Maintaining a Healthy CubeSat: Analysis of MinXSS FM-1 Data and - - PowerPoint PPT Presentation

Maintaining a Healthy CubeSat: Analysis of MinXSS FM-1 Data and Preparations for FM-2

Chloe Downs University of Virginia, Charlottesville, VA LASP, Boulder, CO Mentors: Tom Woods, James Mason

Questions I Will Answer

• What is MinXSS?
• How well is the first MinXSS performing in orbit?
• Is it within its required temperature ranges?
• Is it using too much power?
• How much data are we collecting from it?
• Is the second MinXSS ready for flight?

Photo credit: NASA

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What is MinXSS?

• Miniature X-Ray Solar Spectrometer CubeSat
• Goal is to better understand

flares/CMEs, the emission they produce, and their impact on the Earth’s upper atmosphere

• Two Flight Models: FM-1 deployed May

2016; FM-2 to be launched Dec 2016

Spectrum by Tom Woods

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X123 COMM CDH Batteries EPS

Image by James Mason

Solar Arrays ADCS Antenna SPS/XP

MinXSS Components

Motherboard: not visible, located along the back of the components

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MinXSS FM-1 Temperatures Within Their Operating Ranges

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Temperatures Vary with Orbit Beta Angle

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Hot and Cold Case Data: What Does it Look Like?

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MinXSS FM-1 Models and Data Show Good Agreement

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Hot and Cold Case Results: Everything Looks Good!

• Hot Case:
• All 6 components are within 10°C, 3 of those are within 5°C, and 2 of those

are within 3°C

• Largest difference: -9°C for the Batteries
• Cold Case:
• All 6 components are within 10°C, 4 of those are within 5°C, and 3 of those

are within 3°C

• Largest difference: -7.2°C for the EPS
• X123 is the the most critical component. It is within 5°C on the cold case and

within 3°C on the hot case - very good

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Solar Arrays: Better Than They Look

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MinXSS’s Basic Power Diagram

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Is MinXSS Power Positive?

• It is critical for a satellite mission that the power produced is more than the

power consumed. In other words, is the system power positive?

• Difference (%) = Generated Capacity- Consumed Capacity

Mode Consume med Capac acity ity Differe renc nce, e, β = 0° Differe renc nce, e, β = 73° Science 12.9 Whr 35% 58% Safe 8.4 Whr 57% 72% Phoenix 4.1 Whr 79% 86% Generated Capacity * 100

Yes!

• Generated capacity at β = 0˚ (60 minutes of sunlight) is 19.6 Whr; β = 73˚ (92

minutes of sunlight) is 30.0 Whr

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How Much Data Are We Getting from MinXSS?

• How many of the requested packets do we decode?
• We use a ground station on LASP’s roof and another run by Jim White in Parker, CO
• The antenna was fixed on 6/24

Image by James Mason

• 63.18 % data capture rate
• Lower than planned due to

unforeseen complications with antenna and overheating radio

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Data Capture Rate Has Been Good Throughout Mission

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I2C Bus Anomaly

• Most of the MinXSS voltage, current, and temperature monitors are read from

devices on a shared data bus called the I2C (Inter-Integrated Circuit). MinXSS has 14 I2C devices.

• If one of I2C devices stops working then it can hang (stop) the I2C data transfers.

This anomaly with the I2C bus has occurred 3 times so far, but it is not related to being in a radiation belt.

• MinXSS would broadcast 14 error messages every 3 seconds, making it extremely

difficult to communicate with the spacecraft (because the radio can’t talk and listen at the same time)

• The only way to clear the error is to do a power reset on the spacecraft

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Simple Fix for FM-2

• Solution for FM-2: addition
• f mechanical relay
• This solution has been

designed, built, and tested on FM-2

Images by Tom Woods

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Closing Remarks

• Temperature, power, and data capture rate all bode well for FM-1 and 2
• The power reset relay is working as expected; it will have more testing during

thermal vacuum cycle testing in August

• We have every reason to expect FM-1 and 2 will remain healthy for the duration
• f their missions

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Questions?

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This work was supported by the NSF REU grant 1157020 to the University

• f Colorado. Additional thanks all the members of the MinXSS project.