentatively)

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Rømer Overall Schedule

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Rømer Overall Schedule –2

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RØMER SCIENCE OBJECTIVES

Study the structure, evolution and internal dynamics of a sample of

stars showing stochastically excited, solar-like oscillations.

This will substantially extend the very successful helioseismic studies of the

solar interior.

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Corresponding Observations (SOHO)

- Note:- Extremely small amplitudes, of order parts per million (ppm).- Blue amplitude much larger than red amplitude. Hence also

signal in (blue)/(red) ratio, to be observed by MONS.- Background is entirely due to solar granulation.

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Main MONS Observational Requirements- Photometric precision. Need detection limit below 1 ppm.

- The instrumental noise must match, but be below, the intrinsic stellar granulation noise.

- Requirement on precision demands strong defocusing.- Temporal coverage. Each primary target must be observed

almost continuously for at least one month.- Sky coverage. Primary targets are distributed over the

whole sky.- Hence choose orbit giving access to entire sky during the

mission.- Mission duration. At least two years (baseline), to allow

study of sufficient number of stars.- Exclusion of variable neighbours. Include MONS Field

Monitor to detect and correct for faint variable stars within telescope field of view.

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RØMER Science Payload Characteristics

The primary science instruments include:

MONS Telescope having a 32 cm aperture, equipped with a high-precision photometric CCD detector for measuring oscillations of stellar intensity and color

MONS Field Monitor for examining the field of view of the MONS Telescope for faint variable stars

The secondary science instruments: Forward- and aft-looking Star Trackers of

the Attitude Control Subsystem, to be used for studying variable stars

The MONS Field Monitor

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Ground Segment Architecture

- One or more Ground Stations- A Control Center which shall have total control of

the mission and shall provide data processing, storage and display

- A Science Data Center which shall prepare the specified user data products and disseminate them to the involved research institutes and organizations

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Orbit Requirements

Maximize time outside the trapped proton radiation belts

Allow momentum unloading using only magnetorquers

The operational orbit shall be delivered by the upper stage of the launch vehicle.

Visibility from a ground station in Denmark

Frequent launch opportunities to the proposed orbit (1 per year)

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RØMER in Molniya Orbit

- Largest separation from Earth (Apogee): ~40000 km

- Smallest separation from Earth (Perigee): ~600 km

- Angle between orbit and Equator (Inclination): 63.4°

- Period: 11 hours 58 min. 02 sec. (= ½ siderial day, ideal)

- 10 hours of observations outside the radiation belts.

- A satellite in Molniya orbit is subjected to a large dose of radiation from high-energy protons and electrons trapped in the Earth’s radiation belts.

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SOYUZ/FREGAT Launcher

FREGAT with Cluster II Satellites

FREGAT Upper Stage

RØMER is foreseen to be launched with a Russian SOYUZ/FREGAT rocket in mid 2004 from Plesetsk Cosmodrome

The SOYUZ rocket has been launched more than 1650 times and its reliability exceeds 97%

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Launch Configuration

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Satellite Specification

- Configuration, Mass and Envelope, Orbit- Nominal sun facing diagonal [+X,-Y]- – Solar panels on [+X] and [-Y]- – Single payload, MONS- – Main telescope, FOV in [+Z]- – Field monitor, FOV in [+Z]- – Radiators on [-X] and/or [+Y]- – Communication antennas on the exterior of the

satellite, [±X], [±Y]- – Launch Vehicle I/F on [-Z]- – Mass: <120kg, Envelope: 600x600x710mm- – Orbit baseline: Molniya

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Structure, Mechanism and Thermal Requirements- Accommodation of payload and platform subsystems- Accommodation of various CCD radiators (cold faces)- Accommodation of solar panels (hot faces) assuring

optimal power input- Accommodation of battery assembly (with easy

access)- Accommodation of COM antennas assuring

coverage- Accommodation of the PAA- Platform and payload electronics shall be enclosed in

a common structure- Fundamental lateral/longitudinal frequency

requirements: >45Hz />90Hz

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CDH requirements

- The CDH on-board computer shall act as satellite brain

- Task requirements:- C&DH- ACS- Star Tracker handling- Parallel Star Tracker science if possible

- Packet Utilisation Standard- SW patching and dumping- Power safe mode- Command loss timer- HW/SW watchdogs

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Autonomous Control (requirements)

– MONS observation three axis control– Modes:

– Fine pointing (science observation)– Coarse pointing (target slew)– Momentum unloading– Safe mode (startup, sun acquisition)

– Sensors:– Primary: Star Tracker (2), Rate sensors (4)– Secondary: Sun sensors (steradian), Magnetometer

(3 axis)

– Actuators:– Reaction wheels (4)– Torquer coils (3)

– Fault detection and management (SW)

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Platform network structure

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Design Philosophy

- Model philosophy- EBB (subsystem level)- E(Q)M (subsystem level)- STM (subsystem and satellite level)- RF model (satellite level)- FM (subsystem level)- FS (subsystem level, optional)- Proto-flight satellite- Satellite simulator (EM setup)

- Cleanliness TBD- Satellite magnetic stray field <1Am2

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Structure

1.Solar panels 2.Star tracker 3.Radiator 4.S-band antenna 5.Sun sensors 6.Radiator for the MONS telescope 7.The MONS telescope 8.Field Monitor 9.Sunlight protecting lid (closed during launch)

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Key Specification

- Mass: 80 kg, 100kg incl. 25% Margin.- Size: 60 x 60 x 71cm in Launch

Configuration- S/C Power: 70 W avg.- Battery: 33V, 4.5Ah, Li-ion- Mission Life Time: 2 years

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Attitude Control Precision

- Attitude movements have a dramatic effect on photometric precision, due to small spatial variations in CCD sensitivity (pixel-to-pixel and sub-pixel).

- Need to design the instrument, telescope and platform carefully.

- Detailed computer simulations include:- effects of flat-field structure- ACS jitter and shape of telescope PSF (including off-axis

aberrations).- readout and photon noise.

- Results: photometric errors from ACS errors form a non-white noise source whose power spectrum has the same shape as the ACS errors themselves.

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Required ACS power spectrum

- Assumed flat at frequencies below 10 mHz (should be true if the control loop is operating correctly).

- Assume power spectrum falls off as frequency squared (i.e., as 1/f in amplitude), as seems likely. The spectrum can then level out at frequencies higher than 10 Hz.

- If ACS power spectrum shape is significantly different then further simulations will be needed to specify new requirements.

- Preliminary study by the Rømer ACS group shows feasibility of reaching 1.2 arcmin RMS

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Required ACS precision

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ACS Requirements What is the ACS Supposed to do?- Stabilise Satellite from tumbling situation (2 deg/

sec)- Stop the tumbling and,- Perform Sun Acquisition Maneuver

- Provide a three axis stabilised attitude for commanded attitudes- Orient to desired attitude and keep it fixed (coarse)

- Provide a stable platform for science observations- Requirements to attitude error spectrum

- Provide sufficient onboard autonomy to handle fault events related to ACS- Handle one fault to prevent loss of mission

- Environment:- Molniya Orbit

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ACS Requirements 95% confidence numbers:

Pointing Error:

- P/ Y: 2 arcmin

- R: 60 arcmin

RMS Stability Error:

- 1.2 arcmin

Slew Capacity

- 180 deg in 10 minutes

Sun Exclusion:

- 60 degrees

- max 30 seconds with

Sun <3 deg from MONS

boresight

Earth/ Moon Exclusion:

- 55 degrees

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Hardware Config and concept diagram

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Disturbance Environment

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Rømer Overall ACS Architecture

REACTIONWHEELS

WHEELDRIVERS

TACHOMETERS

REACTION WHEEL ASSEMBLY (RWA)

MOMENTUMMANAGEMENT

MAGNETICCONTROLLAWS

MAGNETICTORQUERS

TORQUERDRIVERS

MAGNETIC TORQUER ASSEMBLY (MTA)

CONTROLLAWS

CONTROL LAWS

Wheel momentumreference

PROPAGATOR -+

Rate and attitudereference

SENSORUPDATE LAWS

SUN SENSORASSEMBLY(SSA)

EPHEMERISMODELS

STAR TRACKERASSEMBLY(STA)

Model update fromground

RATE GYROASSEMBLY(RGA)

ATTITUDE ESTIMATOR

MAGNETOMETER(MAG)

SAFE MODEDETERMINATION

SAFE MODECONTROLLER

CTRL. TORQUEFEEDBACK(RWA+MTA)

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Attitude Estimator Concept DesignSingle axis analysis

- Optimal estimator update both the spacecraft attitude and the gyro drift rate. Kinematic gyro based prediction.

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Attitude Estimator Concept DesignSingle axis analysis - 2

- Attitude and attitude rate from dynamic model of the spacecraft’s angular motion. (uncertainty due to RWA etc.). Gyro data are observations.

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AD Structure

CONTROLLAWS

SENSORUPDATE LAWS

EPHEMERISMODELS

COVARIANCE /GYRO STATEPROPAGATION

DYNAMICSMODEL

CTRL. TORQUEFEEDBACK(RWA+MTA)

PROPAGATOR

STAR TRACKERASSEMBLY(STA)

UPDATE GAINCALCULATION,STA

FINE POINTINGUPDATE

COVARIANCEUPDATE

State vector

Noise properties

SUN SENSORASSEMBLY(SSA)

UPDATE GAINCALCULATION,STA

COARSE MODEUPDATE

COVARIANCEUPDATE

EPHEMERISMODELS

Noise properties

Covariance

Covariance

M AG N ETO M E TE R(M AG )

RATE GYROASSEMBLY(RGA)

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ACS concept diagram

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AD modes

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AC modes

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ACS Workpackage breakdown

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3620

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3621

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3622

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3624

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3625

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3640

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3650

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Development Schedule

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Development Philosophy

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