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AEROSPACE ENGINEERING

Zero gravity

Ethanol and liquid oxygen are used to fuel suborbital rocket developed in Brazil

Suborbital rocket VSB-30

Léo RamosSuborbital rocket VSB-30Léo Ramos

Expectations are high at the facilities of the Aeronautics and Space Institute (IAE), the research arm of the Aerospace Science and Technology Department (DCTA), located in São José dos Campos, in the state of São Paulo. The agency, under the Ministry of Defense, plans to launch four suborbital rockets in the second half of 2014 that will exceed an altitude of 100 km in a parabolic flight path and provide a microgravity environment. The first to go into space, the probe vehicle VS-30, will carry the Liquid Propellant Rocket Booster Stage (EPL) as a payload. This equipment consists of the first rocket engine produced in Brazil employing liquid fuel and its respective supply system. These two pieces of equipment, with a high technology content, are essential to Brazil’s advancement in the attractive field of satellite launch vehicle technology. The liquid fuel to be tested in the Brazilian rocket has an innovative aspect: it is composed of a mixture of ethanol made from cane sugar and liquid oxygen, which includes Brazil among the nations that contribute to sustainable technological innovation in the aerospace industry.

The VS-30/EPL launch campaign, dubbed Operation Fox, is scheduled to begin on August 12, 2014 at the Alcântara Launch Center (CLA), located 30 km from São Luís, the capital of the state of Maranhão. If everything goes as planned, the rocket will be launched into space three weeks later, in early September. Additionally, the IAE plans to launch the suborbital vehicle VS-40M later this year. This rocket, designed in the early 1990s, will launch the Atmospheric Reentry Satellite (Sara), which will house a series of microgravity experiments. Under microgravity conditions, one can perform various scientific experiments intended, for example, to better understand the structure of proteins in order to create new drugs. In the absence of gravity, the protein crystals become larger because their growth on Earth is limited. Better knowledge of the protein structure of a parasite can help develop more effective drugs against various diseases. In microelectronics, microgravity facilitates preparation of ultrapure silicon for semiconductor studies.

Rocket Sonda IV, in São José dos Campos

Léo RamosRocket Sonda IV, in São José dos CamposLéo Ramos

The last launch, planned for the second half of 2014, for which two rockets are being prepared, is of type VSB-30, a successful suborbital vehicle built in partnership with the German Aerospace Center (Deutsche Zentrum für Luft und Raumfahrt, or DLR). Equipped with two boosters, the VSB-30 made its maiden flight 10 years ago, in October 2004. Since then, 14 rockets have been successfully launched.

A select group
“Brazil has a consistent program for developing suborbital rockets. These low-cost spacecraft are ideal for conducting scientific research of the atmosphere and ionosphere and for the study of new materials and processes in microgravity environments,” says the researcher and head of the IAE space division, Colonel Avandelino Santana Júnior. “These rockets also help in the training of human resources in the aerospace field and have proved ideal for maintaining cooperation programs with foreign research institutions in this industry.” Since the beginning of its activities in the late 1960s, when it was still called the Institute for Space Activities, the IAE has developed seven different suborbital rocket models: Sonda II, Sonda III, Sonda IV, VS-40, VS-30, VS-30/Orion and VSB-30. This achievement places Brazil among the select group of nations with a command of the manufacturing technology needed for these vehicles, alongside the United States, France, China and England. The use of an ethanol-based liquid propellant in its engines is, according to Santana Júnior, another advance in the field. “As far as we know, the use of ethanol (or ethyl alcohol) as a liquid fuel in vehicles of this kind is unprecedented.”

The development of the L5 Engine, powered by ethanol and liquid oxygen (LOX), is the result of a research program on liquid propulsion started at IAE about 15 years ago. Its ultimate goal is to power orbital rockets used to launch satellites into space with a safer liquid fuel than hydrazine-based propellant, a corrosive, toxic liquid, which needs to be imported. Ethanol and liquid oxygen, in turn, are less aggressive on the environment, easier to handle and emit low quantities of soot. The L5 was conceived and designed by IAE with resources from the Brazilian Space Agency (AEB), while the rocket-engine fuel supply system (SAMF) was developed by Orbital Engenharia, a company in São José dos Campos, and made possible through approximately R$2 million in public funds from the Brazilian Innovation Agency (Finep). An important step towards launching the Liquid Propellant Rocket Booster Stage (EPL) was taken in December 2013. The engineers at IAE and Orbital conducted a successful ground test of the flight model of this stage. During the test, all system components functioned as expected. The test consisted of burning the L5 engine on a test bench, connected to the fuel supply system responsible for storing and injecting the mixture of ethanol and liquid oxygen into the engine.

After the success of the ground test, the liquid propulsion equipment needs to be tested during an actual flight, and that is the goal of Operation Fox. During the launch scheduled for early September, the VS-30/EPL will be powered by a booster stage equipped with solid fuel. Twenty-four seconds after launch, this engine will disengage from the payload—in this case, the EPL, which will undergo ignition. The L5 engine will convert the chemical energy contained in the fuel stored in the tanks—ethanol and liquid oxygen—into a propelling force to generate a 5 kN thrust, enough energy to push a block weighing five metric tons.

Powered by the liquid propellant, the payload will follow a parabolic trajectory, typical of suborbital rockets, until it falls into the sea. The mission will be considered successful if both the rocket-engine fuel supply system and the L5 engine function perfectly in flight. “We are confident that the launch will be a success,” says IAE engineer Eduardo Dore Roda, manager of the VS-30 and VSB-30 rocket lines. “The liquid propellant permits controlled burning, which is ideal for satellite rocket launchers. The last stage of these vehicles normally uses liquid propulsion, which allows us to control placement of the rocket in orbit,” he says. According to Roda, mastering this technology in small rocket engines, such as the VS-30, is a significant step toward the development of larger engines. The orbital rockets complete at least one entire trajectory around the Earth at an altitude over 100 km.

The success of IAE’s line of suborbital rockets has transcended Brazil’s borders. Of the 14 missions already carried out with the VSB-30, 11 were launched from the Esrange Space Center, located 200 km from the Arctic Circle, near the town of Kiruna, Sweden. The other three missions were launched from Alcântara, Maranhão. The design of these vehicles began in the early 2000s. “They were manufactured in conjunction with the German Aerospace Center to meet the demand of the European Space Agency (ESA) Microgravity Program. Until then, the DLR used British Skylark rockets to launch their experiments into space, but the vehicle was scheduled to be discontinued and the Germans needed something to replace it,” says the engineer Eduardo Roda. The VSB-30 was designed to carry a payload of 400 kg up to an altitude of 260 km, with more than six minutes of microgravity. The flight of suborbital rockets is of short duration and they experience microgravity conditions for just a few minutes. In that brief period, a series of scientific experiments can be performed.

The VSB-30 V14 launch in 2011 november, in the Esrange Space Center , Sweden

SWEDISH SPACE CORPORATION (SSC)The VSB-30 V14 launching in November 2011, at the Esrange Space Center , Sweden SWEDISH SPACE CORPORATION (SSC)

Until now, the space agencies of Brazil, Sweden, Norway and Germany, in addition to the ESA itself, have done launches with the VSB-30. Two more vehicles will be launched in October and November 2014 from the Andoya Launch Center, in Norway, and a third will be launched in Brazil in 2015, as part of the Brazilian Space Agency Microgravity Program. “The probe rocket is an inexpensive option for performing scientific experiments under microgravity. And the VSB-30, a suborbital vehicle with two solid-propulsion stages, is a very successful rocket,” he says.

The cooperation between IAE and the German DLR dates back to 1969, when the Barreira do Inferno Launch Center (CLBI), in the state of Rio Grande do Norte, was used to launch scientific experiments for the Max Planck Institute for Extraterrestrial Physics in Germany. The cooperation strengthened in subsequent years and resulted in the construction of the VSB-30, produced entirely at IAE and with 70% of its components provided by Brazilian business partners. “The agreement between IAE and DLR to jointly develop a two-stage probe rocket based on the existing Brazilian S30 engine was signed in 2000. Four years later, on October 23, 2004, the VSB-30 successfully completed its test flight,” recalls Colonel Avandelino Santana Júnior.

Two years ago, DLR employed another Brazilian suborbital rocket in its missions, the VS-40M, which is more powerful than the VSB-30. Equipped with two booster stages and capable of carrying a payload of 500 kg to an altitude of 640 km, the VS-40M carried the German Sharp Edge Flight Experiment (Shefex II) into space. These experiments, among other objectives, evaluate the behavior of materials used in the construction of manned space vehicles when subjected to the severe conditions of reentry into the Earth’s atmosphere.

The VSB-30 V16 launch in 2011 April, in the Esrange Space Center , Sweden

THILO KRANZ (DLR)The VSB-30 V16 launching in April 2011, at the Esrange Space Center , SwedenTHILO KRANZ (DLR)

Inertial system
Reentry is also one of the goals of the Sara, manufactured by IAE, which will be launched from the Barreira do Inferno Center in November 2014 aboard the VS-40M, as part of Operation São Lourenço. The satellite is a space platform for microgravity experiments, designed to operate at an altitude of 300 km for a maximum of 10 days. After this period, the Sara will re-enter the Earth’s atmosphere and fall into the Atlantic Ocean, where it will be retrieved for evaluation of the experiments carried out in space. “Among the various experiments aboard the Sara, one of the most important is the test of an inertial system that, in the future, is planned for use on the VLS-1,” says the engineer Nelson Snellaert Tavares, manager of the VS-40M project. It serves as part of the vehicle’s guidance system.

Equipped with two solid-propellant boosters, the VS-40 made its maiden flight in 1993. It was designed to test the S44 engine in flight, in a vacuum, similar to the fourth and final stage of the VLS-1. The other VS-40 booster, called the S40, is equivalent to the third stage of the VLS-1. Five years later, a second VS-40 rocket was launched from Alcântara. Due to the success of these two flights, IAE concluded that the vehicle could be used for microgravity experiments and as one of the probe rockets developed by the agency. “In 2008, DLR showed interest in the rocket. Although at that time the VS-40 was already a very reliable vehicle, we made changes and improved its operational safety, assembly and integration. Hence, it became known as the VS-40M, a modified version of the original,” says Tavares.

The inaugural mission of the VS-40M took place on June 22, 2012, when it was launched from the Andoya Launch Center in Norway, carrying the Shefex II experiment, valued at €7 million. “The mission fully satisfied its objectives,” says the VS-40M project manager. According to engineer Nelson Tavares, the Germans have shown interest in acquiring a new rocket and IAE was also contacted by an international aerospace company interested in a unit of the vehicle. “We are already thinking of future improvements and optimizations, in order to make the VS-40M even more competitive from a commercial standpoint for government agencies and companies that require rockets for suborbital flights and microgravity environments,” he says.

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