Space Sunday: lunar landers, asteroids and more

A GSLV Mk III lifts-off with the Chandrayaan-2 mission from India’s Satish Dhawan Space Centre, Sriharikota, 09:13 UTC, Monday, July 22nd, 2019. Credit ISRO

The Indian Space Research Organisation (ISRO) successfully launched its Chandrayaan-2 mission to the lunar south pole on Monday, July 22nd, after suffering a week’s day to the schedule. This is an ambitious mission that aims to be the first to land in the Moon’s South Polar region, comprising three parts: an orbiter, a lander and a rover.

Although launched atop India’s most powerful rocket, the GSLV Mk III, the mass of the mission means it cannot take a direct route to Mars, as the upper stage isn’t powerful enough for the mass. Instead, Chandrayaan-2 was placed into an extended 170km x 39,120 km (105 mi x 24,300 mi) elliptical orbit around the earth. For the next month, the orbiter will gradually raise this obit until it reaches a point where lunar gravity becomes dominant, allowing Chandrayaan-2 to transfer into a similarly extended lunar orbit before easing its way down to a 100 km (60 mi) circular polar orbit around the Moon, which it is scheduled to achieve seen days after translating into its initial lunar orbit.

How Chandrayaan-2 will reach the Moon and its operational orbit. Credit: ISRO

During this period, the combined vehicle will carry out multiple surveys of the Moon’s survey, focusing on the South Pole. It will also release the 1.47-tonne Vikram lander (named for Vikram Sarabhai, regarded as the father of the Indian space programme) which will make a soft decent to the lunar surface, which will take several days prior to making a soft landing.

The orbiter vehicle is designed to operate for a year in its polar orbit for one year. It carries a science suite of eight systems, including the Terrain Mapping Camera (TMC), which will produce a 3D map for studying lunar mineralogy and geology, an X-ray spectrometer, solar X-ray monitor, imaging spectrometer and a high-resolution camera.

The Vikram lander, with four science payloads, will communicate both directly with Earth and the orbiter. It will also facilitate communications with the Pragyan rover, which will be deployed within hours of the self-guiding lander touching down. Between them, the lander and rover carry 5 further science experiments and both are expected to operate for around 14 days.

Testing the deployment of the Pragyan rover from the Vikram lander. Credit: ISRO

Craters in the South Polar region lie in permanent shadow and experience some of the coldest temperatures in the solar system and NASA’s Lunar Reconnaissance Orbiter (LRO) has revealed they contain frozen water within them, water likely unchanged since the early days of the Solar System, and thus could hold clues to the history of the Solar System – hence the interest in visiting the region and learning more. The frozen water is also of interest to engineers as it could be extracted to provide water for lunar base; water that could be used for drinking, or growing plants and could also me split to produce oxygen and hydrogen  – essential fuel stocks.

The Chandrayaan-2 mission marks a significant step forward for India’s space ambitions; assuming the Vikram lander is successful, the country will become only the forth nation to land on the Moon after the United States, Russia and China. As a part of its expanding activities in space, the country hopes to fly it first astronauts into space in 2022 and have an operational space station by the end of the 2020s.

2019 OK

No, I’m not making a statement about the year – that’s the name of a chunk of space rock measuring 57 to 130m (187 to 42ft) across that passed by Earth at a distance of around 73,000 km (45,000 mi), putting it “uncomfortably close” to the planet. What’s more, we barely released it was there: 2019 OK was positively identified by the Southern Observatory for Near Earth Asteroids Research (SONEAR), just a couple of days prior to is passage past Earth, and was confirmed by the ASAS-SN telescope network in Ohio, leaving just hours for an announcement of its passage to be made.

Since then, the asteroid’s orbit has been tracked – forward and back (which revealed it had been previously spotted by observatories, but its small size and low magnitude meant its significance wasn’t realised). These observations confirmed 2019 OK is a reactively short-period object, orbiting the Sun every 2.7 years. It passes well beyond Mars before swinging  back in and round the Sun, crossing the Earth’s orbit as it does so. However, while it may pass close to Earth on occasion, it’s highly unlikely it will ever strike us.

Credit: NASA

It does, however, remind us that near-Earth objects (NEOs) are common enough to be of concern; 2,000 were added to the list 2017 alone. The size of 2019 OK reminds us that there are more than enough of them to be of a significant enough size to pose a genuine threat.

In 2013, an asteroid measuring just 20m across entered the atmosphere to be ripped apart  at an altitude of around 30 km above the Russian town of Chelyabinsk. The resultant resulting shock wave shattered glass down below and injured more than 1,000 people. 2019 OK is at a minimum 2.5 times larger than the Chelyabinsk object – and possibly as much as 10 times larger, putting it in the same class of object that caused the Tunguska event of 1908, when 2,000 sq km (770 sq mi) of Siberian forest was flattened by an air blast of 30 megatons as a result of a comet fragment breaking up in the atmosphere.

Hence why observatories such as SONEAR, ASAS-SN telescope network, the Catalina Sky Survey, Pan-STARRS, and ATLAS and others attempt to track and catalogue NEOs. The more of them we can located and establish their orbits, the more clearly we can identify real threats  – and have (hopefully) a lead time long enough to take action against them.

A computer model show the passage of 99942 Apophis on April 13th, 2029. The blue dots represent satellites in orbit around Earth and the pink line the orbit of the International Space Station. Credit: NASA JPL

Oh, and if you thought 2019 OK was big, consider 99942 Apophis. It’s around 400-450m across, and will swing by Earth at a distance of just 31,000 km on  – wait for it – Friday, April 13th, 2029 (so get ready for a lot of apocalyptic predictions in the months leading up to that date!).

Starhopper Belches – then Hops

Thursday, July 25th saw the SpaceX Starhopper take to the air in its first untethered flight. largely hidden by a huge cloud of exhaust gases and dirt, the flight of the vehicle was hard to discern when seen from the ground, but as the smoke cleared, it was evident the test vehicle had moved, and SpaceX later indicated the flight had achieved an altitude of around 15-20m (up to around 65 ft).

The flight came after a static test fire of its Raptor engine on Tuesday, July 16th, resulted in a localised fire at the SpaceX Boca Chica test area in Texas, the flames seeming to engulf the Starhopper, which actually suffered little or no damage. Fire struck again during the first attempt at  untethered flight on Wednesday, July 24th, forcing the attempt to be aborted. Following it, Musk later tweeted that the chamber pressure in the Raptor engine was too high as a result of propellants being colder than expected, causing a much more violent reaction on ignition than had been expected.

The July 16th static fire test of the Starhopper Raptor engine that resulted in a pad fire. Credit: Everyday Astronaut

The July 25th flight was filmed from the ground and from the air via a drone. the latter footage clearly shows the Starhopper rising into the air, looking like a bizarre flying water tank, thanks to it being without the upper conical section, which was not replaced after being damaged in a storm at the start of the year (coincidentally, the company that fabricated Starhopper for SpaceX builds water tanks). After a moment hovering, the vehicle translated sideways before it settled back onto the pad and the engine shut down.

Musk later released video footage recorded by both the drone and via a camera mounted under the Starhopper that recorded the clean exhaust plume from the engine and showed it gimballing smoothly.

Further Starhopper tests are expected in the coming weeks / months. In a June 2019 tweet, Musk indicated that he expects SpaceX to be flying “Starship Mk 1” to a height of 20 km “within a few months”. Whether he was referencing Starhopper as “Starship Mk 1”, or whether he meant an actual Starship prototype, is unclear.

The Planet with Three Suns

LTT 1445Ab is the name given to a planet about 22.5 light-years away from Earth, discovered by NASA’s Transiting Exoplanet Survey Satellite (TESS), which is also celebrating its first year of full operations.

A artist’s impression of a triple star system as seen from the surface of a planet orbiting one of them – showing how things might look from the surface of LTT 1445Ab. Credit: Mark Garlick

Classified a super-Earth, being about a third larger than Earth and around eight times as massive, the planet orbits a red dwarf star once every 5 days – and that star is only own of a triple system that puts the other two Stars further way to hang in the sky like “ominous red eyes”, to use the words of astronomer Jennifer Winters, co-author of the paper on the new planet.

The TESS data reveals the planet to be a solid world that likely has a surface temperate of 160° C (320° F) – and that it may have an atmosphere. It is this latter point that makes LTT 1445Ab so interesting. Due to the relative closeness of the triple star system to our own, coupled with the fact the planet actually passes between all three and Earth whilst orbiting its primary, means astronomers have an excellent opportunity to probe and analyse that atmosphere as it is penetrated by the light of the three stars.

This is precisely what TESS is designed to so – although deeper study will have to wait, as the satellite completes the second year of its pre-planned survey of the sky around us. In the meantime, LTT 1445Ab may well be the subject of study using telescopes on Earth and perhaps even the Hubble Space Telescope.

In Brief

China Tiangong-2 De-orbited

China has confirmed its Tiangong-2 (“Heavenly Palace 2”) space laboratory was de-orbited on Friday, July 19th, and burned up above the South Pacific Ocean. According to the China Manned Space Agency, Tiangong-2 entered the atmosphere at 13:06 UTC. While some debris fell into a “predetermined safe sea area in the South Pacific”, most of the space lab burned up during the re-entry.

In all, the 10.4m (30 ft), 8.6 tonne unit spent 1,000 days in space, far exceeding its planned 2 years of operations. During that time it was visited by a single crew who stayed 30 days, and was used as a target vehicle for automated docking by an unmanned cargo vehicle required for use with China’s future space station.

It had been announced that the laboratory would be de-orbited some time in July or August due to it running low on fuel reserves, and China wished to avoid a repetition of the Tiangong-1 situation. This saw the country’s first orbital lab make an uncontrolled re-entry in April 2018, amidst concerns debris from the vehicle – of a similar size to Tiangong-2 – might survive re-entry and possibly strike a populated area.

Toyota to Build a Pressurised Lunar Rover

Toyota, the second largest car manufacturer in the world, has signed a development agreement with the Japan Aerospace Exploration Agency (JAXA) for the development of a pressurised crewed lunar vehicle that runs on fuel-cells.

Toyota has teamed with JAXA to develop a pressurised lunar rover, show to scale with an astronaut. Credit: JAXA / Toyota

The goal of the project is build a vehicle capable of carrying up to four on the lunar surface, and which has a potential range of up to 10,000 km (which means it could practically circumnavigate the entire Moon). Other specifications for the vehicle call for it to be 6.0m in length, 5.2m wide and stand 3.8m tall (19.5 ft x 17 ft x 12.4 ft and provide 13m3 (460 cubic ft) of living space.

The anticipated development cycle will by around 9 years, including five years of initial development and construction of a prototype (based on a standard production car) and then four years developing the actual rover vehicle. A possible launch of the completed rover, using and automated lander / development craft, has been mooted for 2029.

As well as being a lunar development project, Toyota see the work with JAXA as a means of developing new, “clean” technologies for use with vehicles on Earth.

NASA: SLS and Gateway Mini-Update

NASA has announced the “green run” test of the first stage of its upcoming Space Launch System (SLS) rocket will now go ahead, most likely in early 2020.

The green run is intended to see a core stage of the SLS undergo a static fire test of all four of its main engines for 8 minutes – the length of time the core and its motors would operate during a launch. It is seen as a vital means o gather data on how the entire, integrated core functions in launch conditions.

However, the test adds around 6 months to the development schedule of the first SLS rocket, dues to the logistics of moving the core stage between different NASA locations. As this could lead to a delay in the rocket missing its maiden flight test in 2020, NASA Administrator James Bridenstine suggested in March the systems of the core stage could perhaps be tested in”other ways”, avoiding the 6 month “delay”. His suggestion received considerable push-back from both within and without the Agency – including from the Aerospace Safety Advisory Panel – and so the idea of not doing the full test has been dropped.

An SLS Structural Test Article sit before the stand that will be used to conduct the Green Run test at NASA’s Stennis Space Centre. Credit: NASA

Documents published on July 19th reveal that NASA has quietly awarded the contract to build the “minimal” habitation module for the Lunar Orbital Platform and Gateway (LOP-G) to Northrop Grumman.

The decision comes after NASA awarded contracts in 2016 to Bigelow Aerospace, Boeing, Lockheed Martin, NanoRacks, Orbital ATK (now Northrop Grumman Innovation Systems, or NGIS) and Sierra Nevada Corporation for study concepts for habitation modules.

The decision to go with Northrop Grumman is said to be because NASA believe the company is the only one that can realistically meet the time frame for developing the initial habitation module – which must be in orbit around the Moon by 2024 – as they intend to use a modified variant of the Cygnus craft used to resupply the International Space Station. Doing so dramatically reduces the development time frame for the module.

Northrop Grumman Innovation Systems (NGIS) – formerly Orbital ATK – will base their LOP-G “minimal” habitation module on the successful Cygnus resupply vehicle for the International Space Station. Credit: NASA

Some US $87 million has already been provided by NASA for the initial studies for the module, with Northrop Grumman receiving US $18 million. The anticipated cost of the completed module has not been released.