Space Sunday: sunsets, ring-hunting, airships and to boldly brew

NASA’s Mars Science Laboratory rover Curiosity is continuing onwards and upwards in its ascent of “Mount Sharp”, en route to a feature mission staff have dubbed “Logan Pass”. At the start of May, however, the rover made a slight detour in order to study a small valley of interest to the science team.

In planning the route up to “Logan Pass”, which sits at the head of a series of shallow valleys cut into the side of “Mount Sharp”, the rover was ordered to carry out a panoramic study of the terrain in its vicinity to help with route planning. In doing so, it imaged a small valley cut into one of the uprisings on the mound’s lower slopes, dubbed “Mount Shields”. The valley was of interest as it appeared to have been carved into the rock – possibly by liquid water action – at some point in the past and has since gradually been filled-in.

Gotcha! A view from NASA’s Mars Reconnaissance Orbiter (MRO) on April 8th, 2015 (Sol 949 for the rover), reveals Curiosity passing through the valley dubbed “Artist’s Drive” on the lower slope of “Mount Sharp”. The image was captured using MRO’s High Resolution Imaging Science Experiment (HiRISE) camera, and the rover, complete with right-pointing shadow, can be seen in the inscribed rectangle. The view in this image covers an area 500 metres (550 yards) across (click for full size)

This kind of geological feature is called an “incised valley fill”, and it is of interest because the material filling the valley cut is different to the material comprising the bedrock of the mound itself, being mostly sand. Thus the science team wanted to understand more about the possible mechanisms that might have deposited it there. Was it carried by wind or water or a mixture of both? Is there a variation in age between the rock of the mound and the material deposited in the incision? Answering these questions help in better understanding many of the environmental (geological and climatic) changes which have occurred on Mars.

Planning for the rover’s progress up the side of “Mount Sharp” is a complex process, involving multiple teams and consultations, particularly as a balance had to be achieved between reaching potential science targets and avoiding undue wear on the rover’s components and systems. To explain how the rover’s route is planned,NASA JPL recently issues a Curiosity Update video discussing the process.

Following its diversion to examine the incised valley, Curiosity resumed its upward path towards “Logan Pass”. As noted in the video, this is also of particular interest to the science team as it marks the intersection of two geological layers – the “Murray Formation”, which forms the transitional region between the slope of “Mount Sharp” proper and the floor of the Gale Crater basin, and the “washboard” region above it. It’s likely that the rover will spend some time in the “Logan Pass” are, before resuming its climb towards a further site of scientific interest, dubbed “Hematite Ridge”.

Sunset on another world: on April 15th, 2015 (Sol 956 for the rover), Curiosity captured a series of images of a setting sun as to stopped to survey the route towards “Logan Pass”. The images were captured after a dust storm had left a significant amount of particulate matter suspended in the atmosphere. Thus, the individual pictures making up this animated image allow the science team to understand the vertical distribution of dust in the Martian atmosphere and how it might influence regional climatic conditions. The blue tinting to the sky evident around the sun is due to the suspended dust particles being just the right size to allow blue wavelengths to penetrate the atmosphere with a slightly greater efficiency than other wavelengths (click for full size)

 New Horizons turns  Moon Hunter

New Horizons is the name of NASA’s mission to perform a high-speed flyby of the dwarf planetary system of Pluto and Charon. The craft, which achieved the fastest launch of any space vehicle to date, with an initial velocity 16.26 km/s when it lifted off the pad at Cape Canaveral Air Force Station on January 19th, 2006, is currently approaching Pluto and Charon at a relative velocity of 13.8 km/s.

Currently, the mission is closing on the period the mission team have dubbed the “seven weeks of suspense” – a reference to Curiosity’s “seven minutes of terror” during the entry, descent an landing phase of that mission – as New Horizons makes its closest flyby of Pluto and Charon, coming to within 10,000 kilometres of the former on July 14th, 2015 and 27,000 kilometres of the latter.

The nuclear-powered (RTG) New Horizons - one of the fastest man-made craft ever made to date, now closing on the Pluto-Charon system
The nuclear-powered (RTG) New Horizons – one of the fastest man-made craft ever made to date, now closing on the Pluto-Charon system

On May 15th, 2015, New Horizons’ ability to image Pluto and Charon exceeded those of the Hubble Space Telescope. While the images are still blurry – but will massively improve – they are enough to start to show surface features on Pluto, including what might be a polar ice cap.

May also saw New Horizons enter a new phase of its mission: the discovery of further moons within the system. While Charon has traditionally been regarded as Pluto’s moon since its discovery in 1978, the relative size of Charon compared to Pluto, and the fact that the barycenter of the Pluto–Charon system lies outside Pluto, technically makes them a binary dwarf planet system, with a number of tiny moons orbiting them both – and there is a chance there may be more such little moons waiting to be discovered.

The Pluto-Charon system images by the Hubble Space Telescope in 2012, showing the moons orbiting both which have so far been discovered:
The Pluto-Charon system imaged by the Hubble Space Telescope on July 7th, 2012, in which the tiny moon Styx was first imaged. This picture also shows the other moons within the system so far discovered: Hydra (May 2005), Kerberos (July 2011) and Nix (jointly discovered with Hydra in May 2005) image: NASA / STSCI

Locating such moons is an important part of the mission not just scientifically but also technically. There is a fair chance that the Pluto-Charon system might be surrounded by dust and tiny debris, and little moons like Hydra, Nix, et al, do much to “shepherd” this debris into a ring system (as is the case in planetary systems such as Jupiter, Saturn, Uranus and Neptune). Given that any any impact with a mote of dust at New Horizon’s velocity could be potentially devastating to the craft, despite it being “armoured” with kevlar, locating where and how dense any such ring system might be is vital to the mission.

Expect to see more about New Horizons in these pages in the coming weeks.

Airships over Venus

One of the most inhospitable places for humans in the solar system is Venus. Sometimes referred to as Earth’s “sister planet” due to their similar sizes and mass, Venus is a radically different would from our own. Sheathed in a perpetual blanket of cloud, it is home to a runaway greenhouse effect, where the surface atmospheric pressure is 92 times that of Earth’s with a mean surface temperature of 462 °C (863 °F), the atmosphere itself more than 96% carbon dioxide. To attempt to walk on its surface unprotected would have you simultaneously cremated evaporated and crushed.

This being the case, you’d think that Venus would be the last place to send astronauts. But that is precisely what a group of engineers at NASA’s Langley, Virginia, field centre are proposing – although they are admittedly suggesting astronauts only be sent as far as the upper reaches of the planet’s atmosphere, where they can spend 30 days studying it from inside an airship.

NASA Langley's HAVOC mission
The proposed HAVOC mission. Image: NASA Langley

HAVOC (High Altitude Venus Operational Concept) proposes two ships fly to a rendezvous in orbit around Venus.  The first carries a huge (roughly twice the length of a 747) airship and the helium required to inflate it. The second carries a crew, two of whom transfer to the waiting “airship carrier”, which then de-orbits, enters the Venusian atmosphere and starts inflating the airship while descending under parachutes to an altitude of around 50 kilometres above the surface of the planet, where it would commence operations. At the end of the mission, the crew use a small rocket ship to fly back up to orbit and rendezvous with their compatriots for the journey home.

The altitude for the mission is significant, as it would place the airship in an operational environment similar to that of Earth’s atmosphere – with a surrounding atmospheric pressure of one bar – while ensuring it would be both above the more turbulent layers of the atmosphere but deep enough within the atmosphere to be shielded from much of the incoming UV radiation from the Sun.

A further point of intrigue about the idea is that these airship flights could be extended to up to a year in duration, and that they could potentially pave the way for a permanent human presence within the Venusian atmosphere with people living and working aboard a floating environment.

The Langley Reserch Centre team's concept of a permanent human presence in the Venusian atmosphere
The Langley Research Centre team’s concept of a permanent human presence in the Venusian atmosphere – a floating operational centre and airships. Image: NASA Langley

It’s an intriguing concept – one that is being sold on the idea that Venus offers a better potential target than Mars, or at least offers a means by which technologies intended for use on Mars can be tested. However, While Mars does offer significant challenges for exploration and perhaps eventual colonisation, it is in many respects a far more practical destination for human space flight endeavours than Venus – and really, there are few technologies it realistically requires which cannot be tested here on Earth or in orbit around Earth or by flying test articles to Mars as a part of broader robotic missions there.

Furthermore, it is not unreasonable to suggest that given the early phases of HAVOC utilise entirely automated airships, there is no reason why the scientific benefits of the mission cannot be achieved purely by robotic means and without the additional expense of sending humans as well. But even so, it is an intriguing idea.

To Boldy Brew

It’s been one of the most eagerly awaited arrivals aboard the International Space Station, with complaints about its absence stretching back some 13 years. And in April 2015, it finally arrived. I am, of course, talking about the world’s first orbital expresso machine.

ISSpesso, jointly developed by Italian coffee-house Lavazza and technology firm Argotec, is sponsored by the Italian Space Agency. As well as producing a real cup of expresso, the system – which is roughly the same size as an Earth-based coffee maker, and uses pressure to ensure both the proper heating of the water and its delivery – can also be used to make a range of other beverages, including tea and consommé. However, it is for the coffee that it is mostly prized – ISS instant coffee being uniformly regarded as both “tepid” and “tasteless”.

Samantha Cristoforetti enjoys the first cup of expresso aboard the ISS
Samantha Cristoforetti enjoys the first cup of expresso aboard the ISS via Twitter

The first cup of expresso was rightfully enjoyed by an Italian, Samantha Cristoforetti, a Captain in the Italian Air Force and member of the European Astronaut Corps.

A confirmed Star Trek fan, Ms. Cristoforetti donned a Star Trek: Voyager style uniform as the Dragon resupply vehicle carrying ISSpresso rendezvoused with the station, and then tweeted a photo of herself floating in the ISS observation cupola with the Dragon capsule as a back drop, offering a modified quote from Captain Janeway from the Voyager show, “There’s coffee in that nebula … ehm, I mean … in that #Dragon”.

She later followed-up the Tweet with an image of her, still in her Star Trek uniform, enjoying that very first cup (yes cup – six special expresso cups were also flown up to the station as a part of an experiment into fluid dynamics which uses ISSpresso) of space-brewed expresso, complete with a suitable Trek quote (above).

It’s actually fitting that Cristoforetti took the honours with the first cup of space-brewed expresso, and not just because she is Italian. The original version of the machine had been slated for delivery to the ISS about a Cygnus resupply vehicle set to reach the station as she started her tour of duty in late 2014. Unfortunately, both the Cygnus vehicle and its cargo were lost when the Antares rocket that was to lift them into orbit suffered a catastrophic failure just after launch, leading to its destruction by the launch safety officer.

All images and video, unless otherwise stated, courtesy of NASA JPL.