Small Satellite Conference – Utah State University

STPSat-3: The Benefits of a Multiple-

Build, Standard Payload Interface

Spacecraft Bus

August 5, 2014

Kenneth Reese DOD Space Test Program

SMC, Space Development and Test Directorate

Alex Martin The Aerospace Corporation

David Acton Ball Aerospace & Technologies Corp.

Distribution A: Approved for public release; distribution is unlimited.

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STP-SIV program and current status

The Space Test Program – Standard Interface Vehicle (STP-SIV)

program is sponsored by the DoD Space Test Program

STP is the primary provider of spaceflight for the DoD space science and

technology community

Provides spaceflight and on-orbit operations for DoD experiments as

prioritized by the Space Experiments Review Board (SERB)

SMC/SD awarded an Indefinite Delivery Indefinite Quantity (IDIQ)

contract to Ball Aerospace for rapid acquisition of satellites

Ball Aerospace is the prime contractor with end-to-end responsibility

STP-SIV #1 (STPSat-2) currently in extended on-orbit operations

Launched 19 Nov 2010 on a Minotaur IV from Kodiak, AK

Supporting three DoD payloads

STP-SIV #2 (STPSat-3) currently in normal operations

Launched 19 Nov 2013 on a Minotaur I from Wallops Island, VA

Payload manifest completely re-defined to six unique payloads (DoD and NASA) less than one year before Pre-Ship Review

Design is now available commercially from Ball as the BCP-100

spacecraft bus

A contracting model that enables rapid technology advancement

STPSat-2

STPSat-3

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The Standard Interface Vehicle –

Designed, analyzed, and tested for mission flexibility

Spacecraft Parameter STP-SIV Capability

Orbit altitude 400 – 850 km

Orbit inclination 0° – 98.8°

Launch mass ESPA: ≤ 180 kg

SV dimensions (cm) 60.9 x 71.1 x 96.5

SV lifetime No life-limiting consumables

Reliability Ps = 0.93 @ 1 year; 0.81 @ 3

years; 0.71 @ 5 years

Stabilization method 3-axis

Pointing modes Nadir, Solar, Inertial, Ground

Track, Safe

Attitude knowledge 0.02° 3σ

Attitude control 0.03° 3σ

Bus voltage 28 V ± 6 V

Comm frequency S-band: Secure SGLS via AFSCN

Command rate 2 Kbps uplink (via AFSCN)

Telemetry rate 2 Mbps downlink (via AFSCN)

Robust configuration designed for variety of LEO orbits

ESPA compatibility increases launch options

Lifetime only limited by component reliability

Flexible pointing options allow for expanded mission

ConOps

Ball-heritage precision pointing algorithms

High-margin lithium-ion battery

Robust ground interface

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STP-SIV defined standard interfaces

Mission Ops

Center (RSC)

AFSCN

Launch Vehicle

• Multi-Mission SOC Ground Support Architecture

(MMSOC-GSA)

• Operating multiple missions on same ground system

allows reuse of command and telemetry databases

• Operators familiar with spacecraft operations

Spacecraft bus

Payloads

SIV Space Vehicle • Designed to SIS-00502

• Defines SIV RF system

• Pre-approved frequencies for future DoD SIVs –

allows production of “on-the-shelf” bus for

responsive space application

• Payload interface

standardization maximizes

SMC/SD’s ability to

manifest SERB payloads

• Documented standard allows

payload manifest process to run in parallel with spacecraft integration

• Reduced risk and schedule at payload integration

• Designed for wide range of primary and secondary launch

options (Minotaur I, Minotaur IV, Pegasus, ESPA)

• Maximizes SMC/SD’s spaceflight opportunities

• Powered off once integrated on LV, reducing LV interfaces

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Standard interfaces for rapid payload accommodation

Open-source Payload Users’ Guide

allows payload development without

intensive interaction

with bus provider

(similar to a Launch

Vehicle users’ guide)

Accommodation

Parameter

SIV Payload Support

Capability (total for all payloads)

Number of payloads Four. More with minor harness modifications.

Payload mass ESPA: Up to 70 kg

Dedicated launch: 100 to 120 kg (depends on

LV)

Payload orbit-average

power

200 watts (best case orbit)

100 watts (worst case orbit)

Payload volume ESPA: 0.14 m3

Dedicated launch: >0.93 m3 (depends on LV)

Payload field of view Clear 3 steradian (2 str each in the nadir

and anti-velocity directions)

Payload data handling Up to 2 Mbps per payload

Payload data storage 15.6 Gbit

Payload digital

command and data

interface

RS-422 provides high rate payload data,

command, and bi-level discrete input/output

Payload analog data

interface

8 analog channels per payload for health and

status

Payload heat rejection 100 watts

Six payloads demonstrated on STPSat-3

Robust mounting, electrical, and data

interfaces accommodate a wide variety of

payloads

S/C simulator with payload

interface electronics and

software available to

payload providers for risk

reduction testing

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STPSat-3 – the ability to flexibly adapt to payload changes

Jan 2009 – Bus started prior to payload manifest

June 2010 – Four payloads manifested post-CDR

SASSA (primary), SWATS, iMESA, SSU

Nov 2010 – SASSA inrush issues led to power

interface change

May 2011 – Interface issues between SASSA and

SSU led to significant delay

Sept 2011 – SSU direct interface box (IDL) begun

as risk reduction

Dec 2011 – SASSA withdraws from the mission

(80% of payload volume and 60% of payload

mass)

SSU IDL interface becomes baseline

May 2012 – J-CORE and TCTE manifested as

SASSA replacements

May 2012 – DoM manifested for de-orbit capability

Payload

Interfaces

Power

Data – RS-422

Data – Spacewire

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STPSat-3 – the ability to flexibly adapt to payload changes

Jan 2009 – Bus started prior to payload manifest

June 2010 – Four payloads manifested post-CDR

SASSA (primary), SWATS, iMESA, SSU

Nov 2010 – SASSA inrush issues led to power

interface change

May 2011 – Interface issues between SASSA and

SSU led to significant delay

Sept 2011 – SSU direct interface box (IDL) begun

as risk reduction

Dec 2011 – SASSA withdraws from the mission

(80% of payload volume and 60% of payload

mass)

SSU IDL interface becomes baseline

May 2012 – J-CORE and TCTE manifested as

SASSA replacements

May 2012 – DoM manifested for de-orbit capability

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Efficient requirements verification with the standard bus

STP-SIV design based on Technical

Requirements Document (TRD) containing

167 requirements on the spacecraft bus

STPSat-2 verifications leveraged to

streamline the STPSat-3 effort

Full system heritage of the bus made this

possible

STPSat-3 verification effort could focus on

the Mission Unique Requirements Document

(MURD)

Final payload manifest resulted in seven

unique payload ICDs

Development of individual payload ICDs was

efficient, leveraging the similarity of the

interfaces and lessons learned from prior

efforts

Confidence in the bus heritage allowed focus

on verifying compatibility on the payload side

of the interface

Spacecraft Bus Requirements Payload Requirements

TRD 167 TRD ~

MURD 68 MURD ~

SSU PL ICD 27 SSU PL ICD 56

IDL PL ICD 47 IDL PL ICD 71

SWATS PL ICD 52 SWATS PL ICD 73

iMESA-R PL ICD 52 iMESA-R PL ICD 73

TCTE PL ICD 51 TCTE PL ICD 74

J-CORE PL ICD 56 J-CORE PL ICD 72

DoM/SoM PL ICD 25 DoM/SoM PL ICD 56

TOTAL: 545 TOTAL: 475

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Heritage from STPSat-2 allowed very early start to the

requirements verification process

Many verification artifacts for the heritage bus were available and approved early on

Staggered submittal of sell-off packages (SOP) stretched the verification effort over a

longer period of time, avoiding a rushed effort just prior to Pre-Ship Review

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Lower inherent risk through use of the standard bus

Risk management focused on

STPSat-3 unique risks, most of

which were mitigated and closed

(white rows) Most risks carried forward from STPSat-2

(blue rows) were easily accepted without

further mitigation effort

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… 2010 2011 2012 2013 2014 …

25

20

16

15

12

10

9

8

6

5

4

3

2

1

# of identified risks with indiciated score

Ris

k Sc

ore

At launch, the program enjoyed a medium

risk posture, not typical for STP missions

Focus on mission specific risks led to low overall risk

posture for a technology demonstration mission

With STPSat-2 operating successfully on-orbit, the second

build had an inherent lower risk posture at inception

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Flexibility for short term launch opportunities

STPSat-3 bus integration underway

well before launch opportunity

identified

Key design features allowed launch

flexibility and quick manifesting on the

ORS-3 Minotaur I mission:

Overdesigned to allow wide range of

orbits

Standard LV interface (Motorized

Lightband)

Designed and tested to worst-case

environments of multiple LVs

With refined procedures, lessons

learned, and expertise from STPSat-2,

launch processing went smoothly and

kept STPSat-3 off the critical path to

launch

STPSat-3 atop the

ORS-3 Integrated

Payload Stack

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Commissioning efficiency leveraged standard

procedures and veteran operations team

Bus commissioning completed very quickly (72 hours)

All initialization objectives met according to the nominal schedule

Success directly attributable to lessons learned and implemented from

previous mission (STPSat-2)

Fast bus commissioning allowed prompt payload initialization

J-CORE was even turned-on

during first orbit

TCTE initialized on Day 5,

allowing full instrument check-out

prior to critical cross-calibration

with the Total Irradiance Monitor on

NASA’s SORCE mission in mid-

December

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Investment in standardization paid off on STPSat-3

STPSat-3 bus cost 37% less than STPSat-2 bus

Ball projects next BCP-100 bus would save

additional 35% from STPSat-3 bus cost

Key factors in cost reduction are staff continuity

and investment in documentation and GSE reuse

Reuse also results in significant schedule

reduction and responsiveness to external

stakeholders such as launch provider

Heritage reviews replace design reviews

Cost benefits extend to ground segment as well

Reuse of documentation (On-Orbit Handbook,

Space Vehicle Handbook, Space/Ground ICD)

Command/telemetry database virtually

unchanged

Carryover of telemetry screens and commanding

interface

Streamlined launch readiness/rehearsals

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The future of the Standard Interface Vehicle

Next BCP-100 flight: NASA’s Green

Propellant Infusion Mission (GPIM)

Will demonstrate Air Force-

developed high performance

“green” propellant alternative to

traditional hydrazine

Will also fly three SERB secondary

payloads

Launch expected Q2 2016

Applying lessons of STP-SIV to

even smaller standard vehicle

concepts

E.g. Ball’s BCP-50 sized for two

SERB-like payloads

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