Conference PaperPDF Available

Testing and Operations of a Store and Forward CubeSat for Environmental Monitoring of Costa Rica

Authors:
  • Costa Rica Institute of Technology (ITCR)

Abstract and Figures

Costa Rica is world-renowned for its environmental conservation and its clean energy generation. The government-led programs such as the Environmental Services Payment Program has resulted in an increase of the country's forest coverage from 21% in 1987 to 51.4% in 2010. Additionally, the country has established an ambitious goal of becoming a carbon neutral entity by 2021. Many efforts have been developed to contribute to this objective, including Irazu, a project consisting of designing, manufacturing, launching and operating the first Central American satellite to monitor carbon fixation in an experimental forest plantation in Costa Rica. The Irazu project is an initiative of the Central American Association for Aeronautics and Space (ACAE) and the Costa Rica Institute of Technology (TEC), along with many contributors from academia, government, and the private sector. Irazu uses a 1U CubeSat that will act as a Store and Forward system, to collect data from ground sensors in a remote location and forward them to a data analysis and visualization center in TEC. The ground sensors measure tree diameter growth, soil humidity, and meteorological parameters. The data collected is used to estimate the amount of carbon that the trees are absorbing and to observe how this is affected by meteorological variables. Furthermore, this data, along with the spacecraft operating parameters, will be published in a user-friendly website to promote science and technology for Costa Rica's future generations. This paper focuses on the final testing of the spacecraft, which is critical for launch certification, and mission operations. The final testing was performed at the Laboratory of Spacecraft Environment Interaction Engineering of the Kyushu Institute of Technology. Strict requirements set by the launch provider had to be met, which is why this phase included vibration testing, thermal vacuum testing and fit tests of the CubeSat in the JEM Small Satellite Orbital Deployer, among others. Furthermore, the process of obtaining the operating frequency and license of the satellite for a first-time applicant nation is explained. An overview of the operations is presented as well, including a summary of the ground sensor network and how they establish the communication link with the CubeSat, how the satellite stores the data, and how it forwards it to the research center at TEC.
Content may be subject to copyright.
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IAC-18,B4,1,4,x46761
Testing and Operations of a Store and Forward CubeSat for Environmental Monitoring of Costa Rica
Marco Gómez Jenkinsa,o*, Julio Calvo Alvaradob, Ana Julieta Calvoc, Adolfo Chaves Jiménezd,o, Johan
Carvajal Godíneze,o, Alfredo Valverde Salazarf, Julio Ramirez Molinag, Luis Carlos Rosalesh, Esteban
Martinezi, Vladimir Jiménez-Salazarj, Luis Diego Mongek, Carlos Alvarado Briceñol, Juan José Rojasm,p,
Marcos Hernandezn
a Electronics Engineering, Costa Rican Institute of Technology, Cartago, Costa Rica, 30101,
marco.gomez@itcr.ac.cr
b Rector, Costa Rica Institute of Technology, Cartago, Costa Rica, 30101, jucalvo@itcr.ac.cr
c School of Forest Engineering, Costa Rican Institute of Technology, Cartago, Costa Rica, 30101, ajcalvo@itcr.ac.cr
d School of Electronic Engineering, Costa Rican Institute of Technology, Cartago, Costa Rica, 30101,
adchavez@itcr.ac.cr
e Faculty of Aerospace Engineering, Delft University of Technology, Delft, The Netherlands, 2629 HS,
J.CarvajalGodinez@tudelft.nl
f School of Aerospace Engineering, Georgia Institute of Technology, Atlanta, GA, U.S.A, 30332,
avalverde3@gatech.edu
g Institute of Communication and Navigation, German Aerospace Centre, Oberpfaffenhofen-Wessling, Germany,
82234, Julio.Ramirez@dlr.de
h School of Electronic Engineering, Costa Rican Institute of Technology, Cartago, Costa Rica, 30101,
lrosales@itcr.ac.cr
i School of Electronic Engineering, Costa Rican Institute of Technology, Cartago, Costa Rica, 30101,
j School of Forest Engineering, Costa Rican Institute of Technology, Cartago, Costa Rica, 30101,
vjimenez@itcr.ac.cr
kCentral American Association of Aeronautics and Space, Curridabat, Costa Rica, 11801, luis.monge@acae-ca.org
lCentral American Association of Aeronautics and Space, Curridabat, Costa Rica, 11801, carlos.alvarado@acae-
ca.org
m Laboratory of Spacecraft Environment Interaction
Engineering, Kyushu Institute of Technology, Kitakyushu, Japan, 804-8550, q595909h@mail.kyutech.jp
n Laboratory of Spacecraft Environment Interaction
Engineering, Kyushu Institute of Technology, Kitakyushu, Japan, 804-8550, q350937h@mail.kyutech.jp
o Space Systems Laboratory, School of Electronics Engineering, Costa Rican Institute of Technology, Cartago, Costa
Rica, 30101
p School of Electromechanical Engineering, Costa Rican Institute of Technology, Cartago, Costa Rica, 30101,
juan.rojas@itcr.ac.cr
* Corresponding Author
Abstract
Costa Rica is world-renowned for its environmental conservation and its clean energy generation. The government-
led programs such as the Environmental Services Payment Program has resulted in an increase of the country’s forest
coverage from 21% in 1987 to 51.4% in 2010. Additionally, the country has established an ambitious goal of becoming
a carbon neutral entity by 2021. Many efforts have been developed to contribute to this objective, including Irazu, a
project consisting of designing, manufacturing, launching and operating the first Central American satellite to monitor
carbon fixation in an experimental forest plantation in Costa Rica. The Irazu project is an initiative of the Central
American Association for Aeronautics and Space (ACAE) and the Costa Rica Institute of Technology (TEC), along
with many contributors from academia, government, and the private sector. Irazu uses a 1U CubeSat that will act as a
Store and Forward system, to collect data from ground sensors in a remote location and forward them to a data analysis
and visualization center in TEC. The ground sensors measure tree diameter growth, soil humidity, and meteorological
parameters. The data collected is used to estimate the amount of carbon that the trees are absorbing and to observe how
this is affected by meteorological variables. Furthermore, this data, along with the spacecraft operating parameters,
will be published in a user-friendly website to promote science and technology for Costa Rica’s future generations.
This paper focuses on the final testing of the spacecraft, which is critical for launch certification, and mission
operations. The final testing was performed at the Laboratory of Spacecraft Environment Interaction Engineering of
69th International Astronautical Congress (IAC), Bremen, Germany, 1-5 October 2018.
Copyright ©2018 by the International Astronautical Federation (IAF). All rights reserved.
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the Kyushu Institute of Technology. Strict requirements set by the launch provider had to be met, which is why this
phase included vibration testing, thermal vacuum testing and fit tests of the CubeSat in the JEM Small Satellite Orbital
Deployer, among others. Furthermore, the process of obtaining the operating frequency and license of the satellite for
a first-time applicant nation is explained. An overview of the operations is presented as well, including a summary of
the ground sensor network and how they establish the communication link with the CubeSat, how the satellite stores
the data, and how it forwards it to the research center at TEC.
Keywords: CubeSat, Earth observation, offset carbon emissions, remote sensing
Acronyms/Abbreviations
ACAE
Central American Association of
Aeronautics and Space
ACS
Attitude control system
CAN
Controlled Area Network
CDR
Critical Design Review
DBH
Diameter at breast height
DEP
Deployment
DISP
Disposal
EPS
Electric power subsystem
I2C
Inter-Integrated Circuit
IMU
Inertial measurement unit
INA
National Institute of Apprenticeships
INIT
Initialization
ISS
International Space Station
ITAR
International Traffic in Arms
Regulation
JAXA
Japanese Aerospace Exploration
Agency
LEO
Low earth orbit
LNA
Low noise amplifier
MCU
Microcontroller Unit
MM
Main Mission
NASA
National Aeronautics and Space
Administration
OBC
Onboard computer
PDR
Preliminary Design Review
RCCR
Radio Club of Costa Rica
S&F
Store and Forward
SDK
Software Development Kit
SETEC Lab
TEC’s Space Systems Laboratory
SM
Secondary Mission
SOBC
Secondary onboard computer
SRR
System Requirements Review
TEC
Costa Rican Institute of Technology
TRL
Technology readiness level
TNC
Terminal node controller
UHF
Ultra-high frequency
1. Introduction
Costa Rica has played a world-leading role in the
conservation of natural resources. Recent evidence of this
includes the country’s continuing forest restoration,
increasing its forest coverage from 40,7% in 1986 to 48%
in 2005 [1], and its ambitious goal to become a carbon
neutral country by 2021 [2]. The Costa Rica Institute of
Technology’s (TEC) School of Forest Engineering has
been actively monitoring tropical forests and tree
plantations to evaluate provision of ecosystem services
such as the conservation of soil, water resources and
biodiversity, biomass growth and carbon fixation among
other things. Forest ecology researchers, in Costa Rica
and around the world, have faced severe difficulties
accessing remote tropical forest locations for data
extraction, and when they are accessible, valuable
financial and human resources must be allocated to carry
out the manual collection of field information.
TEC and the Central American Association of
Aeronautics and Space (ACAE) conceived Project Irazú
(named after Costa Rica’s tallest volcano) to address
these hindrances. The project consists of using a 1U
CubeSat to demonstrate a Store and Forward (S&F)
system for the transmission of environmental data from a
remote region in Costa Rica to a data processing centre
in TEC. The Store and Forward protocol is a technique
used in telecommunications that consists of sending data
to a node, storing it and transmitting it to another node
after a given period [3]. With the successful launch of the
CubeSat in April 2nd, 2018, it became the first satellite
made in Central America and the smallest satellite that
has demonstrated S&F capabilities to date [4]. The
mission is designed not only to collect scientific data
from remote areas but to train engineers and scientists in
the execution of a space project as well. The project is a
proof of concept, aiming to demonstrate CubeSat S&F
capabilities using one experimental site and one ground
station receiving and transmitting data. The goal is to
expand this technology for future missions, placing
remote stations in tropical countries all over the world
and having a constellation of CubeSats collecting this
data through international collaboration.
This article describes the development and operations
of a CubeSat S&F system for environmental monitoring,
specifically for the estimation of biomass growth and
carbon dioxide fixation from one fast-growth tree species
plantation. The paper is divided into seven sections
corresponding to the different features of the system,
such as the ground sensors, the spacecraft and ground
communications systems.
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2. Project overview
Project Irazú has two main objectives: (1) To
demonstrate the capability to develop and operate a space
engineering project in Costa Rica and (2) to develop a
scientific mission that will allow Costa Rican scientists
to collect field data on a daily basis to estimate the growth
in tree biomass of a remote tree plantation located in the
north lowlands of the country. The first objective relates
to all the components necessary to execute a space-
related project, including developing and identifying a
well-trained technical team, identifying key
organizations interested in space mission development,
and operating the system once the spacecraft is in orbit.
This process yielded a cadre of highly trained
professionals enabling them to execute future space
missions to address other Costa Rican needs. The second
objective describes the purpose of the scientific
component of the mission. It seeks to address one of the
country’s needs, more specifically the study of the
ecology of tree plantations and tropical forests.
The stakeholders of the Irazú mission are ACAE, the
Space Systems Laboratory of TEC (SETEC Lab), TEC’s
School of Forest Engineering, the Kyushu Institute of
Technology (Kyutech), technical collaborators and the
project sponsors. The last one includes individuals from
civil society that sponsored the project through the
Kickstarter platform, which was successfully used to
raise USD 81,369 for the development of the project [5].
Being a multidisciplinary project, other Schools of TEC
participated in the development of the project, including
the Department of Mechatronics Engineering and the
School of Industrial Design.
The team has made considerable advances, as
demonstrated in the schedule presented in Table 1. The
schedule is divided into seven phases, because the team
is using a tailored version of the National Aeronautics
and Space Administration (NASA) project lifecycle.
There are reviews for each of the first five phases of the
project to ensure that the team is following the correct
procedures and executing the project in a responsible
fashion. Only after an external group of experts has
approved the work is the team allowed to advance to
the next phase. The experts carrying out this work on
Project Irazú are from different international institutions
including NASA, Kyushu Institute of Technology
(Kyutech), Delft University of Technology (TU Delft),
and Ad Astra Rocket Company. Project Irais currently
in Phase E, focusing on the operations of the CubeSat and
receiving data from the experimental plot where
measurements on biomass growth are taking place at the
time of the writing of this article.
Table 1. Phases of Project Irazú and deliverables.
Phase
Time Period
Deliverable
Pre-Phase A:
Mission
Definition
Jan 2015-
July 2015
Mission Concept
Review
Phase A:
Requirements
Definition
Aug 2015-
Nov 2015
System Requirements
Review (SRR)
Phase B:
Preliminary
Design
Nov 2015-
Feb 2016
Preliminary Design
Review (PDR)
Phase C:
Final Design
March
2016-July
2016
Critical Design Review
(CDR), CubeSat
subsystems, ground
station components,
ground sensors
Phase D:
Assembly,
Integration
and Testing
Aug 2016-
April 2018
Flight Readiness
Review, CubeSat flight
model, mission control,
ground segment,
Operational Readiness
Review.
Phase E:
Mission
Operations
May 2018-
Oct 2018
CubeSat is operating in
orbit and
communicating with
remote/ground stations.
Phase F:
Mission
Disposal
Nov 2018
Final mission report,
lessons learned,
scientific report.
3. Science
The scientific mission is designed to respond to one
of the most significant global threats: global climate
change. Irazú will focus on how tree plantations fix
atmospheric carbon (CO2) on a daily basis and how the
rate of biomass growth is affected by changes in
environmental variables. This contribution is relevant
because, to the best of our knowledge, there have been no
studies that have provided daily data to understand how
planted trees grow and accumulate biomass. Daily
measurements of tree diameters (growth) are
unprecedented in forest ecology research, given that
previous studies use only annual or monthly averages.
The general objective of the science mission can be
formulated as: To monitor the environmental service of
carbon sequestration of a forest plantation and to study
the dynamics of biomass growth and its relationship with
environmental variables on a daily basis. To accomplish
this objective, the scientific mission team is developing
new technologies to improve efficiency, precision,
frequency, and automation of data collection to measure
tree growth. Hence, the innovation of Project Irazú is to
migrate from manual measurements of tree diameter to
multiple, fully automated digital measurements, which
are taken by an electronic device and transmitted using a
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satellite link, a cellular network, or a radio frequency
network.
3.1 Pilot experimental study
To understand how tree diameter growth varies and
how precise the daily measurements need to be, a pilot
study was established in March 2016 in a commercial
Gmelina arborea (fast growing tree) forest plantation [6],
which was 1.5 years of age and located in the northern
lowlands of Costa Rica. At this site, we also installed an
automatic weather station and three plots with 40 trees
per plot. The diameter and height of all trees were
measured manually every month. After 10 months of
measurements, the general results were: a) average
monthly rainfall 280 mm, average temperature 26.6 C°,
average relative humidity 93%, b) average growth rate of
tree diameters, 0,3mm/day, equal to 11cm/year, and c)
estimated annual accumulation of total biomass (areal +
root) 39 Mg/Ha, total carbon 18 Mg/Ha, and equivalent
CO2 79 Mg/Ha. All calculations were made using models
that were recommended in the literature [7], [8], [9], [10],
and [11]. These results demonstrated a remarkably high
rate of diameter growth and equivalent fixation of CO2.
3.2 Experimental design and data collection
Once the pilot study concluded, we established the
final experimental design in January 2017 on a site
owned by TEC, located in the province of Alajuela,
County San Carlos, in the North of Costa Rica (Figure 1).
This experimental site was selected because of its secure
perimeter and access to electrical power. The region's
topography is relatively flat, with an average slope of
1.24° (±1.51°), an elevation of
𝟑𝟓
𝐦
𝟏𝟏𝟎
𝐦
, mean
annual temperature of
𝟐𝟒
𝟐𝟕
°
𝐂
, and an annual rainfall
of
𝟏𝟗𝟓𝟎
𝟑𝟎𝟎𝟎
𝐦𝐦
. The climate in the region has a
highly variable dry season for 0-3 months [12]. Three
plots of 180
𝐦𝟐
(12 m x 15 m) each were established at
the selected site. This site will provide all the
experimental data to be transmitted to the satellite during
2018. Therefore, these trees will be 1 - 1.5 years of age,
and the estimated daily diameter growth rate will be of
±0.3 mm.
The monitoring of daily growth (diameter) will be
carried out by placing electronic dendrometers (under
final calibration) on three selected trees. The three
electronic dendrometers will be synchronized with a data
aggregator that stores the information. The daily average
of tree diameter growth will be transmitted to the satellite.
In the middle of the site, a tower 15 m high was placed
and it contains: a) an automatic weather station, b) two
pyranometers that measure the incoming and outgoing
solar radiation, and c) two photosynthetic active radiation
sensors that measure radiation between 400 700 nm.
The information from all sensors in the tower, which
include the dendrometers and soil moisture sensors, will
be transmitted to a data aggregator every 30 min. Also,
the tower will be used to install the antenna for the
satellite data transmission system, solar panels, and data
aggregators.
Fig. 1. Pilot experimental site for Project Irazú in San
Carlos, including communications tower.
3.3 Integration of Ground Instuments
To measure daily diameter growth and environmental
factors the team designed a basic data- logger (named
Eco-logger) that will control two main tasks: a) collection
of all data from remote sensors (i.e., dendrometers,
weather station, and soil moisture station) and b) packing
of all collected information in a single data packet that is
ready to be transmitted to the satellite relay. The
Ecologger is a microcontroller-based device, which holds
a repetitive software pattern to measure environmental
variables and poll data from remote sensors at a
configurable frequency. Additionally, the Ecologger
contains a precise time reference, which enables tracking
measurements at the time (and therefore, events) when
they occurred. It also offers an external storage system
using an SD card that acts as data backup storage to
retrieve information if communication with the satellite
is lost, and as a verification method for the transmitted
data. Additionally, it has a backup communication
interface using a USB protocol, which can be used to
connect to a different transmitter or to connect to ground-
based communication technologies if required. On the
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communication interface, the Ecologger acts as a data
aggregator, featuring an XBee master node, which can
collect information from all the remote dendrometers
(Figure 2).
Similar to the dendrometer design (battery operated),
the Ecologger will use a battery to support its life
operation (including an energy-saving mode). For the
initial prototype and test runs, one of the plantation’s
electrical outlets will be used. Future implementations
will use a lithium battery that is dimensioned to support
up to 10 days of continuous operation, with recharging
provided by a solar panel.
Fig. 2. a) Wireless transmission network and b) Block
diagram of the remote ground station for Project Irazú.
3.4 Remote communications station
The objective of this station is to create an
autonomous communication system that will collect the
data from the ground sensors and transmit it to the
spacecraft. The first element to consider is the Ecologger,
which packages the data and sends it to the transceiver.
This device creates a signal that passes through the low
noise amplifier (LNA) and finally to the antenna for
transmission to the spacecraft. An omnidirectional
antenna was selected for this communication station,
because a directional antenna would require rotor control.
This feature is difficult to implement in an independent
station given that the orbital elements of the spacecraft
must be updated frequently during operations. The
remote communications station design demonstrates a
cost-efficient and simple, yet robust mechanism, for
environmental monitoring. Except for the customized
software modem, all ground station hardware is
commercial off-the-shelf (COTS) amateur radio
hardware. This hardware was selected to meet the
requirements that were imposed by the uplink and
downlink budgets. The Remote Ground Station is formed
by a Kenwood TM-D710G Radio (46.9 dBm), a Microset
UHF power amplifier RU 2-45 (46.9 dBm), a Low Noise
Amplifier (LNA) model MIR-KP-2-440 (20 dB), and an
omnidirectional circular polarized UHF antenna (5.5
dBi). The computer that runs the CSP application is a
Raspberry Pi 3 model b+, running in Raspbian (Debian).
Scientific data is collected from sensors wirelessly,
using the radio frequency module: RFM69HCW. After
all data is obtained from the network of sensors and
stored in the Raspberry, each data frame is encoded with
the same AX.25 data frame used with the AX100
transceiver. Both uplink and downlink are performed at a
baud rate of 9600 bps. 1200 bps was originally intended
to be used, but after testing between both radios, better
performance was identified at 9600bps. This increase in
the baud rate was implemented to reduce risks in
transmitting the scientific data. The CSP protocol
implements interfaces and drivers, to transmit data over
different protocols to conserve the CSP structure. A KISS
interface is already carried out in the CSP open source
software commonly used for serial communication [13].
The approach of the KISS interface is to send data to the
CubeSat radio and/or OBC over a USB-Serial converter.
In case the AX100 is in AX.25 mode, the AX.25 header
is added by its microcontroller. Therefore, the AX.25
header is not included in either the KISS CSP interface
or the Kenwood in KISS mode. To include the AX.25
Header and the correct CRC, a “KENWOOD” interface
was developed inside the CSP protocol that was based on
the KISS interface.
The main problem faced with the link was the
modulation incompatibility between radios. The AX100
uses G3RUH FSK modulation and the TM-D710G uses
FM modulation with two-tone AFSK encoding that is
generated by its built-in TNC. Taking advantage of the
“DATA” 6-pin mini-DIN connector in the TM-D710G,
which includes an audio data IN/OUT pin and a PTT pin,
a software TNC modem was implemented. In this way,
the G3RUH FSK modulation can send and receive audios
that contain the encoded data. In fact, plenty of software
modems for amateur radios exist. The open source
Software Defined Radio (SDR) called Direwolf was
selected for this operation. With just a configuration file,
the encoding from a virtual serial port to the audio output
of the Raspberry Pi can be done easily. The PTT can be
controlled with a GPIO pin, and it is configurable with
Direwolf.
a)
)
b)
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3. Space mission overview
The mission consists of using a CubeSat S&F system
to transmit data from a remote experimental station to a
data analysis centre for processing and publishing. From
Figure 3, it can be observed that the system is divided
into three segments: the remote station segment, the
flight segment, and the ground segment.
Fig. 3. Irazú project concept of operations.
The three segments are defined as:
1) Remote station: The location where the
measurements take place. Here the sensors are used
to measure tree diameter growth, temperature,
humidity, rain, wind direction, air pressure, and soil
moisture, among other variables. TEC developed the
sensors, the platform that centralizes the data from all
sensors, and the communications module that
transmits the data to the space segment
autonomously.
2) Flight segment: The segment consists of a 1U
CubeSat that collects the data generated by the
sensors and forwards it to a ground station using a
satellite-to-ground communication standard platform.
3) Ground segment: The ground segment consists
of the ground station, mission analysis, and data
visualization. The operators will provide the retrieved
data to a scientific data analysis and visualization
system.
The concept of operations (ConOps) describes how
the segments of Irazú interact and operate, as presented
in Figure 3. The spacecraft was deployed from the
Japanese Aerospace Exploration Agency’s (JAXA) Kibo
module located aboard the ISS on May 11th 2018. Its
estimated operational period is of 6 months due to
atmospheric effects leading to its orbital decay. Thirty
minutes after being deployed from the ISS, the Irazú
CubeSat released its antenna, initialized the main
subsystems and started transmitting telemetry. Once its
health was confirmed, the spacecraft began transmitting
scientific data from the remote station to the ground
segment. After analysis, all collected data will be
published on a public website in a visually appealing
fashion for the worldwide scientific community and to
promote science and technology in Costa Rica.
4. Spacecraft
The design of the Irazú CubeSat has considered one
important factor: given that this is the first satellite built
in the country (and all of Central America), the failure of
its mission would have a profound impact on the
feasibility and marketing of future space projects in the
region. Nevertheless, to comply with the mission’s
requirements related to the participation of the Costa
Rican team in the design and development of the system,
and in more general terms, showing the local capabilities
to work on a space mission, a compromise on the plan
was undertaken. To balance both objectives, the design
team has taken the following approach:
1) Develop the critical parts of the CubeSat using
systems with a Technology Readiness Level (TRL) of
9, meaning that they have been flight proven during
successful missions. By doing this, the team is
considerably reducing the risk involved in the design.
These subsystems include the solar panels, power
unit, onboard computer (OBC), communications
module, antenna, and antenna deployment system.
2) Have an experienced precision manufacturing
entity fabricate the 1U CubeSat structure in Costa
Rica. Given that the structure is already defined by
the CubeSat standard, and that there already exist
groups within Costa Rica with the capability of
building structures according to the requirements, it
was possible to manufacture this subsystem in the
country, thus minimizing the risk involved with the
mechanical subsystem and reducing hardware costs.
These actions aimed to reduce the risk associated with
the flight segment while allowing the Costa Rican team
to acquire experience in design and development of
subsystems. The CubeSat standard was selected for this
project since it has been used successfully for various
Earth observation missions by universities around the
world [14]. The approach resulted in the purchase of 1U
CubeSat platform (excluding the structure) from
GomSpace, a European CubeSat subsystem provider
with extensive flight heritage [15]. The structure was
manufactured by INA, a Costa Rican autonomous
institution specializing in technical education. A more
detailed explanation of the design and architecture of the
spacecraft can be found in [16].
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4.1 Assembly
The assembly of the CubeSat took place in October
of 2017 in a clean room class 100,000 that is owned by
MOOG Medical, a medical manufacturing company that
is located in the Coyol Free Zone, one of the project’s
sponsors. The assembly procedure is based on the
CubeSat Integration Manual that was written by
researchers at the California Polytechnic State University
[18]. Assembly manuals for the Irazú CubeSat were
developed as well, given that the satellite had to be
reassembled at Kyutech for testing. Activities that were
related to the assembly include verifying the internal
component distribution of the final designs, verification
of final mass distribution, and an overall compliance to
the requirements specified by JAXA, the launch
provider, and the CubeSat standard. The Irazú team took
the necessary precautions when handling the spacecraft
components, which include the use of safety gloves, an
anti-static mat, and grounding each of the individuals
present in the assembly room in order to avoid
electrostatic discharges. Figure 4 displays the CubeSat
during the assembly process.
Fig. 4. Integration of the Irazú CubeSat in MOOG
Medical’s 100,000 class clean room.
4.2 Testing
The tests performed to the Flight Model were
Vibration Test, Thermal Vacuum Cycle Test, Cold
Antenna Deployment Test, and Battery Verification Test.
The purpose of the Vibration Test is to demonstrate that
the satellite can withstand the random vibrations with no
structural failure, no malfunction of components
(accidental turn-on or deployment), and no damage to
electronic, mechanical and electromechanical
components. Thermal Vacuum Cycle Test is performed
to demonstrate that the satellite can withstand the thermal
stress induced by the thermal cycles in its orbit and that
it is able to turn on and operate properly in those
conditions. The Cold Antenna deployment is performed
to assure that even in cold conditions the antenna release
heaters can liberate the deployable antenna 30 minutes
after the release from the ISS. The environmental tests
were carried out at the Center for Nanosatellite Testing
(CeNT) of the Kyushu Institute of Technology, following
the specifications of the JEM Payload Accommodation
Handbook-Vol.8 [17] and Structure Verification and
Fracture Control Plan for JAXA Selected Small Satellite
Released from J-SSOD (JEM Small Satellite Orbital
Deployer). For these tests a Proto-Flight approach was
used, which is Qualification Test levels (QT) with
Acceptance Test durations to demonstrate that the
satellite can survive the launch and operational
environment. After every environmental test, a functional
test and a battery verification test were carried out.
4.2.1 Vibration Test
To perform the test, the Irazú FM was inserted into a
holder fabricated to emulate the J- SSOD, attached to the
vibration machine and monitored by accelerometers. The
test was performed in all three axes. Considering several
vibrations input profiles as follows:
1) Signature Check: a frequency sweep to
determine the natural frequencies of the satellite. It
was applied before and after every other test profile
to detect any displacement on the resonance
frequency.
2) Random Vibration: consist of random vibrations
within a Power Spectrum Density (PSD) profile. For
Irazú, a combination of Power Spectrum Densities
encompassing the potential launch vehicles was used
(SpaceX Dragon, and Orbital Cygnus). A combined
maximum envelope profile was calculated, as is
displayed in Figure 5. Under those conditions the
overall input is 6.383 g. The test duration was set to
60s.
Fig. 5. Signature check result.
The sequence of the test for each axis was: 1)
Signature Check. 2) Random vibration. 3) Signature
Check. As an example of the obtained results, the x-axis
PSD profile of the before and after vibration test
Signature Checks is shown in Figure 8.
69th International Astronautical Congress (IAC), Bremen, Germany, 1-5 October 2018.
Copyright ©2018 by the International Astronautical Federation (IAF). All rights reserved.
IAC-18,B4,1,4,x46761 Page 8 of 10
4.2.2 Thermal vacuum cycling test
For this test, a vacuum chamber with a special cooling
jacket was used to surround the satellite with liquid
nitrogen at a temperature of −192°C. Heaters were placed
around the satellite to control the temperature and
generate thermal cycles as if the satellite were orbiting
the earth. Two cycles were carried out. Irazú was be
powered on using its own battery from a cold start at -
20°C. During this test, thermocouples were installed
inside Irazú to verify the reading of the thermal sensors
on the OBC, battery, and transceiver units, as shown in
Figure 6.
Fig. 6. Component temperatures during Thermal
Cycles Test.
5. Ground Segment
The ground segment is the final component of the
Irazú mission. Its functions include tracking the satellite,
monitoring its health, uploading commands and most
importantly, downloading the data that originated from
the forest sensors. The ground station was designed by
the Radio Club of Costa Rica (RCCR) with the main
objective of creating a low- cost station for operations in
the UHF band. This is accomplished by using
Commercial Off the Shelf (COTS) Components. The
ground segment is composed of three elements, which
are the ground station, mission control and data
visualization. The ground station component relates to
the actual hardware required to contact the spacecraft,
while mission control focuses more on the software
needed to operate the mission. The final element of the
ground segment processes the raw data acquired by the
field sensors to produce scientific imagery that will be
attractive to the public and raise interest in the mission.
Figure 7 displays the block diagram of the ground
segment. The main difference between this one and the
remote communications station is that the TEC ground
station has a directional Yagi antenna, while the remote
station has an omnidirectional Eggbeater antenna. The
latter is essential to the design of the remote station since
it eliminates the need for rotors. The downside is that
there will be greater polarization losses and a lower
antenna gain with the omnidirectional type. When using
the Yagi antenna, rotors must be included, as displayed
in the block diagram, to point the antenna in the direction
of the spacecraft. An LNA is also implemented to
increase the signal strength required to establish the link
between the ground station and the spacecraft.
Fig. 7. Block diagram of the TEC ground station.
The antenna (gain of 13.3 dBi) is connected to an
LNA model MIR-KP-2-440 (gain of 20 dB). The LNA
main functionality is to increase the signal strength
required to establish the downlink between the spacecraft
and the ground station. Several software and mechanical
calibration procedures were made to the rotor system
before and after the rooftop installation. For the
verification of the azimuth and elevation, angles
measurements were made with the gyroscope and
magnetorquer sensors of different smartphones. The FM
transceiver used in the ground station for receiving and
sending the radiofrequency signal is the radio model TS-
2000 by Kenwood. It is connected with a type N
connector and a 40 m long LMR-400 RF cable with
associated losses of 3dB. Due to the G3RUH FSK
modulation scheme used in the spacecraft, the decoding
of the AX.25 packet is performed with Direwolf SDR,
which is the same as for the remote ground station.
6. Launch and Operations
The CubeSat was launched on April 2nd 2018 from
Cape Canaveral Florida onboard a SpaceX Falcon 9
rocket, as part of the Commercial Resupply mission
(CRS-14) headed to the ISS. On May 11th 2018, Irazú
was deployed from the ISS along two other CubeSats:
Ubakusat (Turkey) and 1KUNS-PF (Kenya). Figure 11
displays the release of Irazú and 1KUNS-PF as
photographed by an astronaut onboard the ISS. First
contact with the CubeSat from the ground station located
on TEC’s campus was achieved on the same day,
confirming proper performance of the satellite. The first
data files from the remote station were uploaded on May
17th 2018 and the first download of the files to the ground
segment was completed on May 22nd 2018,
-20
0
20
40
60
80
0 5 10 15 20
OBC
Battery
Transceiver
Time(h)
69th International Astronautical Congress (IAC), Bremen, Germany, 1-5 October 2018.
Copyright ©2018 by the International Astronautical Federation (IAF). All rights reserved.
IAC-18,B4,1,4,x46761 Page 9 of 10
demonstrating the proper operations of the CubeSat S&F
system. At the time of the writing of this article, the
satellite is working nominally, storing data files from the
remote station and forwarding them to the ground
segment.
Fig. 8. Deployment of Irazú and 1KUNS-PF from
JAXA’s Kibo module.
Table 2. Transfer duration and scientific data transferred
for early operations of Irazú.
Function
al Tests
Operations
Transfer
Duration (s)
Upload
11.07
10.91
Download
11.12
10.98
Scientific
Data (kB)
Average
1.00
0.82
The lowest Receive Signal Strength Indicator (RSSI)
obtained from the telemetry downloaded in the TEC
Ground Station is -112 dBm. The RSSI calculated from
the link budget is approximately -113 dBm, this was
considering the minimum elevation angle where the link
margin is more than 3 dB. Only 1 dBm of deviation from
the theoretical RSSI. In this early operations period there
were a total of 12 files transferred, where 7 were
uploaded and 5 downloaded. An additional file was
downloaded, containing the event log file of the
spacecraft, which helped to confirm that all four antennas
were deployed successfully. Both duration processes,
upload and download were registered by the remote
ground station and the ground station, respectively.
These results can be compared with functional tests
performed at the Kyutech facilities, before the Irazú
launch. The transfer durations and the total average are
presented in Table 2, where it can be observed that the
operations are consistent with the functional tests.
6.1 Scientific mission
To date, the scientific mission was able to develop
and evaluate an electronic device to measure daily the
growth in the diameter of fast-growing trees, in this case
of Gmelina arborea. The electronic device was evaluated
for 80 days on the field between February and May 2018,
achieving outstanding results. During this period, 12 days
were eliminated because at least one device failed, which
invalidates diameter average calculations. Figure 9
shows the average daily diameter growth using the three
devices that worked during the field test. As it can be
observed there is a sustained growth in the diameter
starting at an average of 9.59 cm in February and ending
at 10.88 cm in May. This means that there was a growth
of 1.29 cm in 80 days, equivalent to a daily growth rate
of 0.017 cm. To estimate the accuracy of the device, 9
readings were used against manual measurements of high
precision and the error was only 3.4%, which
demonstrates a high accuracy for these type of devices.
Fig. 9. Daily Tree Diameter in cm (Gemelina arborea) ,
Costa Rica. Average daily readings of three electronic
devices during 80 days, from February to May 2018.
In Figure 9 it is observed that there are days of
positive growth while others show a reduction in the
daily rate of growth, something that had never been
observed so clearly. The periods of reduced growth rates
(negative rates) are probably related to the loss of turgor
of the trunk of the tree due to dehydration during short
periods of drought, or perhaps related to the same
measurement error of the instrument. In the following
months more evaluations will be made to understand the
causes of this behavior in the readings of the device or in
the growth of this species.
7. Conclusion
The design, development and operations of a CubeSat
S&F mission for Earth observation is presented in this
paper. Results from early operations validate the design
of the system, given that the spacecraft was successfully
able to store data files from the remote station and
forward them to the ground station located at TEC.
Furthermore, preliminary daily recording of tree
diameter growth, using novel electronic instruments,
showed to be an unparalleled observation method for
gauging tree biomass growth with high precision at a
69th International Astronautical Congress (IAC), Bremen, Germany, 1-5 October 2018.
Copyright ©2018 by the International Astronautical Federation (IAF). All rights reserved.
IAC-18,B4,1,4,x46761 Page 10 of 10
high rate. This design could be expanded to include more
remote stations for Earth observation around the world,
and a constellation of CubeSats to collect data,
demonstrating a low-cost solution for remote sensing.
Acknowledgements
The authors acknowledge the Research Vice-Rectory
of TEC for both their cooperation during the project and
financial support. Additionally, they wish to thank the
sponsors of this project, which include private and public
Costa Rican entities, and supporters of the crowd funding
campaign using the Kickstarter platform. Furthermore,
The authors wish to thank the Radio Club of Costa Rica
for their support in the design of the TEC ground station,
MOOG Medical for access to the clean room to assemble
the CubeSat, and INA for manufacturing the CubeSat
structure. Finally, they wish to thank the project’s
advisers (Dr. Franklin Chang-Díaz, MSc. Sandra
Cauffman and Dr. Andrés Mora) and its evaluating
committee (Dr. Mengu Cho and Dr. Eberhard Gill).
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Conference Paper
Full-text available
Costa Rica became a space nation in 2018, with the launch of the CubeSat "Project Irazú". Also, in 2016 the Costa Rica Aerospace Cluster was created with the objective of strengthening the capabilities of the companies working in aerospace engineering, an industrial area of very high added value. The Space Systems Engineering Laboratory (SETEC Lab) of the Costa Rica Institute of Technology (TEC) was created in 2017, becoming the first of its class in Central America. It was responsible for the technology development of Project Irazú and currently is partner with both George Washington University and Kyushu Institute of Technology in the development of small-satellite missions. Nevertheless, before 2019, no formal space engineering education existed in Costa Rica. The current development in the space area and the capabilities of SETEC Lab led to interested students to request an "Introduction to Space Engineering" (ISE) elective course at the Electronic Engineering School at TEC. It was identified that the capabilities of electronic engineering students with formation in space engineering will improve the development of future projects at both university and industrial level. ISE was proposed with the objective of teaching non-aerospace engineering students the fundamental knowledge needed for them to develop a space mission, focused on the design of small satellite missions. ISE is divided in two: the first segment consists of lectures on the general knowledge needed for non-aerospace engineering students to develop a space mission, including fundamentals of astrodynamics, space engineering concepts, spacecraft subsystems and mission simulations. In the second stage, the students are guided through the NASA Systems Engineering method to develop a mission. This leads to a "Preliminary Design Review" of the design of a satellite or a constellation of satellites using TRL-9 hardware and proving the feasibility of the mission via simulations. A hard requirement for the mission is that it should be a proposal for a mission that creates a non-existing capability useful for a company or an institution in Costa Rica. Examples of missions developed are satellite systems to monitor ships in Costa Rica waters, or volcanoes monitoring, both with better time-resolution than current existing solutions. It is expected that due to the success of this course, a space engineering specialization consisting of three courses would be open as part of the electronic engineering curriculum. Also, it is expected that ISE would be open for students from any career at TEC.
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The potential of space and geospatial technologies (SGTs) for sustainable develop- ment is enormous. In particular, all Sustainable Development Goals can be approached though SGTs utilisation, making it a key area of interest for multilateral development banks (MDBs). This article argues that development banks have the influence and responsibility to mainstream the use of SGTs for sustainable develop- ment. It first presents the current utilisation of such technologies before introducing two specific directions MDBs should follow, namely the development of a space infrastructure and the support to the emerging private space sector. The recom- mendations made in this article are based on a pragmatic analysis of the potential of SGTs and on the actual scope of MDBs' activities. They can be easily implemented, without requiring significant structural or strategic change for any of the major existing MDBs.
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The Costa Rica Institute of Technology (TEC) and the Central American Association of Aeronautics and Space (ACAE) are currently developing the Irazú project, which consists of using a 1U CubeSat to demonstrate the capacity of a Store and Forward system for the transmission of environmental data from a remote region in Costa Rica to a data processing center in TEC. The Irazú project has two main objectives, which are: 1) To demonstrate the national institutional capability to develop and operate an aerospace engineering project in Costa Rica. 2) To develop a scientific mission that will allow Costa Rican scientists to collect data related to the national effort to mitigate CO2 emission by forest carbon fixation.
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The work performed in this project is part of the Test Satellite student project at the Norwegian University of Science and Technology (NTNU). Setting up a ground station for CubeSats is a complex task requiring considerable resources and knowledge in several fields. Extensive work and time is required if all modules and parts of the base station are developed from scratch. This work is an effort to simplify the development process by creating a module/building block for receiving, sending and displaying CubeSat data. Communication with the satellites is achieved through a software defined radio. A network protocol called CubeSat Space Protocol is used. The protocol unwrapping software will run as a background process on a web server, continuously listening for data transmissions from the satellite. Communication between the software defined radio framework and the server will use User Datagram Protocol or Transmission Control Protocol. Whenever a packet is received its content should be written to the server, either to a database or to a text file, ensuring a persistent data structure. The data stored to the server shall be accessed through a graphical user interface taking the form of a web page. It is written in Python using the Django web framework, making it easy to extend and maintain. The GUI will also have the ability to send simple commands to the satellite, requesting data transfers or in other ways command the satellite. The commands will be stored as a time tag list and transferred when the satellite is in range. Commands, defined through Django's administrative pages, are given via a text field. Even though the project is part of the NTNU Test Satellite project the framework is developed to be accessible and allow for uncomplicated integration into other projects. The only required protocols are CubeSat Space Protocol and User Datagram Protocol or Transmission Control Protocol. Our goal is that a module of this kind, if user-friendly in its interface and implementation, may boost the motivation for creating a global network of base stations. Such a network which would ensure continuous contact with CubeSats through their orbits.
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Pico-satellites have recently gained substantial traction in research and educational communities due to their rela tively low cost. The largest factor in keeping the cost down, their small size, also poses their biggest engineering chal lenge. The tiny, low power radios used to communicate with earth have extremely slow data rates. A typical pico satellite is within communication range of the ground sta tion for approximately 40 minutes per day with a theoreti cal maximum data rate of 1200 bps. At this speed a high resolution digital photograph can take weeks to download. This paper presents a novel communication protocol that allows a sparse network of pico-satellites to transfer data directly between one another. This capability is used to get the data to a “data mule”. The data mule is a spe cialized satellite capable of relaying traffic back to earth at higher rates than the current satellites. This work includes an implementation of the commu nication protocol and a simulator used to evaluate the pro tocol. Simulation results show that, regardless of varying satellite topologies and traffic workloads, the protocol has a significant increase in both the quantity of data transferred to earth and a reduction in the total time required to transfer all the data.
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Leaf area index (LAI) is one of the most frequently used parameters for the analysis of canopy structure and it has also been shown to be an important structural characteristic of the forest ecosystem and forest productivity. The objectives of this study were: (1) to calibrate optical estimates of PAI (plant area index) from the LAI-2000 using leaf area index derived from allometric models for six different tropical tree species and (2) to explore the corresponding relationship of calibrated LAI-2000 with stand productivity indices and environmental factors along a strong environmental gradient in the southern region of Costa Rica. From sixteen 6-year-old pure stand plantations (trees spaced 3m×3m) of four fast growing native species (Terminalia amazonia, Vochysia ferruginea, Vochysia guatemalensis and Hieronyma alchorneoides) and two introduced species (Pinus caribaea var hondurensis and Gmelina arborea), the plant area index (PAI) was estimated indirectly using the LAI-2000 plant canopy analyzer (LI-COR, Lincoln, NE), under cloudy sky conditions at a fixed height of 1.3m above the ground with a 45° view cap. In addition, leaf area index (LAI) was estimated allometrically by felling four selected trees and measuring the area and biomass of leaves. The specific leaf area (SLA) showed typical values for each tree species that ranged between 81cm2g−1 (V. ferruginea) and 106cm2g−1 (G. arborea). Based on the characteristic SLA, for all tree species, the leaf area per tree could be estimated by allometric equations using the dbh (diameter at 1.3m) as the independent variable. The calibration of the LAI-2000 PAI data versus the allometric estimate of leaf area showed strong and unbiased relationship for the species: T. amazonia, V. guatemalensis, H. alchorneoides and P. caribaea. In the case of G. arborea and V. ferruginea the LAI-2000 PAI values underestimated and overestimated the allometric measurements of LAI. For all tree species, calibrated LAI-2000 values were used as an independent variable in highly significant regression equations to estimate dominant tree height in each stand (in m) and stand yield in m3ha−1year−1, implying that calibrated LAI-2000 can be used to evaluate site quality and stand productivity. The generalized relationships for all species, between average calibrated LAI-2000 with stands yield or dominant tree height among four Eco-regions, indicated that as soil nutrient and water supply become optimal for tree growth, maximum LAI, dominant stand height and yield values are obtained.
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Early growth performance of six native and two introduced tree species was studied for seven years at 16 sites in the Southern region of Costa Rica. Selected study sites represent a wide environmental gradient that ranges from acid low fertility soils such as Ustic Haplohumults and Typic Haplustults to fertile soils such as Typic Hapludand and Fluventic Eutropepts. Mean annual precipitation ranges from 2600 to 4500 mm and length of dry season from none to more than three months each year. The experimental layout was a randomized complete block design nested within four eco-regions, with all plots on private farms. The size of the experimental plot was 11 × 11 trees planted at a spacing of 3 × 3 m with a sampling plot of 7 × 7 trees. The species included in the initial trials were: Pinus caribaea Morelet var hondurensis (Barret y Golfari) and Gmelina arborea Roxb as the introduced species (from Honduras and southeast Asian regions, both of which benefit from genetic selection), and Terminalia amazonia (J. F. Gmelin) Exell, Vochysia ferruginea Mart., Vochysia guatemalensis Donn. Sm., Hieronyma alchorneoides Fr. Allemao, Calophyllum brasiliense Cambess and Schizolobium parahyba (Vell.) S. F. Blake (collected extensively in this project from indigenous populations from across the Southern region of Costa Rica). All plots were measured annually and data collected for tree height, DBH and mortality. Composited soil samples were taken at three depths in each site to characterize chemical and physical soil properties. In general, the native species were highly responsive to eco-regions, the introduced species much less so. The yield and dominant stand height of the introduced species were higher in acid soils with well defined dry season than the selected native species. As soil nutrient and water supply improved, the differences between introduced and native species decreased in mean stand height and yield. Two species (Calophyllum brasiliense and Schizolobium parabyba) had more than 80% mortality in almost all plots during the first two years of establishment. The results of this study contrasts with findings obtained in the Northern region of Costa Rica on acid Ultisols (Typic Tropohumult), where at least Vochysia guatemalensis and Vochysia ferruginea out-competed the best introduced species, Gmelina arborea and Pinus spp. Results are mainly attributed to the pronounced ustic moisture regime in the Southern region of Costa Rica that is able to be tolerated by Gmelina arborea and Pinus spp. but not by the selected native tree seedlings.
Informe Estado de la Nación. Capítulo Armonía con la Naturaleza. XV Informe Estado de la Nación
  • J Calvo-Alavarado
  • Bosque
Calvo-Alavarado, J. Bosque, cobertura y recursos forestales. 2008. Informe Estado de la Nación. Capítulo Armonía con la Naturaleza. XV Informe Estado de la Nación. San José, Costa Rica. 26 pp.
Meta de Carbono Neutralidad para el 2021 se mantiene y fortalece
  • Costa Presidency Of The Republic Of
  • Rica
Presidency of the Republic of Costa Rica. Meta de Carbono Neutralidad para el 2021 se mantiene y fortalece. 6 September 2016, Available online at: http://presidencia.go.cr/comunicados/2016/09/meta-decarbono-neutralidad-para-el-2021-se-mantiene-yfortalece/ (accessed June 2018).
Potential Use of Nanosatellites for Store-and-Forward (S&F) Remote Data Collection Systems, Space Engineering Seminar
  • A Salces
A. Salces, Potential Use of Nanosatellites for Store-and-Forward (S&F) Remote Data Collection Systems, Space Engineering Seminar 2017, Kyushu Institute of Technology, Kitakyushu, Japan, Jun. 2017.
Irazú Project: The First Satellite Made in Costa Rica
  • A Chavarría
A. Chavarría et al., Irazú Project: The First Satellite Made in Costa Rica, March 21st 2016, https://www.kickstarter.com/projects/irazu/irazuproject-the-first-satellite-made-in-costa-ri, (accessed 13.06.18).
Productivity, aboveground biomass, nutrient uptake and carbon content in fastgrowing tree plantations of native and introduced species in the Southern Region of Costa Rica
  • D Arias
  • J C Calvo-Alvarado
  • D Richter
  • A Dohrenbush
Arias D., Calvo-Alvarado J.C., D. Richter. and A. Dohrenbush. 2010. Productivity, aboveground biomass, nutrient uptake and carbon content in fastgrowing tree plantations of native and introduced species in the Southern Region of Costa Rica. Biomass and Bioenergy. 35: 1779-1788.