Tag: Spaceflight

July is a celebratory month for the US space programme. I’ve already written about July 4th marking the 20th anniversary of America – and the world – having had a continuous robotic presence on or around Mars for 20 years. This week, July 16th and July 20th mark the anniversaries of perhaps the two most momentous days in human space flight – the Lift-off of the Apollo 11 mission to land men on the lunar surface and, on July 20th, the actual landing of the Lunar Excursion Module Eagle on the Sea of Tranquillity. Neil A. Armstrong and Edwin “Buzz” Aldrin  spent 21.5 hours there, while their colleague Michael Collins (the “forgotten third man” of Apollo 11) orbited the Moon aboard the Command and Service Module Columbia, carrying out a range of science work as he awaited his compatriots’ ascent back to orbit.

The Apollo programme, although ultimately dedicated to meeting John F. Kennedy’s 1961 goal of “putting a man on the Moon and returning him safely to the Earth”, actually had its roots in President Dwight D. Eisenhower’s administration, when it was seen as a logical progression from America’s single-seat Mercury programme to a vehicle capable of carrying a crew of three on a range of mission types, including ferrying crews to a space station, performing circumlunar flights, and eventually forming part of manned lunar landings.

Apollo was a bold venture, particularly when you consider Kennedy’s directive that America commit itself to achieving a manned landing on the Moon before the end of the 1960s, given in a stirring address before Congress on May 25, 1961 came just twenty days after NASA had finally managed to pump a man  – Alan Shephard – into space on a sub-orbital flight, while their first orbital success with John Glenn was still nine months in the future. It was a programme which was politically motivated to be sure, but which nevertheless yielded scientific and technological results which helped shape both our understanding of the solar system and helped improve ours lives on many levels. It raised the potential of human space exploration high in the public consciousness, and was illuminated by tremendous successes whilst also and shadowed by moments of tragedy and near-tragedy.

As well as the missions themselves and the hardware required to carry them out – the Command and Service Module, the Lunar Excursion Module, the Saturn family of rockets (including the mighty Saturn V), Apollo perhaps did more than any over programme to shape NASA. It gave rise to the massive launch infrastructure at Merritt Island, Florida – now known as the Kennedy Space Centre – including the historic launch pads of Launch Complex 39, used by both Apollo and the shuttle, and now used by SpaceX and (soon) by NASA’s massive Space Launch System rockets; the Vehicle Assembly Building (then called the Vertical Assembly Building), where the Saturn rockets were assembled ready for launch, the still-used Launch Control Complex, and more. At the same time, Apollo gave NASA its operational heart for human space missions – the Manned Spaceflight Centre (now called the Johnston Spaceflight Centre) on land just outside Houston, Texas, donated to NASA by Rice University.

The entire history of the programme is a fascinating read – the politics, both in Washington (Kennedy’s own s science advisor, Jerome Wiesner, was quite vociferous in opposing the idea of sending men to the Moon) and in NASA (where a fierce difference of opinion was apparent in how the mission should be carried out. It’s a story I may some day plumb in a Space Sunday “special”, but for now I’ll simply say that all things considered, Apollo was a success, albeit one very self-contained. Six missions to the surface of the Moon, nine missions to and around the Moon, and the opportunity to increase our understanding of Earth’s natural satellite both by a human presence there and afterwards, thanks to the equipment left behind.

New Horizons Pluto Flyby

July 14th marked the second anniversary of the New Horizons spacecraft’s flyby of Pluto and Charon – a high-speed dash between the two lasting mere hours, after a nine-and-a-half year flight simply to reach them. Brief though the encounter might have been, the spacecraft returned such a wealth of data and images that our view of Pluto and its companion has been forever changed, with Pluto in particular – as I’ve often referenced in these Space Sunday pieces –  revealing itself to be an enigma wrapped in a puzzle, determined to shatter our understanding of small planetary bodies in the solar system.

Such is the wealth of data gathered by the probe, coupled with the distances involved and the rate at which it could transmit data back to Earth, it took 16 months of all of the information stored aboard New Horizons to be returned to scientists here on Earth.

To mark the second anniversary of New Horizons’ flyby, NASA released a new video using actual New Horizons data and digital elevation models of Pluto and Charon, to offer a unique flight across Pluto.

The movie starts over the highlands to the south-west of “Sputnik Planum’s” great nitrogen ice sheet (visible to the right as the movie progresses), with the track of the film passing directly over the chaotic cratered and mountain terrain of “Cthulhu Macula”. moving northwards, the flight passes over the fractured highlands of “Voyager Terra” then back southwards over Pioneer Terra, distinguished by pitting, before concluding over the bladed terrain of Tartarus Dorsa in the far east of the encounter hemisphere.

Continue reading “Space Sunday: anniversaries, storms and hidden worlds” →

Some call it Betelgeuse others call it Beetlejuice. It is the second brightest star in the constellation of Orion and officially designated Alpha Orionis, the ninth brightest star in the night skies over Earth.

A red super giant of spectral type M1-2, Betelgeuse is around 12 times the mass of our own Sun, and is one of the largest and most luminous stars visible to the naked eye. It is also destined to be – in cosmic terms –  very short-lived. At just eight million years of age, it is already approaching the end of its life and will likely go supernova some time in the next few thousand years.

But it is the star’s sheer size which makes it stunning: it’s an estimated 2.6 AU in diameter. To put this in perspective, were it to be dropped into our solar system to replace the Sun, it would extend out towards the orbit of Jupiter.  Such is its size, it is one of the few stars we can observe via telescope large enough to be resolved as anything more than a point of light.

This was brought home at the end of June 2017, when the Atacama Large Millimetre Array (ALMA) captured the star in a series of images taken at the sub-millimetre wavelength range. The images reveal the star’s chromosphere looking somewhat asymmetrical, the result of the star  generating a massive bow-shock as it moves through the interstellar medium. In short, as Betelgeuse travels through the gas clouds at a rate of around 30 kilometres per second, it own equivalent of the solar wind (much denser than anything the Sun generates) which is thrown off of the star at 17 kilometres / second, slams into this gas in the direction of travel at47 km/ sec, generating a massive shock wave about 3 light-years across in front of the star, which curls around it, influencing its chromosphere.

When Betelgeuse goes supernova, it will be in a blink of an eye – although we’ll only know about it 650 years after it has actually happened. When it does so, it will create an unmistakable light in the night sky – and this bow shock of matter will play a role in the supernova process, as it reacts to the sudden influx of matter slamming into it from the exploding star at a large fraction of the speed of light.

As violent as it will be, the Betelgeuse supernova will not threaten life on Earth, as it’s beyond the “harmful” range. And in case you think that’s a bit of a reach, scientists have shown that the Earth has in fact been influenced by supernovae in the past. This evidence comes from the presence of Iron 60 in the deep oceans, an isotope formed within stars, and which has an exceptionally short half-life: 2.6 million years – so the fact we can detect it suggests it originated in other stars that went supernova.

In fact, for the last 5-10 million years, the solar system has been travelling through a region of space called the “local bubble”, an expanding region of gases some 300 light years across, created by a series of supernova explosions which occurred over a relatively short period  of time about 20 million years ago. Within this bubble, the magnetic field is weak and disordered, which could greatly magnify the impact a large supernova occurring within 100 light years from Earth could have on life here.

At the upper end of this distance, research suggests a supernova could lead to climate changes similar to those which caused a rise in glaciation seen in the Pleistocene period, 2.5 million years ago. At the nearer end of this distance – say, 25-30 light years – a supernova could actually be an extinction level event for much of life here due to the radiation levels striking the Earth, altering the climate, impacting the Earth’s biomass, and giving raise to increases in cancers.

Fortunately, the nearest known star to us which is likely to go supernova is IK Pegasi B, a massive white dwarf star which forms part of the binary star system IK Pegasi in the constellation of Pegasus, and 150 light years away. As a massive white dwarf, IK Pegasi is no longer generating energy through nuclear fusion. However, when its companion star, IK Pegasi A, a main sequence star slightly larger than our own Sun and itself a variable star, reaches the latter stages of its life, it will swell up to a red giant, allowing IK Pegasi B to star accrete matter from it, causing it to swell to as much a 1.4 solar masses – at which point it will explode as a supernova.

China’s Launch Failures

China’s space efforts have been in the news for the wrong reasons of late. In mid-June a Long March 3B rocket – the workhorse of the Chinese fleet – designed to carry a communications satellite to geostationary transfer orbit was declared a “partial failure” when the rocket’s upper stage failed, initially leaving the satellite stranded in a much lower orbit. Since then, mission controller have been using satellite’s manoeuvring motors gradually nudge it up to an operational orbit, although this will drastically shorten its active lifespan.

Then, on July 2nd, 2017, the second launch of China’s powerful Long March 5, capable of launching 8.4 tonnes of payload to the Moon or placing 25 tonnes in low Earth orbit, suffered a major failure shortly after clearing the launch pad at 11:23 GMT. This booster is key to China’s longer-term ambitions in space, as it is crucial to the development of their own space station, as well as vital for a number of deep space missions.

Continue reading “Space Sunday: imaging a star and x-rays from a planet” →

NASA’s Mars Science Laboratory rover, Curiosity continues to climb Aeolis Mons (“Mount Sharp”), and in doing so, it has been once again imaged from orbit by the HiRISE camera system on NASA’s Mars Reconnaissance Orbiter (MRO). The image was captured on June 5th, 2017 (Curiosity’s 1717th Martian Sol), at the same time the rover was engaged in taking colour images of its surrounding using its mast-mounted Navcam system.

MRO has actually been imaging Curiosity roughly once every three months, as the orbiter’s track around Mars carries it over “Mount Sharp” and the rover’s route up the mound’s flank. However, these aren’t simply happy snaps of the rover’s progress: MRO is actively monitoring the terrain around the rover to allow scientists to check for changes – such as movement among sand dunes – and to help plan the rover’s route up the slopes.

The June 5th image, released by NASA on June 20th, has been colour enhanced to better reveal Curiosity as a bright blue feature. To give an idea of scale and resolution, the rover is some 3 metres (10ft) in length and 2.8 metres (9 ft) wide.

Curiosity is currently traversing ground between two points of scientific interest: the “Bagnold Dunes”, an area of sand dunes which are slowly progressing down the side of “Mount Sharp” as a result of both wind action and gravity; and a high-standing ridge which runs parallel to the eastward side of the dune field. Dubbed the “Vera Rubin Ridge” after the American astronomer who pioneered work on galaxy rotation rates, this ridge line is of interest to scientists because it has been shown to exhibit signatures of hematite, an oxidized iron mineral which can provide clues to the environmental conditions on this region of “Mount Sharp” when it formed.

The route to the ridge is slightly circuitous. At the moment the rover is heading east-north-east around a small set of dunes. Once clear of them it will turn south-east and drive to where a potential safe route up onto the ridge has been identified. The drive is further slowed as Curiosity periodically pauses to capture images of the feature to help scientists characterize any observed layers, fractures, or geologic contacts and better understand determine how the ridge formed, and its relationship to the other geologic units found within Gale Crater.

At the same time NASA released the image of Curiosity seen from orbit, half a world away, attempts to correct a wheel problem the solar-powered Opportunity Mars Exploration Rover (MER) had been experiencing appeared to end in partial success.

“Oppy” had suffered a failure with its left-front wheel steering actuator on June 4th, leaving the wheel angled and unable to straighten. After numerous attempts to correct the issue, a new approach tested on June 20th resulted in the wheel turning correctly and resuming its proper alignment with the other wheels. However, what originally caused the actuator to fail remains unknown, and there is concern that it might recur.

To limit the risk of this happening and possibly stranding “Oppy”, the rover will avoid all use of its front wheel steering, and will only use its rear wheel steering when absolutely necessary. To maintain manoeuvrability, it will instead rely on “tank steering” – effectively running the drive motors for the wheels on one side of the rover in opposition to those on the other, allowing Opportunity to turn left or right more-or-less on the spot, a technique the rover is designed to use. This should allow the rover to continue its current survey of “Perseverance Valley” in preparation for a descent into Endeavour Crater.

“Planet Nine” Set to Become “Planet Ten”?

I’ve written extensively in these pages about the hunt for “Planet Nine” (or “Planet X” or “George”, “Jehoshaphat” or “Planet of the Apes” as some would have it): the Neptune-sized world believed to be orbiting the sun at a distance of at least 200 astronomical units (AUs – one AU being the average distance of the Earth from the Sun) in a highly eccentric orbit.  The search for that world is still continuing, but if a new study is confirmed, that mystery world may well have to give up its “Planet Nine” title for another.

Kat Volk and Renu Malhotra of the University of Arizona’s Lunar and Planetary Laboratory, offer compelling evidence of a yet-to-be-discovered planetary body with a mass somewhere between that of Mars and Earth, orbiting the Sun much closer than the mysterious “Planet Nine”, at around 50 AU distance.

Whilst carrying out a detailed studying of Kuiper Belt Objects (KBOs) – the disk of rocky asteroids and comets surrounding the Sun from a distance of around 30 AU to about 50-60 AU, Volk and Malhotra discovered a consistent anomaly. Whilst most KBOs surround the sun with orbital inclinations that average out to what planetary scientists call the “invariable plane of the solar system”, they discovered that the more distance KBOs – those around 50 AU or over from the Sun are tilted away from the invariable plane by about eight degrees.

The pair surveyed around 600 of the 2,000 observed KBOs, and found all of those on the outer reaches of the Kuiper Belt to be inclined from the invariable plane by roughly the same amount and in numbers that tend to preclude a statistical fluke. In modelling possible causes for this, they discovered that an object with a mass of Mars, orbiting about 50-60 AU would cause just such a disruption, as would a Earth-sized body slightly further away.

However, Volk and Malhotra carefully avoid any suggestion there is a Mars- or Earth-sized body is awaiting discovery, noting that the disruption might also be the result of several large (but not planet-sized) masses lying within the outer fringes of the Kuiper belt. Even so, a single body would seem more likely, and given it is effectively sitting within the galactic plane – an area so densely packed with stars that solar system surveys tend to avoid it – could explain why it has been able to remain undetected.

But it might not remain hidden for much longer. 2020 should see the Large Synoptic Survey Telescope (LSST) come on-line. This 8.4 metre (27.6 ft) primary mirror telescope is due to commence a 10-year sky survey in 2022. Among other things, it is expected to increase the number of KBOs so far observed from 2000 – to over 40,000 as it carries out real-time surveys of the sky, night after night. In doing so, it could well find any planet-sized body lurking near them.

Continue reading “Space Sunday: other worlds, near and far” →

Jupiter is the most massive planet of the solar system and its presence had an immense effect on the dynamics of the solar accretion disk (the disk of dust and stellar material which surrounded and formed the Sun). Knowing the age of Jupiter is key for understanding how the solar system evolved toward its present-day architecture. Although models predict that Jupiter formed relatively early in the solar system’s history, until now, its formation has never been dated. Now, an international study suggests it was the very first planet to form.

The team, comprising scientists from the US Lawrence Livermore National Laboratory and Germany’s Institut für Planetologie at the University of Münster, believe that Jupiter’s core started forming within the first million years of the solar system’s existence. By looking at tungsten and molybdenum isotopes on iron meteorites, the team found that meteorites are made up from two genetically distinct nebular reservoirs that coexisted but remained separated between 1 million and 3-4 million years after the solar system formed.

“The most plausible mechanism for this efficient separation is the formation of Jupiter, opening a gap in the accretion disk, preventing the exchange of material between the two reservoirs,” said Thomas Kruijer, lead author of team’s paper, published in the June 12th Proceedings of the National Academy of Sciences.

“We do not have any samples from Jupiter (in contrast to other bodies like the Earth, Mars, the moon and asteroids),” he continued, when discussing the paper. “In our study, we use isotope signatures of meteorites (which are derived from asteroids) to infer Jupiter’s age. Jupiter is the oldest planet of the solar system, and its solid core formed well before the solar nebula gas dissipated, consistent with the core accretion model for giant planet formation.”

The team showed through isotope analyses of meteorites that Jupiter’s solid core formed within only about 1 million years after the start of the solar system history, rapidly growing to a mass of around 20 times that of Earth, then expanding more gradually to around 50 Earth masses over the next 2-3 million years. This rapid formation meant Jupiter acted as a barrier against inward transport of material from the outer reservoir of nebula material to the inner one, potentially explaining why our solar system lacks any super-Earths (a solid planet with a mass and size greater than Earth’s) orbiting the sun – Jupiter effectively vacuumed up the material.

The common belief among planetary scientists has leaned towards the gas giants of the outer solar system having formed relatively early in the solar system’s history, before the complete dissipation of the solar nebula—the gaseous circumstellar disk surrounding the young Sun – which occurred around 10 million years after the solar system formed. These finding fully support that belief, but has been able to far more precisely pin-down Jupiter’s birth date.

“Our measurements show that the growth of Jupiter can be dated using the distinct genetic heritage and formation times of meteorites,” Kruijer said.

Chinese Resupply Vehicle Competes 2nd Lab Refuelling

China’s automated Tianzhou-1 re-supply vehicle has carried out a successful second rendezvous with the currently uncrewed  Tiangong-2 space laboratory, and completed out a further refuelling operation of the orbital facility.

Launched in April 2017, Tianzhou-1 (“Heavenly Ship 1”) is the first of a series of resupply vehicles based on China’s first orbital module, Tiangong-1, designed to deliver up to 6.5 tonnes of equipment, supplies and fuel to orbital facilities – most notably China’s space station, construction of which is due to commence in 2018.

Tianzhou-1 is currently on an extended mission with the Tiangong-2 (“Heavenly Palace 2”) orbital facility, during which automated dockings at each of the laboratory’s two airlock systems are being practised, as is the transfer of fuel to the laboratory. The latter is a complicated, 29-step process, but one vital to the success of an orbital facility, where fuel is used in very small motor systems to help it maintain the correct orientation whilst in orbit and – potentially – help periodically boost the facility orbit to counter the microscopic (but cumulative) effect of atmospheric drag encountered whilst orbiting the Earth.

However, as such “boosts” to a space station’s orbit are more normally provided by an attached vehicle (the space shuttle used to do it for the International Space Station, for example, and the role has been taken over by the resupply craft which periodically visit the ISS). To this end, part of the Tianzhou-1 mission has also been to practice manoeuvring both the vehicle and  Tiangong-2 when the two have been docked. In addition, Tianzhou-1 has been carrying out its own free flight mission when not docked with the laboratory.

Like the European Automated Transfer Vehicle (ATV), Japanese H-II Transfer Vehicle (HTV) and American Cygnus resupply craft used in support of ISS operations, Tianzhou-1 is not designed to return to Earth. Instead, the vehicle will be allowed to burn-up as it re-enters the denser part of the Earth’s atmosphere at the end of its mission.

Following the Tianzhou-1 mission, a further crew of Chinese tiakonauts is expected to visit Tiangong-2 laboratory.

Kepler’s Latest Findings

NASA will announce the latest crop of planet discoveries from the Kepler Space Telescope on Monday, June 19th.

Kepler has been hunting for extrasolar planets since its launch in 2009, although the programme was almost cut short in 2013, following the failure of two of the reaction wheels (essentially gyroscope systems) used to stabilise the platform and allow it to gather data.

However, in November 2013, a new mission for the platform, dubbed “Second Light” and more generally referred to as the K2 mission,  was proposed and, after a successful period of test in early 2014, officially got under way on May 26th, 2014.

Most recently, Kepler has been using gravitational microlensing in an attempt to locate planets  orbiting stars so far away, the dimming of the star’s light by a transiting planet cannot easily be detected.

Kepler was the first mission capable of seeing planets the size of Earth around other stars in the “habitable zone” — the region at a distance from a star where liquid water could exist without freezing or boiling away immediately.

Thus far Kepler has found 4,496 exoplanet candidates. Some 2,335 have been confirmed and 21 are Earth-size planets in the habitable zone. Further, 520 of these exoplanet candidates have been found during the K2 mission, with 148 confirmed as having planets.

Continue reading “Space Sunday: Jupiter, exoplanets, Opportunity, and Wow! again” →

In his general theory of relativity, Albert Einstein predicted that whenever light from a distant star passes by a closer object, gravity acts as a kind of magnifying lens, brightening and bending the distant starlight in an effect known as “gravitational microlensing”.  While such microlensing has been observed using the Sun, it has never been used against an individual star (although it has been used binary pairs of stars) – until now.

During a two-year period between October 2013 and October 2015, astronomers used the Hubble Space Telescope (HST) did just that, allowing them to measure the mass of a star in the process.

The star in question is a white dwarf called Stein 2051 B, roughly 18 light years from Earth and part of a binary system, paired with a red dwarf. Essentially, the team of astronomers used Hubble to observe the effect the white dwarf had on the light being received from a star 5,000 light years away. By measuring the amount of apparent light deflection, the team were not only able to further confirm Einstein’s theory of relativity – they were able to measure the mass of the white dwarf itself, even though the deflection was tiny – only 2 milliarcseconds from its actual position.

“This microlensing method is a very independent and direct way to determine the mass of a star,” Kailash Sahu, the lead researcher on the project, explained following the publication of his team’s findings on June 7th, 2017. “It’s like placing the star on a scale: the deflection is analogous to the movement of the needle on the scale.”

On top of this, the observations confirmed the theory that a white dwarf star’s size is determined by its mass, first postulated in 1935 by Subrahmanyan Chandrasekhar, the Indian-American astronomer. Thus, a single set of observations have further confirmed Einstein’s theory of space-time to be correct (and sits alongside the detection of gravitational waves – see my last Space Sunday update – and observations of rapidly spinning pulsars in doing so), and confirmed the defining limits for a white dwarf star and allowed astronomers effectively measure the mass of a star.

Space Plane News

The United States Air Force has confirmed that the next mission for its X37B automated space plane will utilise a SpaceX Falcon 9 launch vehicle to boost it into orbit in August 2017.  This will be the fifth launch of the X-37B, which is also known as the Orbital Test Vehicle, and the first time a United Launch Alliance Atlas V booster hasn’t been used. It also marks the highest-profile US national security launch SpaceX will have signed-up for.

There are actually two of the uncrewed X-37B vehicles operated by the USAF which have been flown on alternate missions. The second of these two craft returned to Earth in May 2017 after spending an astonishing 718 days in orbit, carrying a mixed classified and non-classified cargo. The August mission will likely use the first of the two vehicles in its third mission, and will feature the Air Force Research Laboratory (AFRL) Advanced Structurally Embedded Thermal Spreader (ASETS-11) to test experimental electronics and oscillating heat pipes in the long duration space environment.

At the same time as the USAF announcement about the X-37B, the South China Morning Post reported China’s own space plane programme is making “significant progress”.

China has been investigating the potential of operating some form of space plane since the late 1980s. Those plans ultimately didn’t go anywhere, and rumours of a new Chinese space plane, capable of flying astronauts and / or cargo to low Earth orbit started circulating in 2016, thanks to a news broadcast on Chinese state television service CCTV. However, as the report used imagery clearly taken from the UK’s Skylon programme, there was some doubt as to the veracity of the report.

 

Like Skylon, the new Chinese vehicle, which the South China Morning Post refers to as athe Casic (the initials of the China Aerospace Science and Industry Corporation, said to be building the vehicle), will be able to take-off horizontally and use a hybrid propulsion system capable of flying it through the atmosphere and into space, carrying a crew and / or cargo to low Earth orbit. At the end of a mission, the vehicle will return to Earth and land on a conventional runway, where it can be re-serviced pretty much like a conventional military aircraft.

The South China Morning Post indicates that the new vehicle has “finished almost all ground experiments and overcome key technical hurdles such as engine design and construction”. However, no dates on when the vehicle might be rolled-out or start flight tests have been given. Nor have any specifics or official images of the vehicle been released. All that has been said is the vehicle will have an “aerodynamic shape” for atmospheric flight, and be larger than Virgin Galactic’s SpaceShipTwo, the VSS Unity.

Continue reading “Space Sunday: more Einstein, plus space planes and Wow!” →