Space Sunday: of Martian and lunar robots, distant worlds and ET

August 2016 sees NASA’s Mars Science Laboratory rover Curiosity rack up four (terrestrial) years of operations on the surface of Mars.

The rover marked this anniversary rather quietly, by preparing to take further rock samples, this time from a target dubbed “Marimba”. Once gathered, the samples will be subjected to on-board analysis by Curiosity using the compact laboratory systems contained the rover’s body.

The sampling take place as the rover is engaged in a multi-month ascent of a mudstone geological unit as it continues its climb towards higher and progressively younger geological areas on “Mount Sharp” (more correctly, Aeolis Mons), which will include some rock types not yet explored.

In the meantime, examining the samples gathered from “Marimba” will allow a direct comparison with mudstone samples gathered further down the slopes of “Mount Sharp” and from the flatlands of Gale Crater. This will enable scientists to  build a more complete picture of the mineral and chemical  environment the rover is travelling through, and so further understand the general conditions which may have once have existed within the crater.

Goodnight from a Lunar Jade Rabbit

China has finally bid farewell to Yutu (“Jade Rabbit”, named for the companion to the Moon goddess Chang’e), its first lunar robotic explorer, after 31 months of surface operations.

The little solar-powered rover arrived on the lunar surface as part of Chain’s Chang’e 3 lander / rover mission on December 13, 2013, and was deployed from the lander some  7.5 hours after touch-down.

However, due to the vast temperature differential experienced between the sunlit and shadowed parts of the rover at the time of the landing, operations didn’t commence until December 21st, when the rover was uniformly lit by the Sun. It’s first activity was to drive part-way around its parent lander and photograph it. After this, the rover travelled some 40 metres (130 ft) from the lander to commence independent science operations studying the lunar surface.

Yutu was designed to operate for just three months and travel up to 10 km (6.2 mi) within an area of 3 square kilometres (1.2 sq mi). Following its expose to the first 14-day long lunar “night”, the rover resumed operations in January 2014. However, as the second lunar night period approached (lasting 14 terrestrial days), the rover suffered a glitch in its drive mechanisms, leaving it susceptible to the harsh cold of the night-time, and on February 12th, following its second Lunar night, the rover was declared lost … only to resume communications with Earth within 24 hours.

Since that time, although immobilised, the little rover has maintained almost regular contact with Earth, but with each night period taking an increasing tolls on its systems. Even so, its continued survival gained it a huge and loyal following on the Chinese micro-blogging site, Weibo, where in a leaf firmly pulled from NASA’s book of social media engagement, Yutu had a first-person account.

It was via that social media account that Yutu’s final demise was announced, as if from the rover itself, on August 2nd 2016:

This time it really is goodnight. There are still many questions I would like answers to, but I’m the rabbit that has seen the most stars. The Moon has prepared a long dream for me, I don’t know what it will be like – will I be a Mars explorer, or be sent back to Earth?

The message gained a huge response from the rover’s 600,000 followers, and the Chinese space agency officially confirmed the rover had “died”, on Wednesday, August 3rd.

Private Venture Given Lunar Good Ahead

In the week that Yutu ceased operations, the news came that the first private company has been granted permission to travel beyond Earth’s orbit.

In 2017, Moon Express plan to place a small lander on the Moon which will be able to “hop” across the surface by re-firing its descent engines. If successful, the project will most likely win the US $30 million Google Lunar X-PRIZE, which is available to any private organisation from around the world which can soft-land on the Moon and travel across the lunar surface.

The permission came via the US Federal Aviation Authority, which is responsible for overseeing all private sector space flights from US territory. Negotiations have been ongoing over many months, as have broader, international discussions on the role of the private sector and commercial activities beyond Earth’s orbit.

While winning the Lunar XPRIZE would be a significant cash boost for Moon Express, the company has far broader goals:  the harvesting resources on the Moon such as water and Helium-3; creating a fuel depot on the surface; and eventually performing round-trip missions with the capability of bringing payloads back to the Earth. Whether any of these can be achieved cost-effectively enough to be commercially viable, is somewhat questionable.

The mission itself has been in development for several years – the company secured a launch vehicle from  Rocket Lab in October 2015, for example. It has also been through an iterative process which has seen a heavier, far more complex mission utilising a “hub” lander capable of deploying “micro-landers” replaced by the lighter, more manageable vehicle currently proposed.

If all goes according to plan, Moon Express should launch in the second half of 2017.

Kepler Recovers Again; TESS Gets Ready to Join the Hunt

I’ve previously mentioned NASA’s exoplanet hunting Kepler mission (most recently here), which has enjoyed remarkable success – accounting for around 70% of all planets orbiting other stars so far discovered, whilst also acquiring data on thousands of other potential exoplanets which has yet to be verified – as well as a few ups-and-downs.

In 2013, for example, the mission had to be revised after Kepler – which occupies a heliocentric orbit, currently trailing Earth by around 121 million kilometres (75 million miles), and so well beyond any means to service it, even were the United States in a position to do so – suffered failures with two of the four reactions wheels vital in keeping the platform stable whilst it observes distant stars.

In April of 2016, the observatory suffered a major communications failure which again put the mission at risk, before a successful recovery was made later in the month. Then, on July 28th, 2016, the observatory abruptly shut down its photometer, the camera-like tool used to detect alien planets. Then, on August 1st, power was restored to the instrument while engineers were still trying to figure out what had happened, and how best to get things back on-line.

It is still not clear what caused the glitch, and there is understandable concern that it might be a symptom of issues within the observatory’s software or systems. Investigations into the shutdown are continuing, but in the meantime, Kepler resumed observations on Wednesday, August 3rd.

Come 2018, Kepler will not be the only space platform seeking other worlds. Due for launch in December 2017 via a SpaceX Falcon 9 FT rocket, NASA’s Transiting Exoplanet Survey Satellite (TESS) is intended to bring the search for other worlds much closer to home. While Kepler has been searching for exoplanets thousands to tens of thousands of light-years away from Earth towards the constellation Cygnus, TESS will search for exoplanets hundreds of light-years or less in all directions surrounding our solar system.

Equipped with four wide-angle telescopes, TESS will occupy a unique orbit, dubbed P/2. Technically, this is a “2:1 lunar resonant orbit“, which will allow the craft to remain balanced within the gravitational effects of the Moon and Earth, thus providing a stable orbital regime which should last for decades. In addition, the orbit means that TESS will be able to survey both the northern and southern hemispheres.

Like Kepler, TESS will use the transit method, searching for exoplanets by watching hundreds of thousands of stars for the tell-tale dimming. This will be done by dividing the space around us into 26 individual “tiles”. The four imaging systems on the craft will then repeatedly observe a “strip” of four tiles at a time for a minimum of 27 days each (and part of some for up to a years at a time) before moving to the next strip, working its way around the sky before starting the next sweep of observations. In this way, it is estimated TESS will be able to survey up to 200,000 stars in both the northern and southern hemispheres over multiple years.

TESS will initially work alongside Kepler, and then with the James Web Space Telescope (JWST), due to be launched in October 2018. The JWST is the spiritual successor to Kepler, and as a part of its many operations, it will be able to keep a segment of the northern ecliptic pole under continuous observation, just as Kepler has been continuous observing one segment of space in the direction of the constellation of Cygnus.

So, Where Exactly IS E.T?

With all these planets being discovered in what is, relatively speaking, our cosmic backyard, where might extraterrestrials be hiding? Are they indeed “out there”? If so, why haven’t we managed to find any evidence that they might be there?

There are, of course, many reasons why life – if it is indeed elsewhere in the cosmos – remains undetected. If nothing else, the huge distances involved make even communications with, much less detection of, other civilisations pretty much impossible, even assuming we know what to listen and look for. Not that we haven’t tried – and continue to try.

Writing in the Journal of Cosmology and Astroparticle Physics, a team of researchers led by Avi Loeb of the Harvard-Smithsonian Centre for Astrophysics, suggest another reason: life here on Earth has simply arisen too soon, cosmically speaking.

Loeb and his colleagues postulate that really, the universe, which is expected to last around 10 trillion years, is – at 13.8 billion years of age – still in its infancy. As such, and despite the fact that the elements we regard as being essential to life have been available ever since the first stars started dying, around 30 million years after the big bang, it’s still far too early for life to have really got a foothold in the cosmos.

In particular, the study points to so-called “low mass” stars – those less massive than our own – which have lifespans not in the billions of years, as with our own Sun (which has around 5 to 5.5 billion years left), but in the trillions of years. Such stars really still in their infancy and are still in hazardous phase of their lifecycles, making it highly unlikely that life will have arisen on any rocky planets orbiting them.

However, as they age, these stars will likely calm down, and they’ll do so billions of years from now, at a time when the elements needed for life are liable to be far more abundant throughout the cosmos, simply due to the deaths of older generations of stars. Thus, the potential for them, and the conditions by which life might arise on any planets orbiting them, have yet to become possible.

There are arguments against this, however. We know, for example, that low mass stars can also be extremely violent, emitting solar flares and ultraviolet radiation quite capable of ripping any a planet’s atmosphere long it ever reaches a time where it might harbour life. But the idea that we have yet to detect life elsewhere might be down to our own life being somewhat premature in cosmic terms, is an intriguing one.

To better determine how likely it might be, Loeb and his colleagues recommend studying nearby red dwarf stars and their planets for signs of habitability using missions such as TESS and James Webb Space Telescope.