sentinel5 precursor solar array technical...

S5p S5P.SP.ASU.SC.00006Issue 01

of 12

Nov. 2011

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S5p S5P.SP.ASU.SC.00006

Issue 01 of 12

CONTENTS

2.1 Introduction ............................................................................................................................................ 5 2.2 Scope..................................................................................................................................................... 5 2.3 Guidelines .............................................................................................................................................. 5 3.1 Applicable documents............................................................................................................................ 5

5.2.1 Electrical Power............................................................................................................................... 5 6.1.1 Mass ................................................................................................................................................ 7 6.1.11 General design requirements and interchangeability.................................................................... 7

12 Annex 1 : Mechanical Interface Requirement ............................................................................................ 8 13.1 Normal mode ..................................................................................................................................... 10 13.3 Decontamination Mode ...................................................................................................................... 11


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2.1 Introduction

The specification defines the design, performance, interfaces and verification requirements for the Sentinel 5 Precursor Solar Array.

[5]

This document is based on the AS250 Solar Array specification [AD-11] and defines the modifications which shall be considered for Sentinel 5 Precursor.

[530]

2.2 Scope

The present specification only provides the differences from the AstroSAT250 Solar Array specification [AD-11]. Three cases are considered:

[8]

[531] when AstroSAT250 Solar Array requirements are applicable, they are not repeated within this specification.

[532] when a requirement or complete section of the AstroSAT250 specification are not applicable, they are declared as Not Applicable.

[533] when a requirement of the AstroSAT250 specification is modified (customised), they are identified by a specific S5p requirement number and associated to the original AstroSAT250 requirement number as explained below.

2.3 Guidelines

S5p-SA-11 /

The Doors Requirement Number is presented under the following format

SA_xxx/a,b/ for the generic specification and S5p-SA_yyy/a,b/ for mission specific specifications where:

xxx is a unique number assigned consecutively,

yyy is the requirement number from original requirement in the AS250 SA specification [AD11] (if any)

a,b are the intended verification methods

3.1 Applicable documents

[AD10] S5P.SP.ASU.SC.00033 Radiation Hardness Assurance Requirements for S5p Project [498]

[AD-11] DIV.SP.00057.T.ASTR AS250 Solar Array Requirements Specification [529]

[AD-12] ECSS-E-ST-20C Electrical and Electronic [544]

5.2.1 Electrical Power

S5p-SA-70 / A

Baseline Power Solar Array Option Power requirement

The Solar Array having a configuration of 19 series cells, 90 parallel strings shall provide at least 1470 W @ 34.2 V at Solar Array interface connector

This figure is considered during sunlit duration in the worst case conditions, computed according to following conditions:

Sun incidence perpendicular to solar cell plane

EOL

Summer solstice, 1321 W/m²

Temperature of 78.5C.

Including harness and blocking diodes voltage drop till interface connector: this voltage drop shall be lower than 1,6 volts.

Including power degradation factors as per SA-71


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considering radiation environment as per SA-211

S5p-SA-539 /

Option Power Solar Array Power requirement

The Solar Array having a configuration of 19 series cells, 78 parallel strings shall provide at least 1204 W @ 34.2 V at Solar Array interface connector

This figure is considered during sunlit duration in the worst case conditions, computed according to following conditions:

Sun incidence perpendicular to solar cell plane

EOL

Summer solstice, 1321 W/m²

Temperature of 78.5C.

Including harness and blocking diodes voltage drop till interface connector: this voltage drop shall be lower than 1,6 volts.

Including power degradation factors as per SA-71

considering radiation environment as per SA-211

S5p-SA-71 / A,R

Power degradation factors and associated computation method are give in Table 5.2-1 for EOL power and BOL maximum current and voltage.

[72] INPUT POWER @ EOL Maximum current @ BOL

Maximum voltage

(a) Current Cell mismatch 0,99 1 1

(b) Possibly better production 1 1,02 1 (c ) Calibration error 0,97 1,03 1,03 ( i ) Total RSS Calculation (a,b,c) 0,968 1,04 1,03 ( j ) Cover Glass gain/loss

(to be cancelled when SCA data set will be available)

0,986

1,01

NA

(d) UV degradation and micrometeorites ( total for EOL , 7 years with 0,25% per year)

0,982

1

1

(e) Random failure At least 1string upon total number of strings

0.987

1

NA

(f) Albedo coefficient ( on poles) 1 1.04 1 (g) Misalignment of the SA 2° misalignment =

0,9994 1 1

(h) Arithmetic total ( d,e,f,g) 0.968

1.04 1

(k) Global loss factor

(j + RSS(i,h) )

0.946

1.064 1,03

Table 5.2-1: Power degradation factors for 7 years mission

Power @ EOL computation in Table 5.2-1 corresponds to Summer Solstice and Maximum current @BOL to Winter Solstice

[391]


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6.1.1 Mass

6.1.1.1 Option power Array

S5p-SA-543 /

The SA total mass in flight configuration (including all margins as defined in [AD01] section 3.2.1.) shall be less than 32 kg, considering 3 complete DSAPs (as per section 4.1) and hold down and hinge interface brackets to Satellite structure.

This shall be verified by mass measurement on the fully assembled wings (accuracy measurement will be better than 0,1 kg for the whole SA)

Mass justification shall be provided according to [AD01] section 3.2.1.

Until final measurement, mass prediction with associated tolerances shall be provided by the Supplier through a mass budget which will be periodically updated.

6.1.1.2 Baseline power Option Array

S5p-SA-83 / T,A

The SA total mass in flight configuration (including all margins as defined in [AD01] section 3.2.1.) shall be less than 42 kg, considering 3 complete DSAPs (as per section 4.1) and hold down and hinge interface brackets to Satellite structure.

This shall be verified by mass measurement on the fully assembled wings (accuracy measurement will be better than 0,1 kg for the whole SA)

Mass justification shall be provided according to [AD01] section 3.2.1.

Until final measurement, mass prediction with associated tolerances shall be provided by the Supplier through a mass budget which will be periodically updated.

6.1.11 General design requirements and interchangeability

S5p-SA-537 / I,R

Mechanical interface requirements of section 12 [AD-09] are applicable to the DSAP with the following requirements of SA-527 and SA-528 applicable.

6.3.4.1 Power interface

S5p-SA-137 / A

Baseline Power Option Solar Array Power Requirement

The maximum total current at SA interface shall be lower than 45A Amp (that is 7.5A per SA section) even in case of failure (as coupling of an additional string on the section by multiple short circuits on substrate).

Computation shall be done in worst case conditions: short circuit mode, BOL, Winter solstice, 1423W/m², max temperature , pole albedo effect …. (see conditions @ BOL in Table 5.2-1)

S5p-SA-540 /

Option Power Solar Array Power Requirement

The maximum total current at SA interface shall be lower than 40A Amp (that is 6.7A per SA section) even in case of failure (as coupling of an additional string on the section by multiple short circuits on substrate).

Computation shall be done in worst case conditions: short circuit mode, BOL, Winter solstice, 1423W/m², max temperature , pole albedo effect …. (see conditions @ BOL in Table 5.2-1)

S5p-SA-138 / A

The maximum open voltage of each section must be lower than 100 volts.

Computation shall be done in worst case conditions for this parameter: BOL, minimum temperature …. (see conditions @ BOL in Table 5.2-1)


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8.1.3.1 Operational lifetime

S5p-SA-238 / R

The Solar Array shall be compatible with a life time of seven(7) years in orbit as specified in [AD01] GDI-137. Environmental conditions are described in Section 7.3.

S5p-SA-424 / A

Deleted.

8.1.3.2 Orbit characteristics

S5p-SA-240 / R

The Solar Array shall be designed for the following Sentinel-5 precursor orbit:

Semi-Major Axis (a): 7206.9 km

Eccentricity (e): 0.00115

Inclination (Sun-Synchronous) (i): 98.742°

Argument of Perigee (): 90°

Local Time at Ascending Node (Ω): 13:30

12 ANNEX 1 : MECHANICAL INTERFACE REQUIREMENT

S5p S5P.SP.ASU.SC.00006Issue 01

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Stowed and deployed (DT0375955 Issue 05) given in AD09 (reproduced below only for information, AD-09 refers.) [293]

[538]

Figure 12-1:Mechanical Interface Drawing


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S5p-SA-527 / I,R

Each solar array pannel much not exceed 435 mm from the centre of hold-down points 1 & 2 in the Z-sat axis.

S5p-SA-528 / I,R

The width of each panel must not exceed 1205 mm.

13.1 Normal mode

The satellite pointing in normal mode is shown in Figure 13.1-1. [374]

Satellite attitude during day:

sun pointing outside imaging period: SA normal to sun direction with -Z axis towards the sun and with -Y axis towards the Angular Momentum axis (ie normal to orbital plane).

Imaging period:

Geocentric +Z axis towards the earth and +X axis along the orbital linear speed with depointing of SA up to 50° worst case (20° average) with respect to geocentric

imaging period duration: 0 to 32 minutes per orbit between 80°N and 80°S latitudes

Satellite attitude during eclipse

Geocentric: +Z axis towards the earth and + X axis along the orbital linear speed [382]

Figure 13.1-1: Satellite pointing during normal mode


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13.3 Decontamination Mode

During periods when decontamination of the reflective radiator surfaces of the main instrument, the spacecraft points the solar array to the Sun throughout the sunlit part of the orbit, reverting to nadir pointing attitude in eclipse

[535]

[536]

Figure 13.3-1: Satellite pointing during decontamination mode


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DOCUMENT CHANGE DETAILS

ISSUE CHANGE AUTHORITY CLASS RELEVANT INFORMATION/INSTRUCTIONS 01 First Issue

DISTRIBUTION LIST

INTERNAL EXTERNAL A.G. Jones K. McMullan

M. Davidson B. Simpson

J. Banting

R. Gray A. Dyne

Configuration Management

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