On July 21, 2011, the American spacecraft Atlantis made its last landing, which put an end to the long and exciting Space Transportation System program. For a number of technical and economic reasons, it was decided to discontinue the operation of the Space Shuttle system. Nevertheless, the idea of a reusable spacecraft was not abandoned. Currently, several similar projects are being developed at once, and some of them have already managed to show their potential.
The Space Shuttle reusable spacecraft project pursued several main goals. One of the main ones was reducing the cost of the flight and preparation for it. The possibility of multiple use of the same ship in theory gave certain advantages. In addition, the characteristic technical appearance of the entire complex made it possible to significantly increase the permissible dimensions and weight of the payload. A unique feature of the STS was the ability to return spacecraft to Earth inside its cargo bay.
The last launch of the Altantis spacecraft, July 8, 2011 Photo by NASA
However, during operation it was found that not all of the tasks were completed. So, in practice, preparing the ship for flight turned out to be too long and expensive - according to these parameters, the project did not fit into the original requirements. In a number of cases, the reusable spacecraft was fundamentally unable to replace "conventional" launch vehicles. Finally, the gradual moral and physical obsolescence of the equipment led to the most serious risks for the crews.
As a result, it was decided to terminate the operation of the Space Transportation System. The last 135th flight took place in the summer of 2011. Four existing ships were written off and transferred to museums as unnecessary. The most famous consequence of such decisions was the fact that the American space program was left without its own manned spacecraft for several years. Until now, astronauts have to enter orbit using Russian technology.
In addition, the entire planet was left without reusable systems for an indefinite period. However, certain measures are already being taken. To date, American enterprises have developed several projects of reusable spacecraft of one kind or another. All new samples have already, at least, taken out for testing. In the foreseeable future, they will also be able to enter full-fledged operation.
Boeing X-37
The main component of the STS complex was an orbital aircraft. This concept is currently being used in Boeing's X-37 project. Back in the late nineties, Boeing and NASA began to study the topic of reusable spacecraft capable of being in orbit and flying in the atmosphere. At the beginning of the last decade, this work led to the start of the X-37 project. In 2006, a prototype of a new type reached flight tests with a drop from a carrier aircraft.
Boeing X-37B aircraft in a launch vehicle fairing. Photo by US Air Force
The program interested the US Air Force, and since 2006 has been implemented in their interests, albeit with some assistance from NASA. According to official data, the Air Force wants to get a promising orbital aircraft capable of launching various cargoes into space or performing various experiments. According to various estimates, the current X-37B project can also be used in other missions, including those related to reconnaissance or full-fledged combat work.
The first space flight of the X-37B spacecraft took place in 2010. At the end of April, the Atlas V launch vehicle launched the vehicle into a predetermined orbit, where it stayed for 224 days. Landing "like an airplane" took place in early December of the same year. In March of the following year, the second flight began, which lasted until June 2012. In December, the next launch took place, and the third landing was carried out only in October 2014. From May 2015 to May 2017, the experienced X-37B performed its fourth flight. On September 7 last year, another test flight began. When it will be completed, it is not specified.
According to the few official data, the purpose of the flights is to study the work of new technology in orbit, as well as to conduct various experiments. Even if the experienced X-37Bs solve military tasks, the customer and the contractor do not disclose such information.
In its current form, the Boeing X-37B product is a rocket airplane of a characteristic appearance. It is distinguished by a large fuselage and mid-area planes. A rocket engine is used; control is carried out automatically or by commands from the ground. According to known data, a cargo compartment with a length of more than 2 m and a diameter of over 1 m is provided in the fuselage, which can accommodate up to 900 kg of payload.
Right now, the experienced X-37B is in orbit and is solving the assigned tasks. When he will return to Earth is unknown. Information about the further progress of the pilot project has not been specified either. Apparently, new messages about the most interesting development will appear not earlier than the next landing of the prototype.
SpaceDev / Sierra Nevada Dream Chaser
Another version of the orbital plane is the Dream Chaser spacecraft from SpaceDev. This project has been developed since 2004 to participate in the NASA Commercial Orbital Transportation Services (COTS) program, but could not pass the first stage of selection. However, the development company soon agreed to cooperate with United Launch Alliance, which was ready to offer its Atlas V launch vehicle. In 2008, SpaceDev became part of the Sierra Nevada Corporation, and soon after received additional funding to create its aircraft. Later, there was an agreement with Lockheed Martin on the joint construction of experimental equipment.
Experienced orbital plane Dream Chaser. Photo by NASA
In October 2013, the flying prototype of the Dream Chaser was dropped from a carrier helicopter, after which it switched to a gliding flight and performed a horizontal landing. Despite the breakdown during landing, the prototype confirmed the design characteristics. Subsequently, some other tests were carried out at the stands. Based on their results, the project was finalized, and in 2016 the construction of a prototype for space flights began. In the middle of last year, NASA, Sierra Nevada and ULA signed an agreement to conduct two orbital flights in 2020-21.
Not so long ago, the developers of the Dream Chaser device received permission to launch at the end of 2020. Unlike a number of other modern developments, the first space mission of this ship will be carried out with a real load. The spacecraft will have to deliver certain cargo to the International Space Station.
In its current form, the reusable spacecraft Sierra Nevada / SpaceDev Dream Chaser is an aircraft of a characteristic appearance, outwardly reminiscent of some American and foreign developments. The vehicle has a total length of 9 m and is equipped with a delta wing with a 7 m span. For compatibility with existing launch vehicles, a folding wing will be developed in the future. The take-off weight is determined at 11.34 tons. Dream Chaser will be able to deliver 5.5 tons of cargo to the ISS and return to Earth up to 2 tons. Descent from orbit "like an airplane" is associated with lower overloads, which is expected to be useful to deliver some equipment and samples in separate experiments.
Spacex dragon
For a number of reasons, the idea of an orbiting aircraft is currently not very popular among developers of new space technology. More convenient and profitable is now considered a reusable spacecraft of the "traditional" appearance, which is launched into orbit using a launch vehicle and returns to Earth without using wings. The most successful development of this kind is SpaceX's Dragon.
The SpaceX Dragon cargo ship (CRS-1 mission) near the ISS. Photo by NASA
Work on the Dragon project started in 2006 and was carried out under the COTS program. The goal of the project was to create a spacecraft with the possibility of multiple launches and returns. The first version of the project involved the creation of a transport ship, and in the future it was planned to develop a manned modification on its basis. To date, Dragon in the "truck" version has shown definite results, while the expected success of the manned version of the ship is constantly shifting in terms of time.
The first demonstration launch of the Dragon transport ship took place at the end of 2010. After all the required modifications, NASA ordered a full-fledged launch of such a device in order to deliver cargo to the International Space Station. On May 25, 2012, the Dragon successfully docked to the ISS. In the future, several new launches were carried out with the delivery of goods into orbit. The launch on June 3, 2017 became the most important stage of the program. For the first time in the history of the program, the repaired ship was re-launched. In December, another spacecraft went into space, already flying to the ISS. Taking into account all the tests, Dragon products have made 15 flights to date.
In 2014, SpaceX announced the promising Dragon V2 manned spacecraft. It was argued that this device, which is a development of an existing truck, will be able to deliver to orbit or return home up to seven astronauts. It was also reported that in the future the new ship could be used to fly around the moon, including with tourists on board.
As often happens with SpaceX projects, the Dragon V2 project timeline has shifted several times. So, due to delays with the alleged Falcon Heavy carrier, the date of the first tests moved to 2018, and the first manned flight gradually "crept away" to 2019. Finally, a few weeks ago, the development company announced its intention to abandon the certification of the new "Dragon" for manned flights. In the future, such tasks are supposed to be solved using the reusable BFR system, which has not yet been created.
The Dragon transport spacecraft has a total length of 7.2 m with a diameter of 3.66 m. The dry weight is 4.2 tons. It is capable of delivering a payload weighing 3.3 tons to the ISS and returning up to 2.5 tons of cargo. To accommodate certain cargo, it is proposed to use a sealed compartment with a volume of 11 cubic meters and an unpressurized 14 cubic meter volume. The unsealed compartment is dropped during descent and burns up in the atmosphere, while the second cargo volume returns to Earth and makes a parachute landing. To correct the orbit, the spacecraft is equipped with 18 Draco-type engines. The efficiency of the systems is ensured by a pair of solar panels.
In the development of the manned version of the "Dragon", certain units of the base transport ship were used. At the same time, the sealed compartment had to be significantly reworked to solve new problems. Some other elements of the ship have also changed.
Lockheed martin orion
In 2006, NASA and Lockheed Martin agreed to create a promising reusable spacecraft. The project was named after one of the brightest constellations - Orion. At the turn of the decade, after the completion of part of the work, the leadership of the United States proposed to abandon this project, but after long disputes it was saved. The work was continued and to date have led to certain results.
The perspective ship Orion as seen by the artist. NASA drawing
In accordance with the original concept, the Orion ship was to be used in different missions. With its help, it was supposed to deliver goods and people to the International Space Station. With the appropriate equipment, he could go to the moon. Also, the possibility of a flight to one of the asteroids or even to Mars was being worked out. Nevertheless, the solution of such problems was attributed to the distant future.
According to the plans of the last decade, the first test launch of the Orion was supposed to take place in 2013. For 2014, they planned to start with astronauts on board. The flight to the moon could be carried out until the end of the decade. Subsequently, the schedule was adjusted. The first unmanned flight was postponed to 2014, and the crewed launch to 2017. Lunar missions were postponed to the twenties. By now, flights with a crew have been postponed to the next decade.
On December 5, 2014, the first test launch of Orion took place. The spacecraft with the payload simulator was launched into orbit by the Delta IV launch vehicle. A few hours after the launch, he returned to Earth and splashed down in a given area. No new launches have been carried out yet. However, specialists from Lockheed Martin and NASA did not sit idle. Over the past few years, a number of prototypes have been built for carrying out certain tests in terrestrial conditions.
Just a few weeks ago, construction began on the first Orion for manned flight. Its launch is scheduled for next year. The task of launching the spacecraft into orbit will be entrusted to the promising Space Launch System launch vehicle. Completion of the ongoing work will show the real prospects for the entire project.
The Orion project provides for the construction of a ship with a length of about 5 m and a diameter of about 3.3 m. A characteristic feature of this apparatus is a large internal volume. Despite the installation of the necessary equipment and instruments, a little less than 9 cubic meters of free space remains inside the sealed compartment, suitable for the installation of certain devices, including crew seats. The ship will be able to take on board up to six astronauts or certain cargo. The total mass of the ship is determined at 25.85 tons.
Suborbital systems
Currently, several interesting programs are being implemented that do not provide for the launch of a payload into Earth's orbit. Prospective models of equipment from a number of American companies will be able to carry out only suborbital flights. This technique is supposed to be used for some research or in the development of space tourism. New projects of this kind are not considered in the context of the development of a full-fledged space program, but nevertheless they are of certain interest.
Suborbital vehicle SpaceShipTwo under the wing of the White Knight Two carrier aircraft. Photo Virgin Galactic / virgingalactic.com
The SpaceShipOne and SpaceShipTwo projects from Scale Composites and Virgin Galactic propose the construction of a complex consisting of a carrier aircraft and an orbital aircraft. Since 2003, the two types of equipment have performed a significant number of test flights, during which various design features and work methods were tested. It is expected that a spaceship of the SpaceShipTwo type will be able to take on board up to six passenger-tourists and lift them to an altitude of at least 100-150 km, i.e. above the lower limit of outer space. Takeoff and landing should be carried out from a "traditional" airfield.
Blue Origin has been working on another version of the suborbital space system since the middle of the last decade. She proposes to perform such flights using a bundle of a launch vehicle and a ship, similar to those used in other programs. Moreover, both the rocket and the ship must be reusable. The complex was named New Shepard. Since 2011, missiles and ships of the new type have been regularly performing test flights. It has already managed to send the spacecraft to an altitude of more than 110 km, as well as to ensure the safe return of both the spacecraft and the launch vehicle. In the future, the New Shepard system should be one of the innovations in the field of space tourism.
Reusable future
For three decades, since the early eighties of the last century, the Space Transportation System / Space Shuttle complex has been the main vehicle for delivering people and goods to orbit in NASA's arsenal. Due to moral and physical obsolescence, as well as in connection with the impossibility of obtaining all the desired results, the operation of the Shuttles was terminated. Since 2011, the United States has no operational reusable ships. Moreover, while they do not have their own manned vehicle, as a result of which the astronauts have to fly on foreign technology.
Despite the termination of the operation of the Space Transportation System, the American astronautics does not abandon the very idea of reusable spaceships. This technique is still of great interest and can be used in a wide variety of missions. At the moment, NASA and a number of commercial organizations are developing several promising spacecraft at once, both orbital aircraft and systems with capsules. At the moment, these projects are at different stages and show different successes. In the very near future, no later than the beginning of the twenties, most of the new developments will reach the stage of test or full-fledged flights, which will make it possible to re-examine the situation and draw new conclusions.
