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

Watch the almost HD-Version.

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

Was die geplante Mondmission anbelangt, greifen die Part-Time Scientists für die meisten benötigten Metallteile auf Know-How und Engagement der Erich Huber GmbH zurück. Als besonders positiv erachten die Ingenieure des Teams die Tatsache, dass bei der Fertigung enge Toleranzen eingehalten werden können. Da man bei Erich Huber auch bereit ist, relativ kleine Stückzahlen rasch zu fertigen und zu liefern, ist für das engagierte Projekt ein effizienter Arbeitsablauf gewährleistet. Der im vergangenen Monat auf der Internationalen Luft- und Raumfahrtausstellung in Berlin präsentierte Mondrover-Prototyp war zwar noch im Rapid-Prototyping-Verfahren hergestellt worden, bestand also größtenteils aus Kunststoff, doch einige Komponenten kamen schon aus dem Hause Erich Huber.

Deren Weltraumtauglichkeit zu überprüfen wird demnächst Aufgabe der Part-Time Scientists sein; so muss etwa sichergestellt werden, dass die Teile bei den enormen Temperaturschwankungen auf dem Mond wie berechnet funktionieren. Auch die Räder von Mondrover „Asimov Jr.“ stammen – wie einige im Inneren verborgene Teile, darunter etwa Encoderscheiben – aus der Fertigung Erich Hubers. Für die Räder werden Traktionstests durchgeführt, die zum optimalen Profil für die Fortbewegung auf der staubbedeckten Mondoberfläche führen sollen. Somit wird die Erich Huber GmbH durch die Partnerschaft mit dem Google-Lunar-X-Prize-Team ihr Produktportfolio im Bereich Raumfahrt insgesamt ausbauen können.

But let not make this to easy on you, to give you hints on our future developments you will have to look into one of our Flyers.

You can find all Flyers we used at the ILA in our Media Section.

Let us welcome this second year of Rocket Science with a loud

To celebrate we’re giving away free Part-Time scientists shirts on Facebook somewhere along this week!

If we cought your attention follow us on , or our team Blog.

Auf der diesjährigen Internationalen Luft- und Raumfahrtausstellung in Berlin kann mit dem zweiten Prototypen von Mondrover „Asimov Jr.“ schon ein wichtiger Bestandteil der Mission besichtigt werden. Bestückt mit Solarpanel, Kameraturm und Antenne wird Asimov Jr. hochspezialisierte Aufgaben ausführen und das unter extremen Temperaturen und erhöhter Strahlungsbelastung. Dabei kommen jeweils Leiterplatten mit hohem Glasfließtemperaturwert zum Einsatz, die gegebenenfalls flexibel oder für Hochfrequenzanwendungen geeignet sind. So könnten die Leiterplatten der LeitOn GmbH künftig das Prädikat „weltraumerprobt“ tragen.

Die LeitOn GmbH – das Silbenkurzwort „LeitOn“ steht für „Leiterplatten-Online“ – wurde 2004 gegründet. Seit 2006 besteht eine Niederlassung in Hongkong. 2007 wird das sogenannte „Ocean-Konzept“ eingeführt, das Kunden vielfältige Möglichkeiten bei der Onlinekalkulation bietet. Auf den mit einer Ausdünnung von Herstellern einhergehenden Strukturwandel in der europäischen Leiterplattenindustrie antwortet LeitOn 2009 mit dem Bezug neuer Büroräume und der Eröffnung einer Niederlassung in Mexiko. Die konstant positive Umsatzentwicklung gibt LeitOn durch soziales Engagement an Andere weiter. Auf der ILA werden die Part-Time Scientists daher gerne als „Botschafter“ für das Unternehmen agieren: Vom 8. bis 13. Juni werden in Halle 9, Stand 305a LeitOns Produkte einer breiten nationalen und internationalen Öffentlichkeit präsentiert.

Almost one year ago, coinciding withLinuxTag 2009, we officially became competitors in the GLXP. This year’s LinuxTag is coming up soon, and we decided to descend on the Internationales Congress Centrum Berlin after last years visit again.

This time, though, there will be a presentation by our very own embedded development and communications expert: Arne Reiners.

At the core of the presentation are FPGAs, field-programmable gate arrays. What these “re-programmable chips”, in more general terms, can do, how they can withstand the harsh lunar environment and why they’re the future of space hardware will be explained in detail by Arne. He’s hoping for lots of questions, so please bring your thinking caps!

When and where?

LinuxTag 2010, Friday, June 11, 5:30 pm – 6:00 pm

or on YouTube shortly after!

We hope to see you there!