Space Sunday: China’s missions and a disappearing “planet”

An artist’s impression of China’s Tianwen Mars lander with the rover vehicle on its back. Credit: CNSA

China is readying for the next phases of its space ambitions.

In July, the country is due to launch its first mission to Mars. Officially referred to as the Mars Global Remote Sensing Orbiter and Small Rover mission, it comprises an orbiter, a lander vehicle and a small rover, with the orbiter and rover between them carrying the majority of the mission’s 18 scientific instruments.

The priorities for the mission include finding evidence of current or previous microbial life, and evaluating the planet’s surface and environment. In addition, solo and joint explorations of Mars, the orbiter and rover will produce maps of the Martian surface topography, and obtain data on soil characteristics, material composition, water ice, atmospheric composition, ionosphere field intensity, and other scientific data.

On April 24th, the Chinese announced the lander vehicle is to be called Tianwen, or “Quest for Heavenly Truth.” It will use a landing system comprising a parachute, retrorockets, and an airbag to achieve a soft landing. The rover will be solar powered, as with China’s Yutu family of lunar rovers.

A test article of the Mars lander undergoing retro-rocket tests in China, November 2019. Credit: CNSA

The name represents the Chinese people’s relentless pursuit of truth, the country’s cultural inheritance of its understanding of nature and universe, as well as the unending explorations in science and technology.

– China’s National Space Administration (CNSA) statement

The Chinese tend to be fairly close-lipped about their space missions (among many other things), but from what has been announced, the mission is being built along similar lines to both NASA surface missions like InSight and MSL, and Europe’s ExoMars orbiter / lander missions. Following its arrival in Mars orbit in February 2021, the combined orbiter / lander will remain there for an unspecified period while the intended landing site is confirmed.

Once on the surface, the 200 gram 6-wheeled rover is expected to operate for at least 3 months, with a selection of its science systems comprising Ground-Penetrating Radar (GPR), to image about 100 m below the Martian surface, a magnetic field detector, a Mars meteorological instrument and multiple camera instruments. The rover is expected to be given its own name in due course.

Chinese national television footage of a 53.7 m tall Long March 5B launch vehicle, carrying the first of China’s new generation of crewed launch vehicle, being rolled out to the launch pad.

At the same time, China rolled out a Long March 5B launcher in preparation for a mission to prove space station launch capabilities and to test a new spacecraft for deep space human space flight. It is expected to lift-off on, or around, May 5th 2020, carrying the first of China’s new generation of crew-capable vehicles designed to supersede the Soyuz-derived Shenzhou craft.

The new craft resembles an Apollo command and service module (CSM) combination, comprising a conical capsule vehicle protected by an atmospheric entry heat shield, and a cylindrical service module that provides the primary source of power and propulsion when operating in space. For the first flight, it will carry around 10 tonnes of fuel, intended to allow the vehicle to offer a similar mass to the core stage of the upcoming Chinese space station. The fuel will also allow the vehicle to reach a high orbit and and achieve a fast re-entry velocity.

This latter is important as the the new vehicle is intended for deep space crewed missions, including acting as the carrier for crews engaged in future missions to the Moon. Such missions will – like America’s Orion coming back from the Moon – return to Earth as a higher velocity than an orbital craft. As such, the first flight of this new Chinese vehicle will be somewhat similar in nature to the Orion’s first uncrewed flight in 2018.

The 14-tonne and 20-tonne next generation Chinese crewed vehicles. Credit: Beijing Institute of Space Mechanics and Electronics

To achieve its full envelope of uses, the new crew vehicle comes in two variants: a capsule and small service module which together weigh 14 tonnes, to be used in local orbital flights, and a version with a larger service module, giving a mass of 20 tonnes for the combined craft. This will likely be used for missions into deeper space. Either craft be able to carry up to six astronauts, or three astronauts and 500 kg of cargo to low Earth orbit.

Overall, the May launch of the vehicle has a lot hinging on it. A successful flight will clear the way for the two-month-long launch campaign required for the Mars Global Remote Sensing Orbiter and Small Rover mission mentioned above, using a Long March 5. In will also be see as opening the way for the Long March 5B vehicle to undergo a series of launches ahead of placing the 20-tonne Tianhe module, intended to be the core element of China’s new space station, due in early 2021. Weighing 20 tonnes, the module’s launch will mark the first in about a dozen that will be needed to complete the station between 2021 and 2022 /23.

When is an Exoplanet Not and Exoplanet?

As I’ve frequently remarked in these pages, we’ve so far confirmed the presence of over 4,000 exoplanets orbiting other stars. The number is such that it’s easy to think that detecting these worlds is just a matter of observing and waiting for that regular tell-tale dipping of brightness in a starts luminosity as seen from our orbiting telescopes, and which has been the more common means of detecting the worlds around other stars.

However, finding and confirming the presence of exoplanets is a complicated process, one that can be ripe with false positives. An example of this is Fomalhaut b, which has been puzzling astronomers since it was first observed in 2004. Orbiting the A-type main-sequence star Fomalhaut, some 25 light-years from Earth in the constellation of Piscis Austrinus, the planet was first observed by the Hubble Space Telescope, marking as the first to be detected in visible wavelengths (that is. the Direct Imaging Method).

Hubble images of the dust cloud around Fomalhaut. Credit: NASA/ESA/A. Gáspár and G. Rieke (University of Arizona)

At the time, it appeared to be a planetary body around half the mass of Jupiter orbiting within an accretion ring of icy dust and debris surrounding the star, with follow-up observations in 2008 and 2012 marking it as a significant object orbiting the star. However, the odd thing about it was that it did not have any accompanying infra-red signature, as would be expected from a planet orbiting a relatively young star. Also, over the period of some 10 years, it slowly faded before vanishing from visible light recording altogether.

Various theories were put forward for why this should be, with no clear consensus of opinion being reached, including the idea that the accretion disk surrounding the star and planet could be blocking visible and infra-red light from the planet, or that it could be the result of a collision between between planetismals orbiting the star.

Now, a new study suggests the last theory is likely to be the case, that Formalhaut-b is in fact the expanding cloud of icy particles and debris that result from the collision of two much larger icy bodies once present on the inner edge of the ring of debris surrounding the star, its fading being due to the expanding cloud of debris losing its ability to collectively reflect the light from its parent star.

An Artist’s impression of what Formalhaut-b might have looked like, were it a planet. Credit: ESA, NASA, and L. Calcada (ESO for STScI)

Such collisions are believed to have been common in the Solar System billions of years ago during a period known as the Late Heavy Bombardment. At the time, the system was littered with smaller objects that were essentially leftover material from the formation of the planets, which resulted in countless impacts and collisions. The results of these collisions can be seen today in the asteroid belt between Mars and Jupiter and the Kuiper Belt. With Formalhaut-b, such a collision would also explain why no infra-red signature expected of a planet.

To try determine if the latter theory might be correct, the team behind the study developed a series of computer models to analyse what might have caused an object like Formalhaut-b to fade in a manner consistent with observations from Earth. All of the results from the models pointed to Formalhaut-b being a slowly-fading debris field. What’s more, the models all pointed to the fact that such collisions might happen once every 200,000 years, and that this particular collision likely took place shortly before Hubble first observed it in 2004 – or rather, it took place in 1979 – light from the star taking 25 years to reach us.

Combing through all the data from observations of Fomalhaut b’s trajectory, the study team were also able to learn more about the path the debris is taking. Based on what they found, they ventured that Fomalhaut-b may be on an escape path and not in an elliptical orbit around its star – thus explaining the apparently oddly distended nature of the object’s orbit that had been observed.

Further studies are required to completely confirm the study’s findings, but at the moment it offers the most consistent explanation for Formalhaut-b’s nature and “disappearance”.

NASA Selects Three Teams For Artemis Lunar Landings

On April 30th, NASA announced it has selected three teams to move forward with designs for lunar landing vehicles capable of delivering astronauts to the surface of the Moon by the end of 2024 as part of America’s Artemis programme. The selections have been made as a part of the agency’s Human Landing System (HLS) programme, with the the combined value of the associated contracts – which cover a 10-month study period – total US $967 million.

The Blue Origin / Northrop led HLS proposal. Credit: Blue Origin

The largest portion of the money – US $579 million – will go to a so-called “national team” lead by Jeff Bezo’s Blue Origin. This group includes Draper, Lockheed Martin and Northrop Grumman.

Blue Origin will develop a descent vehicle, based on their Blue Moon lunar lander vehicle, while Lockheed Martin will be primarily responsible for the the ascent module, used to carry the crew back up to orbit. Northrop will supply the transfer vehicle stage and Draper the avionics and related control systems. The vehicle will be designed to be launched by either Blue Origin’s New Glenn launcher or the United Launch Alliance (ULA) Vulcan Centaur.

The Dynetics team’s all-in-one lander / ascent vehicle proposal. Credit: Dynetics

Dynetics, leading a team of 25 subcontractors including Sierra Nevada Corporation, the builders of the DreamChaser, will receive US $253 million. Their proposal features a single module capable of both descending to the Moon’s surface and ascending back to orbit. The primary launch vehicle will be the United Launch Alliance (ULA) Vulcan Centaur, with the vehicle designed to work with other launchers if required.

The remaining US $135 million is to go to SpaceX Corporation for a proposal to use a modified version of their Starship vehicle, to be launched by their super heavy booster. It will include a spacious cabin capable of housing a full crew of astronauts, with two airlocks for surface operations. This award came as something of a surprise in some quarters, as SpaceX had previously indicated it would not be bidding for HLS.

The modified Starship HLS lander proposal from SpaceX. Credit: SpaceX

A notable absentee from the programme is Boeing, responsible for the CST-100 Starliner. It had been assumed that the company would likely be at the forefront of the programme, having already submitted a proposal for a two-stage lunar lander / ascent vehicle suitable for lunch by the Space Launch System (SLS). However, given the Block 1b SLS system that would be required to launch it will not be available until at least 2025, this may be a reason why Boeing were not selected.

None of the proposals selected require the use of the Lunar Orbital Platform-Gateway (LOP-G), the station intended to operate in cislunar space and act as a staging area for lunar surface operation. This was removed from the “critical path” for an initial return to the Moon by the United States. Instead, whichever lander system that’s selected will be flown to lunar orbit uncrewed, where it will rendezvous and dock with a crewed Orion vehicle, with some of the crew then transferring to it for the trip to the Moon’s surface and back.

Meet Ingenuity, NASA’s Mars Helicopter

In the wake of naming the Mars 2020 rover Perseverance, NASA has announced the small technology demonstrator helicopter the mission will carry to the Red Planet is to be called Ingenuity. The name was suggested by Vaneeza Rupani, a junior at Tuscaloosa County High School in Alabama as a part of NASA’s nationwide competition to name the rover.

The 1.8 kg rotary craft, constructed of lightweight materials. Fully automated, it will be carried under the rover, but will not be deployed immediately after arrival. Instead it will be carried until the rover’s operations are settled and conditions are right. At that point, the helicopter will be lowered to the surface before the rover backs away. It will then operate on the surface to start with before commencing flight operations, which are designed to last for a period of 30 sols (31 days), operating both on the ground and in the air.