The newest near space flight computer from NearSys is the NearSpace Simple-18. It’s a PICAXE-18M2 based datalogger in parallel with a TinyTrak 3 APRS tracker. Input/output devices, like sensors, connect to the NearSpace Simple-18 through its four ports. 1. Analog Port: used to digitize the voltages of three sensors 2. Digital Port: used to interface three digital devices or sensors 3. GPS Port: shares GPS data with both the APRS tracker and the PICAXE-18M2 4. Camera Port: used to operate two cameras Analog sensors are supplied +5 volts and ground as soon as you connect them to the Analog Port. The PICAXE-18M2 can digitize sensor voltages with either eight or ten bits of resolution. The Digital Port is a two way port. You can connect input (like sensors) or output devices to this port. An example of a digital sensor is the Geiger counter. The cameras operated by this flight computer need by-passed shutter switches. Alternatively, a single camera with a by-passed shutter and power switch can be operated through the Camera Port. The flight computer also includes a Commit Pin. This is used to prevent the flight computer from recording data prior to launch. When launch is immanent, the pin is removed, signally the PICAXE to begin collecting data. Data from the four analog and digital sensors is stored in a 24LC256 I2C memory chip. This gives the flight computer enough memory to record 256 kb of data. The chip can be replaced with a larger version if additional data storage is required. The flight computer has four LED status indicators. These indicate when the flight computer has power, when the tracker side is transmitting a position report, the status of the GPS Receiver (when its connected and when it has a satellite lock), and the current status of the flight computer. The last indicator, the status indicator is a programmable bi-color LED. The PICAXE-18M2 is programmed to illuminate the LED as desired. The NearSpace Simple-18 flight computer kit also includes a two meter antenna kit. The antenna connects to the flight computer through an SMA connector. The NearSpace Simple-18 makes a great first flight computer. It’s simple plug and fly operation makes collecting data in near space quite simple.

The Assembled NearSys GPS Simulator

NearSys LLC now sells a GPS Simulator. It allows you to test a near space APRS tracker or flight computer for its behavior during a mission. It's a way to simulate a mission on your bench top, saving you money and difficulty should something go awry.

The GPS Simulator models all the events of a GPS that's making a trip to near space. These events include GPS lock and loss of lock, launch and ascent of the balloon, balloon float, balloon burst, descent, and landing. The GPS lock can be lost at any time during the mission and can be regained at will. The ascent rate, landing speed, float altitude, and burst altitude of the mission are easy to set and vary by adjusting four well-described variables at the top of the GPS Simulator program.

This level of functionality is useful if you programmed your flight computer to respond to conditions like too slow of an ascent rate, unexpected loss of GPS lock, unplanned for neutral bouyancy, passing specific altitudes, balloon burst, approaching landing, or touchdown.

The NearSys GPS Simulator lets you test and debug these programmable features of your near space mission.

You can view the kit and its instructions at the GPS Simulator page at NearSys.com

Vacuum Cannon

What can you accelerate using a vacuum? How about a ping pong ball to several hundred miles per hour? The vacuum cannon evaculates the air from a PVC tube. Both ends of the tube are sealed using sheets of aluminized mylar and inside is a ping pong ball. After the air is evacvuated, you puncture the mylar film closest to the ping pong ball. As the air rushes back in, it creates a force on the ping pong ball. Since the air pressure is 101.3 kP and the ping pong ball has a low mass of three grams, the ball's acceleration can exceed 1,000 g's. By the time the ping pong ball reaches the end of the tube, it bursts through the other mylar film cap with a loud bang.

The kinetic energy of the ping pong ball is equal to the energy required to evacuate the PVC, minus losses due to friction and drag. Still, a ping pong ball capable of flying through an aluminum can is mightly impressive.

You can see a video of my vacuum cannon on my YouTube channel

NearSys has updated its BalloonSat Mini flight computer to version 4.0. This version is more convenient to program and to interface sensors. Rather than programming the flight computer through a serial adapter cable, the flight computer now incorporates a DB-9 connector. Interfacing sensors is easier because sensor arrays are available with simple to solder connectors that plug right into the flight computer’s I/O port.

Like the older versions, the BalloonSat Mini v4.0 also operates a camera. The flight computer can operate any electronic camera with a by-passed shutter switch. Cameras modified to work with the BalloonSat Mini v4.0 are available from NearSys.

The BalloonSat Mini v4.0 has memory to record 256 sensor readings. Since it can collect data from two sensors, the BalloonSat Mini v4.0 can record one reading per sensor per minute for the entire ascent of a typical high altitude balloon. However, it will not begin recording data until after the BalloonSat crew removes the Commit Tag.

The BalloonSat Mini v4.0 kit is available from NearSys for $23.50. The kit contains all the necessary parts except for solder. Directions for the kit and sample code are available from the NearSys website at, http://nearsys/catalog/balloonsat/mini.htm.

I am experimenting with taking pictures in the near infrared (NIR) and ultraviolet (360 nm) again. The picture below was taken outside my apartment in visible light.

This image was taken in NIR with the camera set to monochrome

This is the ultraviolet image in color.

And the same image, but with the camera set to monochrome

I am rather surprised by the blandness of the ultraviolet image.

Venus and the Pleiades

Venus is passing by the Pleiades (Seven Sisters). If you get a chance, get your binoculars out and take a look.

NearSpace Simple 18

I am developing a new flight computer, the NearSpace Simple 18. The flight computer is an upgraded BalloonSat flight computer with tracking capability. It has the following capabilities.

• Collect three analog sensor values
  
• Collect or operate three digital experiments
  
• Operate two cameras
  
• Collect GPS data
  
• Indicate status with a bi-colored LED
  
• Indicates when the GPS has a lock and when transmitting a position
  
• Store data in a 32kb EEPROM memory
  
• Hold collecting data until the Commit pin is pulled
  
• Transmit APRS position reports
  

The flight computer is built around the PICAXE-18M2. Therefore, the flight computer is fully programmable (very flexible). If you can write it in BASIC, then the NearSpace Simple 18 can do it.

the tracking portion of the NearSpace Simple 18 is Byonics TinyTrak 3. The Tiny Trak is a well developed APRS trackers and fully programable with settings like callsign and transmit rate.

This is an entry level flight computer that only needs you to connect the GPS and antenna.