Appendix C

Epsilon User’s Manual

Appendix C
E-SSOD Interface

This document defines the technical interface requirements for a CubeSat to be released from theEpsilon LV using the Epsilon Small Satellite Orbital Deployer (E-SSOD).

CubeSat
1U
OR
2U
OR

Cover for satellite
access window
Satellite lock door

3U
OR
1U

1U

OR
Pin Puller

2U

CubeSat Deployer
CubeSat放出装置(E-SSOD)(E-SSOD)

1U

OR
1U

2U

OR
1U

1U

C-1

1U

Appendix C

Epsilon User’s Manual

C1. Details of Mounting Position
The definitions of the coordinate systems are shown in Figure C1-1.

Xsc

Rocket Body Axis
XB
XES

Zsc

ZES
Ysc

CubeSatCoordinate System (Typical)

YES
E-SSOD
Coordinate System(Origin is Geometric Center)

180°
ZB

Zsc
Direction of theDeployment

XB

90°
YB
Ysc

Xsc

（ 38ZES0）

E-SSOD#1

270°

XES

YES

（ 60E-SSOD#20）

YES
XES

ZES

64°

304°

(90°)

Zsc
0°Directionof the
Deployment

Micro-satellite×3

CubeSat Deployer(E-SSOD)×2

Xsc(BOTTOM VIEW)（11YscXsc27）

Multi-satellites
Mount Structure

Ysc（2Small-Satellite

3.5）

The Door of the
CubeSat Deployer（E-SSOD)* Sizes and positions of CubeSats are examples.

DamperFigure C1-1 Coordinate System Definition

C-2

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C2. CubeSat Envelope
PL usable volume is defined in Section 4.1.1.
The usable volume of a CubeSat shall meet the requirements in Figure C2-1.
When stored in an E-SSOD, a CubeSat shall hold its deployable components inside its usable
volume all by itself and shall not use any structure of the E-SSOD, such as the rail guides and walls,for any purpose.
If there is any possibility that deployable components might be released and then contact the insidewalls of the E-SSOD, the possible contact surfaces of such deployable components shall have thethickness of 1 mm or more.

Commonfor four positions
The
same dimensions
for all the four corners
6.5

0.5

A

Rail

0.5

6.5
8.5

8.5

+Zsc
Maximum
Allowableusable
Dynamic
volumeEnvelope(See Note3))

See Note2)

0.5

A

Cross Section
A-A【Note】
1)
Unit：mm2)
componentsshall
shallbebestoredrecessed
fromthe –Zscrail ends.
2)
Any component
withinthetherailedge
end ofsurfaceline.
3)
All externalcomponents
shallwithin
be within
the dynamicenvelope.
Anyprotrusion
shall be held
the maximum
usablevolume.

Figure C2-1 Allowable Usable Volume

C-3

CubeSatmainSC structurestructure

Appendix C

Epsilon User’s Manual

C3. Mechanical Interface
C3.1 Exterior Dimension Requirements
Allowable sizes of and dimensional requirements for CubeSats are shown in Table C3-1 and Figure
C3-1.
Table C3-1 Allowable Sizes of CubeSats
Exterior Dimensions of PL main structure (including rails)
Xsc

Ysc

1U
CubeSat113.5 ± 0.1 mm

2U

100 ± 0.1 mm

100 ± 0.1 mm3U

0.2

BA

(Common tolerance zone
In 2 places)

0.2

B

0.2

A

(Common tolerance zone
In 2 places)

8.5min8.5min(2 places)

100±0.1

4 – at least R1

See Note 3)+Ysc

0.2square

B(Common tolerance zone
In 2 places)【Note】
1)
Unit：mm2)
All value shall be met after the surface coating
3)
Main structures of a SC in±Xsc、±Ysc shallnot exceed the edge of the rails
4)
Bold portion （）shall be rounded off
in atleast R1.(Also applicable for -Zsc plane)
5)
Arrangement type of the separation switches
and separation springs is shown in FigureC3-3.

C+Xsc

A

⊥

at least 8.5 mm

227.0 ± 0.1 mm
340.5 ± 0.3 mm⊥⊥

Rail Dimensions

Zsc

100±0.1(2 places)

Ha*1

Hb*21U113.5±0.1

111.5±0.1

2U

227±0.1

225±0.1

3U

340.5±0.3⊥ 0.2 B A
(Common tolerance zone
In 2 places)

N/A(*1)Rails
for separation
Springsprings
RailsNOTWITHOUT
separation(*2)Rails
Separation
Springsprings
RailsforWITH
separation

Ha （Diagonal 2 places）

Hb （Diagonal 2 places）
7min(Surface of the rail)
1.6μm

7min

(Surface of the rail)
1.6μm(Surface of the rail)
1.6μm

6.5min

7min

Separation Spring

CubeSatmain structure
衛星主構体

CubeSatmain structure
衛星主構体

CubeSat mainstructure
衛星主構体

+Zsc

+Zsc

+Zsc
Rails

Rails

Rails
+Ysc

+Ysc

+Ysc

Separation Spring
6.5minHa （4 places）

B

0.2(Common tolerance zone In 4 places)

Arrow View C(Arrangement of separation switches
and separation springs:
Type1 & 4)

Ha （Diagonal 2 places）

Hb （Diagonal 2 places）

BB

0.2(Common tolerance zone In 4 places)

Arrow View C(Arrangement of separation switches
and separation springs:
Type2)

Figure C3-1 Dimentional Requierments for CubeSats
C-40.2(Common tolerance zone In 4 places)

Arrow View C(Arrangement of separation switches
and separation springs:
Type3)

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Epsilon User’s Manual

C3.2 Requirements for CubeSat Rails(1) A CubeSat shall have four rails on the edges parallel to the Zsc-axis so that it can slide out along
the rail guides of an E-SSOD.
(2) The dimensional requirements are defined in Figure C3-1.
(3) Each rail shall have a square cross-section of 8.5 mm or more.
(4) Each rail shall have a surface roughness of Ra 1.6 µm or less.
(5) Outside edges of a rail shall be rounded off to a radius of at least 1 mm.
(6) Both rail ends shall have a minimum surface area of 6.5 mm x 6.5 mm.
(7) Outside surfaces along a rail shall have 75% or more contact area with a rail guide. The remaining
25% or less may have recessed areas from the rail guide. (This means that at least 85.1 mm of arail shall have the contact area for a 1U CubeSat, at least 170.3 mm for a 2U CubeSat and at least
255.4 mm for a 3U CubeSat.)Any rail, if devided, shall have its end edges rounded off to a radius of at least 1 mm. The common
tolerance zones of such rail surfaces shall satisfy the requirements in both perpendicularity andparallelism specified in Figure C3-1.
Any CubeSat need to be designed to have sufficient structural strength in consideration ofcompressive load to its body generated at the rail ends.
(8) All surfaces of rails contacting E-SSOD’s rail guides and those of rail ends, or standoffs,
contacting adjacent CubeSat standoffs, shall be hard-anodized after machining process. The
coating thickness shall be 10 μm or more in accordance with MIL-A-8625, Type 3.

C-5

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C3.3 Stracture Strength
For CubeSats to be stabilized during launch, the gap between the backplate and the back panel of theE-SSOD needs to be adjusted by 4 bolts (see Figure C3-2).
Therefore, each rail shall have a sufficient structural strength in consideration of the maximum preloadof 27.9 N applied to four rails in total by the main spring of E-SSOD, and the acceleration to the total
mass* of other ridesharing CubeSats in the same E-SSOD and the back plate weighing 0.25 kg (seeFigure C3-2).
* For a 1U CubeSat: 1.5 kg (other CubeSat mass) x 2
For a 2U CubeSat: 1.5 kg (other CubeSat mass) x 1
For a 3U CubeSat: 1.5 kg (other CubeSat mass) x 0
The load from the main spring, much smaller than the random vibration load, does not need to be
simulated in the vibration test and impact test of PL.

Back Plate

Clearance Adjustment

Double NutBack Panel
Adjust Bolt
Adjusting
Bolt
Main Spring

Figure C3-2 Back Plate and Adjusting Bolts of E-SSOD

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C3.4 Separation Spring

When a CubeSat is stored with others in a single E-SSOD, such CubeSat is required to have spring
plungers (P/N：251D939002-1) as shown in Figure C3-3 as separation springs to keep enough distanceduring release from the E-SSOD for collision avoidance; however, a 1U CubeSat of Type 4 as shown inFigure C3-4 and a 3U CubeSat, which is stored alone, does not need any spring plunger. A pair of spring
plungers shall be diagonally installed on standoffs, rail ends of a CubeSat, as shown in Figure C3-4.
Figure C3-3 shows the appearance and dimensions of the spring plunger.
Figure C3-4 shows the mounting positions for the spring plunges, whose installation is compulsory, andthe allowable positions for the deployment switches (separation switches), whose installation is optional.
Figure C3-5 shows the detailed mounting position of a separation spring (spring plunger)/separation
switch (deployment switch) on a standoff.
The flange of a spring plunger shall be firmly attached to the standoff surface as shown in Figure C3-6.

C-7

Appendix C

Epsilon User’s Manual(M5×0.8)(φ7)(2±0.05)(18MAX)
Unit：mm

About 2g par piece
Figure C3-3 Spring Plunger

C-8

Appendix C

Epsilon User’s Manual(1) A single
CubeSatin an E-SSOD(1)SingleSC
installsstoredin E-SSOD
PLXsc

Zsc

Type１３U

Ysc

Type１２U

Allowable positions for
Allowablerail edges that
deployment switches
havea deployment switch(optional)

Type１

PositionsspringRailedgesforthat
must haveplungers (compulsory)a separation spring

1U(2) Two CubeSats
in an E-SSOD(２)TwoSCs installstoredin E-SSOD
Type２Type３２U1U

Type２Type３1U２U

Type２Type３1U

1U(3) Three 1Uin an E-SSOD(３)Three
SCsCubeSats
install instored
E-SSOD
Type２
Type４1U

1U

Type３1U

Figure C3-4 Positions of Spring Plungers and Deployment Switches

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M5×0.8, Thread depth 19 Min

φ0.3

PL

4.25

8.5 Min

Body

4.25

Unit: mm
8.5 MinFigure C3-5 Detailed Mounting Position of Spring Plunger/Deployment Switch on Standoff(113.5 mm(1U))(227.0 mm(2U))
Hb(2 mm)
Separation Spring

0CubeSat RailStandoff

Flange of Spring Plunger※Refer to Figure C3-1 for Hb

Figure C3-6 Flange of Spring Plunger Firmly Attached to Standoff Surface

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C3.5. Separation switch(1) A CubeSat shall have deployment switches (separation switches) on its standoffs as shown in
Figure C3-4 to prevent activation in an E-SSOD. For the number of deployment switches to beinstalled, refer to Section C4.1. The allowable mounting positions are shown in Figure C3-4 andthe Detailed mounting position is shown in Figure C3-5.
(2) CubeSats need to remain inactive while any one of the deployment switches is kept depressed toa maximum distance of 0.75 mm from the standoff surface as shown in Figure C3-7.
(3) Battery charging, if needed, shall be conducted with all deployment switches being depressed.
(4) The stroke of a deployment switch shall be 2.0 mm or less from the standoff surface as shown inFigure C3-7.
(5) The force generated by each deployment switch shall be no greater than 3 N.
Depressed
0.75 mm max

Deployment Switch

2.0 mm max

Standoff Surface
StrokeFigure C3-7 Maximum Distance and Stroke of Deployment Switch

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C3.6. Access Window(1) A CubeSat installed in an E-SSOD can be only accessible through the +XES (=+Xsc) axis side asshown in Figure C3-8.
(2) Any device needs to be accessed after the installation shall be located in the area near accesswindows.
(3) Access through a PLF is not available.
MLIXESZES

YESAccess Windows（86.5）（27）（86.5）

AccessWindowAccessWindow

AccessWindow（27）（76）（86.5）（12）（340.5）（27）

3U CubeSat（27）（86.5）（27）（76）（86.5）

AccessWindow

AccessWindow

（12）

（227）

2U CubeSat（113.5）

AccessWindow

Xsc（12）

（27）

Zsc

Ysc

（76）

（86.5）【Note】
1) Unit：mm2) All dimensions are nominal value(without tolerance).

1U CubeSat

Figure C3-8 Normal Positions of Access Windows

C-12

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C4. Electrical Interface
C4.1. Deployment Switch and Software
A CubeSat shall have at least three inhibits, deployment switches and RBF pins (Remove beforeFlight Pins), to prevent unintentional activation in an E-SSOD by on-board batteries or solar cells.
Typical circuits are shown in Figure C4-1.
Refer to Chapter C3 for the mechanical interface of the deployment switch.
CubeSats need to remain inactive while any one of the deployment switches is depressed.
In addition, if all development switches are released but one of them is pressed again within 200 s, its
timer shall be reset so that the CubeSat can remain inactive. This is to prevent inadvertent activation
while CubeSats are being installed in an E-SSOD.

PBFpinDeployment SW1

Solar Cell

BatteryLoad

Deployment SW1

Solar Cell

Deployment SW2

Deployment SW2

BatteryLoad

Deployment SW3

RBF：Remove before flight
ex. 1

ex. 2

Figure C4-1 Typical circuits with Deployment switches and PBF pins

C4.2. Bonding
A CubeSat shall have a bonding interface on the side of access windows (Figure C3-8) in case accessis required after the installation in an E-SSOD.

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C5. Tools for CubeSat Verification Test
C5.1. Vibration Test Case
A vibration test case simulating an E-SSOD as shown in Figure C5-1 is used for the vibration test of aCubeSat. When multiple CubeSats are mounted in a single E-SSOD, such CubeSats arerecommended to carry out the test using the mass dummy attached to the vibration test case.
Part NumberName

Note

113C122012-1

VIB TEST CASE 3U

For 3U

113C122012-2

VIB TEST CASE 2U

For 2U

113C122012-3

VIB TEST CASE 1U

For 1U

Figure C5-1 Vibration Test Case

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C5.2. Fit-check Case
A fit-check case shown in Figure C5-2 is used for fit-check between a CubeSat and an E-SSOD. Itsinternal dimensions are 100.2 ± 0.1 mm in height and width while those of the E-SSOD are 100.5 ±0.2 mm.
Part Number

Name

Note

113C122011-1

FITCHECK CASE

For All Sizes (common)With Spring
Without back plate
Shapes of the access windows are the same as Flight model
Without doors

Figure C5-2 Fit Check Case

C-15