Category: Space Sunday

In March 2000 a United Launch Alliance Delta 2 rocket lifted-off from Vandenberg Air Force Base, California. It was carrying NASA’s Imager for Magnetopause-to-Aurora Global Exploration (IMAGE), built by the South-west Research Institute (SwRI) Arizona, which was placed in a highly elliptical 1,000×46,000 km (625 x  28,750 mi) polar orbit, passing around the Earth once every 14.2 hours.

This orbit allowed the satellite to carry out its mission – to study the global response of the Earth’s magnetosphere to changes in the solar wind, the first ever such mission to be fully dedicated to an in-depth study of the magnetosphere – with great success. In fact, the mission was so successful, it was twice extended, from 2002 to 2005, and from 2005 through until 2010.

Or that was the plan. Unfortunately, on December 18th, 2005, the vehicle fell silent, missing a scheduled data transfer – which took place one average between once and twice a day. An earlier transfer the same day had passed without any indication the satellite was experiencing any problems. Despite numerous attempts to re-establish contact, IMAGE failed to resume contact with NASA’s Goddard Applied Physics Laboratory, responsible for managing the mission.

The mission was officially declared lost in September 2006. However, fault analysis suggested the satellite may have shut itself down as a result of a false indication of an short-circuit in part of its own power supply as the result of a ionised particle impact with it solid state power converter. This would cause the spacecraft to place many of its system in a “safe” mode. Engineers calculated that the vehicle could be recovered if the power converter could be tricked into resetting itself. Unfortunately, there was no means to manually trigger such a reset – but there was a potential for a reset to occur naturally.

As a result of its highly elliptical orbit, coupled with the Earth’s orbit around the Sun, IMAGE would spend an extended period in Earth shadow early in October 2007. If sufficient enough, the drop could trigger the desired reset.

Sadly, following the period of eclipse, no signal was received from the craft, and it was again considered lost. And it remained so, right up until January 2018, and the USA-280 spy satellite mystery.

In January 2018, the super-secret spy satellite no-one in the US government will admit to owning and code-named “Zuma”, was reported lost not long after launch. The nature of the mission and the mystery of its loss – which has still not been publicly confirmed – led radio hams and satellite trackers to scan the skies in attempts to locate the satellite’s transmissions.

On January 20th, 2018, one of these radio hams, Canadian Scott Tilley, detected S-band transmissions which he thought were from “Zuma”, and forwarded his findings to NASA. A  team from Goddard, using five separate antennae were able to confirm they were receiving transmissions consistent with expected frequency fluctuations in s-band broadcasts from IMAGE, on January 24th. Further, the signal had an oscillation consistent with the last known spin rate for IMAGE. Following this, on January 30th, analysis of further received data, the Goddard team were able to obtain an identification number from the craft: 166 – IMAGE’s “call sign”.

The challenge now is determining the spacecraft’s overall condition. This is a problem because the hardware and operating systems used to manage IMAGE no longer exist, so engineers are having to reverse-engineer current systems to analyse the received IMAGE signals. So far, this has allowed them to read some basic housekeeping data from the spacecraft, suggesting that at least the main control system is operational. The hope is that over the next several weeks, it will be possible to analyse IMAGE’s overall condition, and possibly even re-activate its on-board science systems. In the meantime, re-examination of old data recorded by Tilley and fellow satellite tracker Cees Bassa shows they picked-up transmissions from IMAGE in May 2017 and October 2016 without realising they had.

Discovering Planets in Another Galaxy

Exoplanets – planets orbiting stars other than our own – have been a subject of many of my Space Sunday reports. As of February 1st, 2018, 3,728 planets have been confirmed in 2,794 star systems, 622 of which have more than one planet. However, a study published on February 2nd, 2018 points to the first discovery of a planet in another galaxy.

Probing Planets in Extragalactic Galaxies Using Quasar Microlensing, by Xinyu Dai and Eduardo Guerras, a post-doctoral researcher and professor from at the University of Oklahoma’s Physics and Astronomy department, appeared in The Astrophysical Journal Letters. It outlines how the two used  Gravitational Microlensing to make their discovery, combining it with data on  a distant quasar known as RX J1131–1231, gathered by NASA’s Chandra X-Ray Observatory. 

Gravitational Microlensing uses the gravitational force of distant objects to bend and focus light coming from a star. As a planet passes in front of the star relative to the observer (i.e. makes a transit), the light dips measurably, which can then be used to determine its presence. So far, 53 planets have been discovered within the Milky Way galaxy using the technique.

RX J1131–1231 is located 3.8 billion light years away and at its heart it has a super-massive black hole (SMBH). This has made it an ideal subject for a number of microlensing studies, including measuring the Hubble Constant – a fundamental quantity that describes the rate at which the Universe is expanding.

In this case, the team were able to use the microlensing properties of this black hole to observe line energy shifts among the quasar’s stars and study fluctuations within them which could only logically be explained by the presence of unbound – or rogue – planetary bodies between the quasar’s stars.

While none of the planets can be directly imaged, the team used the super computer facilities at the University of Oklahoma to analyse the high frequency of the microlensing signature. This provided them with some determination of the broad mass range of the planets, indicating they likely range in size from bodies roughly the size of the Moon up to planets at least the same size as Jupiter.

Prior to this study, the presence of planets in other galaxies had been hotly debated, with some doubting any such bodies could exist. Xinyu Dai and Eduardo Guerras have now opened the door for the discovery of planets far beyond our reach – abeit worlds beyond our ability to study them directly. Their work may also help refine our ability to detect planetary bodies much further afield in our own galaxy. What’s more, with the range of extremely large telescopes (ELT) currently under construction, such as the European Southern Observatory’s OWL (that’s “OverWhelmingly Large”) telescope, as well as new orbital facilities such as the James Webb Telescope, we’re bound to make more discoveries of planets within – and beyond – the Milky Way.

Continue reading “Space Sunday: satellites, spacewalks and galaxies far, far away” →

One of the major issues in sending humans to the Moon – as the United States, China, Russia and Europe want to do (either individually or in some sort of joint venture among some of them) – is where, exactly, to send them. The Moon is an uncompromising place: without any discernible atmosphere or magnetosphere, the lunar surface is open to the full fury of both solar and cosmic radiation. This makes living there without adequate protection somewhat hazardous. Then there is the question of consumables – notably water.

Protection can be found in one of two possible ways: by covering a base under a substantial layer of lunar “soil” – more correctly called regolith – or by placing it underground. While the former is feasible, and could even be achieved via 3D printing, excavating the space needed for a base would be a hefty undertaking, requiring heavy equipment.

However, things could be eased if advantage could be taken of lunar lava tubes. These are natural conduits formed by flowing lava moving beneath the hardened surface of a previous lava flow,  draining lava from a volcano during an eruption. When the lava flow has ceased and the rock has cooled, they can form a long cave, or network of tunnels – some of which can break the lunar surface in what are called “skylights”, resembling  distinctive pits in a landscape. In recent years, over 200 of these pits have been discovered on the Moon’s near side, notably in the great lava plains around the equatorial regions, many of which have been confirmed as entrances to underground lava tubes.

Water is also present on Mars in the form of subsurface ice located around the polar regions – the only parts of the Moon where there is little or no sunlight. If it can be extracted, it could be invaluable to a human presence on the Moon: it could be purified and used for drinking; through electrolysis it could be broken down into its components, hydrogen and oxygen, with the latter used to help maintain the air within a base, the former used alongside carbon dioxide in processes for creating fuel stock space vehicles or surface craft. The difficulty is in accessing the water ice in volume. One way of doing so might be through drilling – although this would again be costly and slow. Another way might be through finding lava tubes which may have become repositories for water ice deposits. The problem is, until now, little evidence for polar region lava tubes has been found.

Pascal Lee, the co-founder and chairman of the Mars Institute, a planetary scientist at the SETI Institute, and the Principal Investigator of the Haughton-Mars Project (HMP) at NASA’s Ames Research Centre – and, totally coincidentally, whom I’ve had the pleasure of meeting a number of times – reports he’s now discovered pits in the north polar region which could be indicative of lava tube skylights.

He found the pits while studying images gathered by NASA’s Lunar Reconnaissance Orbiter of the north-eastern floor of Philolaus Crater, about 550 km (340 mi) from the North Pole, on the lunar near side. They appear as small rimless depressions between 15 to 30 metres (50 to 100 ft) across, with completely shadowed interiors. Most particularly, the pits are located along sections of winding channels criss-crossing the crater floor. Called “sinuous rilles”, these are generally associated with collapsed, or partially collapsed, lava tubes, increasing the possibility they might be skylights leading to intact lava tubes.

“The highest resolution images available for Philolaus Crater do not allow the pits to be identified as lava tube skylights with 100 percent certainty,” Lee states, “but we are looking at good candidates considering simultaneously their size, shape, lighting conditions and geologic setting.”

Should they prove to be entrances to lava tubes, the pits offer an exciting prospect for lunar explorers. They could present a means to access sub-surface water ice – particularly if some of the tubes contain frozen water – which is not yet certain. They might also provide the necessary protection from radiation, making them an ideal location for a subsurface base. If there is water ice in the tunnels, solar collectors ranged on the crater floor could be used to channel heat into the tunnels to melt it, allowing it to be stored and used. A further benefit with Philolaus Crater is that it is one of the Moon’s younger craters, one of the few large craters formed during the Copernican Era formed within the last 1.1 billion years. Scientists located there would be able to study the Moon’s more recent evolution.

In terms of a location for a base, the crater has two additional benefits. The first is that as it is on the lunar near side, it will be in direct line of communication with Earth. The second is more poetic, as Lee himself notes:

We would also have a beautiful view of Earth. The Apollo landing sites were all near the Moon’s equator, such that the Earth was almost directly overhead for the astronauts. But from the Philolaus skylights, Earth would loom just over the crater’s mountainous rim, near the horizon to the south-east.

He continued, “Our next step should be further exploration, to verify whether these pits are truly lava tube skylights, and if they are, whether the lava tubes actually contain ice. This is an exciting possibility that a new generation of caving astronauts or robotic spelunkers could help address” says Lee. “Exploring lava tubes on the Moon will also prepare us for the exploration of lava tubes on Mars. There, we will face the prospect of expanding our search for life into the deeper underground of Mars where we might find environments that are warmer, wetter, and more sheltered than at the surface.”

Continue reading “Space Sunday: lava tubes and politics” →