Reliability of University-Class Spacecraft: A Statistical Look

Reliability of University-Class Spacecraft:

A Statistical Look

Michael SwartwoutSaint Louis University

NASA Academy of Aerospace Quality Mini-Workshop

Cape Canaveral, FL22 March 2012

SwartwoutReliability of University-Class Spacecraft

“University-Class Satellite”• Working definition

– Self-contained device with independent communications, command & control

– Untrained personnel (i.e. students) have key roles in design, fabrication, integration and operations

– Training is at least as important as the rest of the mission

• Excluded (by definition)– Many, many satellites with strong university

participation (especially as science PI)– Most Amateur satellites

• Exclusion does not imply lack of educational value!


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Spacecraft On Rockets

The NumbersGrowth!• 10th: 1994 (13 years)• 50th: 2003 (9 years)• 100th: 2008 (5 years)• 150th: 2012 (4 years)Is “steady state” 8 or 15

(or 25?)


Mission Lifetime

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Not yet

> 3 yrs

1-3 yrs

0-1 yr

S/C Failure

Launch failure


What Breaks?

What Breaks?• Radiation: 1*• Launch interface: 1• Launch thermal: 1• ADCS: 2• Mechanism: 3• Communications:

5½• CPU lockup: 2• Power: 5½• DOA: 11*

What Doesn’t Break?• Structures• Thermal*• Commercial

Electronics in Radiation Environment*

32 of 120 orbited spacecraft “failed”

Perhaps we should worry more about system-level functional testing and less (?) about the space environment…

Lifetimereduction


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Independent

Flagship

It Helps to Be Somebody (but not as much, now)

Flagship School• Significant government

sponsorship• Often a leading space

education/technology program for that nation

Independent School• Self-funded or sponsored

(at school’s initiative)• On their own for launches


To Grossly Oversimplify• Flagship schools

– Build “real” missions that work (90% success)

– Use CubeSats as stepping-stones– Sustain programs around a larger (20-100

kg) bus– Move up the “value chain” and out of the

university class• Independent schools

– Build one satellite that might work (58%), then fly no more (75% of schools)

– Build CubeSats and, if sustained, it’s a series of E-class CubeSats


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Repeat Independents

Singleton Independents

Repeat Flags

Singleton Flags

Repeat Business: Encouraging Trends!

Flagship Schools• 29 schools built 67 spacecraft

(47%)• 8 schools built 46 spacecraft• 5 have graduatedIndependent Schools• 54 schools built 76 satellites

(53%)• 45 schools built 44 one-shot

missions(but 23 launched in 2010-2011!)

• 10 active, repeated-flight schools (up from 4 in 2009!)

• 1 has graduated


Beyond the Beep?

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Science

Technology Demo

Communications

No External Payload


Shortest-Ever Course on CubeSats• Twiggs (Stanford) and Puig-Suari

(Cal Poly) defined a standard for carrying 10 cm, 1 kg cubes into space

• [The real innovation was the P-POD]

• Timeline– 1999 concept definition– 2003 first flight– 2010 70th flight– 2012 NASA selects 33

CubeSats to fly (backlog of 59)


Here Come the CubeSats (and Friends)

85 CubeSats in 12 years79 in the “CubeSat Era” (2003-

now)30 Manifested for 2012

(or is it 50?)

2012


Not as International as You’d Think (yet)


CubeSat by Developer


Beepsat = No Mission (except beeping)


What happened?• Ten years of groundwork

– Infrastructure and capabilities built up through the University Nanosat Program (AFOSR/AFRL)

– Government/industry funding in CubeSat technologies (e.g., NRO/Colony)

• Strategic government investment in university CubeSats– National Science Foundation (2008)– ESA Vega (2008)– NASA ELaNa (2010)

• “Will this be on the final?”’– NSF, ESA, NASA required missions– Suddenly, universities can find missions!


Conclusions & Recommendations• University-class spacecraft are real, in

growing (ballooning) numbers– Thank you, NASA!– Thank you, AFRL!

• A 25% failure rate isn’t great (but it’s better than 50%)– Flagships get all the breaks– Independents, well, break

• Universities need help– External reviews– Emphasis on functional testing

Reliability of University-Class Spacecraft:

A Statistical Look

Michael SwartwoutSaint Louis University

NASA Academy of Aerospace Quality Mini-Workshop

Cape Canaveral, FL22 March 2012


It’s Not Just CubeSats! [Okay, it’s mostly CubeSats]

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Manifested >40 kg

Manifested 10-40 kg

Manifested < 10 kg

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Reliability of University-Class Spacecraft: A Statistical Look