ESTCube-1

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ESTCube-1
ESTCube-1 illustration.jpg
ESTCube-1 illustration
Mission type Technology
Operator University of Tartu
COSPAR ID 2013-021C
SATCAT № 39161
Website http://www.estcube.eu/en/home
Mission duration 12 months
Spacecraft properties
Launch mass 1.048 kilograms (2.31 lb)
Start of mission
Launch date 7 May 2013, 02:06:31 (2013-05-07UTC02:06:31Z) UTC
Rocket Vega
Launch site Kourou ELA-1
Orbital parameters
Reference system Geocentric
Regime Low Earth
Inclination 98.129 degrees
Period 98.03 minutes

ESTCube-1 is the first Estonian satellite. Developed as part of the Estonian Student Satellite Program, it was launched on 7 May 2013 aboard a Vega carrier rocket[1] and successfully deployed into orbit.[2] Student Satellite is an educational project in which university and high school students can participate.[3][4] The CubeSat standard for nanosatellites was followed during the engineering of ESTCube-1, resulting in a 10x10x11.35 cm cube, with a volume of 1 liter and a mass of 1.048 kg.[5]

Scientific purpose[edit]

The first image of Earth taken by ESTCube-1 on May 15, 2013.[2]
ESTCube-1 E-sail experiment
The structure illustration of cubesat ESTCube-1
ESTCube-1 structure

While emphasis was placed on educating students during creation of ESTCube-1, it does have a scientific purpose. On board the satellite is an electric solar wind sail (e-sail) which was invented by Finnish scientist Pekka Janhunen. During an ESTCube-1 flight, 10 meters of 20–50 micrometer thick e-sail wire, sometimes referred to as "Heytether," is deployed from the satellite. The deployment of the Heytether is detected by a decrease of the satellite's rotation speed or an on-board camera.[6]

To control the e-sail element's interaction with both the plasma surrounding the Earth and the effect it has on the spacecraft's spinning speed, two nanotechnologic electron emitters/guns are on board. The electron emitters are connected to the e-sail element which it loads positively to 500 volts by shooting out electrons. The positive ions in the plasma push the e-sail element and influence the satellite's rotation speed. The effect of the plasma on the e-sail is measured by the change in said rotation speed.

After the measurements on the e-sail effect are completed, the Heytether is used as a plasma-brake by loading its ionosphere opposite to the plasma's ionosphere. This demonstrates a possibility for returning small satellites from orbit. A color CMOS camera is also on board that is capable of making RAW-format pictures with VGA-resolution. This camera is used to take a picture of Earth and to monitor deployment of the Heytether.

Orbit[edit]

To complete the scientific experiment and communicate with the satellite on several occasions the orbit chosen was a sun–synchronous circular orbit at an altitude of 670 kilometers. ESTCube-1 was launched into orbit by Arianespace, using a Vega rocket which lifted off from ELA-1 at Kourou at 02:06:31 UTC on 7 May 2013. The satellite was placed into orbit and communication successfully established,[7] with the first photo of the Earth taken on May 15 and transmitted to the ground on the amateur radio band.[2]

Lifespan of the satellite[edit]

  • Start in spring of 2013.
  • Half an hour after the satellite's deployment from the start capsule, the satellite's antennas will be opened and radio transmitter and important subsystems will be switched on.
  • During first 48 hours after the deployment, satellite will send only safe mode CW beacon
  • The first days or weeks will be used to test the satellite and set it to work at full capacity.
  • Orientation of the satellite so the on-board camera will be faced to earth and to take picture of Estonia.
  • Rotation of the satellite on an axis with a speed of 1 revolution per second.
  • E-sail element deployment from the satellite by a centrifugal force and confirmation of the deployment via the on-board camera.
  • Activation of the electron emitter and the loading of the e-sail
  • Measurement of the e-sails and Lorentz force via satellite's revolutions per second
  • If possible using the negatively charged e-sail to take the satellite off orbit and reenter the earth's atmosphere.

If everything goes perfectly the mission can be completed within a few weeks to a month.

Design[edit]

Measurements and weight[edit]

During the development of the Estonian satellite mission it was decided to make a 1U CubeSat. By standard 1 unit (1U) CubeSat base side length must be 100.0±0.1 millimeters and satellite height must be 113.5±0.1 mm. Mass is also set in CubeSat standard, the highest possible mass for 1U CubeSat is 1300 grams.

Communications[edit]

Communication from the satellite is made at two International Amateur Radio Unions registered frequencies

  • 437.250 MHz
  • 437.505 MHz[8]

Periodic but very slow communication is made by using 18 WPM telegraphy signal on a frequency of 437.250 MHz. At that frequency, the most important satellite parameters are returned every 3 to 5 minutes. For fast connections FSK-modulation radio signals on a frequency of 437.505 MHz with a 9600 baud connection speed and AX.25 packet standard is used. The relatively slow connection speeds result from the use of amateur radio frequencies which limits the bandwidth to 25 kilohertz. Besides FSK-modulation there are also GFSK-, MSK-, and GMSK-modulations possible. Using the GFSK-modulation, the maximum possible connection speed is 19,200 bits per second. The fast connection is used only when the satellite has been given a specific order.

Commands sent to the satellite use the 145 MHz (2 meter) amateur band.

Software[edit]

ESTCube-1 microcontrollers use the following operating systems:

  • FreeRTOS on the satellite's Command and Data Handling System and camera module.
  • TinyOS on the satellite's communication module. (Typically used with devices running on low power)

Mission Control System is currently being developed by the students of Tartu University under the supervision of the company CGI Group.

Financing and costs[edit]

ESTCube-1 presentation in January 2013.

The least expensive satellite launch is offered by European Space Agency. Because Estonia is an associated member of ESA, most of the launch expenses (about 70,000 euros) will be covered by the Estonian member fee for educational expenses. With the launch, total expenses for the project are approximately 100,000 euros.

See also[edit]

References[edit]

  1. ^ ESA: Launch schedule
  2. ^ a b c Southgate Radio Amateur News, First picture from ESTCube-1 ham radio CubeSat, May 22, 2013 (accessed Aug. 16 2013)
  3. ^ "The two primary payloads for Vega’s second launch are readied at the Spaceport". Arianespace. March 14, 2013. Retrieved March 25, 2013. 
  4. ^ "Arianespace Awaits... Vega Tops Off While Sats Prep For Vegies (Launch)". satnews. March 14, 2013. Retrieved March 25, 2013. 
  5. ^ "Estonia’s student cubesat satellite is ready for the next Vega launch". Arianespace. Retrieved March 25, 2013. 
  6. ^ "Proba-V’s fellow passenger". European Space Agency. February 2013. p. 17. Retrieved March 25, 2013. 
  7. ^ Matteo Emanuelli, Estonian Cubesat on a Collision Course with Iridium-Cosmos Debris, August 1, 2013, Space Safety News (accessed Aug. 16 2013)
  8. ^ "ESTCube-1". International Amateur Radio Union. 15 Mar 2013. Retrieved March 25, 2013. 

External links[edit]

Videos