An Indian rocket deployed 104 spacecraft into orbit 300 miles above Earth on Tuesday, the largest pack of satellites ever launched on a single booster.
The satellites from India, the United States, the Netherlands, Switzerland, Israel, Kazakhstan and the United Arab Emirates will take pictures of planet Earth, monitor the environment, validate new technologies, and serve as tools in the education and training of future aerospace engineers.
The smooth flight notched 38 straight successful missions for the Polar Satellite Launch Vehicle, India’s workhorse launcher, and nearly tripled the record for the most spacecraft ever sent into orbit on one rocket, besting a mark set by a Russian-Ukrainian Dnepr booster in 2014.
“This remarkable feat by ISRO (the Indian Space Research Organization) is yet another proud moment for our space scientific community and the nation,” Indian prime minister Narendra Modi tweeted. “India salutes our scientists.”
The Polar Satellite Launch Vehicle, India’s workhorse rocket, blasted off at 0358 GMT Wednesday (10:58 p.m. EST Tuesday) from the Satish Dhawan Space Center on the country’s east coast about 50 miles (80 kilometers) north of Chennai.
Flying in the PSLV XL configuration with six enlarged solid rocket boosters, the 144-foot-tall (44-meter) launcher took off on 1.7 million pounds of thrust. Four of the boosters fired with the PSLV’s solid-fueled first stage at liftoff, and two other strap-on motors ignited 25 seconds later.
The four ground-lit motors burned out and separated around T+plus 1 minute, 10 seconds. The two air-lit boosters peeled away from the PSLV at T+plus 1 minute, 32 seconds, as the rocket streaked downrange southeast over the Bay of Bengal.
The first stage jettisoned and gave way to the second stage’s liquid-fueled Vikas engine at T+plus 1 minute, 51 seconds, for a firing that lasted about two-and-a-half minutes with around 180,000 pounds of thrust.
The rocket’s on-board computer transitioned to closed-loop guidance during the second stage burn, and the PSLV’s 10.5-foot-diameter (3.2-meter) payload fairing fell away from the launcher at T+plus 2 minutes, 38 seconds.
The PSLV first headed east from the Indian space center, then turned south in a “dogleg” maneuver to avoid flying over Sri Lanka, accelerating to orbital velocity over the Indian Ocean.
Once the Vikas second stage engine emptied its 42-metric ton (90,000-pound) supply of hydrazine and nitrogen tetroxide propellants, the PSLV’s third stage — another solid rocket motor — ignited around T+plus 4 minutes, 24 seconds, for nearly two minutes, then coasted until separating from the rocket’s fourth stage at around T+plus 8 minutes, 12 seconds.
Dual thrusters on the PSLV’s fourth stage burned for nearly eight-and-a-half minutes to place the 104 satellites into orbit.
Less than a minute after reaching orbit, the fourth stage released the Cartosat 2D environmental satellite — the mission’s primary payload — about 17-and-a-half minutes into the mission. Ten seconds later, two experimental Indian nanosatellites separated to test new types of sensors to observe Earth’s surface, atmosphere and the conditions in the harsh environment of space.
Then came a carefully-choreographed deployment sequence for the remaining 101 payloads stowed inside 25 Dutch-built “QuadPacks” for the ride into orbit.
The QuadPacks opened two at a time to eject their CubeSat passengers. Most of the CubeSats separated while the PSLV was flying over a remote stretch of the Indian Ocean between ground stations in Mauritius and Antarctica.
Once the PSLV passed in range of the receiving antenna in Troll, Antarctica, launch controllers at the Satish Dhawan Space Center confirmed all 104 satellites separated as planned.
Telemetry data beamed down from the PSLV’s fourth stage indicated it reached an orbit around 313 miles (504 kilometers) in altitude and tilted 97.5 degrees to the equator, a near-perfect injection.
“My hearty congratulations to the entire ISRO team for the wonderful job they have done,” said S. Kiran Kumar, ISRO’s chairman, during post-launch remarks.
The Dutch company Innovative Solutions in Space, which specializes in arranging rideshare launches for small spacecraft, arranged for the multi-satellite launch and produced the QuadPacks for the CubeSats in less than six months. The company secured rights with Indian authorities to add secondary payloads to the flight in August.
The addition of more than 100 extra satellites required Indian engineers to ensure the rocket’s fourth stage could hold pointing, guaranteeing the CubeSats would not collide with each other after separation.
“Our teams came up with very good solutions at the right moment,” said B. Jayakumar, the mission director at ISRO. “The first one was finding real estate for accommodating all of the satellites within the payload compartment.”
Seattle-based Spaceflight Services purchased space for nine CubeSats in the QuadPacks — eight 10.1-pound (4.6-kilogram) Lemur commercial weather satellites owned by Spire Global of San Francisco and the BGUSat payload developed by Israel Aerospace Industries and Ben Gurion University.
Most of the satellites launched Tuesday were owned by Planet, another San Francisco company that has already sent up more than 100 shoebox-sized miniature Earth observatories.
Planet’s 88 spacecraft on the PSLV nearly doubled the number of satellites the company has launched since its founding in 2010. The majority of Planet’s orbiting camera platforms have been ejected from the International Space Station in orbits that do not fly over the entire globe, while the satellites that went up from India launched into polar orbit, enabling worldwide coverage.
The small 10.3-pound (4.7-kilogram) CubeSats, nicknamed “Doves,” carry a sharp-eyed camera, extendable solar panels, and high-speed data transmitters to beam images to antennas around the world. Each “flock” of Planet satellites debuts upgraded technology, with the suite of spacecraft launching Wednesday named “Flock 3p.”
“This is the fifteenth time Planet is launching Dove satellites; and it will be our biggest launch to date,” Planet wrote in an update on its website earlier this month. “Combined with the 12 satellites of Flock 2p operating in a similar orbit, this launch will enable Planet’s 100 satellite “line scanner” constellation of Doves. With our RapidEye satellites and Doves operating in other orbits, Planet will be imaging the entire Earth daily.”
With the satellites sent up on Tuesday’s launch, Planet said it has 144 spacecraft in its current fleet, accounting for members that are no longer working.
Planet’s satellites do not have the high resolution of larger, more expensive Earth observatories — like those owned and operated by DigitalGlobe — but their large numbers allow customers to refresh views of a specific location on the ground more often.
The launch of 88 Dove satellites came less than two weeks after Planet announced the acquisition of Terra Bella from Google, which has a constellation of seven higher-resolution spacecraft capable of recording high-definition video during passes over ground targets.
Spire’s Lemur craft carry GPS radio occultation antennas, using satellite navigation signals passed through Earth’s atmosphere to derive temperature and humidity profiles that can be fed into numerical forecast models.
Spire’s satellites also track ships out of range of terrestrial receivers.
With Tuesday’s launch, the company has put a total of 29 CubeSats into orbit, some of which have ended their missions.
Spire won a $370,000 contract from NOAA in September to supply pilot data for the weather agency to determine the information’s usefulness. If the pilot program proves fruitful, NOAA could place an order for more weather data from Spire and other commercial satellite startups to supplement measurements from government-owned satellites.
The other international payloads on Tuesday’s launch were four CubeSats for institutes and companies in the Netherlands, Switzerland, the United Arab Emirates and Kazakhstan.
The Piezo Electric Assisted Smart Satellite Structure, or PEASSS, project will validate a new class of composite structures and power systems for future space missions.
Backed by European Union research and development funding, the PEASS mission will help “develop, manufacture, test and qualify ‘smart structures’ which combine composite panels, piezoelectric materials, and next-generation sensors, for autonomously improved pointing accuracy and power generation in space,” officials wrote on the mission website.
“Smart structures will enable fine angle control, thermal and vibration compensation, improving all types of future Earth observations, such as environmental and planetary mapping, border and regional imaging,” according to mission officials.
The 6.6-pound (3-kilogram) PEASSS spacecraft was developed by a consortium of Dutch companies and scientific institutes.
The Swiss-headquartered company SpacePharma launched its first satellite Wednesday. Named DIDO 2, the 9.3-pound (4.2-kilogram) CubeSat is the first in a line of small spacecraft SpacePharma hopes to send into orbit hosting miniature microgravity research experiments.
The student-built Al-Farabi 1 and Nayif 1 CubeSats from Kazakhstan and the United Arab Emirates, respectively, are also heading to space on the Polar Satellite Launch Vehicle. Al-Farabi 1 will test out a communications system, and Nayif 1 carries an amateur radio transponder.
Meanwhile, the chief purpose of Tuesday’s mission was the launch of Cartosat 2D, the fourth in India’s latest line of mapping satellites fitted with black-and-white and color cameras.
M. Annadurai, director of the ISRO Satellite Center, said after the launch that Cartosat 2D’s solar panels extended as planned following its separation from the PSLV. Ground teams were expected to switch on the satellite’s mapping cameras as soon as Feb. 18.
The 1,574-pound (714-kilogram) Cartosat 2D spacecraft will help analysts update maps, plan urban and rural infrastructure, monitor coastlines and track water usage during its five-year mission.
“This year’s first launch has turned out to be a remarkable event that will be inscribed in golden letters in the space history of India,” said P. Kunhi Krishnan, director of the Satish Dhawan Space Center.
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