September 6, 2010

Some 3-D pictures of the cloud chamber, modelled with Google Sketchup:









The CO₂ supply to drive the expansion diaphragm is a modified CO₂ bike pump with integrated pressure reducer.

August 31, 2010

Two pressure sensors have been tested for our upcoming weather balloon experiment:

- Sensor A: Intersema MS5541C, 0..14bar - Sensor B: Intersema MS5540C, 10..1100mbar

Both sensors have integrated temperature sensors for temperature compensation. The sensors are factory calibrated with calibration values stored inside the sensors. The software reads out the temperature and calibration values and corrects the raw pressure values accordingly.

Two sensor boards were connected to laptop; both boards started simultaneously. Measurement started on 17th floor, then the elevator moved to first floor, up to 25th floor, down to B2, up to 25th and down to 17th.

The time in the plots below is not measured in seconds but in a Δt of roughly 1/2s:





Interpretation:

Sensor A has a relatively large absolute error. Pressure readings are too low (compared to weather report). Error is within the specs of the data sheet.

Differential readings of the sensors are quite similar and plausible: 7.5mbar difference between B2 and 25th floor (floors 4,13,14,24 missing!)

Results on 17th floor at the beginning and at the end of the measurement differ. This is caused by imperfections in temperature compensation. Possibly the temperature sensor and the pressure sensor do not warm up at the same speed, although they are on the same chip.

The “skewed” shape of Sensor A’s data is caused by the same effect.

Author: Dr. Lampe

August 25, 2010

A second prototype of a Wilson cloud chamber for weather balloons has been built to test saturations, different pressures and temperatures, clearing field voltages, cameras, illuminations:



Good results were achieved with a line laser for illumination. The alpha emitter is on the top, the laser on the left side.





Prototype 3 to 4 is probably able to be launched with a 2 m diameter hydrogen weather balloon to capture cosmic radiation.

August 21, 2010

The picture below shows an initial Wilson cloud chamber design for weather balloons:



An interesting article in this regard was published in the July 1948 edition of Popular Science:



Full article

This movie in flash format, made from 25 single images, shows cosmic ray tracks in a homemade Wilson cloud chamber (Credit: Dr. Thomas Rapp, Rapp instruments)

August 19, 2010

Atom physics in a marmelade jar

A weather balloon is the poor man's satellite... A lot of new ideas popped up during the preparations for our first weather balloon experiment. One idea is to use an expansion cloud chamber to visualize the paths taken by ionizing cosmic radiation and sending the images and videos back to earth. The most common type of cloud chamber found is the diffusion cloud chamber. The diffusion cloud chamber operates continuously and is very easy to build, but has the disadvantage of requiring dry-ice. Instead of dry-ice peltier elements could be used, but they have high weight and power consumption. By contrast an expansion cloud chamber could be operated by a CO₂ -cartridge and two micro solenoid valves. Contrary to popular belief it is not very difficult to build an expansion cloud chamber and could be a fascinating school or college project as well. The picture below shows an expansion cloud chamber design with common parts:



The alpha particle source is Am241 from a dismantled ionization smoke detector. Water, methyl alcohol or ethyl alcohol vapor work too, but isopropyl alcohol is the best choice. The operating voltage for the electrostatic clearing field between the platform and the grounded wire loop at the top of the chamber is not critical, can be between 200 and 1000 V, but it's essential to the operation of the chamber. The best results we achieved not in abruptly withdraw the syringe plunger to drop the pressure, but compressing the air in the chamber first by the syringe, putting the squeezed rubber hose from the syringe and open then the hose suddenly to release the overpressure.



The following two photographs show typical alpha particle tracks. The alpha particle source is on the right. The photographs are individual frames, converted from the video. The tracks are displaced from the original paths by the air flow during expansion. As the tracks only last for a fraction of a second, we slowed down the video sequence 4 times.

August 18, 2010

First picture shows the finished ground station antenna. You see right, the frame is made from a large carbon fiber umbrella. The white material is actually just some thin paper used for easier handling of the wire mesh the reflector is made of. It will be removed later, but can be kept as a protection during transport. After removing the paper, wind can go right through the reflector so the wind load should be quite low. The diameter of the reflector is somewhere slightly above 150 cm. The man behind the ground antenna is in the true sense of the word Dr. Lampe from Siemens.




Second picture shows the sensor board. The little radio module is mainly used as a microcontroller but can also transmit a beacon for several days to help us find the payload. The little round white thing in the middle is the pressure sensor. One temperature sensor is hidden below the radio module, a second one can be attached with a wire. One of the left I/O pins will be used for the Geiger counter. The board will also supervise the voltage of the main battery so it won't deep-discharge.

August 18, 2010

Parachute test for weather balloon experiment with a payload of 1.3 kg and similar drag coefficient, dropped from 15 m:

August 15, 2010

The article below discusses the possibility of cargo delivery on the Moon via hydrogen - powered cannon again as well as the derivation of the muzzle velocity and the determination of the maximum muzzle velocity as a function of the combustion chamber length:

Cargo delivery on the Moon via hydrogen - powered cannon



Text edit was done by Peter J Brown. Thanks again.

August 12, 2010

The picture below shows the Geiger counter prototype for our weather balloon experiment to measure the cosmic radiation in different altitudes:



The Geiger counter weighs only 41 g and draw just 10 mA at 5 V.

The Geiger tube has a mica window for alpha radiation. To test the Geiger counter we used americium-241 from a dismantled ionization smoke detector. Americium-241 is a so called alpha emitter and has a half-life of 432 years. About one percent of the emitted radioactive energy of ²⁴¹Am is gamma radiation.



Geiger counter circuit diagram

Test video:

August 1, 2010

Just back from a workshop at the College of Astronautics, Nanjing, preparing the payload for our weather balloon experiment.

Determinating the weight of all components:


A lot of soldering work:


Dr. Lampe measuring the amplifiers and antennas:


Lambda 1/4 antenna, motherboard, GPS, 2 W amplifier placed in a customized foam box. We will have a continuous downlink of 3 cameras as well as pressure, temperature and GPS data. One camera will be pointed vertically upwards (balloon explosion), one camera vertically downwards, one camera horizonally. Minimum transmitting range 40 km. Maximum transmitting range 300 km (even enough for a satellite).


Group portrait with ladies. Our tardigrade researchers Susan and Kristin proudly presenting the 'white box':


Further steps: Programming, low temperature chamber, manufacturing of the sensor and battery (Li-Po 11.1 V/5000 mAh) monitoring board, parachute and transmission test.

Estimated launch: End of August 2010.

Update August 2, 2010:

Low temperature test successful. Here are the results:



TBC

July 25, 2010

The Moon, captured with a Celestron NexStar 4SE telescope and a Canon 5D Mark 2 on July 24/25, Shanghai...







The girls (FLTR: Selene, Kristin, Susan) had obviously fun during observation...



Full size images:

Shanghai Moon July 25
Shanghai Moon July 24-1
Shanghai Moon July 24-2

July 20, 2010

The video below shows an oxy-hydrogen cannon test we did primarily to assess empirical data derived from a complex oxy-hydrogen cannon equation. We have already decided to use an oxy-hydrogen cannon to deliver small payloads from one moon base to another. The idea of rocket mail first surfaced nearly 80 years ago when Friedrich Schmiedl launched the first rocket mail with 102 pieces of mail on February 2, 1931. Five years later the first successful delivery of mail by a rocket in the United States was made, when two rockets that were launched from the New Jersey shore of Greenwood Lake landed on the New York shore, some 300 metres away. But due to high costs and numerous failed rocket launches, this concept was never deemed a viable option for mail delivery. Things could be different on the Moon. Hardware on the Moon is extremely valuable. Needless to say, two or more moon bases could benefit enormously by sharing equipment or measuring tools. Rock samples etc. could be distributed between isolated bases by oxy-hydrogen cannons as well. If the surface between two moon bases is relatively even, the cannon can be always aligned at an optimal vertical angle of 45° --- due to the lack of air drag and any adverse weather conditions (besides variations in temperature or solar storms) only the amount of oxy-hydrogen in the fuel tank defines the range of fire, which can be precisely controlled, so the optimal amount of explosive is used. The generation of electricity for electrolysis can be done by photovoltaic arrays, water as an electrolyte could be extracted from the top layer of the lunar surface, and the combustion product is just water again. If the extraction of water on the Moon is not possible, it can be carried to the Moon because drinking water is also needed. Besides, carrying explosive fuel mixtures 400,000 km through space is simply too risky.

July 6, 2010

Below you'll find two pictures of the antennas for our weather balloon experiment.





The red one is the balloon side antenna. It looks big, but most of it is just foam. It will have to be mounted "upside down" on the balloon. The larger, colourful thing is the feeder for the ground antenna. It will be combined with a parabolic reflector to (hopefully) achieve the required gain. The four colourful antenna elements will each look into a slightly different direction, which will increase the reliability of the connection and make it easier to track the balloon (i.e. adjust the antenna direction towards the balloon). The WLAN adapters of the ground station will be attached directly to the back of the feeder, i.e. there will be no RF cables at all. This minimizes signal loss and also simplifies the cabling quite a bit. The transceiver system is developed by Dr. Lampe from Siemens, Beijing. Thanks again at this point!

The launch is scheduled for August. Will we be the first team who reaches at least an altitude of 40 km :P?

June 16, 2010

We have derived the ideal rocket car equation earlier. Next step was to compare the result of the equation with an experiment. The test rocket car vehicle is shown below. The rocket car weighed 460 g and was propelled by two C6 blackpowder model rocket engines.



On one of the front wheels was a wheel encoder with two Hall sensors mounted. The wheel encoder had a resolution of 30°. The ignition of the rocket motors was remote controlled. After the burnout time was reached, a small PIC counted the wheel encoder impulses in a defined time intervall (30 ms) and displayed the value on a 2-digit-7 segment display. It was then easy to calculate the velocity by the given wheel diameter. Several tests showed a burnout velocity of 20 m/s, which is in accordance with the rocket car equation, if we consider the neglected air drag.

Seleneteam - Burnout velocity measurement from seleneteam on Vimeo.

June 11, 2010

Short outdoor exploration of the mosquito rover:



This robot concept won the 2nd Place Prize at the GoRobotics competition. The prize, an Oomlout Arduino Experimenters Kit, goes to a Chinese student, who can not afford to buy it and will be now able to start with robotics!

May 3, 2010

The design process for many robots often has its roots in the natural world. "Bioluminescence" or the ability to generate light is the hallmark of the Lampyridae family -- commonly known as the firefly or lightning bug -- and this particular attribute has attracted the interest of many researchers in the field of robotics.
What stands out is that this species can create "cold light" or a transmission of light with no infrared or ultraviolet light present. This cold light results from a chemical reaction which occurs in specialized light-emitting organs that are located in a firefly's lower abdomen.
A behavioral trait of the firefly is also fascinating. Although every single firefly starts to flash randomly, fireflies rapidly synchronize themselves so that hundreds and thousands are able to blink all together, and ultimately, all the fireflies in question flash at once. This spontaneous phenomenon takes place without an alpha firefly leading the collective light display, and it can often involve hundreds and even thousands of fireflies.
This synchronization of fireflies has been simulated successfully in the lab with small circuits using microcontrollers. (see for example here: How to synchronizing firefly). We went one step further in our attempt to embed the chemiluminescence (or "chemoluminescence") process itself in a robot. To achieve our objective in this instance, we used hydrogen peroxide and phenyl oxalate/ fluorescent dye solution, which is normally used in glow sticks. Our man-made light-emitting organ is shown below:



An air-tight glass tube, filled with hydrogen peroxide solution is mounted on a servo. The glass tube contains a second reservoir with the phenyl oxalate / fluorescent dye solution. If the servo turns the glass tube, the two solutions get mixed and the chemiluminescence process starts. The glow lasts up to 12 hours.
Our prototype firefly robot was created and assembled as follows:



The robot's navigation is controlled by an ultrasonic sensor, supported by an array of tactile sensors, controlled by a MCU. A LDR (Light Dependent Resistor) is mounted in the antenna shaped hose. If the robot proceeds into a dark area, the chemiluminescence process is triggered automatically. For further information, please visit Let's make robots and watch the embedded video below.

April 21, 2010

According to China Daily, China has created more than 10 lunar rovers able to move, collect and analyze samples on the moon. We have tested many rover concepts, too. Here is our newest creation -- The Mosquito Rover -- just taking a sunbath on the roof garden of our laboratory:



The Mosquito Rover, like our Hybrid Rover, has the ability to fire off a second smaller vehicle with a mosquito-like shape -- hence the name -- in the event that the main rover becomes stuck in the lunar regolith or suffers a failure for other reasons and cannot travel the 500 meters required under the GLXP competition rules.

The cannon has an internal fuel generator which breaks down the stored water solution into hydrogen and oxygen gases by electrolysis -- powered by a photovoltaic array. The hydrogen and oxygen gases collect in the upper chamber of the cannon until there is enough for a launch to proceed. The fuel generator needs about 20 minutes to generate enough oxyhydrogen for a launch. To ensure success, a special spark generator ignites the oxyhydrogen. The expanding gases from the ignition of the oxyhydrogen thrusts the second vehicle into its trajectory.

The Rover can automatically adjust the cannon to the proper inclination via a servo motor based on the inclination of the Rover itself. This is done in order to obtain the maximum trajectory length. A second servo adjusts the inclination angle of the photovoltaic array. Should the Rover find itself in an area which is too dark, the photovoltaic array will set itself automatically at an angle of 45º. If the light yield is still too low, the Rover will proceed on to a more suitable location.

Specifications --

Weight: 800 g
Dimensions: 300 x 150 x 300 mm (l x w x h)
Actuators / output devices: Spark generator, Oxyhydrogen cannon, 3 Control LEDs, 2 Gear motors, Servo for Sharp IR, Servo for photovoltaic array, Servo for cannon, Loudspeaker
Sensors / input devices: Sharp IR, LDR, 2 Push buttons, 1-degree-inclination sensor
Control method: Autonomous
CPU: Picaxe 28x1 and 08M
Motor control: Darlington transistor h-bridge
Power source: 4x1.5V AA, 4.8V / 700 mAh / NiCd, Photovoltaic array 5.5V / 90 mA
Electrolyte: 5 ml CH3COOH, 30%
Electrode material: Graphite

April 12, 2010

A new rover creation is on the way. More soon...

March 23, 2010

Two Americans, Susan Clark and Kristin Rhodes from the University of North Carolina at Chapel Hill and the College of William & Mary will soon be coming to China for five weeks in order to work with Team Selene. In preparation for Team Selene's CubeSat launch, these two physics majors have been focusing on tiny Tardigrades -- microscopic animals often referred to as "water bears" -- by performing experiments at Dr. Bob Goldstein's lab at the University of North Carolina at Chapel Hill. Their research involves running simulations of Tardigrades growth in different media. This May, a month prior to their trip to Shanghai, both will head to Italy where they will continue their work with two leading researchers, Dr. Lorena Rebecchi and Dr. Roberto Bertolani, at the Università di Modena e Reggio Emilia in Modena.

March 19, 2010

Outdoor test of RLR - drive on rough surface, rocket launch and tracking of the rocket landing site:

March 13, 2010

The hybrid rover prototype 2 is completed and ready for outdoor tests and launches. We gave the rover the name RLR - short form for Rocket Launching Robot.

March 9, 2010

Never stop discovering

March 4, 2010

First video of the second hybrid rover prototype - obstacle avoidance and ignition system tests:



Because IR and lasers have blind spots with no coverage, we decided to add a bumper sensor:

February 28, 2010

Test of the the space microscope with slipper animalcule:

February 28, 2010

The hybrid rover prototype 2 got its motors & wheels...



a Sharp distance sensor...



and the rear wheel resp. rear ball...

February 16, 2010

The second prototype of the hybrid rover is in progress:



The rover is now controlled by a 28-pin microcontroller from PICAXE, programmed in BASIC. The image above shows the PICAXE project board, the voltage regulator board, the control panel, the power dual h-bridge and the 27 MHz-receiver.
The nose cone of the rocket will be equipped with a 27 MHz-transmitter, to transmit data from the rocket to the rover. Again reverse engineering has been used. The 27 MHz-transmitter/receiver is from a toy RC car. The transmitter was rebuilt space saving on a perfboard, modified to run with a lower voltage and additional equipped with a bright flashing LED to indicate the trajectory visual better:



On the servo will be a Sharp distance sensor and a directional antenna mounted, so it's possible that the rover not only launch the rocket automatically but also track back then the landing site of the rocket. Yes, comfortable time has started at model rocketry ;-)
The two front wheels of the rover also have been manufactured:

February 13, 2010

The space microscope, which will be launched with a 2 m-diameter hydrogen weather ballon, has been built:



The microscope weighs 280 g. 1.2 kg remain for the video transmitter and power supply. Here is a snap shot of condensed water in the slide chamber. As soon as our mini astronauts are successfully grown, a video will follow.

January 9, 2010

First test run of the hybrid rover prototype:


The recovery system of the rocket was not very sucessful. The nose cone came down with the parachute, the rest got separated in the sky and fell in a river.

January 8, 2010

The manufacturing of the space microscope pump system, which will be launched with a weather ballon, is finished and works well.



Weight: 74 g
Voltage: 5 V
Max. current 60 mA

December 26, 2009

The proof-of-concept prototype of our proposed space microscope is finished:



We will now start with the CAD software modeling and manufacturing of a microscope which is workable as a payload on a weather ballon till an altitude of 40 km.

November 22, 2009

An idea for a CubeSat mission:



The video of the single-celled organisms was taken with following experiment set-up:

October 16, 2009

Some additional theoretical notes about the oxyhydrogen cannon

October 7, 2009

Oxyhydrogen Rover

September 29, 2009

Short work on a lunar surface to surface missile

September 20, 2009

Motion analysis of a rocket-propelled moon rover

August 3, 2009

Spiral rover study

July 8, 2009

Our latest LuRoCa prototype is now ready for testing. The wireless camera system remains mounted in the nose cone. Our new design is capable of skidding over 500 m on a relatively flat lunar surface area -- breaking the lunar surface speed record in the process -- and / or covering a distance in excess of 5 km configured as a surface to surface missile in order to win the Range Bonus Prize as described in the competition guidelines (Section 2.3.3).

June 20, 2009

Here you can see our new wireless camera system which will be mounted on the latest prototype of our lunar rover during upcoming engine tests and public displays.



Range of the transmitter: Max. 700 m. Operating voltage: 12 V. Battery type: Nickel-metal hydride. Color CMOS camera main parameter:

NTSC: 510 x 492
PAL: 628 x 582
Illumination: <3 lux @ f 1.2
Lens focus and visual angle: 6.0 mm - 52º
Consumption of current: 120 mW

If the wireless camera survives the tests, it will maybe end as a video baby monitor :-)

June 16, 2009

First APCP rocket engine for our rocket propelled rover LuRoCa completed and ready for testing. Casing diameter: 80 mm. Casing length total: 332 mm. Casing mass: 0.874 kg. Propellant mass: Max. 1.2 kg. Total impulse: Max. 2600 Ns.

June 9, 2009

The initial prototype of our lunar firework rocket is ready for testing. It is equipped with a nose cone and fins, and instead of silver nitrate (AgNO₃), we are using potassium nitrate (KNO₃) as an oxidizer. Mixing magnesium and potassium nitrate for flash photography applications has been a standard procedure since the 19th Century, for example. Our updated design now calls for the delay charge of the rocket engine to directly ignite the flash powder in the glass jacket -- simply a common test tube. Therefore, we have removed the plug and cover on top of the delay charge, so the flash powder is in direct contact with the black powder of the delay charge.

May 29, 2009

Magnesium and silver nitrate flashpowder demonstration of the proposed Moon firework rocket.

May 18, 2009

Fig. 1

An innovative design for a Moon firework rocket appears in Fig.1. After the rocket reaches the desired altitude, the delay charge ignites, and that in turn triggers another ignition to jolt the needle. A reaction occurs after the needle pierces the membrane causing water to enter a glass jacket which is filled with silver nitrate and magnesium powder. Silver nitrate is an unstable oxidizer, while magnesium is a strong reducer. Farragoes from an oxidizer and a reducer always yield an explosion in a sealed container which, in this case, is the result of only a few drops of water that deliver enough energy to activate the explosive reaction. The igniting magnesium is the source of a bright flash of white light.

The chemical equation is:



In order to produce different colors and even different patterns, the glass jacket can be filled with an oxidizer -- including different combinations of gases serving as oxidizers -- a reducer, and various metal particles and metal salts for a range of colors. The gas pressure inside the glass jacket can also be adjusted so that the boiling point of the trigger liquid increases.

April 29, 2009

Fig. 1

We are now pursuing a new lunar rover concept which involves deploying a rover that hovers above the lunar surface once the lander is secure on the lunar surface. This new lunar rover uses a tether on a spool attached to a counterbalance. As the spool rotates, the cable unwinds in a measured and tightly controlled fashion ensuring a gradually increasing, spiral orbit for the rover around the lander as the rover attempts to travel the required 500m distance. Because centripetal force will vary based on the radius of the path travelled by the rover, the rotation speed of the spool must be constantly adjusted to hold the altitude of the rover steady. If we assume that the total distance of the rover has a shape of an Archimedean spiral (see fig. 2), we can calculate the distance L as follows:

L =a/2[φ(φ²+1)^0.5+Arsinh (φ)]

with

a= k/(2π) (k=constant distance of the spiral arms) φ= n2π (n=number of turns)


Fig. 2

Once the required 500m distance threshold has been reached, the rover will cease to hover above the lunar surface and will drop down in order to commence taking samples from the lunar surface. Once that remote sampling process is complete including any requisite analysis, the rover will be reeled back to the lander using the tether.

March 20, 2009

To commemorate the 40th anniversary of NASA's Apollo 11 mission, the German TV station WDR plans to make a documentary about past and future lunar missions. The Google Lunar X Prize and several of the participating teams will be featured as well. Here, you see some of the filming that took place at the Bochum Radio Observatory in Germany. The part of this documentary involving Team Selene will air at [W] wie Wissen on April 5, 2009 and Quarks & Co on June 2, 2009.

March 8, 2009

☠ Rock(et) 'n' Roll ☠

February 22, 2009

Travel through our planetary system.

February 13, 2009

Microbes on the Moon.

February 8, 2009

That's life!

January 14, 2009

First LuRoCa mockup sample for some general tests finished.

January 5, 2009

Fig. 1

Our rocket-driven lunar rover can be transformed into a surface-to-surface missile using a simple adjustable inclined ramp (see Fig. 1). Or it can be driven over the lunar surface as a conventional rocket-powered car. The mode of travel will be determined by the actual conditions at the lunar landing site including any topographic challenges or obstacles present on site. The reason we have designed our propulsion system to allow for all 10 solid fuel rocket engines in the back of the rover to be ignited in clusters or, if needed, all at once is to allow us greater flexibility following the landing of our Selena 1 spacecraft. If we set the start altitude h₀ = 0 and the optimal start angle α_o = 45º, the trajectory length s is the following function of the start speed v₀: s(v₀)=v₀²/g. The lunar gravitational acceleration g is approximately 1.63 m/s² and the required trajectory length s is 500 m, so we get a start speed v₀ of approximately 28.55 m/s or 102.78 km/h, which is not very high.


Fig. 2

Fig. 2 shows the flight parable. With the optimal start angle α_o = 45º and the calculated start speed v₀ we get a maximum altitude of 125 m. Our LuRoCa vehicle as a rocket-propelled lunar rover offers distinct advantages over electric motor-driven lunar rover concepts in terms of its ability to maintain mobility in challenging terrain, in addition to its overall simplicity and reliability. Should one or more of the wheels lock or suffer a mechanical failure, or should the vehicle overturn -- we are exploring several attitude recovery and stability control options -- it will still be possible to propel the rover forward. In contrast, if the landing site for a remote-controlled electric motor-driven lunar rover happens to be situated in very rocky terrain, it will be extremely difficult if not almost impossible for this type of rover to travel the full distance of 500 meters as required by the rules of this competition.

December 31, 2008

3-D drawing of LuRoCa prototype finished.

December 23, 2008

First Solid rocket engine mockup for lunar rover finished. The 10 solid rocket engines in the cylinder can be ignited individually, in clusters or all at once, depending on actual conditions including any topographic challenges or obstacles encountered on the lunar surface.

December 13, 2008

First rocket car test.

December 2, 2008

Shanghai-based Team Selene is designated as an official Google Lunar X Prize team.

November 25, 2008

Shanghai-based Team Selene makes final decision to proceed with the Lunar Rocket Car (LuRoCa-1) concept.