Space Sunday: Moon flights and the winds of Mars

The Dragon 2 crew capsule attached to its service module. Credit: SpaceX

The Dragon 2 crew capsule attached to its service module. Credit: SpaceX

While most private space tourism companies are busily going about various routes to offer sub-orbital flights to those who can afford them, Elon Musk’s SpaceX has stepped into the arena – and, as might be expected, made the bold announcement it will go one better: fly paying passengers around the Moon and back. And they plan to do it in 2018.

The announcement was made by Musk on Monday, February 27th during a press teleconference. If the flight goes ahead, it will allow two fare-paying passengers the opportunity to undertake a week-long journey out to and around the Moon, before returning to Earth. The flight would use a “free return” profile which would see it skim over the surface of the Moon and continue outward beyond it, possibly as far as 480,000 Km (300,000 mi) from the Earth (the average distance of the Moon from Earth is around 384,400km /  240,000 mi), before Lunar gravity takes over and hauls the vehicle back towards the Earth, where it would splash down.

It’s not clear how much the passengers would pay to be on the flight – but the going price for a seat aboard the Dragon 2 vehicle, which would be used for the flight, will be around US $58 million a pop to get to the International Space Station, once it enters service. It’s also far from clear if SpaceX can actually deliver on the goal of launching the flight in late 2018.

SapceX plan to use the Falcon Heavy as the launch vehicle for the lunar flight. When it enters service later in 2017, the Falcon Heavy will be the most powerful launch vehicle in the world today

SapceX plan to use the Falcon Heavy as the launch vehicle for the lunar flight. When it enters service later in 2017, the Falcon Heavy will be the most powerful launch vehicle in the world

In order to take place, the flight first and foremost needs a launch vehicle and a suitable space vehicle. SpaceX plan to use their mighty Falcon Heavy and – as noted – their new Dragon 2 crewed vehicle. There’s just a couple of problems with both.

The Falcon Heavy is not due to fly until some time later in 2017, and even then it will not be rated for crewed launches. For that to happen, it will have to be certified for crew use, and depending on how the initial flights go, that could take time. In terms of the Dragon 2, that is not scheduled to enter service until 2018 – and even then, its primary function is to fly crews to and from  the International Space Station (ISS).

Ferry flights to the ISS are vastly different to going out around the Moon and back. To start with, the outward flight from Earth to the ISS can be measured in just a couple of days – around a quarter of the time needed for the lunar trip.  The velocity (delta vee)  imparted to a spacecraft going to the ISS (28,000 km/h / 17,500 mph) is also a lot less than required to go to the Moon (40,000 km/h / 25,000 mph).

Elon Musk unveils a mock-up of the Dragon V2 capsule in May 2014. SpaceX now has their firs NASA contract to fly a crew to the ISS aboard the vehicle, probably in 2018

Elon Musk unveils a mock-up of the Dragon 2 capsule in May 2014.Credit: SpaceX

This means a returning Dragon 2 will be re-entering the Earth atmosphere a lot faster than the same craft coming back from the ISS, and will have to face much higher re-entry temperatures and a harsher deceleration regime. While the Dragon 2 can in theory do so, it is likely that significant testing on uncrewed vehicles will be required before the Federal Aviation Authority and NASA agree to any such flight taking place. On top of this, it will have to be demonstrated that the Dragon 2 can be outfitted for a deep space mission and keep a crew alive and well for around 7-8 days.

Given all this, there are widespread doubts the company can meet a 2018 deadline for such a mission – and SpaceX has tended to be ambitious with its time frames for achieve goals. They had originally slated 2013 as the year in which the Falcon Heavy would make its first flight – although in fairness, setbacks following the loss of two Falcon 9 vehicles also contributed to its launch being pushed back to 2017.

Red Dragon Delayed

As further evidence of SpaceX presenting time frames which are perhaps a little ambitious, on February 17th, the company announced its mission to land a variant of the Dragon 2 – dubbed Red Dragon – on Mars has been pushed back from 218 to 2020.

The aim of the mission so to fly an uncrewed 10-tonne Dragon 2 vehicle to Mars and land it safely. In doing so, the company hopes to gain valuable data on landing exceptionally heavy vehicles on Mars using purely propulsive means. This is because crewed landing vehicles on a Mars mission are liable to have a mass of at least 40 tonnes – far too much to be safely slowed in a descent through the thin Martian atmosphere by parachutes.

A SpaceX / NASA infographic outlining the Red Dragon mission - now slated for 2020

A SpaceX / NASA infographic outlining the Red Dragon mission – now slated for 2020

The planned mission would be undertaken entirely at the company’s own expense, although it would can science instruments and experiments supplied by NASA. For Musk it, and possibly three further Red Dragon mission which could follow it in the 2020-2024 time frame, is a vital precursor to greater ambitions for Mars.

As he outlined in September 2016 (see: Musk on Mars), Musk plans to start launching crewed missions to Mars, possibly before 2030. The initial missions will doubtless be modest in size in terms of crew and goals. However, his overall stated goal is to kick-start the colonisation of Mars. To do that, he plans to use vehicles massing at least 100 tonnes and which can make a propulsive landing on Mars. Whether he can succeed in even the step to land a crew on Mars  – and bring them back to Earth – remains to be seen. However, his Red Dragon mission is an important first step.

The Winds of Mars

Sol 1,65, March 2017: with its robot arm raised, Curiosity examines another area of the "Bagnold Dunes" on "Mount Sharp", a area it first examines lower down the side of the mound in December 2015 / January 2016. Credit: NASA / JPL / M. Di Lorenzo

Sol 1,625, March 2017: with its robot arm raised, Curiosity examines another area of the “Bagnold Dunes” on “Mount Sharp”, an area it first examined lower down the side of the mound in December 2015 / January 2016. Credit: NASA / JPL / M. Di Lorenzo

The Martian atmosphere may be less than 1% as dense as Earth’s, but the winds which can form within it have been over time, and since the end of other factors such as free-flowing liquids and volcanism, the most significant  factor in the formation and look of the planet’s surface features.

I’ve previously written about how the Martian wind played a key role in forming “Mount Sharp”, the huge, layered formation abutting the impact peak of Gale Crater on Mars (see Space Sunday: of water, Apollo and space spies), as revealed by both NASA’s Curiosity Mars Science Laboratory which is currently exploring the mound, and the orbiting Mars Reconnaissance Orbiter (MRO). Now, with summer having arrived in Gale Crater, Curiosity is taking the opportunity to examine sand dunes on the flank of “Mount Sharp” and monitor / observe how great an influence the Martian wind plays in affecting the landscape.

The studies are being carried out in the up-slope part of dune field dubbed “Bagnold Dunes” after British military engineer Ralph Bagnold, who pioneered the study of sand dune formation and motion which furthered the understanding of mineral movements and transport by wind action. This is the same dune field the rover first encountered further down the slope of “Mount Sharp”, back in December 2015 / January 2016. With the summer winds now blowing within Gale Crater, the field is an excellent place to witness how it can affect and change the landscape, simply through the movement of Martian sand (or “fines” as it is collectively called).

Curiosity captures a dust devil whipping across the "Bagnold Dunes" on Sol 1,597 (February 1st, 2017), picking up Martian sand (called "fines" and carrying them to be re-deposited elsewhere. Credit: NASA/JPL

Curiosity captures a dust devil whipping across the “Bagnold Dunes” on Sol 1,597 (February 1st, 2017), picking up Martian sand (called “fines” and carrying them to be re-deposited elsewhere. Credit: NASA/JPL / TAMU

Because the atmosphere is so thin, the winds of Mars are much weaker than we might think. Forget all the Hollywood visuals and the conceit of writers portraying a 200km/h wind on Mars as being as powerful as the same wind speed here on Earth (it would actually be more like a light breeze). However, that doesn’t mean they are ineffective in moving material around – the massive dust storms which mark the changing of the seasons on Mars are proof of that. These not only move huge amounts of Martian fines around, they can, over the millennia, use the grit and dust suspended in them as a means of scouring and shaping hills and mountains.

Take the 160 km (100 mile) wide Gale Crater and “Mount Sharp” for example. It was formed as a result of an impact of an asteroid or comet around 3.6 billion years ago. Over time, as I explained in the Space Sunday article linked to above), periods of flooding gave rise to the crater gradually being filled with sedimentary deposits. Then, after the water receded / vanished, the wind took over.  Studies using data gathered by both Curiosity and MRO suggests that around 64,000 cubic km (15,000 cubic mi) of material was removed from the crater to sculpt “Mount Sharp” as we see it today. While that might sound a lot, orbital observations have shown it is entirely consistent with wind effects within the crater rim when measured over billions of years.

Another sequence of images showing a dust-carrying whirlwind on Sol 1,597 (February. 1st), 2017). The black rectangle in both this image and the one earlier marks the area on which Curiosity's Navcams were focused in the hope of capturing passing dust devils. Credit: NASA/JPL / TAMU

Another sequence of images showing a dust-carrying whirlwind on Sol 1,597 (February. 1st), 2017). The black rectangle in both this image and the one earlier marks the area on which Curiosity’s Navcams were focused in the hope of capturing passing dust devils. Credit: NASA/JPL / TAMU

Outside of the huge dust storms, it is possible for the wind to affect the landscape in other ways. As images by Curiosity show, “Bagnold dunes” are currently experiencing frequent dust devils – tiny tornadoes which can whip up Martian fines and carry them a fair distance before depositing them once more. These help form and change the local landscape, adding to the slow downward movement of the dunes under the influence of gravity.

As I’ve mentioned elsewhere in these updates, these dust devils can even help NASA’s solar-powered Opportunity rover: when one blows over “Oppy”, it tends to pick up all the dust which has gathered on the rover’s solar arrays, effectively cleaning them and restoring a fair portion of their ability to harness sunlight and turn it into electrical power.

Curiosity’s study of the Martian wind come as a time when engineers continue to investigate an issue with the rover’s drill feed mechanism which is currently preventing sample gathering activities. The problem is thought to be an obstruction which is preventing the drill from extending from and retracting into its housing – a necessary part of feeding samples into the rover. Also under investigation is the lens cover for the robot arm-mounted Mars Hand Lens Imager (MAHLI), which failed to respond to commands sent to it on February 24th.

This pair of images shows effects of one Martian day of wind blowing sand underneath Curiosity on a non-driving day. Each image was taken just after sundown on on January 23rd, 2017 (Sol 1587) and January 24th, 2017 (Sol 1588). by the rover’s downward-looking Mars Descent Imager (MARDI). The area of ground shown in the images spans about 1 metre (39 inches) across. They reveal how the wind quickly scours the treadmarks left by one of the rover's wheels, even when protected by the vehicle. Credit: NASA/JPL / MSSS

This pair of images shows effects of one Martian day of wind blowing sand underneath Curiosity on a non-driving day. They were taken just after sundown on January 23rd, 2017 (Sol 1587) and January 24th, 2017 (Sol 1588) by the rover’s downward-looking Mars Descent Imager (MARDI). The area of ground shown in the images spans about 1 metre (39 inches) across. They reveal how the wind quickly scours the tread-marks left by one of the rover’s wheels (seen top left), even when protected by the vehicle. Credit: NASA/JPL / MSSS

After completing the planned dune observations and measurements, Curiosity will proceed southward and uphill toward a ridge where the mineral hematite has been identified from MRO observations. The Curiosity science team has decided to call this noteworthy feature the “Vera Rubin Ridge,” commemorating Vera Cooper Rubin (1928-2016), whose astronomical observations provided evidence for the existence of the universe’s dark matter.

MAVEN Manoeuvres to Avoid Phobos

To read some of the space headlines you’d think it was a dire situation. “NASA Spacecraft Avoids Collision with Martian Moon Phobos” blared one headline; “NASA’s MAVEN craft dodges Martian moon Phobos” screamed another, as if it the NASA craft had to suddenly swerve to avoid a collision. In fact, things were a little more sedate than might have been imagined.

An artist's impression of MAVEN as it looks down on Mars' Vallis Marineris. The NASA mission, which arrived in orbit in September 2014, is studying the Martian atmosphere

An artist’s impression of MAVEN as it passes over the Vallis Marineris. The NASA mission, which arrived in orbit in September 2014, is studying the Martian atmosphere. Credit: NASA

MAVEN – the Martian Atmosphere and Volatile EvolutioN spacecraft occupies a highly elliptical orbit which can cross the altitudes of other bodies orbiting the planet. On February 27th, it was noted that come Monday, March 6th, both MAVEN and Phobos would pass through the same spot within seven seconds of one another, risking a potential collision.

To avoid this, commands were sent to MAVEN on February 28th, ordering it to fire a thruster to increase its velocity by 0.4 metres per second – less than one mile per hour. Doing so means that MAVEN and Phobos will now pass the same place in their orbits two and a half minutes apart, completely eliminating any chance of a collision on March 6th, 2017.

Fun Fact: What Human Made Structures Can You See With the Naked Eye From Space?

Ask most people this question, and they’ll respond with, “the Great Wall of China” – and they’d be wrong. The fact is, you can’t see the Great Wall from orbit with the naked eye; even with a 180mm telephoto lens, it is far from easy to spot. Why? Because it largely follows the contours of the land on which it is built and shares what is from space, more-or-less the same colours.

By contrast, roads can be relatively easy to see with the naked eye from orbit, particularly where they cut, ruler-straight, through deserts and similar terrain. Astronauts aboard the ISS also say that the Great Pyramids are pretty easy to spot, and obviously the large stains of our towns and cities are visible. However, there is one feat of human engineering which is increasingly visible from space, and that’s the solar energy farms which are gradually cropping up all over the world.

The Longyangxia solar farm, China. In 2016, China installed the equivalent of one and a half soccer fields of solar panels every hour. Credit: NASA / Landsat

The Longyangxia solar farm, China as seen from orbit. In 2016, China installed the equivalent of one and a half soccer fields of solar panels every hour. Credit: NASA / Landsat

The biggest of these is the Longyangxia Dam Solar Park in China. Occupying 27 square kilometres (10.42 square miles), it comprises nearly 4 million solar panels, capable of providing 850 megawatts of power. It is operated alongside a wind turbine plant and the Longyangxia Dam, which generated 1,280 megawatts of power.

China is planning an even bigger solar farm – capable of producing 2,000 megawatts  of power  – enough to provide energy to around 300,000 homes – all as part of a pledge to reduce its carbon emissions. By 2020, the country intends for at least 1% of its total energy needs to be met through renewable sources, and then build from there.

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