In the first of three launches scheduled worldwide Friday, ISRO’s Polar Satellite Launch Vehicle has conducted its fortieth launch, deploying a Cartosat-2 Earth imaging spacecraft and a host of small satellites. Liftoff from the Satish Dhawan Space Centre in India was on schedule at 09:29 local time (03:59 UTC).
Friday’s launch deployed the sixth Cartosat-2 satellite. ISRO has stopped individually naming these spacecraft, instead describing the payload as a “Cartosat-2 series spacecraft” although the spacecraft is informally known as CartoSat-2E – continuing the series used before the spacecraft stopped being named.
Joining the Cartosat spacecraft for its journey into orbit were thirty small spacecraft from fifteen different countries, including the first Latvian and Slovakian satellites.
Designed for Earth observation, CartoSat-2E is the latest in a series of spacecraft which have been used for both military and civilian applications. following on from the civilian Cartosat-2 which was launched in January 2007.
The first dedicated military satellite, CartoSat-2A was launched in April 2008, followed by CartoSat-2B in July 2010. The series’ latest three satellites have been deployed over the space of a year and a day – with Cartosat-2C launching on 22 June 2016 and Cartosat-2D on 15 February this year. All of the constellation’s launches have used ISRO’s PSLV rocket.
Like its predecessors, Cartosat-2E carries a panchromatic imager, along with a multispectral imaging system that has been flown on the last two previous satellites. The spacecraft is based on ISRO’s IRS-2 bus, with a liftoff mass of 712 kilograms (1,570 lb). It is expected to operate for five years. The spacecraft achieves three-axis stabilization through a combination of reaction wheels, magnetorquers and hydrazine-fuelled reaction control thrusters. Power is generated by a pair of solar arrays, charging two lithium-ion batteries. The solar arrays can generate 986 watts of electrical power for the spacecraft.
It is not clear whether Cartosat-2E will be used for civilian or military imaging, or a mixture of the two. ISRO literature surrounding the launch suggests a more civilian role than other recently-launched spacecraft in the series, however given the nature of military spacecraft operations it is not possible to ascertain whether this is an accurate representation of expected operations.
Cartosat spacecraft operate in circular sun-synchronous orbits, with Cartosat-2E destined for an orbit of approximately 505 kilometers (314 miles, 273 nautical miles) with an orbital period of 94.72 minutes and a local time at equatorial crossing of 09:30. Friday’s launch will deploy the satellite directly into this orbit.
Cartosat-2E will likely be the last Cartosat-2 series spacecraft to launch, with a follow-on series, Cartosat-3, due to begin launching next year.
The thirty secondary payloads consist of NIUSAT, for India’s Noorul Islam University, and twenty-nine foreign spacecraft being carried under commercial arrangements contracted through ISRO’s commercial arm, Antrix Corporation.
NIUSAT is a fifteen-kilogram (33-pound) remote sensing satellite intended to support agriculture and natural disaster management. The spacecraft carries a multispectral imaging payload with a ground resolution of 25 meters (82 feet), capable of imaging a square region measuring 50 by 50 kilometers (31 by 31 miles).
Japan’s Canon Electric Satellite, or CE-SAT 1, is a fifty-kilogram (110 lb) microsatellite built by Canon Electronics. Canon will use the spacecraft to demonstrate a high-resolution imaging system in orbit, with a ground resolution of up to one meter (3 feet).
The Max Valier Satellite, or Max Valier Sat, will be operated by Italy’s Max Valier School, in cooperation with Germany’s OHB System and the Max Planck Institute. The satellite’s primary instrument – the Miniature X-Ray Telescope, or µRosi – will be used to conduct an all-sky survey at x-ray wavelengths, with data being downlinked via amateur radio. Max Valier also carries an amateur radio beacon and is expected to operate for one year.
Venta-1 is Latvia’s first satellite. Built by Ventspils University College in cooperation with Bremen University, the 7.5-kilogram (17 lb) spacecraft carries an automated identification system (AIS) receiver, which will pick up identification signals from ships at sea. The satellite will demonstrate how these signals are received in orbit, and relay them to Earth via an s-band downlink. Venta and Max Valier will be attached for launch, being deployed from the PSLV together before separating to begin their individual missions.
The 3 Diamonds are a constellation of three British CubeSats being carried for Sky and Space Global (SAS). The three satellites: Red Diamond, Blue Diamond and Green Diamond, are pathfinders for what their owner hopes will eventually become a 200-strong constellation of S- and L-band communications satellites providing worldwide voice, instant messaging and data relay services. The satellites, built by GOMSpace, are three-unit CubeSats each with a mass of around six kilograms (13 lb).
Friday’s launch also carried eight Lemur-2 satellites for Spire Global, also using the three-unit CubeSat form factor. These are the thirty-fourth to forty-first Lemur-2 spacecraft to launch. Each satellite carries two payloads. STRATOS, a metrological payload, uses the occultation of GPS navigation signals as they pass through the Earth’s atmosphere to measure the temperature, pressure and humidity around the globe. SENSE picks up AIS signals from ships, relaying them back to land to improve tracking and speed up the response to emergencies that develop at sea
Finland’s Aalto-1 is that country’s second satellite after Aalto-2, which was launched in April. Aalto-2 was carried to the International Space Station by a Cygnus mission and deployed on 25 May, however encountered communications problems four days into its mission and is currently out of contact with controllers.
A student-built three-unit CubeSat from Aalto University, Aalto-1 will demonstrate a spectral imaging payload, a radiation detector and the Electrostatic Plasma Brake (EPB), a gravity-stabilised tether which is intended to speed up the decay of the spacecraft’s orbit through an electrostatic interaction with plasma in Earth’s ionosphere.
Community Initiative for Cellular Earth Remove Observation 6 (CICERO-6) is the first spacecraft to be launched in a multi-satellite constellation of six-unit CubeSats for American firm GeoOptics Incorporated. The satellites, which were built by Tyvak Incorporated, will measure the occultation of signals from navigation satellites to map pressures, temperatures and moisture content within Earth’s atmosphere. Signals from both the US Global Positioning System and Europe’s Galileo navigation satellites will be used, with data collected expected to benefit weather forecasting and climate research.
D-SAT is being carried for Italian company D-Orbit is intended to demonstrate the use of a small solid rocket motor to deorbit the satellite following a short technological research mission. Prior to testing its deorbit motor, a prototype of the D3 motor which D-Orbit intends to offer commercially, the spacecraft will test an in-orbit relay system – SatAlert – for the Multiple Alert Message Encapsulation (MAMES) emergency broadcasting protocol. The D3 motor forms part of the spacecraft’s Decommissioning Device, or Decommissioning Electro-Explosive Subsystem (D-EES), an independent unit of the satellite designed to perform the end-of-mission disposal.
After two months in orbit, D-SAT will be deorbited. The D3 motor will provide 450 newtons (100 pounds) of thrust, with a burn time of 3.2 seconds. As the satellite reenters, two further experiments will be conducted. The Debris Collision Alerting System (DeCAS) consists of what D-Orbit have described as a “smart fragment” which will activate as the spacecraft breaks up, determining its position. D-Orbit hope that this device will allow future reentering spacecraft to broadcast debris warnings as they fall. The second experiment, D-Orbit Atmo-Analyzer (DAA), will measure the temperature, magnetic fields and GPS signal occultation as the spacecraft descends into Earth’s atmosphere.
The target site for D-SAT’s reentry is the Pacific Ocean, at a latitude of 30 degrees north and a longitude of 165 degrees East. D-SAT is one of five CubeSats on Friday’s launch which will be used to demonstrate systems for deorbiting CubeSats.
Radiation on Bipolar University Satellite Test Application 1B, or ROBUSTA-1B, is a single-unit CubeSat being launched for France’s Montpellier University in conjunction with French national space agency CNES. The satellite is a replacement the original ROBUSTA, which failed a few days after its launch – in February 2012 aboard the maiden flight of Europe’s Vega rocket. The satellite will conduct testing of electronic systems based around bipolar-junction transistors (BJTs) in orbit, to determine the effects of radiation upon these components.
A single-unit CubeSat, skCUBE will be the first Slovakian satellite since the country’s independence from Czechoslovakia in 1993. The spacecraft is a partnership between the University of Zilina, the Slovak University of Technology in Bratislava and the Slovak Organisation for Space Activities (SOSA), intended to build experience with spacecraft manufacture and operation and to kickstart the country’s space program. skCUBE carries a very low frequency (VLF) receiver, which will be used to try to pick up radio emissions in the ionosphere and from lightning strikes. The satellite also carries a small, low-resolution camera.
The University of Chile’s Suchai, or Satellite of the University of Chile for Aerospace Investigation, satellite is another single-unit CubeSat which was developed to give the university’s staff and students experience with carrying out a satellite mission. Suchai is equipped with a Langmuir probe to monitor variations in electron density within Earth’s ionosphere and an electronics research payload to study out-of-equilibrium fluctuations in the space environment. The satellite is also equipped with a camera and a GPS receiver.
The Tvyak-53b satellite, a three-unit CubeSat, will be operated by American company Tyvak Incorporated to validate technology aimed at helping to deorbit small satellites.
Eight of the spacecraft aboard the PSLV are part of the QB50 program, an international effort to deploy scientific instruments into low Earth orbit aboard a large constellation of CubeSats. The constellation’s goal is to collect in-situ measurements from within Earth’s ionosphere over a long period of time.
The QB50-PL mission, as Friday’s launch is designated within the project’s context, follows the launch of twenty-eight satellites aboard Orbital ATK’s OA-7 Cygnus spacecraft, the SS John Glenn, in April. These satellites were carried to the International Space Station, from where they were deployed between 16 and 26 May. Friday’s launch will provide the satellites with an orbit at a slightly higher altitude and with much higher inclination than those deployed from the space station.
QB50 satellites carry either one of three standard instrument packages, or a technology demonstration payload to support potential future missions. The three standard instruments are an Ion-Neutral Mass Spectrometer (INMS), a Flux-Phi Probe Experiment (FIPEX) or a Multi-Needle Langmuir Probe (m-NLP).
Two of the QB50 satellites aboard Friday’s launch are technology demonstrators. Compass-2 – also known as DragSail-CubeSat or by its QB50 program designation, DE04 – is a three-unit CubeSat to be operated by Germany’s FH Aachen University of Applied Sciences. The satellite is intended to test thin-film solar arrays in orbit, which will be deployed following launch. The spacecraft will also deploy an experimental sail in order to increase the amount of drag it generates, hastening its decay from orbit.
The second QB50 technology demonstrator is InflateSail, or GB06, from the University of Surrey in the United Kingdom. Like Compass-2, InflateSail is a three-unit satellite designed to test a deployable sail as a means to deorbit the satellite. InflateSail will use a 3.3-metre (11-foot) sail at the end of a one-metre (3-foot) boom deployed from the body of the satellite. Using sails to speed up orbital decay at the end of missions is seen as a cost-effective way to mitigate creation of space debris as more and more small satellites are deployed.
The remaining six satellites are evenly split between the three instrument packages. Pegasus – or AT03 – will be operated by Austria’s Fachhochschule Wiener Neustadt. It is a two-unit satellite equipped with an mNLP payload. Pegasus carries its own propulsion system in the form of a pulsed plasma thruster (PPT) assembly with four individual miniaturized thrusters. The assembly can provide a total delta-V of 5.5 meters per second (18 feet per second).
The second mNLP satellite aboard Friday’s launch was the University of Rome la Sapienza Micro Attitude in Orbit Testing (URSA MAIOR), or IT02, for the University of Rome in Italy.
URSA MAIOR is another two-unit satellite and also carries propulsion and deorbit experiments. The satellite’s propulsion system, the MEMS Microthruster Experiment (MEMIT) consists of ion thrusters incorporating microelectromechanical systems (MEMS). As with Compass-2 and InflateSail, the deorbit experiment will see the satellite deploy a sail to increase its drag coefficient.
The two satellites which carry INMS payloads are NUDTSat for China’s National University of Defence Technology and UCLSat for University College London, in the UK. Both of these satellites are two-unit CubeSats, with QB50 program designations CN06 and GB03 respectively. The two FIPEX-equipped satellites are Lithuania’s LituanicaSAT-2, a three-unit spacecraft for Vilnius University which will also demonstrate a monopropellant thruster, and VZLUSAT-1 (CZ02) for the Czech Republic’s Aeronautical Research and Test Institute, VZLU.
Friday’s launch was the fortieth flight of India’s Polar Satellite Launch Vehicle (PSLV). Flying in the PSLV-XL configuration – its heaviest-lift version – the rocket which launched Cartosat-2E was assigned flight number C38. The PSLV is the workhorse of India’s space program, and one of three orbit-going rockets the country currently has operational – alongside the larger Geosynchronous Satellite Launch Vehicle (GSLV) Mk.II and the new GSLV Mk.III which made its first orbital launch earlier this month.
The PSLV is a four-stage rocket, with a mixture of solid-fuelled and liquid-fuelled stages. PSLV first flew in September 1993, although its maiden flight ended in failure and the loss of the IRS-P1 satellite. Although its maiden flight remains the only time the PSLV has failed to achieve orbit, the rocket’s first operational launch – and fourth flight – in September 1997 was a partial failure. On that launch, the fourth stage underperformed leaving IRS-1D in a lower than planned orbit. Since then, the PSLV has achieved thirty-five consecutive successful launches.
PSLV launches take place from the Satish Dhawan Space Centre, on Sriharikota island. Formerly known as the Sriharikota High Altitude Range, the facility was renamed in 2002 following the death of former ISRO chairman Satish Dhawan. The PSLV can fly from either of two launch pads at the site, designated the First Launch Pad (FLP) and the Second Launch Pad (SLP). Friday’s launch will be from the First pad – a pad which was built for the PSLV ahead of the rocket’s 1993 debut.
Rockets launched from the First Launch Pad are assembled vertically on the launch pad, with the aid of a mobile service tower, in contrast to those launched from the Second pad, which are assembled atop a mobile platform and transported to the launch pad from a nearby integration building. In preparation for Friday’s launch, ISRO began a twenty-eight hour countdown at 05:29 local time on Thursday (23:59 UTC on Wednesday).
The launch of PSLV C38 began with ignition of the first stage once the countdown reached zero. The first stage, or PS1, is solid-fuelled and powered by a single S-138 motor. Six strap-on PS0M-XL motors, also solid-fuelled, provide additional thrust during the early stages of flight, with four igniting on the ground and the other two shortly after liftoff. The ground-lit boosters ignited their S-12 motors in pairs, 0.42 and 0.62 seconds after first stage ignition. Ignition of the two air-lit motors occurred twenty-five seconds after liftoff.
The first two ground-lit boosters to ignite burned out and separated from the rocket 79.9 seconds into flight, with the second pair following suit two tenths of a second later. The air-lit solids separated 92 seconds after liftoff, leaving the core stage burning. First stage flight continued until one minute and 50.26 seconds mission elapsed time, when the stage burned out and was jettisoned. The second stage ignited two tenths of a second later, with the stage burning for about two and a half minutes.
The second stage of PSLV, designated PS2 or L-40, is a liquid-fuelled stage with a single Vikas engine. Vikas is a license-built version of the French Viking engine, which was previously used on the Ariane 1, 2, 3 and 4 rockets. It burns UH25 – a mixture of three parts unsymmetrical dimethylhydrazine and one part hydrazine hydrate – oxidized by dinitrogen tetroxide.
Forty-eight and a half seconds after second stage ignition, the payload fairing – or heat shield in ISRO’s parlance – separated from around the satellites at the nose of the rocket. The second stage continued to burn until cutting off about 1.2 seconds before separation, at four minutes, 21.72 seconds elapsed time. Ignition of the solid-fuelled PS3 third stage, which is powered by an S-7 motor, took place 1.2 seconds after staging. This burned for about seventy seconds before the mission enterd a coast phase, with the combined assembly of the third and fourth stages along with the payload coasting towards the apogee of their trajectory.
At eight minutes and 11.22 seconds into the mission, the third stage separated. Fourth stage ignition took place 9.9 seconds after separation, with the stage burning for seven minutes, 37.82 seconds. The fourth stage – designated PS4 or L-2.5 – is liquid-fuelled, burning monomethylhydrazine and mixed oxides of nitrogen.
The fourth stage performs orbit insertion and circularisation, precisely injecting Cartosat-2E and its fellow passengers into the pre-planned orbit. Forty-two seconds after fourth stage cutoff, Cartosat-2E separated from the rocket. NIUSAT separated ten seconds later, with CS-SAT deployed after a further ten seconds. The remaining payloads were deployed over the space of the next six minutes and eighteen seconds, with the final separation event coming twenty-three minutes, 18.94 seconds after liftoff.
Following spacecraft separation, the fourth stage will perform a series of additional burns to test its restart capability. This will entail two short burns of around six seconds, followed by a longer burn lasting around 40 seconds, which will lower the perigee of the upper stage’s orbit to around 350 kilometers (217 miles, 189 nautical miles).
Friday’s launch was India’s fourth of 2017 and the second to use a PSLV. India began 2017 with the launch of the previous Cartosat-2 spacecraft aboard a PSLV in February, along with over a hundred small satellites. In May, a GSLV Mk.II successfully deployed GSAT-9, while earlier this month the new GSLV Mk.III – on its first orbital flight – launched GSAT-19.
India’s next launch is expected in late July or early August, with another PSLV-XL deploying the IRNSS-1H satellite to bolster India’s NavIC, or Indian Regional Navigation Satellite System (IRNSS) constellation. Another IRNSS launch is also expected by the end of the year, along with up to two flights of India’s Geosynchronous Satellite Launch Vehicle (GSLV) Mk.II – one of which is planned for September with the GSAT-6A communications satellite.
The PSLV launch was one of three scheduled for Friday. A Soyuz-2-1v rocket with a Volga upper stage is scheduled to lift off from the Plesetsk Cosmodrome at 18:04 UTC (21:04 local time) carrying a payload for the Russian military. Less than six minutes later a two-hour launch window opens for a SpaceX Falcon 9 mission from the Kennedy Space Center in Florida, which will carry the BulgariaSat-1 communications satellite into geostationary transfer orbit.