Extending the life of Hubble adds color to commercial spaceflight

Recently, NASA has demonstrated whether it is possible to use the Dragon spacecraft on commercial missions to provide on-orbit maintenance, orbit raising and life extension services for the Hubble Space Telescope. In fact, from conducting novel space experiments to "rescuing" spacecraft, from space travel to undertaking certain national missions, the field of commercial space services is constantly expanding and becoming more and more colorful. Let's take a look at the interesting or amazing tricks of commercial space.

Helping Hubble survive until 2050

Recently, NASA and SpaceX signed an agreement, mainly funded by business tycoons, to study how to use the Dragon spacecraft to help extend the life of the Hubble Space Telescope. The initial plan is that the Dragon spacecraft will act as a tugboat to raise the orbital altitude of Hubble by tens of kilometers, restore the originally designed orbital altitude of 600 kilometers, and maintain stable operation until 2050.

Hubble Space Telescope

Hubble has been working in space for more than 30 years. Since its maintenance in 2009, its orbital altitude has gradually decreased due to the combined effects of atmospheric drag, the earth's electromagnetic field, and solar radiation pressure. It is estimated that if no rescue measures are taken, there is at least a 50% chance that Hubble will re-enter the atmosphere in 2037. However, all space shuttles have been retired. In recent years, NASA hopes to extend the working life of Hubble, but faces the dilemma of "a good cook cannot cook without rice".

As the saying goes, "there is always a way out." The space shuttle once installed a circular flexible capture device on Hubble to facilitate docking with robots or spacecraft, handle emergencies, and to tow Hubble out of orbit when it was retired. Unexpectedly, this device made it possible for the Dragon spacecraft to extend Hubble's orbit.

However, SpaceX still faces great difficulties in completing this task. NASA did not provide the latest data and information, so the data required for the Dragon spacecraft to dock with Hubble and the energy consumed to increase the orbit need to be calculated by SpaceX itself. This requires a large amount of historical data, with the help of modeling and simulation methods, so that the ground team can have an accurate grasp of it.

In addition, even if the actual orbit of the spacecraft deviates from the designed orbit, the error will generally remain within a given range. If the deviation is too large, the orbit-maintaining power actuator will start in time to autonomously correct the error and adjust the orbit. Hubble's orbital altitude has dropped by more than 30 kilometers. It is estimated that its orbit-maintaining power device has stopped working, perhaps because it has run out of fuel or has a stuck fault. The specific cause needs to be determined by the ground team based on a large amount of historical telemetry parameters.

Taking these difficulties into account, it is estimated that the Dragon spacecraft's operation to raise Hubble's orbit may not be implemented until 2028.

Cleaning up the garbage and rescuing the spacecraft

If the Dragon spacecraft can really extend the life of Hubble, NASA will reap huge economic benefits - not to mention that Hubble itself is worth $1.5 billion (this is the value of the US dollar in 1990 before it was over-issued). Previously, NASA had planned to ensure that Hubble was safely and controlledly deorbited before 2030, and the effort and cost required can be imagined. More importantly, this mission is expected to bring good news to the cause of cleaning up space junk.

Hubble Space Telescope

With more and more space launches and on-orbit tests, a large amount of space debris has accumulated in low-Earth orbit, causing "space collisions" from time to time, threatening the safety of spacecraft. If large low-Earth orbit spacecraft such as the Hubble Space Telescope can be successfully rescued, it will undoubtedly encourage new commercial space forces to rush into the fields of space debris cleaning and spacecraft replenishment and rescue.

Previously, some foreign commercial aerospace companies have proposed a variety of space debris cleaning plans: some plan to use a large net woven with high-strength fibers to intercept a large number of space debris; some envision deploying higher-power laser transmitters to melt the fine space debris due to heat or "knock it off" to a farther orbit; some suggest developing space robots that rely on robotic arms to hold space debris, or use super adhesives to tightly stick to space debris; others want to give space debris "wings", that is, launch a foldable film, which will unfold after docking with the space debris and drag the space debris away.

As technology advances and experiments progress, cost-conscious commercial aerospace companies have decided to go “one step further,” believing that it would be a waste to destroy space junk or drag it to a graveyard orbit. Instead, they would be better off resurrecting expired spacecraft by adding propellant, or recycling high-value materials from space junk and processing them in orbit.

On February 25, 2020, the on-orbit life extension vehicle MEV-1 successfully docked with a satellite that was about to reach the end of its service life, allowing the satellite to continue to work for another five years. Since then, the on-orbit life extension service has entered the normalized operation stage.

Some commercial aerospace companies are more ambitious and are not satisfied with one-to-one services, but are planning to build "space gas stations". Starting from the concept of cubic satellites, the research team uses a truss structure as the main body, places multiple cubic satellite-sized fuel tanks on both sides, and installs a docking mechanism at the end to facilitate in-orbit refueling of satellites with insufficient propellant.

As spacecraft use more and more orbits, future "space gas stations" are likely to be widely distributed in low-Earth orbit, lunar orbit and even farther along the way of deep space exploration.

On May 25 this year, the Mars Outpost Demonstration-1 commercial payload flew into space, demonstrating the safe and efficient cutting of metal sheets in orbit. The material of those metal sheets is the same as the upper stage shell of the Vulcan-Centaur rocket, which has not yet flown for the first time. Obviously, commercial aerospace companies are trying to "pan for gold" in space, obtain high-value materials, and may even manufacture spacecraft parts in orbit in the future to reduce the pressure of launch supply.

Commercial space travel also has a national team

In recent years, commercial space tourism has attracted the attention of many non-official people. In 2021, Virgin Galactic and Blue Origin successively realized suborbital tourism. On September 16, 2021, SpaceX realized the first "all-civilian" space orbital tourism, taking four space tourists to an orbit at an altitude of 550 kilometers to orbit the earth for 3 days. At the same time, some tourists paid to go to the International Space Station and planned to conduct space walks. Commercial aerospace companies have even planned a number of space stations or space laboratories with the goal of making profits. In the future, after the cost of space transportation drops further, space tourism will have broad prospects.

As commercial aerospace companies' manned launch technology gradually matures, some national teams, environmental protection organizations, etc. simply purchase commercial manned space services.

Recently, Axiom Space has reached commercial manned space cooperation agreements with the United Arab Emirates, Turkey, Canada, Saudi Arabia and other countries, and is preparing to send astronauts from multiple countries into space.

It is reported that an Emirati astronaut will go to the International Space Station in 2023 for a long-term mission. Saudi Arabia has launched an astronaut training program to prepare astronauts to participate in space science experiments, joint research with international partners or independent flights, and plans to send two astronauts to the International Space Station in 2023. After establishing its space agency in 2021, Turkey plans to send its first astronaut into space in 2023 and live and work on the International Space Station for 7-10 days to commemorate the 100th anniversary of Turkey's founding.

In fact, this is not surprising. After all, the official crews of the United States, Russia, Europe and Japan have already boarded the SpaceX manned Dragon spacecraft to the International Space Station. I believe that commercial aerospace companies will receive more orders from national teams in the future. (Author: Wen Xin, Li Xiang, Niu Ruoyu)