PRISM
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LAST UPDATED: Feb. 4, 2011

PRISM'S APPEARANCE

OVERVIEW

PRISM Image
* The picture above is based on the latest design.
* The picture above is NOT exact fot simplicity.
* You can check part names by mouseovering.
LAUNCH
    Jan. 23, 2009
ORBIT
 - Altitude: 660 km
 - Eccentricity: 0.00
 - Inclination: 98.06 deg
LAUNCH
SIZE
 - 19cm x 19cm x 23cm (ONLY Body)
 - 19cm x 19cm x 37cm
    (INCLUDING boom)
WEIGHT
    8.5 kg
MISSIONS
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BACKGROUND:   HOW WE STARTED?

Since 2000, ISSL has developed very small satellites, which are also referred to as "cubesat". Its first model for the demonstration on orbit, XI-IV[sai-four], was launched in June 2003 and the second model, XI-V[sai-five], flied into space in October 2005, respectively. Both XIs are working well even now! (Please visit XI series' website.) We started "CubeSat2" project in 2002, aiming at a more sophisticated satellite based on the pico-satellite bus system such as power and communication which we have cultivated through XI series. In addition to the improvement of the bus function, we will perform a remote sensing mission as our new challenge. Cubesat-sized satellites are classified into pico-satellites and we expect our new satellite to obtain Earth's images with the highest resolution in this class.

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DERIVATION: WHY "PRISM"?

PRISM is the code name of cubesat2 and PRISM stands for "Pico-satellite for Remote-sensing and Innovative Space Missions". As you know, this name carries the double meaning as an optical term, prism. The perfect name for this mission, don't you think?

In general, small satellites are classified into...

  • Pico-satellite : under 1 kg
  • Nano-satellite : 1 - 10 kg
  • Micro-satellite : 10 - 100 kg

This means... PRISM is not pico-satellite BUT actually nano-satellite!! (We like this name and will not change it, though.)

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SIZE: HOW SMALL?

The size of PRISM is a little bit bigger than the initial design. PRISM is almost a 20cm cube and its weight is about 8kg in the final design. (Please visit here if you would likt to know more!) This size makes it possible to put it in a case and carry it easily.

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MISSION I: Demonstration of Imaging Technology by using "Extensible Boom" as a Telescope

The method for imaging which we adopted for PRISM is not a "reflection-type" telescope, which general remote-sensing satellites use, but a "refraction-type" telescope. While a reflection-type telescope collects light with a mirror, a refraction-type telescope focuses light with a lens. The advantage of this approach is that the optical system can be rather resistant to structure alteration. In order to utilize this point, we designed and developed a flexible and extensible boom as a telescope.
The ground resolution depends on the aperture and the focal length of camera and a long focal length needs a long telescope. On the other hand, the cost for launch depends mainly on the size and the weight of satellite. As you expect, a long and heavy telescope makes it quite higher.
Our solution is...

Small during the launch, Large on the orbit

The demonstration of this optical system is the most important mission of PRISM. The mission like this has never been done before and we could accomplish the 30m ground resolution if the boom extends successfully.


MISSION II: Demonstration of COTS-oriented Components for Nano-satellites
* COTS = Commercial-Off-The-Shelf

COST products means general components, which is NOT designed for the space utilization. In XI project, the demonstration of the basic system of satellite (also referred to as "bus system") was the mission. In PRISM project, however, we aim to enhance the bus technology and demonstrate it in order to make PRISM's mission a success.
It should be noted that a COTS component is more likely to have a failure due to the ultimate environemnt such as radiation. The most important thing in the design of nano-satellites is the redundancy to avoid the single point in the design.

MISSION III: Advanced Amateur Radio Service

PRISM utilizes the amateur radio for the downlink/uplink as well as XI. PRISM can provide the amateur radio service to entertain radio HAMs all over the world by partially opening the uplink system. (Of course, this function is designed not to affect the main control system of PRISM.) This service includes the uplink/record/downlink of your own message. We will discuss this topic in detail by considering our past experiences.

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DEPLOYMENT SEQUENCES

PRISM is a box-type shape when launched so that PRISM can endure the launch vibration. After launch, PRISM transfer its mode step-by-step as listed below.

  1. Released from the rocket on the orbit
  2. Relesased form the POD and deploy the antenna for transmission
  3. Deploy the receiving antennas
  4. Deploy 4 solar panels to generate more power
  5. Extend the telescope boom!
The FLASH Movie below is the deployment sequences and it starts after release from the POD.
* PRISM deploys the antennas and panels by clicking PRISM and extends the boom by second click.

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PROJECT TEAM

PRISM project team is composed of ISSL members and other students who are interested in PRISM's project.

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HISTORY

We have developed components comprising PRISM in each subsystem and have completed its BBM (Bread Board Model) until 2003, although the development was suspended once because of the launch and the operation of XI and other missions. However, we started developping again in 2006 and we have finished making PRISM 2nd-EM (Engineering Model) in November 2007. EM is a pre-model of FM (FM stands for Filght Model which will be launched actually). PRISM fortunately got a launcher(HII-A,JAXA), which was plannd to be launched in 2008. (PRISM was actually launched in the beginning of the next year.) Now we are oprating PRISM to accomplish its great missions!

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