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To introduce this next talk, I will
first ask you another question
has anyone here ever had the chance
to send something into space?
One person, two persons, three?
Well, more than I expected,
less than I hoped for.
This next talk might be giving
you a small introduction
to how how to do
that.
So our next speaker,
let's just call him Uncle
Um, has studied first
in Brunswick and pulled
hypertrophic the Eric, which
I am proudly representing here, not
an advertisement,
and then moved over to Cohuna,
where he studied space science
and then designed a CubeSat.
For the next hour, he will introduce
you to this topic.
And I hope he will answer
this one important question.
How hard can it be?
Audience give a warm applause to
with. So you want to build the satellite.
Yeah, thanks for the introduction, as
has been said. I've studied in Kiruna
and up there we have reindeer's
iron ore mining and space research.
And I just want to give you a brief
glimpse of the complexities of designing
a spacecraft, especially a CubeSat.
So what is the CubeSat?
And CubeSat is a picture on our satellite
phone to keeps us and people.
Now, satellite is a satellite which
folds in the arbitrary weight class of
one to 10 kilograms.
And the special thing about CubeSat
is inside the picture.
And NASA just launched not only as a
secondary payload, but as a containerized
payload data to tell you what
this means.
And the interesting thing about CubeSat
are that they provide a relatively
low entry hurdle into satellite
technology.
So a short history about CubeSat.
There were small satellites before,
especially amateur radio satellites,
which acted as relay stations for amateur
radio users.
But most of them didn't follow any
standard. So there was a lot of
reinventing the wheel with
progressing miniaturization of electronic
components. It was possible to
shrink these small satellites that
formerly had about a cubic meter, maybe
in size, down to just
the CubeSat form factor.
And therefore chipsets were invented
mostly as a way to for students
to learn how to build a full fledged
satellite without having to a long delay
with previous small satellite projects.
But since then, CubeSat has not only been
used in educational
context, but also in scientific research
and technology demonstrations and even as
commercial applications.
So what is in the CubeSat design
specifications?
And most importantly, it defines the
CubeSat shape and Mars, but
also defines what makes the CubeSat
so easily transportable as a
secondary payload.
So, for example, it ensures that the
launch vehicle is safe from the CubeSat,
but also that the launch provider
doesn't have to worry about any
liability for not
adhering to regulations.
So mostly with
regards to radio communication and all
to degree.
But in general, these standards inside
the CubeSat design specifications, which
is the official document you can
download, is just a
minimum, the minimum common denominator
between a different launch providers
of CubeSat. So if you adhere to this
standard, you will definitely be fine.
But often you can handle
waveforms which give you a small
exceptions, or you can accuse the
provider of more volume
in certain directions or something.
So the CubeSat envelope,
basically almost a 10 by 10 by 10
centimeter block.
I had chosen to teach the
metric system to American students.
It's not really 10 centimeters in height
because we have small standards here,
but close enough.
And on the edges you have these guideway
which have a defined minimum
hardness because they're so important
to hold the CubeSat in place and later
put them into space.
So from these space units, you
have different defined form factors,
usually whole multiples
of the base one unit.
So one, two, three, four and so
on.
But sometimes you also see half units,
CubeSat or one and a half units.
So another standard you might encounter
is to keep the kids thus
PCB, which follows the P.S.
104 standard for the shape of the
PCB and the mounting holds, but has a
special, uh, follow connector.
And on the smaller connectors, you have
common voltages, better voltages,
Digital BOCES general-purpose
and a lot of commercial CubeSat
components and substances you can buy for
to this form. Of course, this is a
pretty, pretty big PCB and some
manufacturers have gone on
to define proprietary formats for
fitting more functions in this same
PCB
form factor with supports and so on,
and something which you might find
and is that the mounting holes are not
really symmetric.
So, yeah,
it's, uh, you have to pay attention how
to mount a strong intellectual structure.
And these PCBs are then stacked.
And the connector here is just for the
electrical connection.
The real mechanical connection which
holds the PCB inside the CubeSat
structure is done via threated what's
inserted here in the edges.
And then the piece holds
together with spacers.
So how is it keeps that launched ships
that are integrated in so-called pot
dispensers so you can see six
pot dispensers in a bigger box and just
dispensers that are mounted on the upper
stage of the rocket.
So, for example, on the payload adapter,
somewhere in between or even below
near the engine and after
the main payload is gone and it had a
good head start, so you can't hit it
anymore.
These pots are opened and the chipsets
are released.
You can see such a
pot. So the most important
will to work this pot does is it contains
the CubeSat during launch.
So it holds it in place.
And even if something breaks inside the
CubeSat, it will not hurt the
main satellite because this is
all the rocket operator.
So you integrate
it into this port and this is the last
time you see a satellite.
It has some access hatches to remove
and safety plugs after integration,
but then it's integrated
a chip to launch site and you don't see
them inside this CubeSat,
this case, a three year old CubeSat is
hosted by whales and sitting on top
of a spring-loaded push a plate.
And then when time comes and you're in
space, the box opens and the push
up just pushes out a satellite into
space.
So some about payload safety,
the CubeSat design specifications
have a couple of them.
So, for example, the payload has to be
dead doing
doing launch.
So there is no power going anywhere
inside your satellite.
The batteries and solar panels are
physically via launch switches
separated from the electronics.
This means that you get no communication
after integration.
You also can't emit
any RF frequencies
or magnetic fields by accident and
therefore ensure that you're a good
passenger.
Also, of course, because the airport
has to contain your satellite, you
are also not allowed to have very high
density of energy inside
your satellite because that has the
potential of getting out of the port.
Let's put it this way.
And so this is especially important
if you want to have some pressurized
containers on board or if you would have
if you wanted to have a kind of
propulsion, for example, the chemical
propulsion, this is usually not possible
because of this energy limit,
therefore, the limits, for example, on
hazardous substances.
So the workers on the ground say from
your satellite, also on volatile
materials which evaporate from your
satellite, and might we condense on
other people's satellite on their optics
or something like that?
So it is not allowed.
So I just want to go over the most
important subsystems of CubeSat,
which you can see here, they are mostly
similar to big satellites.
It's just the difference is that they're,
uh, miniaturized and you
have a much tighter integration between
different components. So you see that
there are some a lot of interdependencies
between these systems.
So starting with mechanisms and
structure.
So a mechanism and structures,
everything that holds things in place
of makes things move.
And you have to see that mechanisms
are common points of failure in space
project. So it's important that if you
don't want to be one of the 50 percent
of first time satellites, CubeSat first
CubeSat would fail without doing anything
significant in orbit.
You have to verify them.
And the common mechanisms include, for
example, antenna deployment.
If you have external, uh, deployable
solar panels that can be deployed and
this is usually just done by spring,
loading them and holding them back by a
burn wire, which you burn in orbit and
then it releases.
So verification, what are common
verification methods, for example, for
launch vibration, the vibration during
launch are much more severe for your
satellite than just a static Gillard's.
So how do you find
out what kind of vibrations do
you expect? You could read the manual.
Nearly nearly any major
commercial satellite launcher
has a publicly available user manual
search area and five soldiers and so on.
So you can just find it on the Internet.
The promise they give you a vibration
profile, which is meant for the main
main payload and your mountainside put
on somewhere else on the upper
stage. So you would need to know
the behavior of the port and amounting
to really know what your satellite feels.
So it's better to just look at your
CubeSat launch provider.
They also have documents and they specify
an acceptance level of operations you
have to withstand
before and during launch.
So that's usually what you test for
and for the mechanisms.
Of course, it's usually easy to get it
working on Earth under ambient
temperature and so on.
And so it's very important if you have a
crucial mechanism that you test under the
conditions that you might actually
encounter in space. So, for example,
after it has been shaken from the launch
or the temperature
profile to a counter in space,
so it might have different extensions
and much stuck or a
vacuum might be affected and also low
battery levels because of her wires.
And you want to deploy solar panels and
you don't have enough battery.
How do you get more battery power?
Because you can't play with solar panels,
so please test them also under these
circumstances.
So a next few words about
thermal.
So there was often a question of space,
hot or cold. It totally depends,
because in space, due to the lack of
atmosphere, the
heat can only be transported
over conduction inside the satellite
radiation and such a satellite.
And so the outside only radiation.
And due to the small thermal
mass of CubeSat, you can get
very high temperature variations
even over one orbit.
So from the eclipse you had inside
the shadow of the Earth and then in the
sun.
So, for example, the Sun Cube satellite
published its data online,
has surface temperatures from
minus 20 degrees to 40 degrees,
just maybe over one orbit.
And so what you get is a radiation
balance between solar
radiation, also some reflected solar
radiation from Earth, also emission
of some radiation from Earth.
And then, of course, your satellites
heats up, also emits some radiation,
and then you get a kind of balance
or let's say a
budget.
So what can you do for externally,
usually you can just on
keep that level change to
and inner the values of the of
the surface.
So let's say the color of the
surface for irradiation and so
on. The problem is that the large
contribution of the surface will be
covered in solar panels because you
really need this power.
So you can't really just make it
reflective. That would be not a good
idea.
What you can do.
For example, if you have a problem with
uneven heating, if you have one side of
the satellite which might always face the
sun and overheat while the other one is
relatively cool, you can go in something
we call the barbecue mode, which
basically means you rotate your
satellites and make it crispy from all
from outside.
Uh, yeah, but internally,
if you have some very sensitive, heat
sensitive components, you might
want to insulate them to keep
them away from this huge temperature
swings you see on the outside of the,
uh, of the satellite.
So, for example, you can start by
insulating the side panels.
So these most important things are kept
away from your inside.
But then you also have to see that the
heat you generate with electronics inside
or a fetus inside has to go somewhere.
So you need some kind of conduction path
to the outside.
This is a very complex tradeoff.
So how can you verify it?
First thing you could do would be just
think about if the satellite would just
be masked with a surface in
orbit under certain illumination
conditions. Would it heat up to a certain
temperature or would it cool down
to a certain temperature?
So what is the radiation really balance
temperature? So it just gives you a first
idea of what problems
you're facing. But in the end, you
usually do a fine
analysis and try
to just calculate what is the temperature
difference, temperature distribution and
such a satellite, especially because with
this earth shattering
time and time and sunlight, you really
have a transient behavior you want to do
you want to know about, and then to
finally verify it, you usually
do a thermal vacuum test.
Also to know if the models you did
here have anything to do with reality
that isn't always the case.
So thermal vacuum
vacuum because of course, if you would
have convection, this changes the physics
a lot because it's much more prominent.
So we want to do it in a vacuum
environment.
And of course, you might think, OK,
this is relatively late in the
development schedule because you always
need your components.
And maybe if there was a major problem,
this gives you a lot of problems
because everything else is already
developed.
So maybe in the early stages of your
development, you want to test just
the structural model with resistible
heaters as Camelot's basically
for heat.
So, too, the attitude, determination,
control subsystem, so darned
attitude is the orientation of the
CubeSat in space, you can define
different frames. Want to know your
orientation and inertial frames for non
rotating pages with regards to
the stars of Central Frame is
interesting.
If you want to do Earth observations, Sun
Center frame, it's interesting if you
want to know something about the thermal
conditions or your power generation
and for control, what do we have to work
against?
So we have to work against radiation
pressure from the sun magnetic torque.
Uh, we've got the cleanest
basically means if you have built your
satellite, launched into orbit, you might
not have built a satellite into
it. You might, but that comes later.
But if you don't want to have magnets
in your cell that you still have some
kind of magnetic field.
So, for example, of course, you have
connected magnetic, magnetized materials
inside or just because of the currents
flowing inside your satellite.
And this creates a talk with, uh,
with the magnetic field and gives you a
disturbance.
But also, if you have a baby a little
larger CubeSat, you might encounter and
even drag, for example, if you have a
deployable solar panel or something like
that. So even though not very
dense atmosphere might give you some kind
of disturbance, and if you would have a
really big satellite or maybe have a
tether or something, just a change
in gravity with height, induce us to
talk. Uh, we are trying to reorient
the satellite.
So how do we determine our attitude in
space?
The simplest way would be just use the
illumination.
So this just measures the
elimination of the sun, the solar flux
on your sensor, and then says, OK,
I have a sensor on each side of my
CubeSat, and then I try to
determine from where the sun comes.
Of course, you always have a degree of
freedom rotating around the direction
where some comes from because this
doesn't change your reading, but this
gives you a reading in the sun centered
frame. Then you have the magnetic field
so everyone knows
who has a smartphone.
You can use a compass
to determine your, uh, the
way you are heading.
You can use a more sophisticated sansone.
So this is different from inflation
sensors and sensors that you usually have
some kind of powerful system which
projects like a slit
of light on a sensor, and then you can
determine directly an angle where
this light came from.
So this is more accurate.
You can use Earth's horizon sensors,
which basically try to detect the Earth
or just the line where Earth
meets space. And then you get a reference
in the earth centered frame and
the highest class, usually our star
cameras, this little camera cameras
looking at the stars.
And then from the picture they see they
are looking with an algorithm in a star
catalog and trying to determine which
starts. They have seen just by the
brightness, the relative positions
and so on. And from that, you really get
a good
knowledge about your attitude.
So why why would we control attitude?
So after deployment, due to the
deployment mechanism, we have to push up
plate. You usually have some tumbling.
It's not perfect.
So if you think you can just be
still and then do nothing, of course you
have to sell themselves. But you also get
something from the start.
Then of course you might have a payload
which requires pointing your camera wants
to look at Earth or things like that.
Then you have antennas.
If you have directional antennas, they
want to be pointed to the ground station.
And also if you have antennas which are
really only directional but have some
some zeros, some places where you don't
really radiate anything to, then if
you just tumble, you get just
fading signal. So the signal goes down
that you might not be able to send
a complete packet.
And of course, if it is too expensive,
the antennas might actually bend and then
they are behaving in completely different
because our first black magic.
So not a perfect fall collection.
So if you especially if you have a
deployable solar panel, you really want
to use it, then you should, of course,
try to orient yourself towards the sun.
And then you also might want to have
attitude control.
And what problems do we encounter?
I mean, if you think about normal motion,
if I push something in the direction
Newton says, it should start
to move in this direction and continue to
move in this direction. This nice
invitation. If I just would give a talk
around the Nexus, it would probably just
such a tumble.
The problem is that if you look into the
physics, the motion around
just arbitrary exercise usually coupled
so is
very matrix which come into play here.
And there are only three defined
distinguishable galaxies in each solid
body where you don't have any coupling,
the so-called principle axis, but only
even two of them.
The motion is stable.
So if you have just have a small
disturbance, one of 150 axis,
we can start to make a tumble.
So if you want to have a satellite
which moves around a certain axis, maybe
because you want to have a measurement or
something like that, then you should
think about distributing the mass in such
a satellite. So that is easy
for the control algorithm to control it.
So maybe choose a principle axis
for that which is stable.
A couple of methods, how to stabilize
the satellite, especially a CubeSat.
The easiest way would be passive magnetic
stabilization you.
By choice put a satellite
which is fixed to the frame and
it, of course tries to orient itself like
a compass needle to the Earth's magnetic
field.
The problem is, of course, if it starts
turned itself against kinetic energy and
then goes into a pendulum oscillation.
So you also want to have something which
dissipates this movement
away.
So you also have, uh,
hysteresis watts here or out
of heartful magnetic material
in each direction and inside the
movement is then dissipated.
Of course, there are limits because, I
mean, it's easy. So it has to be, uh,
somehow flawed.
So you have interference with your
attitude, determination. I mean, if you
build a huge magnet inside your
compass, then it will not work anymore.
Um, it's not easily changed
for a fixed position over the Earth
because, I mean, if you really built this
heart
into your satellite, then maybe you can
use it to point you satellite to your
ground stations directly above.
But in any other
position above Earth, you don't really
have any wiggle room to readjust
your position that this is not a
good enough force.
You still have a degree of freedom which
just rotates around the magnetic field
line because, uh, then
there is no talking point.
And you might have deployment problems
because let's say we have two of these in
one deployment, but they are
pushed out and then they are just
attracted, just
not good.
So the next step up, let's say, is
active magnetic control.
We have electro magnetic inside the
satellite. So, for example, our coils
integrated into the CubeSat penalty
or maybe also to awards,
which are just slender, uh,
slender electromagnets inside a
satellite structure.
And yeah, just by controlling
the current going forward, we produce our
own variable magnetic field.
So we have a lot more degrees of freedom
to control it and move to satellite
around. So, for example, in combination
with the magnetic attitude,
determination, we can use,
uh, something called the algorithm
to adjust the tumble to satellite.
So then afterwards it's just spinning
around one axis.
That's nice. But of course, this, as
opposed to the other one, uses power.
Power is scarce.
And again, you have one degree of
freedom. So if you're, let's say,
spinning around the magnetic
field line and you want to stop that,
there's not much you can do.
So even more
accurate, are we actually basically
flywheels with an electric motor
and as no excuse me, actually.
So if we put a talk on the flywheel,
the motor itself and the whole satellite,
it's mounted, you will
get to talk in the other direction.
So with this, you can get very high
pointing accuracy.
The problem is that, for example, if you
have a disturbance torque, which always
has a bias that always tends to push you,
let's say clockwise, then you always
have to apply a counter torque in
the same direction C02.
So you add spin to the wheel and spin
to the wheels and maybe the bearings
fail.
Of course, you don't want that to have
the way to have another
type of attitude control
to desaturate your
wheels. And of course, this needs all the
power and its continuous power because we
would just stop power to the
flywheels, then they would slow down due
to friction and this would give the
talk you put into them back into your
satellite. So the whole thing starts to
spin and tumble again because you don't
want that.
So again, it's more
power.
A few words about communication.
So to telemetry, if you can't get
data to your satellite, if your satellite
doesn't respond and the satellite is
passed, so you really want to have this
thing nailed down
first measured usually after you
deploying a satellite or if there was any
fault in the satellite goes into a safe
state, it starts to transmit
a beacon, which is just
a short package, which
includes the most important telemetry
of the satellite. This helps you
to locate your satellites.
So, for example, after launch, you have
just a flock of satellite shots were
released. You don't know which of these
is yours. So you just try to
ping each one and whichever sense
of it might be the right one.
So.
Yeah, and today, in case of failure, just
get the most important values you
need to debunk the problem or at least
find out what's going on.
So a different types of antenna's the
easiest type of just
this kind of extending Youlus.
You bend over the edge and hold
down. So if you burn this wire,
it's flips up and
you have a working antenna.
If you did anything right.
Uh.
You have to distinguish between DirecTV
and omnidirectional antenna,
so these types of antennas are usually,
uh, near omnidirectional.
So they have multiple
configurations and they are very good
for, let's say, lower frequencies.
If you want to have DirecTV, DirecTV
antenna usually go to higher frequencies
because they're it's feasible to
construct such an antenna because
the same structure used, for example,
here for this antenna, uh, would
be much, much larger if you go
to these frequencies.
And yeah, basically you have a patch on
time, which really just is a patch
helical. And of course, you here you
would have another point of failure
because you have to deploy this in orbit.
Uh, yeah, but these are the
most common forms of intensity.
And CubeSat.
So just a few words about frequencies,
common frequencies, if you come
from the amateur radio
edge of the spectrum, are 70
centimeters and two meter frequency, so
about 430, 144 megahertz,
very common, a long time useful
amateur radio purpose.
And the nice thing is, because if we
could say relatively low, you have pretty
efficient components from this because
the frequencies are so low, the available
bandwidth or the bandwidth you're allowed
to use is relatively
small. So you get only about nine point
six kilobits per second while the
satellite is in reach of your
organization. This is only just a
fraction of its orbit. So, uh,
you need a lot of orbits to get, let's
say, a picture and
of course, get a test for these, uh,
wavelengths will get pretty
big. And you can put us on your, uh,
CubeSat probably.
So you might want to go to higher
frequencies, uh, especially
popular with commercial, uh,
chipsets, which get different kind of
licenses, are usually not operated under
amateur radio, uh, regulations.
And those get signal rates up
into the megabits per second rate.
So that's, uh, much nicer because
they have more bandwidth available.
And if you don't need your higher
data rate, you want to use less
power, then you can also use the higher
bandwidth to increase your linked budget.
So the, uh, the transmission is
more reliable.
So just a few
words about protocol and,
uh, really just a few,
um, common protocols, you might
want to look into a few interesting
things that that would be x 25, which is,
uh, amateur radio.
A packet radio protocol, which
is used has been used for lots of
CubeSat, especially in the old days.
If you want to take a look at a as
a satellite communication protocol,
which is a bit more advanced, which is
also used for big missions and big
satellites, one can take a look at the
available documentation on access
which is used for its emissions.
And, uh, yeah, please note that
especially if you need a good connection.
For example, if the satellite just
started tumbling, you want to recover it.
And it's important that you can, uh,
that your protocol is able to
work with a weak signal.
Uh, I heard of people trying
to log on with S.H.
on the satellite.
Not a good idea, at least handshaking.
So, uh, yeah.
Uh, more on regulation.
So, of course, if you want to use, uh,
amateur radio frequencies, you
are, as an amateur radio use, are usually
allowed to do not use them.
But you should go through a frequency
coordination step, which just make sure
that there is no other satellite in
similar orbit sending on the same
frequency.
And then you get a lot of restrictions
based which vary between the jurisdiction
based on, for example,
who are you allowed to
use amateur radio if you get a government
grant or is your ground station
operator allowed to be paid for
operating grants and things like that?
But in general, uh, there is a at least
an exception for commands being sent to
the satellite because they are allowed to
be encrypted.
Everything else under amateur radio, uh,
uh, regulations has to be clear checks.
So it has to be readable, might be
compressed. That's OK as long as it's
documented. But, uh, commands to
satellite is the only thing that is
allowed to be encrypted in amateur radio.
And what's also important is that you
have a fast and permanent transmission
killswitch. So if your satellite goes
haywire and, uh, just sends
a carrier on your, uh, frequency,
you have to be able to shut it down.
And fast could even mean that you
need multiple ground stations in middle
latitudes. So we get it the
let's say half a day or so, and
Poland really means Poland.
So there has been a satellite which has
been shut down, but then there was a
reset and start to transmit again.
That is not good.
So please really make it permanent.
So if you not
if you're not in Russia where you
license, you have to talk
to your National Frequency
Coordination Agency, then you can
something like experimental permits
or things like that which allow you
to use similar frequencies, maybe
even in the same range.
Uh, and yeah.
Get a little bit more freedom.
And what kind of, uh, uh,
uh, applications you use here.
So, uh, but please note that frequency
coordination and allocation takes a lot
of time. So, uh, it would be best
if your satellite is built ready to
launch, but you don't have your location
yet. So please look into it early
in the project.
So electrical power systems.
It's all about power,
so you leave for power collection,
junction solar cells are used.
They're pretty efficient.
If you have a maximum peak efficiency
of usually 27 to 30 percent, if they're
lit directly
and afterwards, you usually have a
maximum optimum power point tracker
which adjusts the load the
solar cell needs so that the power
which is sucked out of it is
optimized because otherwise you might,
especially with the low voltage
you have on just a few cells on a cell
on the CubeSat side,
you don't really get
the maximum power, but of course you lose
some power also due to these thing.
So as every real circuit, it's not
really 100 percent efficient.
But let's say near the
Earth, uh, you get about
two point three watts per CubeSat panel
when they are illuminated perpendicular.
So if you have a cell which is rotating,
then you would get a slightly varying
power power and take.
And you have a collection,
please.
We wanted to include a charging connector
for testing and also for
storage because it
is not very nice if you would have to
put your satellite under a lamp
every time you want to charge it during
testing.
So how could we increase this population?
Obviously, we could try to increase our
social area.
So you have your common
things, you can only see.
So, for example, just winds pulling out
or flaps going up.
Of course, if you look at this
configuration when it started, looks like
this would this might not be a nice
thing if you have to become a satellite.
Something went wrong, an early face
because the battery trains.
So we might also want to include a few
solar cells here on the outside.
But then after they deployed, they are
shadowed and shadow solar cells tend to
become loads if you don't include extra
protection circuits or keys.
Yeah, look into it.
So this doesn't
eat up all your power and gets
hot.
So if you have collected your bet,
your power, you want to start usually so
often, uh, lithium batteries are used,
which are for
just a satellite, but usually the most
temperature sensitive components.
So you want to keep this happy?
Usually they are coming pretty integrated
with a heater. So at least you don't
freeze them.
But what kind of capacity you need,
so you have to supply your satellite
with power throughout the eclipse period,
so the period in the shadow,
but also if you have short bursts of
activity, so, for example, transmission,
if you have a payload, you have to
operate, then you need just short bursts
of power. And this is also.
Cared for by the buffer of the
battery here.
The problem is if you just look at the
advertising and see what our batteries
and you can get should be enough, you
usually are only allowed to
discharge 20 percent of that.
The reason is that if you think about
your phone, I mean, it maybe lasts
the battery last a year without that much
drop in capacity.
But in the satellite, you have a charge
just like discharge cycle, maybe every
90 minutes.
So you really want to limit your depth
of discharge.
So you get maybe two years
of battery.
So what about verification?
It's important that you really test
the whole power chain as one, so
maybe get some kind of language,
simulate solar spectrum and then
see if really your battery gets charged,
if your consumers can get
charged with battery and so on, and also
make sure that the efficiency values
are according to your calculations,
because often in the data sheets, even
if you are buying a satellite electrical
power supply,
you only get one efficiency value, which
is really not enough.
So please make sure that
the efficiencies that occur under
your operational profile are
such that you don't run out of
power.
On the computer, so really,
if you look at flown on board computer
systems, you see everything from really,
really small microcontrollers
to embedded. Suppose you can find
an iPhone, something on the computers,
our phones, but is
not so often.
You can also see some FPGA which have
been flown in chipsets.
And of course, in space you have to
deal with a different radiation
environment than you find on Earth.
And you have two types of effects.
One single event effects, for example,
lets up on this shortly and
bit flaps and corruption, uh,
later just messes with your program.
This can damage your software
hardware if you don't account for it.
And then you get total dose effect, which
don't happen instantly,
but, uh, accumulate
over the life of your satellite and
usually lead, for example, to increase
in power consumption of your, uh,
of your electronics.
So it should size your power system,
take this into account that you have some
Headspaces for later on your satellite's
life.
So, uh, what are laptops
typically a cure
for heavy iron or proton
hits a similar device and
then activates a parasitic transistor.
If you look at the typical Simos
device structure here, there are
these two transistor structures
here which are not really intended
to be there. But just because of the
structure, they can be there.
And now we have a particle going
in here creating charges and those
two are activated, basically short
circuiting your supply.
And this is, of course, not good because
it heats the damages the device.
So if you are seeing a
sharp increase in power
consumption, then it's a good idea
to just reset the circuit because
this will not turn off until the power is
taken off and put them back.
Again, this is for, uh, just
a commercial off the shelf circuits.
If you have a, uh, let's say, better
hardened integrated circuit,
then you sometimes get insulated
substrates. So maybe it's on a sapphire
or something like that.
And they're, uh, this kind of
problem is prevented.
But this is one of the main reasons you
often get resets on your satellite just
because the power supply detects the
latch up and we sell the whole system.
So the of protection here
is often integrated into the electrical
power supply if you're looking at the
commercially available CubeSat power.
A few other effects on electronics, which
you might not have heard of, soaring
whiskers are small, really
small tendrils which are forming
from solid waypoints, but they are big
enough that they might switch
to another voltage potential
and then create a short circuit.
And this is especially problematic if you
use the lead-free
shoulder. So that's the reason
why space applications are usually exempt
from using lead-free
Letteri soldiery.
Another thing, especially for launch
vibration, it's always good to have
strained relief.
So if you want to solve a cable to your
PCB, think about just putting it
once and then up so you can expect
it from the top and have some kind of
strange relief here so that when the
vibrations kick in, you are not damaging
your soloing point.
And also, of course, and remember, you
don't have any convection.
So if you find if you find
the formula describing how to size
your lines on your PCB
to withstand a certain amount of current,
think about if it's also
the same under vacuum conditions without
this cooling effects, because now you
have to dissipate all your heat
through your PCB.
Few things about programing,
unscheduled results, resets
are to be expected, so if your program
has any problems of that, then you should
rewrite it.
For example, if you have some state which
must not be lost, you have to save it in
nonvolatile memory, obviously,
and which also sometimes creates
problems, timing, synchronization.
So after a reset, if you set that has no
idea which time it is, it might not be
able to perform important work
sent when it's over a ground station,
things like that.
So, for example, there was on satellite
which couldn't complete the mission
because its time. We said at one point
and it just the
sequence just didn't get food.
And then also, as I talked about earlier,
the a bit flips.
So just your program could
not get corrupted. So it's a good idea if
you have a bootloader, if it's not
integrated into the silicon of
your processor, then just have a small,
very compact bootloader which is unlikely
you get hurt and which maybe checks
itself and also the other software
program prior to execution.
And then if you have the space, maybe
have several copies so you can
at least reconstruct your program code
afterwards.
And if you want to update your software
in space
that there was always a risk
associated with it.
If you have really long term mission, you
might want to do it.
So then maybe space is
limited apart. If you have different
software, different code blocks
which fall out of your compiler prior to
linking, maybe have a link or file which
spaces them apart in your memory because
then you can override parts of your
memory without having to
shift back all the things that come after
it. So this would make it easier to
update the software in space because you
just have to make
Delta dates instead of reprograming
the whole nonvolatile
memory.
Just some miscellaneous things about
orbit's so available all the time, mostly
dictated, but what kinds of launches are
available because are only secondary
satellites, there are some started to try
to build the rockets just
for CubeSat launches, but they haven't
materialized yet. So just
a few common orbits,
low Earth orbit from ISIS
deployment there. We don't have such
a long life, maybe a month depending on
your size, but they are well
and expensive. So for
I've seen it starting at, let's say,
sixty thousand dollars for this launch
and then
we get a little bit more expensive.
You want to go in something transorbital
that later you start
at, let's say, 100000 US
dollars, but here you get more
interesting illumination properties.
If you want to do Earth observation or
if you want to optimize geothermal
or power, the budget.
And then we have not so common
geo transfer orbits, which are the orbits
that rockets inject into.
If you want to put a satellite on the
geostationary orbit, which is pretty
eccentric, gets you pretty far out if
you need it.
But, uh, yeah, it's much
less common than the previous two.
So what is the drivers on your orbit
selection if you can select
so the distance to have service, for
example?
It's important if you consider the power
you need to transmit your data or get,
uh, commands back to the satellite.
The illumination is important because
different all of the planes have
different, uh, vectors to
the sun. So you have different times
in the shadow of the earth, different
times and sunlight.
This not only messes with your power
collection, but also with your thermal
behavior. A.
Also variations of the year because
the earth moves around the sun.
That's that's not good.
So, uh, then the next
is radiation.
So if you don't want to study the Van
Allen belts, keep out of the Van Allen
belts.
These are in the medium earth orbit
range. And if you stay there for long,
then you probably get just reset all the
time. And something something which just
might not be as obvious is
there is an implicit lifetime
limit. So this is not yet legislation,
but, uh, in general,
it will be probably pretty soon that
every CubeSat put into space
must be we entered before 20
years of its lifetime just
to reduce the amount of space debris.
Not every CubeSat launched
last year has
kept its limits. So we'll probably to
have a much longer lifetime in
orbit. But, uh, many,
many CubeSat launch providers now
required to show that the
orbit you launch and, uh,
is compliant with this also is, of
course, dependent on the type of CubeSat
you have and are currently things
development which reduces
your lifetime. So, for example, balloons
which inflate or things like that.
So about the sun synchronous orbit,
because I found this interesting.
So if you would just have a normal
undisturbed orbit and you would move
along and orbital plane, then as
the year progresses, the plane wouldn't
change because it's static in the
inertial frame.
So you see the illumination conditions
here. You have a midnight lunar
orbit named after the time zones
that it's flying over.
And then it changes to a dusk dawn orbit
here because it moves along the
so-called Terminator line between light
and shadow here.
If you have a sun synchronous orbit, you
are using the, uh,
the fact that the Earth is not a perfect
sphere. It's slightly ablated.
So, uh, this, uh,
distribution of Marzia exerts a
force and tends to, uh,
rotate your orbital plane.
And if you're going into the just the
right inclination. So just about, uh,
just the right angle between the equator
and your with the plane, then this will
rotate at such that as
the earth moves around the sun to
orbit, the plane rotates with it.
So you can see that approximately
at each time of the year the orbit is
stable and then you just need to choose
which which
basically local time you have here
on your satellite. So here, for example,
you would always have a midnight moon
orbit, but you could also always choose,
uh, uh, dust storm.
But so this does not mean
that nearly always you are completely
with one side and sunlight.
This is good for power, maybe not so good
for thermal, but that's a tradeoff
you have to do.
So something about ships, the transports.
Of course, you don't only want to build
your CubeSat, you want to maybe keep it
starts at your university
or heck hackerspace location,
but then at some point, you have to
transport it to your ships, a launch
provider. And then,
of course, it's obvious you want to
prevent excess humidity, particle
combination particle contamination and
electrical distress.
And so a mechanical shock.
But you also really have to think through
your whole transport chain.
So, for example, if you want to transport
your satellite and your hand luggage
at the airport, at the airport, you might
be asked to open it.
And this is especially bad if you have
taken extensive measures to keep
humidity and particles away from the
satellite. So I also heard stories
about experiments headed to Mars
which were asked to be opened at the
airport. So please make
sure in advance that you don't get into
any problems like that.
And of course, then also after the
transport, you want to check for
transport damage.
And if you can't look into your satellite
anymore, maybe think about that.
How do you can verify that there really
was no damage? Just have a basic check.
So, yeah, I hope I could give you a small
glimpse into the
development and what kind of
peculiarities there is and satellite and
CubeSat design.
If you're interested in things like that.
I think it would be best if you look at
other CubeSat projects reports during the
day, especially if the university
projects to write papers about
operation and so on.
And there are lots of interesting things
to found you. And I just want to remind
you that verification is key.
So if you have a thing that must
work, then you have to test it.
Otherwise you can just think it
probably won't work.
And if there is something
a risk you take, then think about a plan
B.. So if the fault occurs,
what do you do?
Is there any mitigation?
At least you can do maybe a reduced set
of science measurements of things like
that. So, yeah.
And does the end of my talk and what
was interesting for you and I think we
can do Cunetio.
Yes, so thank you very much.
So for now, the usual police line
up behind the microphones while we see
if we have questions from the Internet, I
don't see our signal angels standing.
So, uh, just line up.
It wasn't really interesting talk,
by the way, so.
Oh, yeah. Please leave the room
quietly because
we are still wanting to hear
the questions that might occur.
And as or we can see there are
many, many questions.
That's interesting.
OK, we'll just start over there.
Right.
Hello.
Hello, thanks for the talk.
Um, I've heard about,
um, Intel, Edison
reports, Hecate, BCB, something like
that used for concert.
Uh, do you know about any
Hecate Bisbee's like Raspberry Pi
or Arduino clones, which
are, um, which
can work at the space?
Fine. Well,
depending on how you build it, it's more
the question of how well it will work.
So as I showed you about variation,
there are some things you have to design
around for and so on.
So there was at least
Adreno. I know for certain that there was
a mission which used, uh, Adreno
at least compatible hardware as
a computer. But this was also,
as if I remember correctly, mostly done
so that other people can program
for the satellite.
So it was more used as a compatibility
thing and not for any other
obvious advantage in hardware,
architecture or programing.
But it, uh, this Bisbee's
are not specified for such circumstances,
such conditions.
Well, the problems you might get with
just commercial off the shelf
PCP's for Raspberry Pi also
are, for example, as I showed you this
sold to investors Whiskas because they
are certainly produced without that
in their shoulder.
And they have been even full
commercial satellites which failed due to
solar, because at least that's what I
think it was.
So this might be a problem.
And then, of course, yeah, just
the whole way structures might not be
ideal to mount inside a satellite, but
that has to really depend on the
on the PCB. I can't give you a general
answer for that.
Thank you.
OK, then you have two questions from the
signal Angel.
So, um, yes.
Or Niazi. They're asking
for Turness asking if there are any
satellites up there that can be used
freely and legally by hobbyists.
Well, if you're a licensed amateur radio
user, then there are some amateur radio
satellites up there.
So then you get most of
them with a satellites.
So you send an analog
signal, usually sound after,
and then it just gets repeated on a
different frequency down a day.
Also, I'm not sure if there's any one
active right now, but there was also some
actual radio satellites in the past which
used some kind of message, boxing
technique to transmit
messages. But, uh, as I said, getting
you have to need an amateur radio
license to use these satellite.
And the other question is
from handsome pirate.
I'm asking if you would recommend
to use a red hardened CPU
and memory.
Well, the problem with this,
if it's really red heart,
then they cost usually a lot of money
because they have small lots and so on,
and they are usually
at least that I know of not many cubists
which use this kind of technology.
So at least the
consensus among the design seems
to be that you should rather design
around the radiation problem than to
just select hardened components, because
especially if you are using the CubeSat
form factor because it's cheap, maybe you
can accommodate for certain
failure rate then you don't want
to get into this.
Yeah, just expenses with
red hot components.
OK, then we have questions here on the
four you left side.
Yes, I have
one comment and one question, actually.
And the comment is, if you think about
orbit, I think latency, especially
if you do communication, because
at certain altitudes, the light
speed of light actually is your limit for
communications. And it takes a while to
get there. And if you especially go in
high orbits like geostationary orbits,
you have significant
delays.
So that from my experience with
geostationary satellites.
But my question is also
regarding orbits
to what orbit do you know
if GPS available or
is it available at all?
Well, there are lots of tricks.
I mean, I use on CubeSat.
The problem is that if you just buy
a GPS receiver off the shelf,
there are these
limits built into it usually so
that you don't use it to build
intercontinental ballistic missiles.
So they have a
speed limit and an altitude limit.
And while on high altitude balloons, you
usually get away. If you find something
which needs both of them violated to shut
down on a satellite, you violate both of
them. So either you need some
special firmware for that or.
Yeah, or use a component
which is built to meet these
requirements. But of course, those get
pretty expensive.
So it's it's,
uh, it's it's definitely
possible to use GPS, especially on the
low Earth orbit, because GPS is more like
a medium Earth orbit.
But even if you are above the satellite,
uh, uh, the GPS
satellite orbits, they are
uh, I'm not sure.
I think it has been used already,
but the the antennas
of the GPS satellite try to
illuminate basically the whole earth,
but they have some overspill.
So if you look at the Earth, then,
uh, Cheapside Light coming from the other
side might send you a signal.
And by a tricks like that, you get also
some GPS reception on higher
orbit.
So it is possible it
has been done, but I don't know if
any just component you
can grab for that.
Interesting and one more thing.
Are you familiar with the alternate
project, the alternate,
which is actually an attempt
to build the global Internet with
CubeSat?
But they are not very far yet, I guess,
but have you ever heard of that?
I'm not completely sure.
I heard of one project, which I think
wanted to use.
I'm not sure because I think they use
just regular communication satellites to
distribute information,
but I'm not sure if this is the same.
I think it is that currently they're
using the existing satellites to just
broadcast things like Wikipedia and
stuff.
But as I said, if you just use,
let's say, amateur radio frequencies,
then your bandwidth is pretty, pretty
small. The problem is also north of it,
of course. So that just pushes
by. So you maybe have a 10 minute
contact window and you don't get
a lot of data down this time.
And yeah,
so if you will really want to dispute
a lot of information, then
you might have to think about how to time
it and how to maybe use multiple
satellites. You know, of course,
transmission on the satellite as often
some of the more power hungry things.
So if you're looking at your overall
power budget, this might also limit the
time you can transmit at all.
And you need multiple tracking
attendance, which is also
a problem.
I mean, this, of course, depends on what
kind of signal that send
if it's a very robust signal which can
penetrate even noise or something like
that, then maybe you get away with less,
uh, less directive on the underground
station.
But yeah, it's of course, a trade off
and.
Yeah, thanks.
OK, we don't have an endless
amount of time left, so, um,
maybe if you have longer questions,
it would be nice if you could ask them
afterwards and from now
on the side, there might be another
one.
Just wanted to ask if you have, uh,
a tip or something where
we can get some of the
already computer data or something,
something cool. A cool project
that you can recommend.
Well, if you are just interested in,
let's say, CubeSat housekeeping data,
then I already mentioned to fund your
project once they upload
all the housekeeping data they have on
the satellite. So if you just want to
know how just the environment is
approximately on your satellite
in orbit, then you might take a look at
their website.
Yeah, there is a slight
problem with the data we're going to
scrape it is that if they don't have data
for a certain time period, they still
give you data, but it's just repeated
over and over again with a new timestamp.
So if you want to scrape the data, you
might have to filter it out afterwards.
But at least that's why I got some,
uh, just data on housekeeping.
OK, again, we're here the uvo,
so you told that battery
discharge is limited to 20, 20
percent of the capacity
can it can be used
on other types of batteries,
which is more designed
for such kind of temperature
swings? Or I know Ernestas.
I mean, of course, you can look
at the whole range of available
batteries. The problem is that
while chipsets often are more volume
limited than really mass limited.
I mean, often in space you hear about
mass and how much it costs to put a a
kilogram into orbit or something, but it
keeps us from putting
everything into your small space.
So you basically have a similar problem
as you have in your smartphone.
And that's why they both converge maybe
to the same type of technology, because
it's so far above the
energy densities of other alternative
methods.
Thank you.
Um, before you can ask the next
question, everyone that's leaving now, it
would be great if you could leave through
the door near the stage because there's
already a queue outside and
then it's not getting up.
Ringold And, you
know, many people and stuff
this microphone.
Hey, thanks for this amazing talk.
My question is, how do you maneuver your
satellite in a specific orbit once
launched? And then there's a question,
how does the electronics react on the
vacuum condition, such as, um,
uh, capacitor putting it evaporate?
Yeah, well, of course, you can
sometimes see the same ground based
vacuum applications that I just go to
the electrolytic capacitors, so
it's somehow
encapsulated.
But of course if you have a space
application, you might try to get just
away from these kind of capacitors.
The other thing about in orbit
manoeuvers, the problem with that is that
you get into, let's say, rocket
propulsion territory, and that
means you need mass to
get the energy to make any kind
of maneuver. And as I said,
usually, if you would just need a small
engine, let's say a chemical engine
might be the way to go,
but you are not allowed to have dangerous
substances or high energy
content in your satellite.
So these kinds of engines
can be used.
There are some projects at the moment
which try to develop, let's
say, ion engines, which use
the power collected by the satellite
to propel a medium
and thereby generate some thrust.
But even if you would think
if you are brought to applications
and used, the amount of thrust
they give you is not that the amount
of total change in velocity, so-called
Delta V is not that much.
So you might be able to extend, let's
say, your lifetime if you're on a low
Earth orbit.
But it's difficult to,
let's say, ways to orbit significantly
or you can change the orbital plane.
That's that's very expensive.
So, yeah,
it's currently not that feasible
in a CubeSat to make big changes.
I mean, there are lots of projects
going on.
Let's see what they get at.
But at the moment, it's
there's no component
you can use for that.
So you basically stick with the big
satellite.
Yeah, you do stay on the same orbit.
The upper stage left you on.
And of course, then you have all this
disturbance influences which changes your
orbit. But in general, you stay on the
same orbit.
Thank you. OK, we are out of time.
Thank you very much again.