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CHAPTER-I

INTRODUCTION

1.1 INTRODUCTION ABOUT TOPIC

The network would initially support only one-way traffic, with two-way traffic being

implemented once adequate funding is raised. Initial prototype satellite deployments are planned

for June 2014, with the final deployment run scheduled for mid-2015. According to MDIF, the

initial content access includes international and local news, crop prices for farmers, Teachers

Without Borders, emergency communications such as disaster relief, applications and content

such as Ubuntu, movies, music games, and Wikipedia in its entirety.

MDIF plans to formally request NASA to use the International Space Station to test their

technology in September 2014. Manufacturing and launching of satellites would begin in early

2015, and Outernet is planned to begin broadcasting in June 2015. India based "Specify Inc." is a

private non-profit company by Silicon Valley based technocrat and entrepreneur Siddharth

Rajhans along with Space debris mitigation expert Sourabh Kaushal, which is privately working

on using this technology to provide global free Wi-Fi access.

A small team of workers at a New York based non-profit organization called Media

Development Investment Fund (MDIF) has announced its intention to build an "Outernet"—a

global network of cube satellites broadcasting Internet data to virtually any person on the planet

—for free. The idea, the MDIF website says, is to offer free Internet access to all people,

regardless of location, bypassing filtering or other means of censorship.

As the Internet has grown in size and importance, human rights organizations, or those

(such as MDIF) promoting freedom of expression, have begun to propose that access to the

information that the Internet canprovide, is a basic human right. Conversely, they suggest that

restricting access to the Internet is a violation of human rights. MDIF seeks to circumvent those

that might wish to violate such human rights bybypassing their ability to restrict access—they are

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proposing that hundreds of cube satellites be built andlaunched to create a constellation of sorts

in the sky, allowing anyone with a phone or computer to accessInternet data sent to the satellites

by several hundred ground stations.

MDIF claims that 40 percent of the people in the world today are still not able to connect

to theInternet—and it's not just because of restrictive governments such as North Korea—it's also

due to the highcost of bringing service to remote areas. An Outernet would allow people from

Siberia to parts of thewestern United States to remote islands or villages in Africa to receive the

same news as those in NewYork, Tokyo, Moscow or Islamabad. That they say, would guarantee

all people the same Internet rights as everyone else.

The Outernet, as envisioned, would be one-way—data would flow from feeders to the

satellites whichwould broadcast to all below. MDIF plans to add the ability to transmit from

anywhere as well as soon asfunds become available. At this time, it's not clear how much MDIF

has been able to collect for the project,but acknowledge that building such a network would not

be cheap. Such satellites typically run $100,000 to$300,000 to build and launch. Still, the

timeline for the project calls for deploying the initial cubesats as early as next summer.

Figure1.1:- Outernet Plan

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1.2 LITERATURE SURVEY

There are more computing devices in the world than people, yet less than 40% of the

global population has access to the wealth of knowledge found on the Internet. The price of

smartphones and tablets is dropping year after year, but the price of data in many parts of the

world continues to be unaffordable for the majority of global citizens. In some places, such as

rural areas and remote regions, cell towers and Internet cables simply don't exist. The primary

objective of the Outernet is to bridge the global information divide.

Broadcasting data allows citizens to reduce their reliance on costly Internet data plans in

places where monthly fees are too expensive for average citizens. And offering continuously

updated web content from space bypasses censorship of the Internet. An additional benefit of a

unidirectional information network is the creation of a global notification system during

emergencies and natural disasters.

Access to knowledge and information is a human right and Outernet will guarantee this

right by taking a practical approach to information delivery. By transmitting digital content to

mobile devices, simple antennae, and existing satellite dishes, a basic level of news, information,

education, and entertainment will be available to all of humanity.

Although Outernet's near-term goal is to provide the entire world with broadcast data, the

long-term vision includes the addition of two-way Internet access for everyone. For free.

Satellites need to be controlled from earth to fully utilize their functionality. To do this

optimally satellites need the longest and most frequent possible communication access times

with their ground stations. Large satellites currently use services such as NASA’s Tracking and

Data Relay (TDRS), and distributed ground station networks such as SSC’s PrioraNet. These

services are however very expensive and not available for commercial use. The launch of micro-,

nano- and pico-satellites are rapidly increasing among smaller companies and universities. The

use of above mentioned TT&C services are not economically feasible for these smaller satellite

missions. The only option left for these projects is to build and maintain a small ground station

which can amount up to a third of the total mission budget.

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1.3 MISSION OBJECTIVES

To address this shortfall the following mission objectives are set:

- Provide a communication opportunity to any satellite in Low Earth Orbit (LEO) at least once

each orbit.

- Provide this service to worst-case communication link budget client, namely a 1U CubeSat

with VHF/UHF monopole

- The service should be cheaper to use than constructing and maintaining a small ground station

over the mission lifetime

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CHAPTER-II

APPROACHES AND METHODS

2.1 HOW DOES IT WORK

Outernet consists of a constellation of low-cost, miniature satellites in Low Earth Orbit.

Each satellite receives data streams from a network of ground stations and transmits that data in a

continuous loop until new content is received. In order to serve the widest possible audience, the

entire constellation utilizes globally-accepted, standards-based protocols, such as DVB, Digital

Radio Mondiale, and UDP-based Wi-Fi multicasting.

Citizens from all over the world, through SMS and feature-phone apps, participate in building

the information priority list. Users of Outernet's website also make suggestions for content to

broadcast; lack of an Internet connection should not prevent anyone from learning about current

events, trending topics, and innovative ideas.

2.2 THE OUTERNET CONSISTS OF THREE SEGMENTS

1. The Space Segment

2. The Ground Segment and

3. The User Segment.

The space segment (OuterNet) consists of 14 satellites evenly spaced in a 900km circular

equatorial orbit. The constellation’s beam width coverage is such that all LEO satellites in orbits

below 600km altitude will come into range of the constellation at least once every orbit (refer to

orbit/constellation design for details). When within range, the client satellites can be polled by

the constellation to download telemetry and/or upload tele-commands.

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Fig 2.1: Conceptual Illustration of OuterNet

The ground segment consists of several ground stations spread around the equator. Due to

the constellation’s equatorial orbit, each of the satellites will pass every ground station during

every orbit. Three potential ground stations have already been identified: Guiana Space Centre,

Broglio Space Centre and Pusat Remote Sensing.

The user segment consists of clients who register to use the OuterNet service. Pricing will

be based on the amount and frequency of data relayed. Satellite operators will be able to

configure their TT&C schedules, download telemetry, upload tele commands and configure their

communications protocol and modulation technique through a user friendly internet interface.

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Fig 2.2: Interfacing between system segments

Broadcasting data allows citizens to reduce their reliance on costly Internet data plans in

places where monthly fees are too expensive for average citizens. And offering continuously

updated web content from space bypasses censorship of the Internet. An additional benefit of a

unidirectional information network is the creation of a global notification system during

emergencies and natural disasters.

Access to knowledge and information is a human right and Outernet will guarantee this

right by taking a practical approach to information delivery. By transmitting digital content to

mobile devices, simple antennae, and existing satellite dishes, a basic level of news, information,

education, and entertainment will be available to all of humanity.

2.3 PERFORMANCE PARAMETERS

The key performance parameters for the proposed mission are:

(a) Communication latency

(b) Communication Power

(c) Data Capacity

(d) Target Orbit

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Communication latency:

The time it takes for the client satellite to move into range of the constellation

communication footprint. It is dependent on the footprint width on the orbit of the client satellite,

which is in turn dependent on the antenna system and number of satellites in the constellation. A

target intersection occurrence is once per client satellite orbit.

Communication power:

The system must work even if the client satellite has limited communication power.

Worst-case client for this parameter is defined as a standard 1-U CubeSat.

Data capacity:

Data transferred during a single target intersection occurrence depends on the mean

intersection duration and the data rate. The duration depends on the width/area of the

communication footprint, which in turn is dependent on the antenna system beam width. A

transfer rate of 4800bps will allow for a telemetry packet of about 35kb given a 60-second

communication window.

Target orbits:

The constellation must supply this service to satellites in orbits ranging from 300km to

800km altitude.

Fig: 2.3Antenna coverage on different orbits

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2.4 ORBIT/CONSTELLATION DESCRIPTION

The orbit design of the system consists of calculating the orbital

parameters (inclination, eccentricity and semi-major axis) and determining the amount of

satellites needed for the constellation. An equatorial orbit is chosen to ensure that the satellites

will pass a ground station, which will be situated as close as possible to the equator, at least once

per orbit. Any other orbit would cause the satellite to drift away from the ground station because

of the rotation of the earth. The long latency between communication opportunities between

satellites in more inclined orbits (e.g. polar and sun-synchronous) and their ground stations is the

problem that our system will improve upon. With the proposed system, client satellites will cross

our constellation twice per orbit. There exist areas, at different altitudes, where satellites can slip.

Through without being able to communicate with the constellation. These areas are illustrated

in. However, client satellites would never pass through these areas more than once per orbit,

ensuring communication at least once per orbit. A passing client satellite will have access time to

a satellite in the constellation, which depends on the area of the antenna’s beam on the orbital

plane of the client satellite. The access time is also influenced by the inclination of the client

satellite, which would determine the relative velocities of the two satellites. The system is

simulated in MATLAB with the OuterNet at 900 km altitude and the client satellites at various

altitudes and inclinations. The resulting average access times are shown in Figure 4. The altitude

of 900 km was chosen in order to service a wide range of client satellites at altitudes ranging

from 300-800 km, while also keeping the aerodynamic drag force at a minimum. Less drag force

results in less orbital station keeping required and therefore less fuel required. Inter-satellite

communication can also be considered in the future to minimize the latency between client

satellites and a ground station. A message sent from a client satellite to the constellation could

then be relayed around the constellation to a constellation satellite that is above (or close to) a

ground station, allowing a message to reach earth within minutes.

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2.5 SPACE SEGMENT DESCRIPTION

Link budget:

A pointed VHF dipole antenna and a UHF patch antenna array will be used to

communicate with client satellites, while an Omni-directional dipole will be used to

communicate with the ground station. Link budgets were calculated using the UHF downlink /

VHF uplink Full Duplex Transceiver as a worst case client transceiver. The transmitted power of

this module is only 150mW. It shows preliminary parameters of the link budgets with the client

satellite and with a ground station.

For QPSK modulation Space Mission Analysis and Design:

The required OuterNet satellite antenna gains and required power were calculated using

the following link equation:

From this analysis it can be seen that the client downlink will require the most power and

highest satellite antenna gain, justifying the use of a patch antenna array. The antennas will have

a beam width of 60o per antenna spaced out by 22o, producing the pattern shown in Figure 5.

Simulation using STK showed that a client satellite with a 600km sun synchronous orbit, gave an

average access time of 60 seconds, allowing 35kb data per orbit to be transferred at 4800bps. A

pass through the constellations orbit without coverage happened 2 times in 41 passes, and never

sequentially. The range limitation was chosen to reduce LFS so that antenna gains would be

realizable, while still providing good coverage across the equator. The VHF losses proved to be

low enough to allow the use of a low gain dipole antenna. Communication between an OuterNet

satellite and a client satellite will be initiated with an ID, sent out by the nearest OuterNet

satellite. When the client receives its unique ID, communication between the OuterNet satellite

and client satellite will commence. The modulation technique and protocol of the communication

system on the OuterNet satellites will be software programmable, in order to accommodate as

many client satellites as possible.

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Antenna Design:

The key performance parameters identify the need for a lot of attention to be given to the

design of the antenna system. An antenna beam width of at least 150° in the one direction and

60° in the other direction, as well as sufficient gain, need to be achieved. The use of patch

antennas wills bepreferred above other antennas due to their thin package form. Different patch

antennas for different frequencies can be stacked on top of one another to minimize the area

required [9]. Initial design points to the use of three patch antennas with a relative angle to

produce the 150° beam width. The VHF-band (145MHz) requires a very large patch.

Calculations show a patch of minimum length 0.32m, described by:

With the speed of light, the resonance frequency, and 𝜀𝑟𝑒𝑓𝑓 the effective dielectric

constant. Ceramic has an effective dielectric constant of 𝜀𝑒𝑓𝑓≈10. The antenna design thus

becomes unpractical. A dipole array will probably be used for the VHF-band and patch antennas

for the UHF and S-band. Consultation with experts on antenna design confirmed that the antenna

specifications are feasible with an antenna array. The final antenna design will be shown in the

final document.

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Fig 2.4: Antenna coverage pattern

Attitude Determination and Control System:

The satellites in the constellation will only require pointing the S-band antennas to nadir.

A control system is still required to de-tumble the satellite after launch and to keep the satellite

3-axis stabilized at nadir pointing. The proposed altitude of 900km is a bit far for gradient

stabilization and complete magnetic control. The initial ADCS will make use of magnetic de-

tumbling and reaction wheels to get 5° pointing accuracy. The sensors to be used are a

magnetometer, nadir- and coarse sun sensor combination for the determination of attitude. This

can be easily realized using existing off the shelf products to reduce the required development

time for these sensors.

Phasing:

When the launcher reaches the desired orbit, all the satellites will be released at roughly

the same point in the orbit. To achieve the desired ≈25 degree spacing between each satellite,

cold gas (butane) thrusters system (Isp of ≈ 70) will need to be designed or bought and integrated

to allow each satellite to enter and exit a phasing orbit. The satellite would need two thruster

burns: one at the start of phasing and one at the end of phasing. An example system using this

technique is SNAP-1 from SSTL [11]. The phasing of the satellites can confidently be achieved

with a cold-gas-thrusters system without adding too much complexity to the satellite design. The

thrusters will also allow for the capability to deorbit the satellite at end of life.

2.6 WHAT IS CUBESAT?

Introduction:

A CubeSat is a type of miniaturized satellite for space research that usually has a volume

of exactly one liter (10 cm cube), has a mass of no more than 1.33 kilograms and typically

uses commercial off-the-shelf components for its electronics.

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Beginning in 1999, California Polytechnic State University (Cal Poly) and Stanford

University developed the CubeSat specifications to help universities worldwide to perform space

science and exploration.

While the bulk of development and launches comes from academia, several companies

build CubeSats such as large-satellite-maker Boeing, and several small companies. CubeSat

projects have even been the subject of Kickstarter campaigns. The CubeSat format is also

popular with amateur radio satellite builders.

Fig 2.5: Cubesat

Design of Cubesat:

The CubeSat specification accomplishes several high-level goals. Simplification of the

satellite's infrastructure makes it possible to design and produce a workable satellite at low cost.

Encapsulation of the launcher–payload interface takes away the prohibitive amount of

managerial work that would previously be required for mating a piggyback satellite with its

launcher. Unification among payloads and launchers enables quick exchanges of payloads and

utilization of launch opportunities on short notice.

The term "CubeSat" was coined to denote nano-satellites that adhere to the standards

described in the CubeSat design specification. Cal Poly published the standard in an effort led by

aerospace engineering professor JordiPuig-Suari. Bob Twiggs, of the Department of Aeronautics

& Astronautics at Stanford University, and currently a member of the space science faculty at

Morehead State University in Kentucky, has contributed to the CubeSat community. His efforts

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have focused on CubeSats from educational institutions. The specification does not apply to

other cube-like nano-satellites such as the NASA "MEPSI" nano-satellite, which is slightly

larger than a CubeSat.

In 2004, with their relatively small size, CubeSats could each be made and launched for

an estimated $65,000–$80,000. This price tag, far lower than most satellite launches, has made

CubeSat a viable option for schools and universities across the world. Because of this, a large

number of universitiesand some companies and government organizations around the world are

developing CubeSats — between 40 and 50 universities in 2004, Cal Poly reported.

The standard 10×10×10 cm basic CubeSat is often called a "one unit" or "1U" CubeSat.

CubeSats are scalable along only one axis, by 1U increments. CubeSats such as a "2U" CubeSat

(20×10×10 cm) and a "3U" CubeSat (30×10×10 cm) have been both built and launched. In

recent years larger CubeSat platforms have been proposed such as 12U (24x24x36 cm) to extend

the capabilities of CubeSats beyond academic and technology validation applications and into

more complex science and defense goals.

Fig 2.6: Design of a Cubesat

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Since CubeSats are all 10x10 cm (regardless of length) they can all be launched and

deployed using a common deployment system. CubeSats are typically launched and deployed

from a mechanism called a Poly-Pico Satellite Orbital Deployer (P-POD), also developed and

built by Cal Poly. P-PODs are mounted to a launch vehicle and carry CubeSats into orbit and

deploy them once the proper signal is received from the launch vehicle. P-PODs have deployed

over 90% of all CubeSats launched to date (including un-successful launches), and 100% of all

CubeSats launched since 2006. The P-POD Mk III has capacity for three 1U CubeSats, or other

1U, 2U, or 3U CubeSats combination up to a maximum volume of 3U.

CubeSat forms a cost-effective independent means of getting a payload into orbit. Most

CubeSats carry one or two scientific instruments as their primary mission payload. Several

companies and research institutes offer regular launch opportunities in clusters of several

cubes. ISC Kosmotras and Eurokot are two companies that offer such services.

System Design:

The CubeSat program, created at Stanford University’sSpace Systems Development

Laboratory, provides logisticsand launch services for 1-kg cube-shaped satellitesmeasuring 10-

cm on a side. CubeSats are deployed in groups of three from the Poly Picosatellite Orbital

Deployer (P-POD), designed at CalPoly-San Louis Obispo. Launch is aboard a Russian Dnepr

launch vehicle (convertedfrom the SS-18 ballistic missile) from Baikonur Cosmodrome. A

generic CubeSat-based platform capable of satisfying thebasic requirements of LEO-based

science missions was developed. This platform consists of all subsystems neededto support and

power a small science instrument as well ascommunicate data to a ground station. Additionally,

twoseparate science and attitude control subsystems weredeveloped to accommodate the two

science missions.

Internal and External Configuration:

The large toroid on the bottom face is the gravity gradientdamper discussed in the

Attitude Control section below. Thedamper surrounds the tether deployer in this figure; theboom

mechanism used by the GPS mission also fits in thisspace. The communications, C&DH, and

science cards used by the CubeSat are arranged in a stack parallel to the bottomface, and the

batteries are enclosed in a separate box on theright side of the figure.

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Fig 2.7: Internal Configuration

The two missions have slightlydifferent external configuration needs. Common

externalcomponents include solar cells and a communicationsantenna, and both configurations

provide access to an RJ45Ethernet port and a kill switch as specified by the CubeSat program.

The DC/PIP mission also incorporates twopatch antennae for the science experiment, and the

GPSmission includes a pair of redundant GPS antennae. Bothmissions have equal solar cell

coverage.All components, with exception to the science packages, areoff the shelf components

and/or designed by the students.The primary qualification of these components will bethrough

thermal vacuum and vibration testing on both thecomponent and spacecraft level.

Fig 2.8: External Configuration

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Power Supply to a Cubesat:

Satellites in orbit mostly derive their power from the sun. This power is used to energize

the satellite’s systems which include the payload and all of the components that it needs to stay

in orbit and function. Most satellites provide a very short window of time for a controlling

station on earth to manage its internal problems and for user interaction with it. This is why the

satellite needs to be an independent entity which can perform its own housekeeping and its own

fault corrections. This is especially true in the management of power.

Systems in a satellite don’t exactly work at the same time and also an option is needed

from a user in an earth controlling station to be able to switch on or off these systems. Satellites

in orbit are exposed to radiation particles from the sun, this radiation in turn induce and produce

faults where a system drains too much power from its supply and overcurrent and overvoltage or

other power-related conditions take place. Also, satellites, apart from the energy received from

the sun need for a constant supply of energy when the satellite is on the shadow side of the earth

where solar energy collection is at a minimum so a battery pack works along with the solar

collectors in a way that the solar collectors can charge the battery while the batteries supply the

system with the needed power and when the satellite is in shadow the batteries work alone to

give the systems their needed power. From all of these requirements it is then known that it is

necessary to have a self-sustainable and smart power supply.

Eclipse Micro power Design’s project is to develop a smart power supply that can switch

the systems by itself either for necessity of use or because of a fault in the system. An On Board

computer takes charge of receiving data from sensing circuits and a microcontroller to then

switch on or off each individual system. As a future project proposal, this can also be done if a

user from an earth controlling station receives a report from the satellite that such action is

needed. Other options are available in the form of providing backup fuses for systems that use

them, such as the On Board computer. The system would then have to endure and be protected

from radiation in space, especially components having transistors and logic components and

ways of dissipating radiation or retain some for heating as would be in some cases were the

satellite, when in shadow is unable to keep a safe operating temperature for certain components.

The system will also be able to protect itself against temperatures by using circuits which

monitor temperatures in the various systems and are able to switch them on or off as needed.

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The designed system of the group is one such that it could be implemented by any client

with a Cubesat mission, regardless of its particular mission or power needs.

Some of the space environment variables that can affect a satellite’s system are:

1.) Temperature extremes: from -40°C to 80°C.

2.) Heat in the form of radiation, not convection or conduction.

3.) Radiation bombardment that can affect components by leaving “trails” of ionized particles

and cause short circuits. Also gamma rays and solar wind particles can induce overvoltage or

under current conditions and damage systems.

Design Specifications:

Eclipse Micro power’s Design solution for the Cubesat power problem was to design a

distribution system for the components of the Cubesat that monitors, detects and corrects faults

in voltage and current as well as providing temperature monitoring. The group’s intent was to

design a protection scheme for a Cubesat Power Supply Unit that would be flexible, being able

to be modified and used in any Cubesat mission or application.

In order to make a Power Supply Unit that is smart, operates with or without human

intervention and its capable of troubleshooting power issues on its own, the group has come up

with a simple scheme consisting of the following parts:

1. A 8.2V DC BUS connected directly to a 8.2V DC battery array which feeds system their

needed power.

2. A “slave” microcontroller which acts as a protection for the systems, to switch on or off the

systems as needed in the case of faults or simply by user demand and mission needs and provides

this data to the OBC which can be sent as reports to an earth control station.

3. A sensing/ switching circuit at the input of the systems that provides the Microcontroller with

voltage and current data. A current-to-voltage converter (or Transimpedance amplifier) is an

electrical device.

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Input signal and produces a corresponding voltage as an output signal. Three kinds of

devices are used in electronics: generators (having only outputs), converters (having inputs and

outputs) and loads (having only inputs). Most frequently, electronic devices use voltage as

input/output quantity, as it generally requires less power consumption than using current, as it is

the case with our Microcontroller.

4. DC/DC converters connected to the 8.2V DC BUS and to the input of the systems to provide

and control the operating voltages needed for the systems. A simple DC/DC power converter or

in electronics, a voltage divider (also known as a potential divider) is a simple linear circuit that

produces an output voltage (Vout) that is a fraction of its input voltage (Vin). Voltage division

refers to the partitioning of a voltage among the components of the divider.

The equation to calculate output voltage is given by:

Temperature sensing and switching of a warmer for batteries. Temperature sensors that

would monitor the system’s temperature, especially when the satellite is on the shadow side of

the earth and they can activate coil-based heaters to maintain the systems at normal operating

temperatures, especially the battery packs. They can also protect from overheating especially for

the batteries and Microcontroller.

Our design is one where each system in the Cubesat is monitored using a sensing circuit.

The Microcontroller has the minimum/maximum ratings of the system’s voltages and currents

programmed and if fed by the sensing circuit a parameter out of the predetermined values it can

make the decision and switch off the system and then later turn it back on after a set time.

Purpose of using a Cubesat:

The primary mission of the CubeSat Program is to provide access to space for

smallpayloads. The primary responsibility of Cal Poly as a launch coordinator is to ensure the

safety of the CubeSats and protect the launch vehicle (LV), primary payload, and other

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CubeSats. CubeSat developers should play an active role in ensuring the safety and success of

CubeSat missions by implementing good engineering practice, testing, and andverification of

their systems. Failures of CubeSats, the P-POD, or interface hardware candamage the LV or a

primary payload and put the entire CubeSat Program in jeopardy. As part of the CubeSat

Community, all participants have an obligation to ensure safeoperation of their systems and to

meet the design and testing requirements outlined in thisdocument.

P-POD Interface:

The Poly Picosatellite Orbital Deployer (P-POD) is Cal Poly’s standardized CubeSat

deployment system. It is capable of carrying three standard CubeSats and serves as the interface

between the CubeSats and LV. The P-POD is aluminum, rectangular box with a door and aspring

mechanism. CubeSats slide along a series of rails during ejectioninto orbit. CubeSats must be

compatible with the P-POD to ensure safetyand success of the mission, by meeting the

requirements outlined inthis document. Additional unforeseen compatibility issues will

beaddressed as they arise.

General Responsibilities:

1. CubeSats must not present any danger to neighboring CubeSats in the P-POD, the LV, or

primary payloads:

• All parts must remain attached to the CubeSats during launch, ejection and operation. No

additional spacedebris may be created.

• CubeSats must be designed to minimize jamming in theP-POD.

• Absolutely no pyrotechnics are allowed inside the CubeSat.

2. NASA approved materials should be used whenever possibleto prevent contamination of other

spacecraft duringintegration, testing, and launch.

3. The newest revision of the CubeSat Specification is always theofficial version

• Developers are responsible for being aware of changes.

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• Changes will be made as infrequently as possible bearing launch providerrequirements or

widespread safety concerns within the community.

• Cal Poly will send an update to the CubeSat mailing list upon any changes tothe specification.

• CubeSats using an older version of the specification may be exempt fromimplementing changes

to the specification on a case-by-case basis.Cal Poly holds final approval of all CubeSat designs.

Any deviations from thespecification must be approved by Cal Poly launch personnel. Any

CubeSat deemed a safety hazard by Cal Poly launch personnel may be pulled from the launch.

Dimensional and Mass Requirements:

CubeSats are cube shaped picosatellites with a nominal length of 100 mm per

side.Dimensions and features are outlined in the CubeSat Specification Drawing. General

features of all CubeSats are:

• Each single CubeSat may not exceed 1 kg mass.

• Center of mass must be within 2 cm of its geometric center.

• Double and triple configurations are possible. In this case allowable mass 2 kg or3 kg

respectively. Only the dimensions in the Z axis change (227 mm for doublesand 340.5 mm for

triples). X and Y dimensions remain the same.

Fig 2.9: CubeSat isometric drawing.

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Structural Requirements:

The structure of the CubeSat must be strong enough to survive maximum loading

definedin the testing requirements and cumulative loading of all required tests and launch. The

CubeSat structure must be compatible with the P-POD.

• Rails must be smooth and edges must be rounded to a minimum radius of 1 mm.

• At least 75% (85.125 mm of a possible 113.5mm) of the rail must be in contactwith the P-POD

rails. 25% of the rails may be recessed and NO part of the railsmay exceed the specification.

• All rails must be hard anodized to prevent cold-welding, reduce wear, and provideelectrical

isolation between the CubeSats and the P-POD.

• Separation springs must be included at designated contact points (Attachment 1).Spring

plungers are recommended. A custom separation system may be used, but mustbe approved by

Cal Poly launch personnel.

• The use of Aluminum 7075 or 6061-T6 is suggested for the main structure. Ifother materials

are used, the thermal expansion must be similar to that ofAluminum 7075-T73 (P-POD material)

and approved by Cal Poly launchpersonnel.

• Deployables must be constrained by the CubeSat. The P-POD rails and walls are

NOT to be used to constrain deployables.

Electrical Requirement:

Electronic systems must be designed with the following safety features.

• No electronics may be active during launch to prevent any electrical or RFinterference with the

launch vehicle and primary payloads. CubeSats with rechargeable batteries must be fully

deactivated during launch or launch withdischarged batteries.

• One deployment switch is required (two are recommended) for each CubeSat. The deployment

switch should be located at designated points (Attachment 1).

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• Developers who wish to perform testing and battery charging after integrationmust provides

ground support equipment (GSE) that connects to the CubeSat through designated data ports .

• A remove before flight (RBF) pin is required to deactivate the CubeSats during integration

outside the P-POD. The pin will be removed once the CubeSats are placed inside the P-POD.

RBF pins must fit within the designated data ports (Attachment 1). RBF pins should not protrude

more than 6.5 mm from the rails when fully inserted.

Operational Requirements:

CubeSats must meet certain requirements pertaining to integration and operation to meetlegal

obligations and ensure safety of other CubeSats.

• CubeSats with rechargeable batteries must have the capability to receive atransmitter shutdown

command, as per FCC regulation.

• To allow adequate separation of CubeSats, antennas may be deployed 15 minutes after ejection

from the P-POD (as detected by CubeSat deployment switches).Larger deployables such as

booms and solar panels may be deployed 30 minutes after ejection from the P-POD.

• CubeSats may enter low power transmit mode (LPTM) 15 minutes ejection from the P-POD.

LPTM is defined as short, periodic beacons from the CubeSat. CubeSats may activate all primary

transmitters, or enter high power transmitmode (HPTM) 30 minutes ejection from the P-POD.

• Operators must obtain and provide documentation of proper licenses for use offrequencies. For

amateur frequency use, this requires proof of frequencycoordination by the International

Amateur Radio Union (IARU).

• Developers must obtain and provide documentation of approval of an orbitaldebris mitigation

plan from the Federal Communications Commission (FCC).

•Cal Poly will conduct a minimum of one fit check in which developer hardwarewill be

inspected and integrated into the P-POD. A final fit check wills beconducted prior to launch. The

CubeSat Acceptance Checklist (CAC) will be used to verify compliance of the specification

(Attachment 2). Additionally ,periodic teleconferences, videoconferences, and progress reports

may be required.

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Testing Requirements:

Testing must be performed to meet all launch provider requirements as well as any

additional testing requirements deemed necessary to ensure the safety of the Cube Satsand the P-

POD. All flight hardware will undergo qualification and acceptance testing.The P-PODs will be

tested in a similar fashion to ensure the safety and workmanship before integration with

CubeSats. At the very minimum, all CubeSats will undergo the following tests.

• Random vibration testing at a level higher than the published launch vehicleenvelope outlined

in the MTP.

• Thermal vacuum bake out to ensure proper outgassing of components. The testcycle and

duration will be outlined in the MTP.

• Visual inspection of the CubeSat and measurement of critical areas as per the CubeSat

Acceptance Checklist (CAC).

Qualification:

All CubeSats must survive qualification testing as outlined in the Mission Test Plan

(MTP) for their specific launch. The MTP can be found on the CubeSat website.

Qualification testing will be performed at above launch levels at developer facilities.

Insome circumstances, Cal Poly can assist developers in finding testing facilities or

providetesting for the developers. A fee may be associated with any tests performed by Cal Poly.

CubeSats must NOT be disassembled or modified after qualification testing. Additionaltesting

will be required if modifications or changes are made to the CubeSats after qualification.

Acceptance:

After delivery and integration of the CubeSats, additional testing will be performed with the

integrated system. This test assures proper integration of the CubeSats into the PPOD

Additionally, any unknown, harmful interactions between CubeSats may be discovered during

acceptance testing. Cal Poly will coordinate and perform acceptancetesting. No additional cost is

associated with acceptance testing. After acceptancetesting, developers may perform diagnostics

through the designated P-POD diagnosticports, and visual inspection of the system will be

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performed by Cal Poly launchpersonnel. The P-PODs will not be deintegrated at this point. If a

CubeSat failure is discovered, a decision to de integrate the P-POD will be made by the

developers in that PPODand Cal Poly based on safety concerns. The developer is responsible for

anyadditional testing required due to corrective modifications to de integrated CubeSats.

Future development:

An example of one of the ELaNa satellites is the University of New Mexico's Space

Plug-and-play Architecture (SPA) proof of concept flight for the Trailblazer mission. Trailblazer

is a 1U Cubesat to be launched in 2012 under the ELaNa four missions. Kick Sat is scheduled for

launch in early 2014.

The goal of the QB50 project is to use an international network of 50 CubeSats for multi-

point, in-situ measurements in the lower thermosphere (90–350 km) and re-entry research. QB50

is an initiative of the Von Karman Institute and is funded by the European Union. Double-unit

("2-U") CubeSats (10x10x20 cm) are foreseen, with one unit (the 'functional' unit) providing the

usual satellite functions and the other unit (the 'science' unit) accommodating a set of

standardized sensors for lower thermosphere and re-entry research. 35 CubeSats are envisaged to

be provided by universities in 19 European countries, 10 by universities in the US, 2 by

universities in Canada and 3 by Japanese universities. 10 double or triple CubeSats are foreseen

to serve for in-orbit technology demonstration of new space technologies. All 50 CubeSats will

be launched together on a single launch vehicle. The launch is planned for mid-2015. The

Request for Proposals (RFP) for the QB50 CubeSat was released on February 15, 2012.

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CHAPTER - III

CONCLUSION

Outernet is an ambitious project that seeks to create a global WI-FI network that would

provide the entire population of the world with free access to the Internet. A group of American

researchers is out to build a network of satellites that would provide Internet while at the same

time protecting the user’s identity and data. The new network is thought of as a new version of

short radio waves or even a “space torrent”.

There are more Wi-Fi devices in the world than people, yet only 40% of the global

population has access to the wealth of knowledge found on the Internet. The price of

smartphones and tablets is dropping year after year, but the price of data in many parts of the

world continues to be unaffordable for the majority of global citizens. In some places, such as

rural areas and remote regions, cell towers and Internet cables simply don’t exist. The primary

objective of the Outernet is to bridge this global information divide.

Offering continuously updated web content also bypasses censorship of the Internet in

countries that restrict access to independent media. Additionally, Outernet will offer a

humanitarian notification system during emergencies and two-way Internet-access for a small set

of users. The latter feature will be reserved for individuals and organizations that are unable to

access conventional communication networks due to natural disasters or man-made restrictions

to the free-flow of information.

Citizens from all over the world, through SMS and feature-phone apps, participate in

building the information priority list. Users of Outernet’s website also make suggestions for

content to broadcast; lack of an Internet connection should not prevent anyone from learning

about current events, trending topics, and innovative ideas. The project should start running

simulations this year, and in 2015 the initiators want to start the construction phase.

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CHAPTER - IV

BIBILOGRAPHY

REFERENCES

1. NASA. (2010, September) Tracking and Data Relay Satellites (TDRS).

[Online].http://nssdc.gsfc.nasa.gov/multi/tdrs.html

2. CubeSatShop.com, CubeSat Summer Workshop at Small Sat Conference.

Http://www.cubesatshop.com/index.php?

page=shop.product_details&flypage=flypage.tpl&product_id=11&category_id=5&option=com_

virtuemart&Itemid=67

3. Toorian, Armenet. Al, “CubeSats as Responsive Satellites,” Paper no. AIAA-RS3 2005-3001,

AIAA 3rdResponsive Space Conference, Los Angeles, CA, 25-28April 2005

4 .CubeSat Kit (Pumpkin, Inc., San Francisco , CA). http://www.cubesatkit.com

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