Space Sunday: budgets, space planes, landers, oxygen and dust

A new ESA budget confirms the space agency’s commitment to the Space RIDER uncrewed space plane Credit: ESA

On Thursday, November 28th, 2019, European Space Agency (ESA) members agreed to a record €14.4 billion, promising to maintain Europe’s place at the top table alongside NASA and China. The four largest contributors to the budget are Germany (€3.3 billion); France (€2.7 billion), Italy (€2.3 billion) and the United Kingdom (€1.7 billion – ESA is not an EU organisation, so the UK’s involvement will remain unchanged when / if Brexit occurs, although EU funding of UK science and technology projects will be impacted).

The funding will allow ESA to move forward on a number of fronts in space exploration and technology development, including:

  • The Laser Interferometer Space Antenna (LISA) – the first space-based gravitational wave observatory, comprising three spacecraft placed in a triangular formation 2.5 million km apart and following the Earth in its orbit around the Sun. LISA will launch in the early 2030s.
  • Transitioning ESA to the next generation of launchers: Ariane 6 and Vega-C.
  • Continued support of the International Space Station, including continued participation in crew missions.
  • Direct involvement in NASA’s Artemis lunar programme, including technology for the Lunar Orbital Platform-Gateway (LOP-G) and crewed missions.
  • A joint Mars sample-return mission with NASA.
  • Development of flexible satellite systems integrated with 5G networks, as well as next-generation optical technology for a fibre-like ‘network in the sky.’
  • The development of a European reusable space vehicle: Space RIDER.

Space RIDER (Reusable Integrated Demonstrator for Europe Return) is a project I first wrote about in 2015, when ESA flew the European Intermediate eXperimental Vehicle (IXV). An uncrewed vehicle weighing just under 2 tonnes, it had the primary objective to research the re-entry and flight characteristics of a lifting body type of vehicle and test the re-entry shielding technologies for such a vehicle.

The Space RIDER vehicle shown in cutaway, showing the open payload bay, forward parasail deployment system and after avionics. Credit: ESA

IXV paved the way for the initial development for Space RIDER, which will be an uncrewed cargo vehicle designed to be launched by the Vega rocket and capable of carrying up to 800 Kg of payload into orbit. All Space RIDER vehicles will be able to carry out around 5 flights apiece, reducing the overall cost of placing payloads into orbit. Following re-entry into the Earth’s atmosphere, the vehicle will descend to Earth under a parasail, allowing it to glide to a nominated landing zone.

As well as being suitable for launching space payloads into orbit, Space RIDER will itself be a technology development vehicle for possible larger reusable vehicles using similar lifting body technology.

Space RIDER will largely be developed by Italy and the first flight is due to take place in 2022.

Happy Anniversary, InSight

On Monday, November 26th, 2018, NASA’s InSight (Interior Exploration using Seismic Investigations, Geodesy and Heat Transport) lander, built with international cooperation, arrived on the surface of Mars. The focus of the mission is to probe the Red Planet’s interior – its crust, mantle and core in order to answer key questions about the early formation of the rocky planets in our inner solar system – Mercury, Venus, Earth, and Mars – more than 4 billion years ago.

A simulation of InSight touching down on Mars using its 16 rocket motors. Credit: NASA

Since that landing, the year has been an eventful one for InSight, the lander’s super-sensitive seismometer suite has detected more than 150 vibration events to date, about two dozen of which are confirmed marsquakes. However, and I’ve I’ve reported a number of times in these pages, InSight’s other primary science instrument, a burrowing heat probe called the Heat Flow and Physical Properties Package (HP³), has had tougher time.

The self-propelled “mole” probe designed to burrow down into the Martian sub-surface having been stuck for most of the year after only penetrating a few centimetres into the ground. Those operations only resumed in October 2019, and were short-lived after the probe inexplicably “bounced” its way almost completely out of the hole it had burrowed, leaving scientists and engineers still trying to work out what happened.

Side-by-side: (l) the first image returned by InSight using the lander-mounted, Instrument Context Camera (ICC), still with its dust cap in place. Note the lander’s leg in the lower right corner. (r) a photo captured by the robot-arm mounted Instrument Deployment Camera (IDC) as the arm is exercised on November 30th, 2018

The solar-powered InSight is scheduled to operate for at least two Earth years.

Of Oxygen and Dust

Since its arrival on Mars in 2012, the Mars Science Laboratory (MSL) rover Curiosity has used the Sample Analysis at Mars (SAM) chemistry lab carried in its belly for a number of different activities. One of them has been to analyse the composition of the atmosphere in Gale Crater, with SAM confirming that overall, the Martian atmosphere is 95% by volume carbon dioxide (CO2), 2.6% molecular nitrogen, 1.9% argon (Ar), 0.16% molecular oxygen, and 0.06% carbon monoxide (CO). SAM has also, over the time it has been gathering data on the atmosphere, been able to chart seasonal changes in the atmosphere and the why the different molecules mix and circulate.

The major driver for atmospheric changes on Mars is the movement of CO2. This freezes into the poles during each hemisphere’s winter, lowering the atmospheric pressure across the planet as it is redistributed to counter the loss in volume. When spring comes to each hemisphere, this CO2 is released by the poles, raising the atmospheric pressure and causing further redistribution (which among other things, drives the spring dust storms).

While studying Gale Crater, NASA’s Curiosity rover has recorded odd seasonal increases in the amount of methane in the Martian atmosphere – and now oxygen as well. Render created by Kevin M Gill.

As a part of all of this, the nitrogen and argon follow a similar, predictable pattern, rising and falling in relation to the amount of CO2 evident in the atmosphere. It had also been anticipated that the trace amounts of oxygen in the Martian atmosphere would behave in a similar manner – but it doesn’t. Instead, the amount of oxygen tends to increase through spring and summer – by as much as 30% above predicted levels as determined by atmospheric modelling from the SAM data, although the overall amount varies from year to year – before dropping back to predictable levels in the autumn period.  No known chemical analysis can account for this behaviour, suggesting that something on Mars is producing the oxygen and then taking it away.

It took time to verify SAM’s findings, as planetary scientists wanted to be certain the instrument wasn’t giving false results, or that the additional oxygen wasn’t the result of some kind of reaction as a result of a breakdown of either  CO2 or atmospheric water vapour. However, no fault was found in the instruments within SAM, and calculations showed that it would take five times the measured amounts of water vapour in the atmosphere to produce the additional oxygen, while CO2 breaks down far too slowly to result in such rapid seasonal fluctuations.

Nor could the sudden dissipation of the additional oxygen be easily explained. While solar radiation is known to break up oxygen molecules, it would take some 10 years for the volume of increased oxygen in the Martian atmosphere to be eroded in this way, rather than it vanishing in a single season.

We’re struggling to explain this. The fact that the oxygen behaviour isn’t perfectly repeatable every season makes us think that it’s not an issue that has to do with atmospheric dynamics. It has to be some chemical source and sink that we can’t yet account for.

– Melissa Trainer, planetary scientist, NASA Goddard Space Flight Centre

The changes seen with oxygen are similar – if on a much larger scale by volume – to the seasonal changes already noted in methane gas within the Martian atmosphere. While methane is barely discernible (accounting for just 0.00000004% of the Martian atmosphere by volume), it also goes through seasonal changes, increasing by around 60% in the summer season in particular for reasons that have yet to be understood, before falling back to more usual levels later in the year.

While the methane count can spike at other times in the year, the similarity between the oxygen and methane fluctuations suggest that possibly, the two are being driven by similar chemical processes.

Oxygen spikes in the Martian atmosphere. Credit: Melissa Trainer/Dan Gallagher/NASA Goddard

Oxygen and methane can be produced both biologically and abiotically (by the chemistry related to water and rocks). Trainer and her team are a investigating the potential for either one to be responsible for both the methane and the oxygen increases. However, determining which might be responsible is hampered by the fact that Curiosity isn’t capable of making such a determination.

That said, the most likely cause of the oxygen increase is likely abiotic. The Martian surface regolith is rich in oxygen, captured within compounds like hydrogen peroxide and perchlorates. It is possible that seasonal heating of the regolith releases some of this trapped oxygen – although the degree of heating would need to be extraordinary; research has shown that even high-energy radiation of the soil would require hundreds of years or more to release the amounts of oxygen recorded by SAM in a single year. Also, such a release doesn’t explain exactly what happens to the oxygen in the autumn months, when measurable amounts drop back the expected levels.

Thus far, scientist have not been able to come up with one process that could account for the increases and losses of oxygen in the Martian atmosphere. So Trainer has opened the door for others to investigate the data.

This is the first time where we’re seeing this interesting behaviour over multiple years. We don’t totally understand it. For me, this is an open call to all the smart people out there who are interested in this: See what you can come up with.

– Melissa Trainer, planetary scientist, NASA Goddard Space Flight Centre

As noted above, Mars is subject to seasonal dust storms, and every decade or so, conditions combine on the planet to lead to a series of runaway storms breaking out, which can cover the entire planet in a dusty haze. This happened in 2018, and led to the loss of NASA’s Mars Exploration Rover Opportunity, which was unable to gain enough sunlight on its solar panels to maintain its needed electrical power and heat.

However, observations of the storms from orbit allowed scientist to gather data on another of the strange phenomena witnessed on Mars: massive dust towers that climb high into the planet’s atmosphere. They appear to be the result of sunlight warming the atmosphere within a dust storm, resulting in convection currents that lift massive amounts of dust up to 80 km above the surface of the planet.

These towers themselves are massive affairs: as they reach their peak altitude they can spread over hundreds of square kilometres, then as they decay, they can form vast clouds of high-altitude dust around 50 km above the surface of the planet and covering an area the size of the continental United States.

The yellow-white cloud in the bottom-centre of this image is a Mars dust tower rising tens of kilometres above the surface. To give an idea of its scale, to the right of this tower in the deep scar of the 2,000, km long northern half of the Vallis Marineris. Directly below the tower, and partially obscured by it, is the Noctis Labyrinthus, a network of smaller canyons and broken terrain some 1,200 km across that feeds into the Vallis Marineris. The blue-white plumes centre-left of the image are water vapour clouds. This image was taken on November 30th, 2010, by NASA’s Mars Reconnaissance Orbiter. Credit: NASA/JPL / MSSS

Dust towers have been observed rising from Mars on numerous occasions in the past – but have generally been noted as lasting only a few days. The towers witnessed during the 2018 global storms, however, lasted for weeks, being constantly renewed by updrafts of more dust from below. This makes them especially interesting for scientists wishing to understand how Mars continues to lose whatever moisture is left in its atmosphere – it is thought that the towers help carry water vapour in the atmosphere up to high altitudes where solar radiation can break it down – and for them to learn about the overall impact the towers have on the Martian climate.