CubeSats enjoy a up to a 39% industry average failure rate. From most common to least, CubeSat failure (21%), launch failure (12%), and not ejected and not specified are tied at 2% each.
https://www.hindawi.com/journals/ijae/2019/5063145/
Successful deployment made up 61% of the 848 CubeSat launches between 2005 and 2018. So the Fox line has met industry standards (3 of 5 deployed successfully).
The hardware, even if purchased to be space tolerant, is still assembled and ground based testing in a educational or not for profit environment is limited compared to the big commercial companies. It's the reason why Es'hail 2's amateur component was built commercially using AMSAT specifications.
There is also the issue that as secondary payload CubeSats have been developed to not use active means of deployment. Such as hoping their solar cells, and antennas release. Which is suspected to have caused many failures as has been pointed out.
Even so, SpaceX is seeing a 5% failure rate on their $2.5 million Starlink Satellites and even NASA's $4 billion Hubble had issues. Space can be unforgiving. And due to size and weight constraints of CubeSats, unlike larger commercial satellites, it's nearly impossible to build redundant systems to keep the satellite functional after any system failures.
The term acceptable failure rate in engineering comes to mind. And expecting perfection out of a CubeSat just isn't going to happen.
Dimitrios VA3DSZ
Having built four missions and launched two, I can say that the main challenge of cubesats is their really small power budget. The rest of the risks just multiply because of that. Very often, the time from insertion into the ppod to launch is more than six weeks. The batteries drain off, as the batteries drain off, the entire system is browned out. it is a miracle to put up back again. very often, the analog circuitry that would have charged the batteries through solar panels is replaced by software on OBC. But the OBC is unavailable, the analog state is undetermined. There is a colossal fight among schrodinger's cats inside the box. On the other hand, why does the AO-7 continue to work? because it has an all analog design that will turn on the transponder as soon as power is applied and the oscillators can oscillate. If they fail to boot up on one orbit, there is always another orbit to bet on. This is also compounded by the cubesat/IARU specification that insists the satellite should have a way to switch itself off under ground control. This means that unless the CPU decides to wake up the radio, it will remain silent. If the CPU has browned out, then bye, bye, bluebird! - f
On Sun, Jan 31, 2021 at 10:06 PM Dimitrios Simitas va3dsz@gmail.com wrote:
CubeSats enjoy a up to a 39% industry average failure rate. From most common to least, CubeSat failure (21%), launch failure (12%), and not ejected and not specified are tied at 2% each.
https://www.hindawi.com/journals/ijae/2019/5063145/
Successful deployment made up 61% of the 848 CubeSat launches between 2005 and 2018. So the Fox line has met industry standards (3 of 5 deployed successfully).
The hardware, even if purchased to be space tolerant, is still assembled and ground based testing in a educational or not for profit environment is limited compared to the big commercial companies. It's the reason why Es'hail 2's amateur component was built commercially using AMSAT specifications.
There is also the issue that as secondary payload CubeSats have been developed to not use active means of deployment. Such as hoping their solar cells, and antennas release. Which is suspected to have caused many failures as has been pointed out.
Even so, SpaceX is seeing a 5% failure rate on their $2.5 million Starlink Satellites and even NASA's $4 billion Hubble had issues. Space can be unforgiving. And due to size and weight constraints of CubeSats, unlike larger commercial satellites, it's nearly impossible to build redundant systems to keep the satellite functional after any system failures.
The term acceptable failure rate in engineering comes to mind. And expecting perfection out of a CubeSat just isn't going to happen.
Dimitrios VA3DSZ
Sent via AMSAT-BB(a)amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program!
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You would think that the design could contain a small analog charge controller that could act as a failsafe for the digital system. I understand that there is a size and weight limit to these little beasties but my yard lights have analog charge controllers that can fit on a US Quarter. I know that the very small size limits the current that they can handle, especially in a vacuum but who cares if it charges at the rate of a few mA and takes several hours or a day to get the batteries up to power so that the digital system wakes up and takes over.
Just an idea since I don’t have any experience building satellites but I have built several (about 50) small yard lamps that run from a lithium polymer battery. The little solar panels produce 6 volts at 50mA in full sunlight and, as I said, the charge controller is one surface mount five-pin chip, a couple of capacitors and a couple of resistors. I think it’s just a fancy voltage and current regulator that prevents overcharging. You can get them from Digikey for about 50 US cents of you buy one. If I remember right, it’s a MCP73831T-2ACI/OT chip. The chip can handle up to 500mA of charge current without a heat sink (in air) so I’m sure that it could handle 50mA in a vacuum. Is it RADHARD? I doubt it.
Kevin, WB5RUE
From: Ashhar Farhan [mailto:farhanbox@gmail.com] Sent: Sunday, January 31, 2021 12:59 PM To: Dimitrios Simitas va3dsz@gmail.com Cc: AMSAT BB amsat-bb@amsat.org Subject: [AMSAT-BB] Re: Cubesats
Having built four missions and launched two, I can say that the main challenge of cubesats is their really small power budget. The rest of the risks just multiply because of that.
Very often, the time from insertion into the ppod to launch is more than six weeks. The batteries drain off, as the batteries drain off, the entire system is browned out. it is a miracle to put up back again. very often, the analog circuitry that would have charged the batteries through solar panels is replaced by software on OBC. But the OBC is unavailable, the analog state is undetermined. There is a colossal fight among schrodinger's cats inside the box.
On the other hand, why does the AO-7 continue to work? because it has an all analog design that will turn on the transponder as soon as power is applied and the oscillators can oscillate. If they fail to boot up on one orbit, there is always another orbit to bet on.
This is also compounded by the cubesat/IARU specification that insists the satellite should have a way to switch itself off under ground control. This means that unless the CPU decides to wake up the radio, it will remain silent. If the CPU has browned out, then bye, bye, bluebird!
- f
On Sun, Jan 31, 2021 at 10:06 PM Dimitrios Simitas <va3dsz@gmail.com mailto:va3dsz@gmail.com > wrote:
CubeSats enjoy a up to a 39% industry average failure rate. From most common to least, CubeSat failure (21%), launch failure (12%), and not ejected and not specified are tied at 2% each.
https://www.hindawi.com/journals/ijae/2019/5063145/
Successful deployment made up 61% of the 848 CubeSat launches between 2005 and 2018. So the Fox line has met industry standards (3 of 5 deployed successfully).
The hardware, even if purchased to be space tolerant, is still assembled and ground based testing in a educational or not for profit environment is limited compared to the big commercial companies. It's the reason why Es'hail 2's amateur component was built commercially using AMSAT specifications.
There is also the issue that as secondary payload CubeSats have been developed to not use active means of deployment. Such as hoping their solar cells, and antennas release. Which is suspected to have caused many failures as has been pointed out.
Even so, SpaceX is seeing a 5% failure rate on their $2.5 million Starlink Satellites and even NASA's $4 billion Hubble had issues. Space can be unforgiving. And due to size and weight constraints of CubeSats, unlike larger commercial satellites, it's nearly impossible to build redundant systems to keep the satellite functional after any system failures.
The term acceptable failure rate in engineering comes to mind. And expecting perfection out of a CubeSat just isn't going to happen.
Dimitrios
VA3DSZ
-----------------------------------------------------------
Sent via AMSAT-BB(a)amsat.org http://amsat.org . AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program!
View archives of this mailing list at https://mailman.amsat.org/hyperkitty/list/amsat-bb@amsat.org To unsubscribe send an email to amsat-bb-leave(a)amsat.org http://amsat.org Manage all of your AMSAT-NA mailing list preferences at https://mailman.amsat.org
That is interesting and makes sense. A 1U CubeSat has about the same volume to dedicate to power as a typical laptop.
Having to keep a power reserve for 6 weeks on a secondary type battery without charging for 6 weeks is difficult. And the analogy fits as laptops do this as well.
One option might be to include a watchdog. A primary battery with an low power microcontroller to switch from the primary (and therefore shelf stable) to turn on secondary power along with the rest of the CubeSat. Once power is latched through a mechanical relay for the satellite, it could shut down and not drain power. Today there are space rated microcontrollers that drain as little as 0.4uA on standby, shut down 0.02uA on shutdown.
Dimitrios VA3DSZ
On Sun., Jan. 31, 2021, 13:59 Ashhar Farhan, farhanbox@gmail.com wrote:
Having built four missions and launched two, I can say that the main challenge of cubesats is their really small power budget. The rest of the risks just multiply because of that. Very often, the time from insertion into the ppod to launch is more than six weeks. The batteries drain off, as the batteries drain off, the entire system is browned out. it is a miracle to put up back again. very often, the analog circuitry that would have charged the batteries through solar panels is replaced by software on OBC. But the OBC is unavailable, the analog state is undetermined. There is a colossal fight among schrodinger's cats inside the box. On the other hand, why does the AO-7 continue to work? because it has an all analog design that will turn on the transponder as soon as power is applied and the oscillators can oscillate. If they fail to boot up on one orbit, there is always another orbit to bet on. This is also compounded by the cubesat/IARU specification that insists the satellite should have a way to switch itself off under ground control. This means that unless the CPU decides to wake up the radio, it will remain silent. If the CPU has browned out, then bye, bye, bluebird!
- f
On Sun, Jan 31, 2021 at 10:06 PM Dimitrios Simitas va3dsz@gmail.com wrote:
CubeSats enjoy a up to a 39% industry average failure rate. From most common to least, CubeSat failure (21%), launch failure (12%), and not ejected and not specified are tied at 2% each.
https://www.hindawi.com/journals/ijae/2019/5063145/
Successful deployment made up 61% of the 848 CubeSat launches between 2005 and 2018. So the Fox line has met industry standards (3 of 5 deployed successfully).
The hardware, even if purchased to be space tolerant, is still assembled and ground based testing in a educational or not for profit environment is limited compared to the big commercial companies. It's the reason why Es'hail 2's amateur component was built commercially using AMSAT specifications.
There is also the issue that as secondary payload CubeSats have been developed to not use active means of deployment. Such as hoping their solar cells, and antennas release. Which is suspected to have caused many failures as has been pointed out.
Even so, SpaceX is seeing a 5% failure rate on their $2.5 million Starlink Satellites and even NASA's $4 billion Hubble had issues. Space can be unforgiving. And due to size and weight constraints of CubeSats, unlike larger commercial satellites, it's nearly impossible to build redundant systems to keep the satellite functional after any system failures.
The term acceptable failure rate in engineering comes to mind. And expecting perfection out of a CubeSat just isn't going to happen.
Dimitrios VA3DSZ
Sent via AMSAT-BB(a)amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program!
View archives of this mailing list at https://mailman.amsat.org/hyperkitty/list/amsat-bb@amsat.org To unsubscribe send an email to amsat-bb-leave(a)amsat.org Manage all of your AMSAT-NA mailing list preferences at https://mailman.amsat.org
Ashhar, Just to keep the record straight, the requirement to have an independent means of turning the transmitter off does not come from IARU, but from the ITU Radio Regulations, which are binding upon all ITU member nations, and on all radio services. This is discussed more fully in a short paper available on the IARU web site. It's primarily a safety issue. See ITU RR numbers 22.1 and 25.11 73 Ray W2RS
.----Original Message----- From: Ashhar Farhan farhanbox@gmail.com'dTo: Dimitrios Simitas va3dsz@gmail.com Cc: AMSAT BB amsat-bb@amsat.org Sent: Sun, Jan 31, 2021 12:00 pmrather Subject: [AMSAT-BB] Re: Cubesats
Having built four missions and launched two, I can say that the main challenge of cubesats is their really small power budget. The rest of the risks just multiply because of that. Very often, the time from insertion into the ppod to launch is more than six weeks. The batteries drain off, as the batteries drain off, the entire system is browned out. it is a miracle to put up back again. very often, the analog circuitry that would have charged the batteries through solar panels is replaced by software on OBC. But the OBC is unavailable, the analog state is undetermined. There is a colossal fight among schrodinger's cats inside the box. On the other hand, why does the AO-7 continue to work? because it has an all analog design that will turn on the transponder as soon as power is applied and the oscillators can oscillate. If they fail to boot up on one orbit, there is always another orbit to bet on.This is also compounded by the cubesat/IARU specification that insists the satellite should have a way to switch itself off under ground control. This means that unless the CPU decides to wake up the radio, it will remain silent. If the CPU has browned out, then bye, bye, bluebird!- f
On Sun, Jan 31, 2021 at 10:06 PM Dimitrios Simitas va3dsz@gmail.com wrote:
CubeSats enjoy a up to a 39% industry average failure rate. From most common to least, CubeSat failure (21%), launch failure (12%), and not ejected and not specified are tied at 2% each. https://www.hindawi.com/journals/ijae/2019/5063145/ Successful deployment made up 61% of the 848 CubeSat launches between 2005 and 2018. So the Fox line has met industry standards (3 of 5 deployed successfully). The hardware, even if purchased to be space tolerant, is still assembled and ground based testing in a educational or not for profit environment is limited compared to the big commercial companies. It's the reason why Es'hail 2's amateur component was built commercially using AMSAT specifications. There is also the issue that as secondary payload CubeSats have been developed to not use active means of deployment. Such as hoping their solar cells, and antennas release. Which is suspected to have caused many failures as has been pointed out. Even so, SpaceX is seeing a 5% failure rate on their $2.5 million Starlink Satellites and even NASA's $4 billion Hubble had issues. Space can be unforgiving. And due to size and weight constraints of CubeSats, unlike larger commercial satellites, it's nearly impossible to build redundant systems to keep the satellite functional after any system failures. The term acceptable failure rate in engineering comes to mind. And expecting perfection out of a CubeSat just isn't going to happen. DimitriosVA3DSZ -----------------------------------------------------------
Sent via AMSAT-BB(a)amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program!
View archives of this mailing list at https://mailman.amsat.org/hyperkitty/list/amsat-bb@amsat.org To unsubscribe send an email to amsat-bb-leave(a)amsat.org Manage all of your AMSAT-NA mailing list preferences at https://mailman.amsat.org
-----------------------------------------------------------
Sent via AMSAT-BB(a)amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program!
View archives of this mailing list at https://mailman.amsat.org/hyperkitty/list/amsat-bb@amsat.org To unsubscribe send an email to amsat-bb-leave(a)amsat.org Manage all of your AMSAT-NA mailing list preferences at https://mailman.amsat.org
Yes, i forgot. thanks for the reminder. - f
On Tue, Feb 2, 2021 at 12:15 AM Ray Soifer rsoifer1@aol.com wrote:
Ashhar,
Just to keep the record straight, the requirement to have an independent means of turning the transmitter off does not come from IARU, but from the ITU Radio Regulations, which are binding upon all ITU member nations, and on all radio services. This is discussed more fully in a short paper available on the IARU web site. It's primarily a safety issue. See ITU RR numbers 22.1 and 25.11
73 Ray W2RS
.----Original Message----- From: Ashhar Farhan farhanbox@gmail.com'dTo: Dimitrios Simitas < va3dsz@gmail.com> Cc: AMSAT BB amsat-bb@amsat.org Sent: Sun, Jan 31, 2021 12:00 pmrather Subject: [AMSAT-BB] Re: Cubesats
Having built four missions and launched two, I can say that the main challenge of cubesats is their really small power budget. The rest of the risks just multiply because of that. Very often, the time from insertion into the ppod to launch is more than six weeks. The batteries drain off, as the batteries drain off, the entire system is browned out. it is a miracle to put up back again. very often, the analog circuitry that would have charged the batteries through solar panels is replaced by software on OBC. But the OBC is unavailable, the analog state is undetermined. There is a colossal fight among schrodinger's cats inside the box. On the other hand, why does the AO-7 continue to work? because it has an all analog design that will turn on the transponder as soon as power is applied and the oscillators can oscillate. If they fail to boot up on one orbit, there is always another orbit to bet on. This is also compounded by the cubesat/IARU specification that insists the satellite should have a way to switch itself off under ground control. This means that unless the CPU decides to wake up the radio, it will remain silent. If the CPU has browned out, then bye, bye, bluebird!
- f
On Sun, Jan 31, 2021 at 10:06 PM Dimitrios Simitas va3dsz@gmail.com wrote:
CubeSats enjoy a up to a 39% industry average failure rate. From most common to least, CubeSat failure (21%), launch failure (12%), and not ejected and not specified are tied at 2% each.
https://www.hindawi.com/journals/ijae/2019/5063145/
Successful deployment made up 61% of the 848 CubeSat launches between 2005 and 2018. So the Fox line has met industry standards (3 of 5 deployed successfully).
The hardware, even if purchased to be space tolerant, is still assembled and ground based testing in a educational or not for profit environment is limited compared to the big commercial companies. It's the reason why Es'hail 2's amateur component was built commercially using AMSAT specifications.
There is also the issue that as secondary payload CubeSats have been developed to not use active means of deployment. Such as hoping their solar cells, and antennas release. Which is suspected to have caused many failures as has been pointed out.
Even so, SpaceX is seeing a 5% failure rate on their $2.5 million Starlink Satellites and even NASA's $4 billion Hubble had issues. Space can be unforgiving. And due to size and weight constraints of CubeSats, unlike larger commercial satellites, it's nearly impossible to build redundant systems to keep the satellite functional after any system failures.
The term acceptable failure rate in engineering comes to mind. And expecting perfection out of a CubeSat just isn't going to happen.
Dimitrios VA3DSZ
Sent via AMSAT-BB(a)amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program!
View archives of this mailing list at https://mailman.amsat.org/hyperkitty/list/amsat-bb@amsat.org To unsubscribe send an email to amsat-bb-leave(a)amsat.org Manage all of your AMSAT-NA mailing list preferences at https://mailman.amsat.org
Sent via AMSAT-BB(a)amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program!
View archives of this mailing list at https://mailman.amsat.org/hyperkitty/list/amsat-bb@amsat.org To unsubscribe send an email to amsat-bb-leave(a)amsat.org Manage all of your AMSAT-NA mailing list preferences at https://mailman.amsat.org
participants (4)
-
Ashhar Farhan -
Dimitrios Simitas -
Kevin Muenzler -
Ray Soifer