As for the presentation, topics will include an overview of what the Google Lunar X-Prize is all about, details of the mission, status quo of the rover’s development, FPGA development, lander concepts as well as details on our side project ComRay.

In addition, attendees will be witnessing a “world premiere”: for the first time ever, moon rover Asimov Jr. will be operated in front of a live audience!

If you’re located in Hamburg or the surrounding areas, you have no excuse to miss out!

For further details on time and venue, please visit the Attraktor’s homepage (available in German only):
http://www.attraktor.org/

We look forward to seeing as many of you as possible!

Moon Day-/Nighttime Temperature Map; © by NASA

Roving on the moon can be a toasty experience, or a chilly one. The minimum temperature on the lunar surface is -183°C (90K) and the maximum +117°C (390K). This extreme environment can cause significant stresses to the technology used on the moon. One specific stress is due to exposure to the Sun’s radiation. During the lunar day, the Sun is shining from above and is also being partially reflected back up from the lunar surface. Ideally, we would like to keep as much of this heat as possible outside of the rover. In addition, there is heat being generated by the electronic components inside the rover. This heat must be transported to the rover’s surface where it can be radiated away. Thus, the rover should be designed so that the radiation from outside is reflected away while the heat from inside is brought to the surface and then radiated to open space. To understand how this is accomplished, we need to have a closer look at how most materials respond to heat and radiation.

In this picture you can see the spectrum of the sun and the amount of energy it emits depending on frequency of radiation. The sun itself is a so-called “Black body” and emits the most energy at 5777K, which is a nice bright blue color. The electronics on the other side emit most of its energy at 1000K and below. © by pts.com

When radiation strikes a surface, its energy is reflected, transmitted, or absorbed. In addition any surface will emit radiation. When radiation is reflected, the energy is immediately sent back out into the environment. Transmitted radiation will pass through an object with little or no modification, that means, you can see through it. Radiation energy, which is absorbed by a material, is typically converted into heat energy (or electricity in the case of solar panels). Any material that absorbs radiation is also capable
of emitting radiation. The emitted radiation is typically of the same spectral characteristics as the absorbed radiation. If an object is absorbing more energy than it emits, then its temperature will rise. If an object is emitting more energy than it absorbs, then its temperature will fall. Thermal equilibrium is obtained when the amount of energy emitted by an object equals the amount of energy absorbed by an object. For example, the lunar surface achieves thermal equilibrium at 117°C (390K) when exposed to sunlight, and -183°C (90K) in the shade. The temperature at which thermal equilibrium occurs is dependent on the properties of the material and the spectrum of radiation to which the material is exposed. Thus, the temperature of the surface of the moon is dependent on the material properties of lunar regolith and the spectrum of radiation from the Sun.

A rover on the surface of the moon must be constructed out of materials which behave properly when exposed to the radiation environment of the lunar surface. Ideally, we would like to build the rover out of a material that would be able to reflect the most of the spectrum of the sun on the outside while absorbing very little. On the inside, however, we would like there to be very little reflection or absorption of the infrared radiation generated by the heat of the rover’s electronics. Unfortunately, we cannot have it both ways. A material which reflects infrared light from the outside will usually reflect on the inside as well. A rover constructed of this kind of material would turn into a wonderful oven, heated from the inside by its own electronics.

The challenge is to find materials that reflect the spectrum of radiation from the sun, which is predominantly in the visible range, while also absorbing and re-emitting the spectrum of radiation generated by the electronics, which is primarily in the infrared range. We then rely on the ability of the material to reach thermal equilibrium between the infrared radiation being absorbed from the Sun and the electronics with the radiation being emitted by the material back into empty space, which has a temperature of about -271°C (2K).

Surveyor 1 send to moon prior to Apollo missions; © by NASA

Previous NASA missions often used white or silver materials on the parts of the probes that were exposed to light. Other candidate materials include anodized aluminium and gold. Aluminium will typically reflect most of the visible spectrum, but will absorb and emit infrared light. Gold on the other hand reflects infrared through red and orange light and absorbs blue through violet and ultraviolet light. In summary that means: Gold keeps you form getting an cold and Aluminium prevents you from heating up in the sunlight. So for a rover you would use anodized aluminium on top of the rover to reflect the sunlight, absorb the heat from inside and emit it to space and on the bottom gold evaporated foil would be perfect as there’s almost no direct sunlight but infrared light.

Historically, the spacecraft which most closely resemble the rovers being designed for the Google Lunar X-Prize are the Surveyor probes launched by the United States in preparation for the Apollo missions. For more information into the topics discussed in this article, we recommend the following paper available from the NASA archives (page 181ff): Surveyor Program Results.

Authors: Arne Reiners & Daniel Ziegenberg

OK, we know a lot about footsteps on the moon, but how much do we know about wheel tracks on the moon?

We were facing the exact same problem when we first started working on our rover prototype “Asimov Jr.” Designing the wheels of a lunar rover may seem like quite an easy and intuitive thing to do: they’re supposed to be round, as light as possible and they gotta have good traction. Well, things actually weren’t  t h a t  easy …

Let’s start the game by piling up some sheets of paper and call them “mission statement”. Sounds boring? It certainly is. But without such a statement you’re most probably going to sift through various wheel designs for, like, two years, without ever getting to a result.
What’s important is to figure out the conditions of where your wheels are supposed to operate. The rules of the Google Lunar X-Prize state that you have to rove at least 500 meters over the lunar surface and, ideally, survive a lunar night. Key facts for us are: we aim for a landing on a lunar day, which means it’s going to be real hot with temperatures of up to 125 degrees C (that’s 257 degrees F for you imperials and 398.15 degrees K for you trekkies). Second, we plan on landing close to the equator, for compared to the poles the equator is as smooth as a freshly built parking lot and far easier to overcome than the cluttered landscape of the lunar poles. If Asimov Jr. is to survive a lunar night, the wheels need to withstand extreme temperature shifts in the range of +125 to -125 degrees Celsius(-193 degrees F and 148.15 degrees K).

Now, let’s discuss our options a little bit. Air-filled rubber wheels are probably best known, but their fate on the moon – and on space flights – is pretty much doomed. Due to the vacuum, the wheels would explode and burst into pieces. Even without the exploding part, the rubber would soon “vaporize into thin vacuum” due to its outgassing properties. “Outgassing” basically means that all materials contain a certain amount of air, and in space this enclosed air will do anything to break free, destroying the rubber in the process. The amount of enclosed air particles and their behavior defines the material’s distinct outgassing properties.
What about non-air filled rubber wheels then? They perform somewhat better when it comes to outgassing and, of course, they wouldn’t explode, but the extreme temperature shifts would pose a big problem. It’s like pulling a piece of rubber out of the freezer and putting it right into a pre-heated oven: the result isn’t gonna make up a wheel anymore.
Now, let’s skip materials like wood, plastic, steel or iron, and let’s take a look at aluminum.
Aluminum is light as a feather, plus, it is robust and tolerant towards temperature extremes … congratulations! You found yourself a suitable material!

OK, so we handled the temperature. The only thing left is the roving around the lunar equator. The lunar equator is quite a special place in our solar system; the complete lack of an atmosphere means there’s a complete lack of wind, too. The best word to describe the lunar surface is probably: debris. After 4.6 billion years of constant galactic bombardment, the lunar surface is covered in layers of dust which are between 5 to 10 meters – or 16 to 32 feet – thick. Since there are no currents and winds, moon dust has different properties than ordinary earth sand. While a footstep on the beach is gone within minutes, the bootprint of Neil Armstrong was kind of made for eternity. This is due to the characteristics of the particles. Sand grains are round and electrically neutral. You put some on your hand and they will rain down through your fingers. Regolith grains are more like spikes meshed together and they’re electrically charged. You put some on your hand and you just won’t get rid of them easily. But what does this mean for our wheels?
Travelling on wheels is always about good surface traction. The goal is to design the wheel pattern in a way that the wheels have the least weight and the best traction. And in this environment: don’t get clogged up by regolith.
There is no distinct answer on how to find the perfect wheel pattern. The only thing for sure is that using the wrong wheel pattern can leave your rover digging itself deep into the regolith without moving an inch.

We did a lot of regolith and traction surface simulations using SolidWorks and ended up with almost 50 suitable designs. We picked out the most appropriate one from an engineer’s point of view and had the wheels for our prototypes manufactured accordingly. Towards the end of the year, we will be conducting extensive tests with synthetic regolith in different testing facilities. Among the best-known experts in the field are the folks over at the California Space Authority. They have a large and realistic testing site designed for the Lunar Excavation Challenge. If you’re interested in synthetic regolith and cool video footage, just visit this site: (link), or drop them (link to matts official page) an email.

Umm … I got a stupid question!
I mean, if the environment is so complicated … why doesn’t everyone use the exact same wheels?

Well, as with every problem, there are always multiple solutions.

For example, let’s take a closer look at the wheels of the LRV – the Lunar Roving Vehicle, or simply: the Apollo rover.

As you can see, its wheels look as if they were made of rubber, but in fact, they do not contain any plastic at all. They consist of a composite mix of materials, starting with a basic frame of iron and ending up with a mesh of woven piano strings to provide the needed traction. They behave like normal rubber wheels but have the distinct advantage of being more lightweight than filled wheels. As the landing module had already reached its weight limit, those wheels were deemed the best option. Mixing multiple materials to composite materials can lead to a much stronger structure. However, most composite materials need time, intensive development and testing to survive severe temperature shifts.
So, why has it worked for them?
As the Apollo missions only took play during the period of a lunar day, the wheels didn’t have to survive a lunar night. It is most likely that by now the the wheels of the LRV would have dismantled completely.

In other missions with longer lifetimes, NASA/JPL and Russia tried out different wheel designs based on groups of meshes supplying the needed traction. The main reasons for this design change were again weight savings. Cut down costs and spare weight for scientific instruments, while reaching for an extended mission lifetime. The only drawback is that their wheels behave pretty much like tracked wheels, meaning they got a lot of junctions and thus single points-of-failures. All these potential points-of-failures need to be checked and certified to withstand the stress of launch and descent.

As for our wheels and their design, you can we keep up on that by following us on Facebook, Twitter or by reading our blog. The first test results and footage will be available for you by the end of August!

To learn more about wheels on the moon take a look at the following sites:

Science – HowStuffWorks.com

Wikipedia – Apollo Lunar Rover

Wikipedia – Lunokhod Rover

Rockets: not subtle.
Rocket science humor, on the other hand … Let’s clear up a few things with the IPv6 protocol and packets in general.

First of all: address space.
With IPv6, one can uniquely identify 3.4*10^38 items. Now, if we take all the solid components of a rover and lander and compress them together, it would make about 1 cubic meter. If that were entirely aluminum, there would be only 6*10^28 atoms. Without revealing too much, I can tell you we will not need 5 billion network addresses for each atom in our rover. In fact, to add perspective: someday, when we make the sun itself a fully functioning space station, IPv6 will let us support 200 billion network devices per cubic meter! So, we’re going to use a much smaller address space in our packets.

But, why bother with a smaller address space?
Let’s review some rules of good packet design:

Easy to route in hardware.
Simple (i. e. easily validated and verified) hardware should be able to move packets between subsystems without requiring mission-specific knowledge of the contained commands. While an address-free packet is technically smaller, using knowledge that commands such as “drive forward” only apply to a rover not to a lander, it rapidly explodes the testing work and greatly adds to risk.

Error corrected.
The physical transport of information can lose data. At a minimum, a system should be able to detect an error in a packet. Given the time delays and expense of a space mission, a system should be able to correct a little more than the expected typical error rate.

Minimum overhead / Maximum data to wrapper ratio.
Each bit sent into space is a chance to lose data. To send as few bits as possible, send as few packet wrappers around data as possible. An ideal protocol will vary this ratio depending upon quality of service feedback.

There is a balance between these design parameters.
For instance, most error correction schemes provide M bits of error correction for every N bits of data. Thus, there is a maximum packet size at which protection drops below mission standards. Sending very small commands makes for excellent error correction, but means more total bits sent into space and more chance for out of sequence or dropped packets, complicating the network software layer. Combining commands can increase overall throughput but reduces redundancy in the error correction. In addition, IPv6 is very easy to route with tested hardware and software already existing, but as it is larger than most commands, it significantly weakens error correction.

One must also consider mission timing.
When is your deadline and how long will the equipment remain operational? Equipment that will remain operational for many years will be valuable as a communication hub and should strive to use open standards. Short duration equipment, especially on a deadline, needs different engineering tradeoffs. Simple, robust FPGA designs are our preference. For now, we won’t be using the IPv6 headers on our packets, but we look forward to a future with a standards-based space communication network.

Once you’ve got a packet layout, you can work on a protocol, defining timeouts, forwarding, delay tolerance, and authentication. Seek the generalities within families of protocols. You’ll find hotly debated topics often to be single variable changes in the final code. Just remember that your goal is to reliably move information through space. Not on the ground and not within a subsystem in a rover, but through space!

If you are interested in everything around deep space communications, stay tuned!

Wes Faler
A Part-Time Scientist

With a well-prepared presentation, you can impress bosses, convince customers to buy your product, get support for your project or simply tell everybody what you think needs to be done. Giving a good presentation is therefore important for you, and vital to the topic you’re presenting. Why can presentations become scary to everyone involved?
As a casual presenter, you may be an expert on the subject at hand, but
are anxious to speak in front of an audience of strangers. The audience, on the other hand, might be having a hard time to catch up with slides packed full with information, while the monotonous and mumbling voice of the speaker seems to be of no help, either.
Then what makes a great presentation?You know, the kind of presentation everyone is talking about. To my mind, giving great talks is not at all reserved to the few among us who can sell refrigerators to Eskimos.

A good presentation is not about the speaker.
It’s about communicating ideas and igniting the audience!
Pragmatically spoken – less is more!
Even if you’re an expert speaking in front of experts, this is no excuse for misusing slides as transcripts.
Try to be passionate, the way you would when talking to friends about the subject!

… and how we almost failed to deliver a good one!

OK, let’s talk about our presentational endeavors now.
Back in December 2009, our team, the Part-Time Scientists, got invited to give a presentation at the 26C3 Congress in Berlin. It was the single biggest event for all of us speakers. I was obviously one of them, and I’m going to let you in on what went wrong and what went well.

As we wanted to have an expert for each subject – aerospace, engineering, development and organization – we split the presentation into four sections and settled for a two-hour time slot. Three weeks before the presentation, we started working on the slides. To cut a long story short: the four of us ended up preparing tons of notes and page-long text files with information. Then, shortly before the conference, I got myself a copy of the book slide:ology. A good friend of mine had found it on Safari Online. Slide:ology deals with all the things that can ruin your presentation, and shows how real experts do their preparation.

We threw all our text files overboard. We reworked the slides and made them as plain as possible. It was a hell of a lot of work, and in the end, we had two days left for practicing. The amount of last-minute adjustments, however, left me with almost no time for practicing, plus, I got no more than two hours of sleep the night before the presentation!
Not everything worked out as expected but …
against all odds, our presentation went quite well!
And we had learned our lesson.

To give a good presentation, you should:

1. start preparing right away, even if the deadline is three months away.
2. spread the word via Twitter, Facebook or any other medium.
3. invest a good amount of time working on the slides. My advice: do check out slide:ology!
4. practice, practice, practice! The minute you finished your first slides, try to practice with them using a timer. What really helped us was recording our trials on webcam. Be yourself and be authentic.
5. Try to get sufficient rest! If some of your slides aren’t perfect, just leave them that way. You’re the expert, you’re the speaker — your slides won’t change anything about this.

And always remember – have fun!

Robert – a Part-Time Scientist

The last couple of days have been crazy. There’s no other word for it.
Almost every core team member made it to Berlin for the 26C3. Some came from France, Austria and even Hamburg. The presentation went rather well. Most of us are technicans and not used to speaking in front of a big audience. And by big I mean 2000 people in front of you and potentially tens of thousands on the internet.
But you know how you get to Carnegie Hall. Practice.

The feedback has been great so far. A lot of people joined us at our booth after the presentation and asked us out on everything. From minor technical problems to why we’re not selling T-Shirts(We had something prepared but time threw a monkey wrench in our wheels. Expect some sort of webshop in the near future.) Speaking of website. A new one will be up soon. With more ways to let you know what we are up to. For now you can find additional informations on Twitter .

Expect some video content on a tube near you soon.

Cheers
Sebastian

The first 50 years of human spaceflight were marked by explosive growth, culminating with 14 men exploring the surface of the moon, followed by 40 years of relative stagnation.

We need an open frontier.

Open frontier? Like wagon trains and Star Trek?

By open frontier we’re talking about a society that participates in space exploration. Commercial, government, and private organizations all have reasonable access to explore our solar system and beyond. Ok, so it is a little like Star Trek.

Our cultures, at least in the US and most of Europe, assumed that our Governments would open the space frontier for us.

We sat back and waited.

We are nowhere near where most of us dreamed we would be. Several generations of people have had to drastically alter their dreams of a space faring culture.

We aren’t sitting on our hands any longer.

Today, we live in a remarkable world. We have global communications (the internet), technology, computing power, and commodity resources one could only dream of 20 years ago. Robotics components are available at prices in the tens of US Dollars, not the millions of Dollars of the 1960’s.

The participants in the many space related prize competitions largely popularized by the X-Prize Foundation all realize that there is something the average person can do to advance our society into space. We don’t need to wait for a government or large company to enable space exploration. We believe that a small group of dedicated people with diverse backgrounds and even different countries can accomplish meaningful missions that ultimately change the dreams of our generations.

We believe in action.

When I talk about PTS, reactions are always the same. One group is enthusiastic, but hardly believe in success. You get a few nice words and a friendly smile of disbelief. The second group think you are nutty as a fruitcake. You realize that by the way they avoid eye contact. Only a few belong to the third group of the really interested people. They are the ones who want to know everything about the concept, even about minor trifles.

Those are my favorites, they are the most important people, they are like me and all the other PTS members!

Recently, the question arose why we’re doing all of this. Everyone in the team have their own answer. Often it depends on the origin. The common element is the thirst for knowledge, the curiosity! Nothing´s more encouraging! In connection with a competition, it is even better! May the most inquisitive win! From this perspective, we have the best chance! Our team is not only the youngest, it is also the most inquisitive, and we WANT to go to the moon!
As winner of the X-Prize, as the first German team (even though we are on the way to becoming international, which is really great), as the first almost entirely privately funded team, as the first European team, as the first team not supported by a large space agency etc. Enough motivation for a contest! We have the ambition to take this competition and win!
The prize is not only material terms, but the gain in knowledge. The curiosity can not be satisfied! As long as space is out there, people will try to explore it!
Just when such people are coming together on PTS or certainly on other teams.
By the time we will have achieved our common purpose, doubters and those who think we are insane will have disappeared.

Until then, WE ARE LUNATICS … and proud of it!

Michael
A Part-Time Scientist

As I’m starting to write this it’s 40 years ,19 hours ,42 minutes and 19 seconds
after a 32 year old guy from Wapakoneta Ohio set foot on the moon.
105 years, 7 months, and 4 days ago another 32 year old guy from Ohio flew a self-made plane over a field in Kitty Hawk, North Carolina.
“So what?” you may ask…

Guys in their early 30s from Ohio apparently aren’t too comfortable on the ground it seems.
They do their very best to get as far from the ground as possible. But bear with me.
40 years after that flight over Kitty Hawk there were over 130 commercial airlines world wide.
Making it possible for anyone to fly around the world!
Now it’s 40 years after the most powerful and wealthiest nation in the history of the Earth put someone on the moon.
And there are only 35 private companies working on space-flight.

I don’t know about you, but I think that’s not enough.
So why is space-flight taking it so slow while aviation literally took off?

Michael over at evadot.com has his own thoughts on the matter. evadot.com

*And I agree.*

As soon as the government decides to lead the charge, things slow down.
Contrary to a government agency, private enterprises are willing to take risks.
They’re not burdened by a bureaucracy of epic proportions.
I could go on for a about another 100 pages. But that would be boring.
The numbers speak for themselves.
(There’s an interview with us on evadot as well.)

And now to a more happy piece of news.
Because the times they are a changing.
It’s been a month since our official entry in the Google Lunar X Prize.
I’m happy to announce that the Part Time Scientists reinforced their numbers by 7.
6 guys and 1 girl from around the world joined us in our effort to get private people into space exploration.

Here they are in no particular order:

Nicholas Schmidtke from Canada.
A math and science whiz with a degree in philosophy.
He’ll start studying Aerospace Engineering soon.

Armando Gonzalez-Rodriguez from Puerto Rico.
A mechanical engieer student who had his eyes on the moon for quite some time now.

Marco Testi from Italy.
Another engineer who has been working on his own R&D projects since 2003.

Julio Gonzalez from Guatemala, currently Germany.
He’s a Software Developer/Electrical Engineer working in software integration.

Hollye Merton our very own Bachelorette of Science in Information Systems Management,
a Master of Science in Technology Management and twenty years worth of experience in electronic communication from the U.S.A.

Stephan Günther from Germany, currently Spain.
A Professional Pilot/Software Developer who programmed numerous simulation programs including a Lunar Lander.

Jan Dressler from Germany.
A experienced T.V. Producer with many of ad campaigns under his belt.
He provided us with a lot of great insights on how to present ourselves.
Hope we’ll manage to put some of his ideas into practice.

Also a special thanks to David Barkman who helped us a great deal with research.

These dedicated few make great additions to the team.
But we’re still open for anyone willing and able to help.

Sebastian
Team Part-Time-Scientists

So, back in the middle of last year we were throwing ideas around on how to get to the moon.

One of the first ideas we looked into was the Rockoon. Like the name says it’s a combination of a rocket and a balloon. We thought it would be innovative and cheap.

It wasn’t a bad idea. But after some number crunching we figured out that the whole thing had a terrible catch.
And here is why:

Used in late 40s and 50s, Rockoon was used to transport very light payloads to altitudes that are near the edge of earth’s atmosphere. But to carry a full scale moon rocket that high, the balloon would have to have proportions beyond any economical sense.

1 m³ hydrogene or helium can lift something slightly above 1 kg of mass.
At sea level. But when it goes up, the air-pressure halfves every 5500 m.
Therefore the gas doubles its volume. At an altitude of 49.5 km, the gas will have expanded by a factor of 512.
The diameter of the balloon would be 8 times bigger as it’s been at sea level.

Now let’s take a very optimistic mass of 250 kg for a rocket. For that mass the balloon needs 250 m³ of hydrogene or helium. That results in a diameter for the balloon on the ground of 8 m. Growing to 64 m after the ascend. At first that doesn’t sound too bad. But now let’s see the gain of energy the balloon delivered.
We took 250 kg and brought them up to an altitude of 50 km.
This equivalents to 123 MJ (250 kg * 50000 m * 9.81 m/s²).
The energy density of hydrogene is 11.7 MJ/m³.
This shows that it’s not a bad idea to burn all that hydrogen with a rocket instead.

More interesting is the ratio between the gained potential energy and the energy required to reach the earth orbit. A Mass of 250 kg traveling at 7.9 km/s has a kinetic energy of 7800 MJ ( 1/2 m v² ).
Now let’s think of the energy needed to send a rocket into earth orbit as a 100%.
The energy that the balloon brings into the whole equation is a mere 1.58%.
However, it’s a different story with a balloon. Considering the Rockoon approach to the entire matter greatly complicates things. Increasing the number of variables that can lead to a total failure of the launch.

That’s not even taking into account that the balloon will go where the wind pushes it and not where we want it to go.

One argument for a Rockoon is less air drag. For larger rockets the velocity loss due to air drag can be lower than 3% (1). A small rocket has a higher drag, that is one argument more against small launch vehicles. It makes more sense to modify an air-air-missile and to launch it form an airplane flying at Mach 2.5.
But even that only accounts for less than 1/8 of the needed speed to reach earth orbit. The fact that private people will have a hard time acquiring an air-to-air-missile is a matter for another time.
The conditions are still better than with a balloon, though.

Arne Reiners
A Part-Time Scientist
(1) Space Mission Analysis and Design 3rd Edition Chap. 18.1
_The article image is provided by ICHC