NASA has given eight interplanetary spacecraft throughout our solar system a mission extension, which is great news for scientists.

The agency extended these the work of these missions "due to their scientific productivity and potential to deepen our knowledge and understanding of the solar system and beyond." The decision to keep these longstanding missions going happened after independent reviews of their work, longevity, and scientific productivity. Most space missions are given an ‘expected lifespan’ but these can be extended if a robotic probe is working well and has enough fuel and funds to continue to operate. Here is a look at the missions that will continue to explore our solar system.

MARS: CURIOSITY ROVER

Curiosity, also known as the Mars Science Laboratory (MSL), landed on Mars in 2012 and will explore for at least another three years. It has spent several years climbing Mount Sharp (Aeolis Mons) after landing on the Red Planet's Gale Crater. It is on a long-term hunt to understand how water, and potential conditions for life, arose in that region of the planet. 

"In its fourth extended mission, MSL will climb to higher elevations, exploring the critical sulfate-bearing layers which give unique insights into the history of water on Mars." NASA stated. Curiosity became the sole rover on Mars when Opportunity died in 2018, but it was joined by the newer Perseverance rover in 2021. The design of perseverance was based on Curiosity due to its success and longevity.

THE MOON: LUNAR RECONNAISSANCE ORBITER

The Lunar Reconnaissance Orbiter (LRO) has been in orbit around the Moon since 2009, and will work for another three years. LRO carries a powerful camera used for mapping surface detail of the moon in high-definition, tracking down landing missions past and present, and seeking preserves of ice water on the moon. 

NASA will use its data in planning for its Artemis moon-landing programme that plans to land humans on the Moon by 2025.

"LRO will continue to study the surface and geology of the moon," NASA stated of the extension. "The evolution of LRO's orbit will allow it to study new regions away from the poles in unprecedented detail, including the permanently shadowed craters near the poles where water ice may be found. LRO will also provide important programmatic support for NASA's efforts to return to the moon."

ASTEROIDS: OSIRIS-REX

Studying asteroids allows scientists to peer back to the very beginning of our Solar System formation as asteroids are considered the ‘leftovers’ of our Solar System.

The Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer, or OSIRIS-REx, will have another stop after dropping off pieces of asteroid Bennu at Earth in 2023. OSIRIS-REx made history when it touched down on asteroid Bennu in 2020 to collect samples for an Earth return. The probe left Bennu in 2021 and is currently en-route to Earth to return these precious asteroid samples.

The spacecraft will be redirected to visit Apophis, a near-Earth asteroid that was once deemed to be a threat to Earth. NASA will re-name the spacecraft OSIRIS-Apophis Explorer (APEX) for this mission extension. The mission will orbit Apophis shortly after the asteroid safely comes within 32,000 kilometres of Earth in 2029.

MARS: MAVEN ORBITER

The Mars Atmosphere and Volatile EvolutioN mission, or MAVEN, was launched in November 2013 to look at changes in the atmosphere of the planet. It found that over eons, gradual erosion of the atmosphere led to less running water at the surface of Mars, when pressure dropped.

The extended mission, which will clock another three years, "plans to study the interaction between Mars' atmosphere and magnetic field during the upcoming solar maximum," NASA said. "MAVEN's observations as the sun's activity level increases toward the maximum of its 11-year cycle will deepen our understanding of how Mars' upper atmosphere and magnetic field interact with the sun."

A key mystery of Mars was how and why it lost its water, and MAVEN helped unlock the secrets hidden in its atmosphere. Water is the key ingredient for life, and its presence, both past or current, is a key indicator in the search for life.

MARS: INSIGHT LANDER

InSight landed on Mars in 2018 and has been gathering information by detecting "marsquakes" to learn more about the planet's interior and how that evolved over time.

The spacecraft has been working well, aside from the failure of a below-surface probe known as a "mole" and gradual dust build-up on its solar panels.

The mission has a few more months left on its mission until the end of 2022 but it may not last that long. InSight relies on solar panels to gather energy to operate. Dust build-up on the panels has blocked much of the sunlight that hits the spacecraft over time. Power levels have been dwindling for months, sometimes to a critical level, but the lander is still holding on.

"The extended mission will continue InSight's seismic and weather monitoring if the spacecraft remains healthy," NASA stated. "However, due to dust accumulation on its solar panels, InSight's electrical power production is low, and the mission is unlikely to continue operations for the duration of its current extended mission unless its solar panels are cleared by a passing 'dust devil' in Mars’ atmosphere."

InSight will likely be the first mission from these extensions to end, but it has completed its main science goals of understanding how the interior or Mars works.

KUIPER BELT: NEW HORIZONS

New Horizons launched in 2006 and has visited two worlds so far: the dwarf planet Pluto in 2015, and the Kuiper Belt object Arrokoth in 2019.

The mission continues to fly away from the Sun towards the outer regions of our Solar System known as the Kuiper Belt, but what object it will visit next is still unknown.

"The New Horizons spacecraft can potentially conduct multi-disciplinary observations of relevance to the solar system, and NASA's heliophysics and astrophysics divisions. Additional details regarding New Horizons' science plan will be provided at a later date." NASA stated.

The probe will continue to wander space even after it dies, and it will join other famous spacecraft like the Voyager probes as being some of the first human-made objects to leave our solar system.

MARS: MARS ODYSSEY ORBITER

The Mars Odyssey spacecraft started work in 2001 and continues to work well in its record-breaking third decade in space. Odyssey orbits Mars and serves as a relay for other Mars spacecraft on the surface in sending their communications back to Earth.

NASA has warned that the mission is running low on propellant, but it hopes to get another three-plus years from the mission. 

On the science side, NASA stated, "Mars Odyssey's extended mission will perform new thermal studies of rocks and ice below Mars’ surface, monitor the radiation environment, and continue its long-running climate monitoring campaign."

MARS: MARS RECONNAISSANCE ORBITER

The Mars Reconnaissance Orbiter has been in orbit around Mars since 2005 and provides a long-term view of the surface of the Red Planet. It charts changes in sand dunes, ice caps and other features and also keeps an eye on missions. The spacecraft has provided us some of the highest-resolution images of Mars’ surface ever. The camera aboard MRO is powerful enough to see and image spacecraft down on the surface of Mars.

The mission should operate for another three years around Mars, but there is a possibility it could work for even longer. MRO continues its relay services for surface missions, much like the Mars Odyssey spacecraft.

"In its sixth extended mission, MRO will study the evolution of Mars’ surface, ices, active geology, and atmosphere and climate. In addition, MRO will continue to provide important data relay service to other Mars missions." NASA stated.

NASA recently announced that the International Space Station (ISS) will meet a fiery end in 2031 when the orbiting laboratory will be deorbited, burning up in Earth’s atmosphere, ending a 30-year record of being continuously occupied by humans. The ISS has played a crucial role in our exploration of space, and the unique zero-g conditions allow us to do science that is not possible on Earth.

It remains as the largest space station ever built in-orbit; however, the ISS is not the first space station, and it certainly will not be the last as space agencies around the world are looking to a future where multiple stations exist in Earth orbit and beyond.

SALYUT, SKYLAB, AND MIR

A space station is defined as a spacecraft capable of supporting a human crew in orbit for an extended period of time. They do not have landing or major propulsion systems as they do not return to Earth and instead stay in orbit, and they must have docking ports to allow other spacecraft to dock with them. Space stations have played a major role in our understanding of the effects of zero-g on humans, and they allow us to learn about living in space.

The first space stations were built by the former USSR, with the first station, Salyut 1, launching in 1971. The Russian space programme launched several stations as part of the Salyut programme, with the last Salyut 7 launching in 1982. These stations were quite small, and they were occupied by crews of up to three people.

Many consider the first true space station to be the American Skylab, which was launched and first occupied in 1973. The station was much larger than the Russian Salyut stations and it was occupied by three separate crews for 24 weeks. It was a major testing bed in how to sustain a crew in space. It included a solar observatory, orbital workshops, along with hundreds of experiments that were performed by the crew. The final crew left in 1974, and the station was unable to be re-boosted. Skylab’s orbit slowly decayed, and it eventually re-entered the atmosphere and disintegrated over the Indian Ocean and Western Australia in 1979.

With the success of the Russian Salyut programme, the USSR began to plan a much larger and more capable space station in Earth orbit. Mir was the next step in the Soviet Union’s space station programme, and it became the first modular space station - meaning it was constructed by sending multiple modules to space and then putting them together.

Mir eventually became the largest space station and largest artificial satellite to Earth, and it was not surpassed until the current ISS was built. Mir was initially occupied by solely by Russian and European astronauts, but the American Space Shuttles eventually did visit the orbiting laboratory in the later years. During this time, the Americans had planned to launch their own modular space station known as Freedom, however this never progressed past the design stage due to budget and design constraints.

The USSR was facing budget cuts during this time, and both nations came to an agreement to fly American astronauts to Mir, while Russian cosmonauts would fly into space aboard the American space shuttles. This mutual relationship allowed both to save costs while also learning more about life in space in preparation for future ventures.

This co-operation in space eventually led both to sign agreements to construct an even larger space station, and in 1993, the International Space Station was announced as a joint venture between the United States and Russia. Mir continued to orbit the Earth during the 1990’s as construction on its successor began on Earth.

The first module of the new ISS, the Russian Zarya, was launched in 1998. It marked the beginning of a transition period where both the United States and Russia would shift their funding away from Mir and toward the newer ISS. The funding for Mir eventually came to an end in 2001, and the station was de-orbited over the South Pacific in a fiery blaze. Without the advancements and co-operation made on Mir, the ISS would likely have never come to fruition.

More recently, China has made huge leaps in space exploration with multiple robotic probes sent to the Moon and Mars. China's own human spaceflight programme has benefited from this, and it has launched several small space stations. The first was the Tiangong-1  station which operated from 2011 until 2018. The second, Tiangong-2, was launched in 2016 and was in orbit until 2019. Both were small and much more comparable to the early Russian Salyut programme.

These stations were crucial for China to test its own space capabilities, and both proved successful. China’s push for their own space stations has also been driven by the infamous ban on Chinese astronauts visiting the ISS due to American law, a move that was highly criticised by the international community.

THE ISS

The ISS is currently the largest space station ever built. It has been consistently occupied by humans for over 21 years, and it even holds the record of being the most expensive single item ever constructed, with a price tag of over US$150 billion. The ISS is roughly the size of a rugby field, and it can easily be seen with the naked eye passing over a city from almost every major city on Earth.

The project began as a joint effort between the space agencies of the United States (NASA) and Russia (Roscosmos), but it is now a multinational collaboration that includes Japan (JAXA), Europe (ESA), and Canada (CSA).

The giant orbiting laboratory has had new modules and parts added to it continuously since the first module launch in 1998. The last module to be added was as recent as 2021. The ISS serves as a unique microgravity and space environment research laboratory in which space agencies and scientists around the world can conduct research and perform experiments that are not possible on Earth.

A major goal of the ISS is to test equipment and spacecraft systems that will eventually allow humans to conduct long-duration missions back to the Moon and eventually to Mars. It has been visited by over 250 astronauts, space tourists and cosmonauts from 19 different countries.

The station maintains its orbit at roughly 400km above the surface of Earth, completing one orbit in just over 90 minutes, or almost 16 times a day. Constant cargo must be shipped to the ISS to ensure the crew of six to ten astronauts have the supplies needed to sustain a mission lasting six months. 

The eventual fate of the ISS was not clear during the early stages of occupation. It was initially believed that funding would not be given for operation past 2020. This was eventually extended through to 2024, but neither the United States nor Russia indicated they would fund it beyond this point. In 2021, Russian President Vladimir Putin indicated that Russia would likely withdraw funding from the ISS program in 2025. In the same year, the Russian space agency announced plans to collaborate with China on a planned Lunar base. The move to both withdraw from the ISS and partner with China was seen as a reflection on the current political conflicts between the United States and Russia.

Despite the funding troubles, the United States confirmed in 2022 that they are committed to funding the ISS through to 2030. After this, it will be decommissioned and de-orbited over the South Pacific in early 2031. This process will require up to three spacecraft which will dock with the station and then use their thrusters to push the ISS toward the Earth in its final days.

TIANGONG

Though the ISS remains as the current largest space station in operation, China’s own new space station was launched in 2021, known simply as Tiangong. The construction of the station is based on the experience gained from its precursors, Tiangong-1 and Tiangong-2. Tiangong was launched in April of 2021, and once completed it will have a size and mass similar to the Mir space station. Although smaller and fainter that the ISS, Tiangong can also be seen in the skies without a telescope. 

The station has already been visited by two crews of three astronauts each, including astronaut Wang Yaping who was the second Chinese woman in space and the first to conduct a spacewalk. China plans to send two more modules to their space station this year to complete its construction.

The Tiangong programme is just one element of China’s ambitious space plans that include sending more robotic probes to the Moon, exploration of Mars, asteroids, and even the outer planets. The agency is learning more about how to sustain humans in space for long periods of time, along with experiments and tests that further their independent capabilities in space.

Tiangong is said to have a life span of about 10 years, with potential to extend that to 15 years. It will likely meet a similar fate to the other space stations, burning up over the Pacific harmlessly before sinking to the bottom of the ocean.

FUTURE STATIONS: LUNAR GATEWAY AND PRIVATE STATIONS 

NASA has said they see a future where the private sector takes over space stations, much like it has with rockets and spacecraft. In recent years, private companies like SpaceX have revolutionised the aerospace industry. They began to ship cargo to the ISS in 2012, and since 2019 they now send astronauts to space aboard their Dragon capsules. This has freed up funds from NASA and other space agencies to focus on other ventures. Instead of building rockets and space capsules in house, they can now simply buy a seat on a private spacecraft from SpaceX to get their astronauts to space. The cost of this innovation has also significantly bought down the cost of sending things to space, driven by the reusability of SpaceX’s Falcon 9 rockets and completion within the industry. 

NASA’s goals in space have also shifted away from low-Earth orbit. The Artemis programme aims to send the next humans to land on our Moon in 2025, using much of the technology and knowledge that has come from the ISS. However, this will be expensive, and NASA must shift their funds away from the ISS and towards the Moon instead. Plans for a new but smaller space station, known as Lunar Gateway, were announced as part of this programme. It aims to build a smaller outpost that will orbit the Moon instead of Earth. It will act as a waypoint for astronauts before the go to the surface of the Moon, and NASA believes this is a crucial part of returning humans to the Moon for longer duration trips. The gateway will be built on the success of all we have learnt from the ISS, and it will also include collaboration from many countries and the private sector.

Despite NASA indicating that their focus will move away from low-Earth orbiting stations, the space agency has also stressed that these types of space stations will remain a crucial part of human space infrastructure. NASA has directly asked aerospace companies to begin their own conception and construction of private space stations that could be visited by paying astronauts. Since this technology already exists after being pioneered by the ISS, the cost of such stations will be significantly cheaper and much easier to design.

NASA has already awarded three contracts to private companies to build and construct smaller space stations in low-Earth orbit. One of those companies, Axiom Space, is currently building a module which it plans to launch to the ISS in 2024. They plan to send several more modules that will initially be attached to the ISS and will eventually detach, becoming its own self sufficient space station sometime in the late 2020’s before the ISS is decommissioned. Jeff Bezos’ own Blue Origin has announced plans for their own space station, known as Orbital Reef, which is also due to begin construction in the late 2020’s for public and private use of astronauts and tourists alike.

While we still have years of new science to do on the ISS, the decommissioning of this iconic space station will surely be a sad but historic day for people all around the world. It will bring an end to decades of discovery, exploration, and advancements in science and technology that have changed the way we live in both space and on Earth. Space stations have always played a crucial role in our exploration of the cosmos, allowing us to go further than we ever have before while also improving the lives of everyone on Earth.

One of the most daring space missions in recent years was launched in November 2021 from the Vandenburg Space Force Base in California. Strapped atop a Falcon 9 rocket, NASA’s Double Asteroid Redirect Test, or DART, blasted off from Earth on a year-long trek to a double asteroid system known as Didymos and its smaller moon Dimorphos.  

DART - THE FIRST PLANETARY DEFENCE SPACE MISSION 

Unlike other missions that have visited asteroids, DART is not there to take photos or collect samples from the asteroids. Instead, it will accelerate and then smash into the smaller asteroid Dimorphos at speed to see if such an impact could deflect an asteroid from a possible collision with Earth. It sounds like something from the plot of Armageddon or Deep Impact, but NASA says that planetary defence is a real issue for Earth, and such a technology may be needed in the future to prevent catastrophic impacts that could cause serious damage and loss of life.  

The Didymos asteroid poses no threat of impacting Earth, but testing such technologies is crucial to ensure that we could deflect a dangerous asteroid if one was ever discovered. No such asteroids are known to be heading close to Earth within the next 100 years, but we estimate that we have only discovered 40% of near-Earth asteroids to date. Scientists say it’s not a matter of if, but when. 

WHY IS NASA LAUNCHING DART? 

Earth has always been pummelled by asteroids, especially in the early stages of our solar system’s formation. A collision between Earth and an asteroid some 10km wide 66 million years ago caused widespread destruction and was responsible for the Cretaceous-Paleogene extinction event that eventually wiped out almost all dinosaurs on Earth.  

Large collisions are extremely rare, but it is almost certain that such an event will occur again. Recent astronomical events, like the 2013 Chelyabinsk meteor in Russia, have renewed concern about such events happening without warning. The Chelyabinsk meteor exploded in the sky above Siberia and caused a powerful airburst that caused widespread damage and injured thousands of people on the ground. The meteor was only a mere 20 meters across, so it is easy to imagine how much more destructive a larger one would be. The Chelyabinsk meteor also occurred without warning, and we had no idea it was headed for Earth until it hit.  

NASA warned the public in 2016 that such an event will certainly occur again at some point, and the late Stephen Hawking also warned that asteroid impacts pose one of the biggest threats to humanity in his final book Brief Answers to the Big Questions.  

THE DOOMSDAY ASTEROID 

An infamous 370-meter-wide asteroid known as Apophis caused a brief panic in 2004 when it was calculated of having a 2.7% chance of impacting Earth in 2029. It caused a media frenzy that quickly gave it the nickname of the ‘doomsday asteroid’ but further calculations into Apophis’ orbit in recent years have ruled out that chance altogether, and it now poses virtually zero threat to Earth in the next 100 years. 

Astronomers have catalogued objects that orbit in close proximity to us as Near-Earth Objects, or NEOs. We have discovered over 27,000 such objects to date, but that number only represents a fraction of the total that is calculated to exist. Only around 2,000 of the known NEOs are considered hazardous to Earth.  

In the 90s, space agencies around the world began to scan the skies for such objects in an effort known as ‘Spaceguard’ to give us warning of an asteroid on a direct collision course. Thousands of new asteroids are discovered every year, and NASA believes it is imperative that we develop a plan to deflect one should we need to.  

WHAT WILL DART DO? 

The mission’s target is Dimorphos – a small moon of the larger asteroid Didymos – both considered to be in a binary system. Didymos is about 780 meters across, while Dimorphos is about 120 meters across. DART will smash into the smaller moon to see if the kinetic energy from the impact will alter the course of the moon around Didymos. Astronomers will measure the change in orbit using Earth-based telescopes to see how much of an impact it has on Dimorphos.  

NASA has estimated that the impact of DART would cause a velocity change of 0.4mm per second for Dimorphos. It doesn’t sound like a lot, but over time it would lead to a much larger shift in the orbit. This would change the orbital speed of the moon by almost 10 minutes. If Dimorphos were on a collision course with Earth, this change would be enough to successfully deflect it from hitting Earth.  

These are all calculations, however, and we won’t know the true outcome until DART hits the asteroid.  

In a collaborative mission, the European Space Agency intends to send their own probe to the double asteroid five years later to further measure the changes. The mission, known as Hera, will arrive in 2027 and will conduct detailed reconnaissance of the asteroid system and any changes caused. 

The DART mission probe carries no scientific instruments at all - they are practically useless since the spacecraft will intentionally hit an asteroid and destroy itself. It has a star tracker and a small camera for navigation, along with solar panels for power and an ion thruster to move. The probe is described as roughly the size of a vending machine with a mass of 670kg. DART is due to collide with the smaller moon of Didymos on the 3rd of October 2022. 

WILL IT WORK? 

As the T in the name implies, the DART mission is an experiment – Double Asteroid Redirect Test. The mission has been designed with precise calculations as to how big, how fast, and how heavy a spacecraft must be to move an asteroid, but nothing is guaranteed.  

We simply don’t know if it will work because we have never tested such technologies before. Even if the mission is successful, it does not mean that we are automatically protected from all Earth-bound asteroids. NASA has stated that such missions can take around five years to build, launch, and reach an asteroid. If we were to spot an asteroid, we’d need several years to plan and prepare another mission to deflect it. If it was discovered too close to impact, it would be too late to launch a deflection spacecraft.  

The other issue is we simply cannot see every single asteroid that exists. Just like the Chelyabinsk meteor that took us by surprise in 2013, some asteroids strike without warning. Another problem is size; Dimorphous is 120 meters, so the success of DART might mean that only asteroids that are roughly the same size or smaller could be deflected. If we discovered an asteroid say, several kilometres across, it would likely be too large for a spacecraft impact like DART to have any noticeable effect.