Welcome to our next talk.
This is Anja Kohfeldt. And she will be talkin about "Lasers in Space".
Please give her a warm round of applause.
Anja: Ja, hello everybody I also would like to welcome you to my talk.
As the Angel already said.
It is about lasers in space
and they more than just: "Pew! Pew!"
So that's what I want to talk about.
I'm a scientist at the Ferdinand-Braun-Institut in Berlin.
And I am a member of the Quantus Project group.
The Quantus Project has the main goal, to build an optical atom interferometer, in space.
And there we started at the drop tower in Bremen and now we are heading toward our sounding rocket
which will be launched in november next year.
In order to build this atom interferometer, we have to cool down atoms
and for that we semiconductors(?) or we need lasers, at a specific wave length.
And my job in this project is to build these laser modules.
So now you know what I'm doing.
My motivation for this talk today is:
At first lasers are cool!
I think everybody will agree to that.
I hope so.
In the past years there have been a lot of projects concerning lasers.
For example building lasers cutters or building laser projectors, or pimping you laser pointer to laser gun, burning stuff.
There are some pictures I found on the web.
And than there is the space side.
This whole space stuff got more and more affordable in the previous years.
There is more and more private activity in the space sector.
For example private companies building launching systems.
But there are also a lot of student and university programs to build there own satellite to make science in space, science in micro gravity.
And I think when we just follow this development there also will be
more, yeah, there also will be some hacking possible in space in the next years.
There is also a personal motivation.
Whenever I tell somebody that I am building lasers for space applications, there is always this:
"Oh, you are building orbital death lasers!"
No, I don't.
[Someone booing in the audience, causing the others to breaks out into laughter.]
Actually I'm very happy that I don't do that.
This talk will be about other applications of lasers in space.
When you google lasers in space, you find a lot pictures like that.
And they are beautiful. They really are.
They have lasers, they have space.
But I won't talk about that, because these lasers are on earth.
They are guiding the stars very often or laser shows. Both applications.
Very useful, very nice pictures. Here they are.
Okay? Nice.
So, I would like to talk about a little laser 101.
Telling what is a laser? What can you do with a laser? What is space?
And, well, as I said already, the applications of it.
Lasers. Laser: "light amplification of stimulated emission of radiation"
Yeah, ok. We knew that.
It's a device emitting monochromatic and coherent light.
And that's nothing else but:
Light with the same wavelength, in the same direction and the same polarization.
With that properties you can focus photons on a very, very small area,
because there are lot of photons doing the same thing.
And that's why you have a very high power density
and that is why you can use lasers for example for welding, for cutting
or for delivering data over very, very long distance
What do you need to build a laser?
You need active medium.
This active medium, or the electrons in this active medium, are stimulated by a pump.
This either an optical pump or an electrical pump or whatever pump.
And you need a resonator to sort the right photons.
And when it comes to the classification of lasers, you basically vary the active medium.
So for example there are solid state lasers, where you use a crystal.
A very good example for a solid state laser is the neon doped XXX XXX laser. The YaC Laser, as we are used to call that.
This laser or this type of laser is used industry, but you also find it in laser-light-shows.
There are a lot of applications for that.
In contrast there are semi-conductor lasers.
They are a lot smaller.
You see, the green one on the left is the YaC Laser, in the center you find the semiconductor laser.
They a are a lot smaller, they are cheaper, they are more efficient.
And you can tune the wavelength over a certain range.
As an example here, there is the indium gallium nitride laser, which you will find in you Blue-Ray-Player
or the aluminium gallium arsenide diode, which is commonly used in DVD-Players, and stuff like that.
I think everybody owns at least one of them.
There are gas lasers.
For example helium-neon-lasers.
The helium-neon-lasers built in the current wave mode.
And it's now used, for example for calibration or in schools.
And the CO2 laser is one with very, very high power density.
It's a pulse laser, used for example for welding.
And there are the dye lasers, which can tune the wave length on a very, very long range.
They are very often used for spectroscopy, for example.
So whatever you want to do, you have to chose your laser your laser type with your application.
And they vary a lot in their output power, in there mode, whether they are pulsed or not pulsed
and their wavelength, but also in their size and complexity, yeah.
And you just have to chose the right one.
This is important especially when we are going to space.
Here are some common applications for lasers.
You use them in measuring, in optical data transmission,
they are used in the multimedia sector and also in the production sector.
But not only at home, or industrial or in medicine, but also in space.
So space, here we are.
The common definition of space is: "Hundred kilometres above the sea level."
But whenever there is, for example an Apollo astronaut, when they are talking about space,
they are talking about 50 miles, which is an older definition of space, based in the US.
You can go to space via satellite, you have the space station
and sometimes at the space station you have an operator, like a person operating your experiment. Might be useful.
There have been orbital experiments. Especially the times with a space shuttle.
And there are sounding rockets, which are rockets going up up to approximately a thousand kilometres max,
and falling down, but in the meantime you can perform experiments in zero gravity.
Why do you want to go to space?
Well, there are a lot of reasons.
For example the observation of distant galaxies, the earth weather,
there are communication satellites, just to transfer data,
you can or you want to perform science up there.
For example because of the lack of gravity or the lack of atmosphere.
There is navigation and there is also the military purpose, you can't deny that.
But it's not that easy going to space.
Whenever you want to go there, there are a lot of restrictions.
For example the size and the weight.
When you want to launch something into space, you have costs approximately four to five thousand dollar a kilo.
Although this price is decreasing, it's still high enough.
You are very limited in you power consumption, cause you don't have, i mean
it's a closed system, right? You have you solar panel, but that's it.
And sometimes some other energy sources, which may disappear after a while.
Everything you want to send up there has to survive the launch and sometimes it has to survive the landing.
When it's coming back to earth, there might be applications where you might use that.
Very often there is no operator.
Like no one pressing buttons. So everything has to run autonomously.
And your stuff needs quite a long life time, cause you don't want to switch parts once a year on a satellite.
So you normally don't do that.
So, as I said in the beginning, I'm a scientist.
And this is a lab.
It's not my lab, I'm very happy about that.
But this is an experiment quite close to that what we want to do.
And as you might assume, this is not a good idea to launch that.
It won't hold.
It won't survive the launch and probably it won't work up there.
So what did we do? You have to choose an appropriate technology.
That's why we are using semiconductors for exmaple.
They are much smaller, they are much more energy efficient.
You have to space qualify all the components you are using.
You have to take care of the materials you are using.
You can't use whatever a XXX for example, because you have this out gassing problem.
Your device has to operate in vaccum, very often at least.
You have to minimize everything.
You want to fix every part.
You don't want to much movable parts. Because there won't be anybody to fix your setup, afterwards.
And you have to work in a clean environment, when you integrate something.
Dust is a problem, for example.
You don't want to have any particles around.
You have to test and characterize everything and once again and once again.
And you have to document everything. Like more than everything.
So this are some pictures of my lab.
On this side, you see a characterization setup.
In our lab, it's not clean room, yet!
We are not working on a satellite mission, it's just a sounding rocket.
But we wear these funny lab coats and funny hats.
So maybe you see that person there in the middle, it's a colleague of mine.
If you see that: "Hello!" :)
And on the other side it's the integration station, of our lasers.
And some setup around to characterize everything.
So, just to show the result of our effort.
It's a semiconductor based master oscillator power amplifier, of the size of that.
Its like 8 centimetres long and 2.5 centimetres wide.
It has nor movable parts and it's a specific wavelength, cause we need that for our application.
We want to cool down rubidium.
It has an output power greater than 1.2 Watts.
So, how much is that?
Well, a laser pointer has a 1 milliwatt.
An illegal laser pointer has 100 milliwatt.
And this is ten times stronger.
And the efficiency we have now is 22%.
When we fuck of the wavelength, when we don't care about that at all, than we can achieve an even higher efficiency and a higher output power.
But in our application the wavelength is mandatory.
So now, when it comes to testing you need some documents telling you, what to test.
And how to test and so on.
So, there are a couple of standards and most of the standards are based in the military sector.
The standard which is very important for us is, for example, the MIL-STD-883.
Which describe test methods of micro circuits and thats a really huge document.
It's about 630 pages thick.
And it describes the purpose of a test, the apparatus, the test conditions and the procedure and the failure criteria
...of environmental tests, of mechanical tests and of electrical tests.
So in this picture down there you see our laser system.
The silver cube is the entire laser system, we have in our experiment.
It contains 8 lasers and a spectroscopy module and a switching module.
And this setup is on a shaker.
So here we are performing a random vibration test on acceptance level.
And we passed. So I'm very, very happy about that.
And of course there a lot more tests we have to perform.
But it looks good, so far.
So now we have our hardware, what else can we do with that than building weapons and atom interferometers?
Of course we have the interferometer is a very common application.
Just to name the LIDAR system, it's a combination of radar, but with light.
And this one is used for as alterometer(?) for example.
Or to map surfaces. For example of some distant planets, of the moon, of the earth, of whatever.
Systems are sending out a beam
and they are analysing the reflected beam concerning the phase shift
and than they now how far the reflector is away.
And with that you can measure very precisely distance.
You need that for example in docking operations. In the picture up there you see the ATV satellite docking station.
I think it was in 2007. You have several other satellites, for example mapping the planet.
Ant there is also another mission I would like to point out.
This is the LISA mission, which wants to point out gravitational waves.
Unfortunately the LISA project cut down. And now it's just LISA Pathfinder.
A proof-of-concet mission, which is scheduled in 2015.
But there are of course a lot of more applications, I just picked out some which I fond interesting.
Spectroscopy is also a very nice application.
When it comes to spectroscopy, you analyse the beam concerning of the absorption or reflecting photons coming back.
So you are also sending up a laser beam and it comes back and you simply look what is coming back.
And with that you can analyse matter with a chemical composition of matter around.
For example on Curiosity, the Mars rover they are looking for methane gas by spectrography.
So they have at least two spectrometers on board of this little guy.
And another application which gains more and more importance in space are optical atomical clocks.
It's a time keeping device, but optical clocks operating with lasers are even more precise than radio operated ones.
And there are some new generations of optical atomic clocks, cause they are even more precise in space.
For example there is the ACES mission, which is a french mission, which was scheduled at the end of this year.
Unfortunately a newer launching date, but I think it won't be launched next year.
Maybe you know even more than I do.
And there is also another mission called X quest, which is still in preparation.
So, this is everything I have on measurement.
Free space optical communication is maybe an application3, most of you know what it is.
You have your optical carrier, the laser beam,
and you modulate you data either with phase shifting or with binary on-off keying.
The binary on-off keying is the most common one.
Compared to the commonly used RF-transmission you can go over longer distances,
it needs less power and you have a higher transmission rate.
Still it depends on the weather and the atmosphere on earth, when you want transfer data down to earth.
As an example I can name the Laser Communication Terminal.
It's build from TISAD(?) and it was first tested on the satellite ARTEMIS.
It had a downlink and an intersatellite bandwith of 50 Mbps. This was in 2001.
In 2008 there was another inter-satellite connection between XXX and XXX and they received 5.5 Gbps.
There's also another US mission ongoing. It's called the lunar laser communication demonstrator mission.
On the lunar atmosphere dust environment explorer. This was launched in September this year.
And in October they received a downlink of 622 mbps. So this is state of the art right now.
So, that's everything I have... I still think lasers are cool!
And I hope you agree with me that there are a lot of applications for lasers in space.
And I also think that reaching space is challenging, but it's not impossible. It's pretty doable actually.
There are some initiatives for non-professionals or for - I'm not sure how to call that - for you, for everybody.
For example the amateur radio satellite organizations. They are worldwide.
There are for example the rexusbexus experiments. These are sounding rockets and balloon experiments for students.
There are for example the cubesat projects. They design satellites of the size of one liter, like that size.
And they can go as piggyback payload, for example on commercial satellites.
So this is an opportunity to get to space pretty cheap.
I also want to name the Google Lunar X Prize with the part-time scientists as the last German team (I think).
They want to build a lunar rover and there are also a lot of other initiatives and projects which you can find.
Thank you.
[Applause]
Thank you very much, Anja. Thank you very much.
Now if you have questions, could you please line up at the microphones so we can record it?
Our signal angel, do we have questions from the internet?
- No, not right now... OK, then let's start with microphone 1.
There is basically one thing: The French device is going to be launched in 2016. - OK.
And another thing... it's a double question actually. First of all: Why do you go in microgravity with [?] What do you promise yourself from that?
The plan is to find the answer to the question whether Einstein's equivalence principle is still correct.
The main goal is to go up with 2 species up there, measuring the gravitation, and compare that.
And we need to go to space because it's more precise measuring up there. You have a longer measuring time.
And another thing: I happen to know some friends of mine who work scientifically with lasers, and the alignment ends up to be depending on everybody working on that field...
...professors touching random stuff and the experiment is ruined. How exactly do you harden a setup for launch?
I mean you have the G-loads, you have vibrations, you have random stuff happening... So how do you do that?
I mean it's a quite sensitive setup if I'm not wrong.
It's a very sensitive setup, that's true. But when you know that it has to work autonomously from the beginning, you can design it to make it independent of professors running around touching things, for example.
Yeah, that's not the thing... How do you cope with misalignment for example. I mean you will have some mirrors, some beamsplitters or whatever... and if they get moved, that's it.
- We use very very small components like very very small lenses and we glue them, we fix them on a bench, so you can't align them anymore.
When we are integrating our stuff, then we're aligning that actively. So the laser is switched on and then we align the components that the output is what we expect it to be.
OK, let's have a question from the other microphone over here.
First of all, thanks a lot for the straight overview talk. I just have a very quick remark about the Lisa mission.
I'm very happy to announce that just recently we got fully funded by the European Space Agency and in 2034 we will fly with a 1.2 billion dollar budget.
- Which mission?
- The Lisa mission.
Congratulations. Go ahead, please.
My question is about... when you shoot something up and make experiments, you probably won't shoot one satellite for only your project.
So are you working together with other departments and then you... like everyone gets one square meter for his experiments and then you shoot them up and all experiments run independently on one satellite?
- It depends on what you are doing. In our experiment we have one rocket just for our experiment, but it's not just an [...] institute building that stuff. It's a cooperation of a lot of institutions and universities.
And when it comes to these experimental satellites, they very often go as piggyback payloads, that means you have a commercial satellite.
For example a communications satellite which is launched anyway and they're normally much smaller, so they're sitting just on the side and wait for the launch.
When we're talking about piggyback payloads: Don't you have space trash problems because you can't just say people can go and shoot stuff up there if there is one space trash problem anyway?
- I'm not sure I got the question...
You say for example I could just build something and shoot it up as a piggyback payload...
- Well, it's unfortunately not that easy of course. But it's not impossible.
Like some years ago or some decades ago, it was impossible for a private person to even think about building your own satellite.
But you need some funding, you need a group basically and maybe you're lucky and you'll get to your goal at the end.
- So I can't just... if I get to build the rocket myself and shoot it up... Is it allowed? Just from the law?
- I don't think so...
- OK.
- I have one question: You mentioned the mission concerning analyzing the moon dust and this moon mission.
But you didn't mention who was the partners - is it a project by ESA, is it a project of a cooperation of several agencies or is it a private...
- It's a NASA project.
- Ok, thank you. And then another question: A lot of [?] come down by Gigahertz and those frequencies are also reserved for astronomers.
Do we have some feedback from the astronomer community, are they concerned that their frequency will be less and less laser communication we will get... other optical applications or other laser applications?
What's the standing point of the astronomy community? Because they're also using the high frequencies in the 5.5 Gigahertz.
Um, I have no feedback on that...
OK. Any more questions from the internet? How about our signal angel?
No questions from the internet. OK.
Then, Anja, once again: Thank you very much!
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