Category: Space Sunday

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

Posted on by Inara Pey

CuriosityAugust 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.

August 2nd, 2016 (Sol 1,418)T: the Navigation Camera (Navcam) on Curiosity's mast images the rover's extended robot arm over a section of the "Marimba" target rock, ready to use the wire brush mounted on the "hand" at the end of the arm in order to scour surface material which otherwise might contaminate and samples gathered from the rock, prior to the rover taking a drilling sample. Credit: NASA/JPL / MSSS
August 2nd, 2016 (Sol 1,418)T: the Navigation Camera (Navcam) on Curiosity’s mast images the rover’s extended robot arm over a section of the “Marimba” target rock, ready to use the wire brush mounted on the “hand” at the end of the arm in order to scour surface material which otherwise might contaminate and samples gathered from the rock, prior to the rover taking a drilling sample. Credit: NASA/JPL / MSSS

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.

Yutu as imaged from the Chang'e 3 lander (part of the solar pnael from which can be seen in the lower right corner). Credit: National Astronomical Observatories of China
Yutu as imaged from the Chang’e 3 lander (part of the solar panel from which can be seen in the lower right corner). Credit: National Astronomical Observatories of China

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.

Continue reading “Space Sunday: of Martian and lunar robots, distant worlds and ET” →

Space Sunday: rockets, red spots, fireballs and spaceplanes

Posted on by Inara Pey
SpaceX's plan to start down the road to their first human mission to Mars with their 2018 automated mission to the Red Planet -which NASA suggest will cost the company around US $320 million
SpaceX’s plan to start down the road to their first human mission to Mars with their 2018 automated mission to the Red Planet – which NASA suggests will cost the company around US $320 million

NASA has indicated that the SpaceX Red Dragon mission to Mars, which the company plans to carry out in 2018, will likely cost around US $320 million for SpaceX to mount, ad NASA itself will spend around US $32 million over four years in indirect support of the mission.

The Red Dragon mission, first announced in April 2016, will be financed entirely by SpaceX; NASA’s costs will be related to providing technical and logistical support – such as using its Deep Space Tracking Network for communications with the vehicle.

If all goes according to plan, the Red Dragon mission could be launched as early as May 2018. It is the crucial first step along the road towards the company’s ambitions to land a human crew on Mars by the end of the 2020s. If successful, it could potentially be followed by at least three further uncrewed Red Dragon flights in 2020/22, prior to the company commencing work on building-up matériel on Mars in preparation for a crewed mission.

A SpaceX / NASA infographic outlining the 2018 mission
A SpaceX / NASA infographic outlining the 2018 mission. Credit: NASA / SpaceX

Red Dragon is the name of an uncrewed variant of the SpaceX Dragon 2 vehicle, which will enter service in 2018 ferrying astronauts to / from the International Space Station. Intrinsic to the mission is the plan to conduct a propulsive landing on Mars using the craft’s SuperDraco Descent Landing capability. This is vital on two counts.

For SpaceX, a crewed variant of the Red Dragon will likely be the Mars descent / ascent vehicle during a human mission to the planet. So understanding how it operates in the Martian atmosphere is a vital part of preparing to land a crew on the planet. NASA is similarly interested in learning how well retropropulsion works in slowing a vehicle to subsonic speeds in the Martian atmosphere, as it now looks likely they will use the same approach for their human missions to Mars, which may occur in the 2030s. Gaining the data from the SpaceX missions means that NASA doesn’t have to fly its own proof-of-concept missions all the way to Mars.

A Dragon 2 text article test-fires its eight SuperDraco engines during a hover test in 2014

Whether or not Red Dragon will fly in 2018 is still a matter of debate. SpaceX has some significant commitments and obligations on which to focus: commercial Falcon launches, resupply missions to the ISS, the start of crewed flights to the ISS, introducing the Falcon 9 into its flight operations, etc. These all tend to suggest that the development of the Red Dragon capsule, which will require some significant modifications when compared to the Dragon 2, will be subject to the company’s existing commitments taking priority over it.

In the meantime, the company plans to release more information on the overall Mars strategy, up to and including their human mission, in September.

Jupiter’s Great Red Spot: Atmospheric Heating for a Giant

As the Juno space vehicle reached the farthest point from Jupiter in its first orbit around the gas giant and begins a 23-day “fall” back towards the planet, scientists on Earth may have unlocked the secret of why Jupiter’s upper atmosphere is so warm.

The Eye of Jupiter: a CGI recreation of the Great Red Spot based on observations from the Voyager spacecraft and Hubble Space Telescope, and as used in the television series Cosmos: A Spacetime Odyssey. Credit: 21st Century Fox.
The Eye of Jupiter: a CGI recreation of the Great Red Spot based on observations from the Voyager spacecraft and Hubble Space Telescope, and as used in the television series Cosmos: A Spacetime Odyssey. Credit: 21st Century Fox.

Here on Earth, the atmosphere is heated by the Sun. However, despite being five times further from the Sun than Earth, the upper reaches of the Jovian atmosphere share similar average temperatures to our own when they should in fact be a lot colder. Many theories have been put forward as to why this is the case, but now a team from Boston University, Massachusetts,  believe they’ve found the answer: the heating of Jupiter’s upper atmosphere is the combined result of the Great Red Spot (GRS) and Jupiter’s aurorae.

The Great Red Spot is one of the marvels of our solar system. Discovered within years of Galileo’s introduction of telescopic astronomy in the 17th Century, it is a swirling pattern of red-coloured gases thought to be a hurricane-like storm raging down through the centuries in the Jovian atmosphere. Roughly 3 Earth diameters across, its winds take six days to complete one spin around its centre, driven in part by Jupiter’s own high-speed spinning about its own axis, completing one revolution every ten hours.

Continue reading “Space Sunday: rockets, red spots, fireballs and spaceplanes” →

Space Sunday: looking back, looking forward, looking inside

Posted on by Inara Pey
A composite image: The Apollo 11 Saturn V on LC 39A during a countdown demonstration test on July 11th, 1969, and the Apollo 11 crew (l to r): Commander Neil Armstrong; CSM Pilot Michael Collins and LEM Pilot Edwin "Buzz" Aldrin
A composite image: The Apollo 11 Saturn V on LC 39A during a countdown demonstration test on July 11th, 1969, and the Apollo 11 crew (l to r): Commander Neil Armstrong; CSM Pilot Michael Collins and LEM Pilot Edwin “Buzz” Aldrin. Credit: NASA (both)

July 20th marked two anniversaries, the first manned landing on the Moon (July 20th, 1969) by Apollo 11, and the first American automated soft-landing on Mars with Viking Lander 1 (July 20th, 1976). As such, I’m starting this Space Sunday with a short look at both events.

Apollo Lunar Module (LEM) Eagle arrived on the surface of the Moon at 20:18:04 UTC on July 20th, 1969 after being launched atop a Saturn V rocket along with Neil Armstrong, Michael Collins and Edwin “Buzz” Aldrin from the Kennedy Space Centre Launch Complex 39A at 13:32:00 UTC on July 16th, 1969. It was the culmination of John F. Kennedy’s vision to re-assert America’s industrial and technological leadership in the world.

This composite of images from NASA's Lunar Reconnaissance Orbiter (LRO) mission from 2014 highlight elements of the Apollo 11 landing site on the Moon - notably the lower section of the LEM and some of the science equipment
This composite of images from NASA’s Lunar Reconnaissance Orbiter (LRO) mission, released in 2014 highlight elements of the Apollo 11 landing site on the Moon – notably the descent section of the LEM and some of the science equipment – watch the video

The land was dramatic in every sense of the word. On separation from the Command Module, the LEM immediately experienced issues communicating directly with Earth, then there were the infamous 1202 master alarm which triggered the LEM’s landing computer to re-boot itself, followed by a 1201 alarm. Then there was the discovery that, fair from being smooth and flat, the main landing site was boulder strewn, forcing Armstrong to fly the LEM to the limits of its available descent fuel in order to find a suitable landing area.

Armstrong finally set foot on the Moon on July 21st at 02:56:15 UTC, after he and Aldrin (the LEM Pilot)  had been given the opportunity to rest. Aldrin followed Armstrong down the ladder 20 minutes later, and together they spent about 2.5 hours on the surface, collecting 21.5 kg (47.5 lbs) of lunar material for return to Earth. Their total time on the Moon was short – just under 22 hours – but Aldrin and Armstrong between them, seen in fuzzy black-and-white television footage and (later) crisp photos, forever changed humanity’s perception of the Moon and its place in the cosmos.

To Mark the 47th anniversary of the landing, which also saw Collins remain in orbit piloting the Command and Service Module (CSM), The National Air and Space Museum in Washington, DC has produced a 3D tour (with other goodies) of the Apollo Command Module Columbia, as seen from the pilot’s (Collin’s) seat. This can be run in most browsers and offers a first-hand tour of the vehicle.

For those who prefer a visual record, NASA issued a restored film of the entire Apollo 11 EVA on YouTube in 2014. Or you can re-live the entire mission in just 100 seconds, courtesy of Spacecraft Films, which I’ve embedded below.

Apollo 11 was the first of six missions to the Moon (Apollo 13 being famously aborted after a critical failure within the Service Module whilst en route to the Moon), which concluded on December 19th, 1972, when Apollo 17 splashed down in the South Pacific Ocean, the only Apollo mission to fly a fully qualified geologist to the Moon (Harrison Schmitt).

In the 44 years since the end of the Apollo lunar project, human spaceflight has been confined to low-Earth orbit and will not move beyond it until the 2020s (with the uncrewed Exploration Mission 1 serving as the preliminary flight for that move in 2018). As such, it is all too easy to dwell on the political motivations which led to the programme, rather than on the phenomenal achievement Apollo actually was. Today’s plans for moving beyond LEO once more, and for sending Humans to Mars, may seem long overdue but they nevertheless build on the foundations laid down by Apollo.

The first "clean" image of the surface of Mars returned by Viking 1 on July 20th, 1976
The first “clean” image of the surface of Mars returned by Viking 1 on July 20th, 1976. Credit: NASA / public domain

Viking Lander 1 arrived on the surface of Mars seven years to the date after Apollo 11 arrived on the Moon – although that hadn’t been the original intent. 1976 saw the United States celebrating its bicentennial, and it had originally been intended that the Lander would touch-down on the Red Planet on July 4th of that year.

However, after arriving in orbit on June 19th, 1976, the Viking orbiter craft used its imagining systems to survey the proposed landing site, which had been “scouted” from orbit  by the Mariner 9 mission  – the first vehicle to orbit Mars – in 1971 / 72. Unfortunately, the Viking orbiter’s much more capable cameras revealed the primary landing site to be far rougher than had been believed, leading to a decision not to land there, but to survey the back-up sites prior to committing to a landing on July 20th, and thus to instead celebrate Apollo 11’s triumph instead of America’s Independence Day.

Given the state of play of planetary exploration at the time, Viking was a massively impressive mission: two orbiter vehicles launched back-to-back, carrying two lander vehicles in turn carrying an impressive set of 5 experiments intended to seek signs of life on Mars. At the time, no-one actually knew the density of the Martian upper atmosphere or the load-bearing strength of the Martian surface or what they might actually find on the surface. There were genuine fears that the latter might be all dust, and the lander could simply dig itself a hole when firing its retro-rockets at the final point of landing and then fall into it, or if it did arrive safely, whether it might sink into the Martian dust; hence why the first image to be returned by the lander following touchdown prominently featured one of its own landing pads (above).

Continue reading “Space Sunday: looking back, looking forward, looking inside” →

Space Sunday: celestial harmonics, breathing air and singing for Pluto

Posted on by Inara Pey
July 14th: Jupiter with Io, Europa and Ganymede as seen by Juno after the craft had finished its critical orbital burn to slip into a 53.5 day orbit around the giant planet
July 10th: Jupiter with Io, Europa and Ganymede as seen by Juno after the craft had finished its critical orbital burn to slip into a 53.5 day orbit around the giant planet on July 4th. Credit: NASA/JPL / SwRI / MSSS (click and image for full size)

The banner image, captured by NASA’s Juno spacecraft, might look like the one I used in my last Space Sunday update, but there is one important difference. The images used last time around had been captured by Juno on June as it approached the Jovian system on June 29th, five days before the craft had to complete a critical engine burn whilst almost scraping the planet’s cloud tops, to place itself in an extended orbit around Jupiter. The image above was captured on July 10th, as Juno headed away from Jupiter, having successfully completed the manoeuvre.

At the time the picture was captured, 17:30 UTC on July 10th, 2016, Juno was already  4.3 million kilometres (2.7 million miles) distant from the planet, and heading away from it at a relative velocity of 18,420 km / hour (11,446 mph) and decelerating under the influence of the Jupiter’s gravity.

Juno's flight around the poles of Jupiter and it's position on July 10th, as seen by the NASA Eyes application
Juno’s flight around the poles of Jupiter and it’s position on July 10th, as seen using the NASA Eyes simulator (click for full size)

Juno’s imaging system – JunoCam – had, along with other major systems aboard the craft, been shut down prior to the July 4th engine burn, both to conserve power – Juno had to turn its solar panels away from the Sun during the burn manoeuvre, limiting the available electrical power – and to protect them through the initial passage through Jupiter’s tremendous radiation fields. It wasn’t until July 6th that the instruments were all powered back up, and after testing them, the July 10th exercise was the first opportunity to have a look back at the Jovian system.

Juno will keep travelling outwards from Jupiter until the end of July, slowing to a relative velocity of just 1,939 km/h (1212 mph), before it starts to “fall” back towards the planet, making a second close flyby on August 27th. At this time, the craft will pass just 4,142 km (2,575 mi) above the Jovian cloud tops at a speed of 208,11 km/h (129,315 mph). More importantly, all of vehicle’s science instruments will remain powered-up, and JunoCam in particular should gain some stunning images of Jupiter during this second close pass.

To celebrate Juno’s arrival around Jupiter, NASA released a time-lapse video of the Jovian system as seen by the approaching spacecraft. It begins on June 12th with Juno 16 million km (10 million mi), and ends on June 29th, when JunoCam was shut down and Juno was 4.8 million km (3 million mi) distant.

Made possible by Juno’s high angle of approach into the Jovian system, it is the first close-up view of celestial harmonic motion we’ve ever had. Also, the 17-day duration of the movie means we see Callisto (flickering very faintly) make a full orbit around Jupiter, and get to see Ganymede, Europa and Io (counting inwards towards the planet) each experience eclipse as they pass through Jupiter’s shadow. Note that the flickering exhibited by the moons is an artefact of JunoCam, which is optimised to image bright features on Jupiter, rather than capturing the (relatively) dim pinpoints of the distant moons as they circle the planet.

Curiosity Resumes Operations as 2020 “Sister” Takes Shape

In my last update I reported that NASA Mars Science Laboratory, Curiosity, had entered a “safe” mode on July 2nd.  On July 9th, the mission team successfully recovered the rover from this safe mode – a precautionary state the rover will set for itself should it detected an event which could damage its on-board systems – and then subsequently returned Curiosity to a fully operational status on July 11th.

The cause of the problem lay in  a glitch in one of the modes by which images are transferred from the memory in some of the rover’s camera systems to its main computers. This generated a data mismatch warning, prompting the rover to active its “safe” mode and call Earth for assistance. Use of this particular data transfer mode between the identified camera systems and the computers is now being avoided in order to prevent a repeat of the problem.

Meanwhile, NASA’s next rover mission – designated Mars 2020 at present, as it will launch in the summer of that year to arrive on Mars in February 2021 – is taking shape. The basic vehicle will be based on the Curiosity class of rover, but will carry a different science suite and have somewhat different capabilities.

A CAD image of the Mars 2020 rover: visibly similar to MSL's Curiosity rover. Credit: NASA
A CAD image of the Mars 2020 rover: visibly similar to MSL’s Curiosity rover. Credit: NASA

In particular, the new rover will carry an entirely new subsystem to collect and prepare Martian rocks and soil samples which can be stored in sample tubes. About 30 of these sample tubes will be deposited at select locations, so that they might be collected by a possible future automated mission and returned to Earth for direct analysis for evidence of past life on Mars and possible health hazards for future human missions.

Two science instruments mounted on the rover’s robotic arm will be used to search for signs of past life and determine where to collect samples by analysing the chemical, mineral, physical and organic characteristics of Martian rocks, while a suite of advanced camera systems will be housed on the vehicle’s mast. As with Curiosity, Mars 2020 will carry a comprehensive meteorological suite for monitoring the Martian environment and weather, together with a ground penetrating radar system for determining what is going on under the rover’s wheels.

Continue reading “Space Sunday: celestial harmonics, breathing air and singing for Pluto” →

Space Sunday: of Jupiter, Titan and Mars

Posted on by Inara Pey

“NASA did it again!” an elated Scott Bolton, Principal Investigator for the Juno mission to Jupiter, announced on the night of Monday July 4th / Tuesday July 5th. He was speaking shortly after the Juno space craft, having travelled 2.8 billion kilometres (1.7 billion miles), achieved an initial orbit around the largest planet in the solar system, becoming one of the fastest human made objects ever built.

“We are in orbit and now the fun begins, the science,” he added during the post-insertion press briefing. “We just did the hardest thing NASA’s ever done! That’s my claim. I am so happy … and proud of this team.”

Solar powered Juno successfully entered a polar elliptical orbit around Jupiter after completing a must-do 35-minute-long firing of the main engine known as Jupiter Orbital Insertion or JOI. The vehicle approached Jupiter over the planet’s north pole – an orbit which will afford some unique views of Jupiter and its system of rings and moons in the coming months.

Due to the time delay, some 48 minutes for a one-way signal, Juno completed the insertion burn entirely on autopilot and, for this initial pass through the planet’s radiation belts, with many of its more critical systems powered-down as a precaution and to preserve battery power – the manoeuvre meant Juno had to turn its solar panels away from the Sun, limiting its ability to generate electrical power for all of its systems.

This image was captured by Juno on June 29th, 2016, and was the final picture taken by the vehicle's camera prior to major systems being shut down as a precautionary move while the craft made an it's initial approach over Jupiter's north pole. Visible and labelled are the Galilean moons, which today form just 4 of the 53 named moons orbiting the planet
This image was captured by Juno on June 29th, 2016, and was the final picture taken by the vehicle’s camera prior to major systems being shut down as a precautionary move while the craft made an its initial approach over Jupiter’s north pole. Visible and labelled are the Galilean moons, which today form just 4 of the 53 named moons orbiting the planet

As I reported last week, the do-or-die burn of the Leros-1b engine had to be carried out flawlessly if the spacecraft were to achieve and initial orbit around Jupiter. By the time it started at 20:18 PDT on Monday July 4th (04:18 UT, Tuesday July 5th), Juno had already accelerated to an incredible 250,000 kph (156,000 mph) relative to the planet, as a result of Jupiter’s massive gravity well, and the 35-minute engine burn was designed to reduce this huge speed by just 1,939 kph (1212 mph).

As tiny as this velocity change might sound, it meant the difference between Juno simply whipping around Jupiter to be thrown back out into deep space and being trapped in a 53.5 day orbit are the planet by that same enormous gravity well. In October 2016, a further 22-minute burn of the Leros-1b will reduce this orbital period to just 14 day, allowing the primary science mission to commence.

Scott Bolton (with arms raised) celebrates Juno's orbital insertion burn with members of the mission team (l to r) Goeff Yoder, Diane Brown, Rick Nybakken, Guy Beutelschies, and Steve Levin Credit: AP Photo / Ringo H.W. Chiu
Scott Bolton (with arms raised) celebrates Juno’s orbital insertion burn flanked by members of the mission team (l to r) Goeff Yoder, Diane Brown, Rick Nybakken, Guy Beutelschies, and Steve Levin Credit: AP Photo / Ringo H.W. Chiu

That mission is all about peering far beneath Jupiter’s banded clouds for the first time and investigating the planet’s deep interior with a suite of nine instruments. The hope is that Juno will probe the mysteries of Jupiter’s genesis and evolution, and by extension, how we came to be. Or, as Scott Bolton phrased it, “The deep interior of Jupiter is nearly unknown. That’s what we are trying to learn about. The origin of us.”

Life on Titan Without Water?

Further out in space and orbiting Saturn, is massive Titan, another of the solar system’s enigmas. Examined by the NASA Cassini space vehicle and (briefly) by the European Space Agency’s Huygens lander, Titan is fascinating for a number of reasons, including the fact it is the only natural satellite known to have a dense atmosphere rich in minerals and hydrocarbons.

Huygens revealed Titan has a very mixed surface environment, complete with hydrocarbon seas, lakes and tributary networks filled with liquid ethane, methane and dissolved nitrogen. This surface is also very young; while Titan has been around since very early in the solar system’s history – some 4 billion years – the surface environment is estimated to be somewhere between 100 million to 1 billion years old; suggesting geological processes have been and are at work.

Titan's structure (via wikipedia)
Titan’s structure, which includes a subsurface liquid water ocean sealed beneath a mantle of ice just below the moon’s thin trust (via wikipedia)

All of this   – particularly the thick atmosphere (which has a comparable density to that of Earth), the presence of hydrocarbon rich liquids (which also fall as rain) – has caused many astronomers and planetary scientists to speculate that Titan might have all the prebiotic conditions necessary to kick-start life. The only thing which has been seen as potentially mitigating this is the absence of surface water.

However, a team of scientists from Cornell University, New York, led by Dr. Martin Rahm, has proposed that condition on Titan are such that it might support life even without the presence of water.

An image of Titan's surface, as taken by the European Space Agency's Huygens probe as it plunged through the moon's thick, orange-brown atmosphere on Jan. 14, 2005. Credit: ESA / NASA / JPL / Univ. of Arizona
An image of Titan’s surface, as taken by the European Space Agency’s Huygens probe as it plunged through the moon’s thick, orange-brown atmosphere on Jan. 14, 2005. Credit: ESA / NASA / JPL / Univ. of Arizona

Specifically, the team has been examining the role that hydrogen cyanide (HCN) might have on Titan. This is an organic chemical, which although poisonous to life today, is seen in some circles as a precursor to amino acids and nucleic acids, and thus a basic building block in the development of organic compounds which in turn might give rise to life.

In particular, hydrogen cyanide is the most abundant hydrogen-containing molecule in Titan’s atmosphere – although it is missing from the moon’s surface – and has some unique properties. It can, for example, react with itself or with other molecules to form long chains, or polymers. One such polymer is called polyimine, which is capable of absorbing light of many wavelengths and might therefore as as a catalyst for photochemically driven chemistry, some of which might be prebiotic in nature and which might in turn give rise to more complex organic reactions.

Continue reading “Space Sunday: of Jupiter, Titan and Mars” →

Space Sunday: Jupiter and Juno

Posted on by Inara Pey

Update, July 5th: The insertion burn on July 4th/5th was successful, and Juno is safely in its initial orbit around Jupiter. I’ll have an update on the mission in the next Space Sunday.

rAt 20:18 PDT on Monday, July 4th (03:18 UT, Tuesday, July 5th) a spacecraft called Juno will fire its UK-built Leros-1b engine to commence a 35-minute burn designed to allow the spacecraft  enter an initial orbit around the largest planet in the solar system, ready to begin a comprehensive science campaign.

As I write this, the craft is already inside the orbit of Callisto, the furthest of Jupiter’s four massive Galilean satellites,  which orbits the planet at a distance of roughly 1.88 million kilometres. During the early hours of July 4th, (PDT), the vehicle will cross the orbits of the remaining three Galilean satellites, Ganyemede, Europa and Io, prior to commencing its orbital insertion burn.

In the run-up to the burn, Juno will complete a series of manoeuvres designed to correctly orient itself to fire the Leros-1b, which will be the third of four planned uses of the engine in order to get the craft into its final science orbit. Two previous burns of the engine – which NASA regards as one of the most reliable deep space probe motors they can obtain – in 2012 ensured the craft was on the correct trajectory from this phase of the mission.

Getting into orbit around Jupiter isn’t particularly easy. The planet has a huge gravity well – 2.5 times greater than Earth’s. This means that an approaching spacecraft is effectively running “downhill” as it approaches the planet, accelerating all the way. In Juno’s case, this means that as the vehicle passes north-to-south around Jupiter for the first time, it will reach a velocity of nigh-on 250,000 kph (156,000 mph), making it one of the fastest human-made objects ever.

An Artist's impression of Juno approaching the Jovian system. Credit: NASA
An Artist’s impression of Juno approaching the Jovian system. Credit: NASA

Slowing the vehicle directly into a science orbit from these kinds of velocities would take an inordinate amount of fuel, so the July 4th manoeuvre isn’t intended to do this. Instead, it is designed to hold the vehicle’s peak accelerate at a point where although it will be thrown around Jupiter and back into space, it will be going “uphill” against Jupiter’s gravity well, decelerating all the time. So much so, that at around 8 million kilometres (5 million miles) away from Jupiter, and travelling at just 1,933 kph (1,208 mph), Juno will start to “fall back” towards Jupiter, once more accelerating under gravity, to loop around the planet a second time on August 27th, coming to within (4,200 km (2,600 mi) of Jupiter’s cloud tops, before looping back out into space.

On October 19th, Juno will complete the second of these highly elliptical orbits, coming to within 4,185 km (2,620 mi) of the Jovian cloud tops as it completes a final 22-minute burn of the Leros-1b motor. This will be sufficient for Jupiter’s gravity to swing  Juno into an elliptical 14-orbit around the planet, passing just 4,185 km from Jupiter at its closest approach before flying out to 3.2 million kilometres (2 million miles) at it’s furthest from the planet.

Juno's journey to Jupiter, with a flyby-of Earth in 2013
Juno’s journey to Jupiter, with a flyby-of Earth in 2013

The July 4th insertion burn is also significant in that it marks the end of a 5-year interplanetary journey for Juno, which has seen the vehicle cover a distance of 2.8 billion km (1.74 billion miles).

It’s a voyage which began on August 5th, 2011, atop a United Launch Alliance (ULA) Atlas V, launched from Cape Canaveral Air Force Station, Florida.

As powerful as it is, the Atlas isn’t powerful enough to send a payload like Juno directly to Jupiter. Instead, the craft flew out beyond the orbit of Mars before dropping back to Earth, passing us again in October 2013 and using Earth’s gravity to both accelerate and to slingshot itself into a Jupiter transfer orbit.

While, at 35 minutes, the engine burn for orbital insertion is a long time, the distance from Juno to Earth means that confirmation that the burn has started will not be received until 13 minutes after the manoeuvre has actually completed. That’s how long is takes for a radio signal to travel from the vehicle back to Earth (and obviously, for instructions to be passed from Earth to Juno.  Thus, the manoeuvre is carried out entirely automatically by the vehicle

Juno is not the first mission to Jupiter, but it is only the second orbital mission to the giant of the solar system.

The Jovian system was first briefly visited by Pioneer 10 in 1973, followed by Pioneer 11 a year later. Both of these were deep space missions (which are still continuing today), destined to continue outward through the solar system and into interstellar space beyond. They were followed by the Voyager 1 and Voyager 2 missions in January and July 1979 respectively, again en route for interstellar space by way of the outer solar system.

In 1992 the Ulysses solar mission used Jupiter as a “slingshot” to curve itself up into a polar orbit around the Sun. Then in 2000, the Cassini mission used Jupiter’s immense gravity to accelerate and “bend” itself towards Saturn, its intended destination. New Horizons similarly used Jupiter for a “gravity assist” push in 2007, while en route to Pluto / Charon and the Kuiper Belt beyond.

It was in 1995 that the first orbital mission reached Jupiter and its moons. The nuclear RTG-powered Galileo was intended to study Jupiter for just 24 months. However, it remained largely operational until late 2002 before the intense radiation fields around the planet took their final toll on the vehicle’s systems. Already blind, and with fuel supplies dwindling, Galileo was ordered to crash into the upper limits of Jupiter’s atmosphere in 2003, where it burned up.

In the eight years it operated around Jupiter, Galileo complete changed our perspective on the planet. Juno has a 20-month primary mission, and it is hoped its impact on our understanding of Jupiter will be greater than Galileo’s. However, it is unlikely the mission will be extended.

Unlike all of NASA’s previous missions beyond the orbit of Mars, which have used RTG power units, Juno is entirely solar-powered, making it the farthest solar-powered trip in the history of space exploration. However, the three 8.9 metre (29 ft) long, 2.7 metre (8.9 ft) wide solar panels are particularly vulnerable to the ravages of radiation around Jupiter, and it is anticipated that by February 2018, their performance will have degraded to a point where they can no longer generate the levels of electrical energy required to keep the craft functioning – if indeed, its science instruments and electronics haven’t also been damaged beyond use by radiation. This being the case, Juno will be commanded to fly into Jupiter’s upper atmosphere and burn up.

Juno's science instruments - click for full size. Credit: NASA / JPL
Juno’s science instruments – click for full size. Credit: NASA / JPL

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