Human exploration of the vast and boundless universe has never stopped for hundreds or even thousands of years. The universe is so deep and mysterious, which fascinates generation after generation of scientists: everyone wants to uncover more secrets of the universe. As a result, humans have sent out countless artificial spacecraft for various purposes. Some of them are just for the benefit of our daily lives, such as the Global Positioning System (GPS). Many others, like the rover spacecraft, flyby spacecraft, orbiter spacecraft, etc., are for the exploration of our grand universe. With the rapid development of technology, more and more new spacecraft are launched every year. There are still many spacecraft that were launched in the last century, but still in use? In this article, we will talk about the old space technologies that are at least 30 years old but still contributing to the exploration of the universe.
Voyager 1 and 2
Voyager 1 and 2 are two twin flyby spacecraft that were launched by NASA in 1977. Voyager 2 was launched 16 days before Voyager 1, and both of them have already journeyed for more than 40 years. Voyager 1 is slightly further away from the Sun than its twin sister because it takes a shorter route. The two spacecraft are still functioning and regularly communicating via the Deep Space Network on Earth to transmit data and receive commands.
The twin Voyagers are designed very similarly. For power systems, both of them have three radioisotope thermoelectric generators (RTGs). Each of the RTG contains 24 pressed plutonium-238 oxide spheres. The RTGs can generate enough electric power to support the operations of the two Voyager spacecraft until 2025.
The primary mission objectives for the two Voyager spacecraft were flybys of Jupiter and Saturn. For Voyager 1, its route was also designed for the vital observation of the largest moon of Saturn, Titan. Voyager 2 was designed to take a slower route for further encounters with Uranus and Neptune. They were designed to observe the target planets when they pass, including taking closeup pictures and measurements and sending data to Earth after observation. They can also store about 67 megabytes of data when they cannot communicate with the Earth directly, and they will transform it later when available. Both of them completed their primary missions successfully a few years after launch. In 1980, Voyager 1 started the extended mission for the twin Voyagers -- continue outward the Solar System, cross the bounds of the heliosphere -- the protective bubble of particles and magnetic fields created by the Sun and entered interstellar space, and finally penetrate interstellar space. It finally entered the heliosphere in 2004 and successfully entered interstellar space in 2012. The first artificial spacecraft escaped the solar system, while Voyager 2 also did it six years after in 2018. According to NASA, the two Voyager spacecraft are currently collecting and evaluating data on the strength and orientation of the Sun's magnetic field; the composition, direction, and energy spectra of the solar wind particles and interstellar cosmic rays; the strength of radio emissions that are thought to be originating at the heliopause, beyond which is interstellar space; and the distribution of hydrogen within the outer heliosphere. According to NASA, the two space probes' power systems might not be able to supply enough energy for any scientific instruments after 2025. Still, they will continue traveling in interstellar space and remaining in the Deep Space Network range on Earth through about 2036. The two Voyager spacecraft carry a gold-plated audio-visual disc, or Golden Record, which holds human greetings in 55 different languages, different sounds from Earth, including animal sounds and music collection, photos of the Earth life on Earth, and a range of scientific information. Even though they may lose connection with Earth in the future, we never know if another intelligent lifeform will discover them and the Golden Records.
Image Created by Joey Serricchio
Image Created by Joey Serricchio
Hubble Space Telescope
The Hubble Space Telescope (HST) is a space telescope launched in 1990 and remains in use until approximately 2030 to 2040. It is one of the most important research tools for astronomy because it is located in the low Earth orbit. HST is above the Earth's atmosphere and has the advantages that ground-based telescopes do not have: the image is not disturbed by atmospheric turbulence and takes high-resolution images without background light caused by atmospheric scattering. The HST can also observe ultraviolet rays that would be absorbed by the ozone layer.
Left alone with the Hubble Telescope's funding issues, the design and development of HST were also challenging. The design started in 1978, and the mirror's construction began in 1979 and was completed in 1981. The launch date of the telescope was postponed several times from 1983 to the January of 1986. However, the Challenger explosion forced the launch to delay for another four years. During the four years, engineers performed more tests and pushed the total costs higher since the telescope had to be kept very carefully in a cleanroom purged with nitrogen. Eventually, the telescope was successfully launched on April 24, 1990. The Hubble Telescope's full development cost more than 300 million US dollars (about 1 billion US dollars if in 2006), left alone the cost for new instruments, missions, and any cost after it was launched, which was more than any other scientific space program. In total, the Hubble Telescope had at least cost 9 billion US dollars as of 2006.
Even after the launch, the Hubble Telescope was still not thoroughly settled and perfect to use. Scientists found its mirror flawed within the first few weeks after launch -- the mirror had been polished to the wrong shape. The damaged mirror severely reduced the usefulness of HST and made NASA and Hubble the laughingstock for being costly but useless. Fortunately, astronomers found a way to correct the error and made the HST one of the most vital astronomy instruments. It has now made countless discoveries and helped solve many astronomy problems. For example, it estimated the universe's age to about 13.7 billion years, while before the presence of Hubble.
Telescope astronomers were only able to give an estimate of about 10 to 20 billion years old. However, because of the Hubble Telescope's low orbit of Earth, it will re-enter the Earth's atmosphere if not rebooted over time. Re-entry to Earth might happen between 2028 to 2040. Engineers are still trying to figure out ways to keep Hubble working for another few decades, such as performing another repair mission or adding an external propulsion module. The launch of another space telescope James Webb Space Telescope (JWST), is planned to be on October 31, 2021. JWST is the successor of HST. The development of JWST started in 1996. The 2007 launch and budget was scrubbed due to a redesign and many postponements. The new total cost for this project is currently over 10 billion US dollars as of 2019.