Space Sunday: Lunar landers, and robots in space

The bulky Vikram lander, with the Pragyan rover”garaged” inside, is hoisted aloft in a clean room, ready to be mated to the “top” of the Chandrayaan-2 orbiter (right). One section of the payload fairing that enclosed the craft during launch is visible in the background. Credit: ISRO

On Friday, September 6th, India was due to become the fourth country to successfully reach the surface of the Moon, with the touch-down of the Vikram lander, part of the Chandrayaan-2 (“moon craft-2” in Hindi) mission.

Launched in late July 2019, Chandrayaan-2 was set to be the latest in a series of high-profile missions undertaken by the Indian Space Research Organisation (ISRO) over the course of the last 11 years, which have included the  Chandrayaan-1 lunar orbiter (2008/2009) and the Mangalayaan (“Mars-craft”), launched in 2013 and still operational today.

As I’ve noted in recent Space Sunday articles, Chandrayaan-2 comprises three parts: the orbiter vehicle, the Vikram lander and a small rover called Pragyan (“Wisdom” in Hindi) carried by the lander. Vikram departed the orbiter vehicle on Monday, September 2nd, allowing it to begin a series of manoeuvres in readiness for a final decent and landing, scheduled for Friday, September 6th (western time, the early hours of Saturday, September 7th for India) in the Moon’s South polar region.

An artist’s impression of the Vikram lander coming in to land in the Moon’s south polar region. Credit: ISRO official video

Initially, that final descent started well enough, with the lander about 550 km (344 mi) from the south pole as it fired its descent motor start the start of its final approach. At an altitude of 6 km (3.75 mi), it started a final sequence of engine burns referred to as the “fine braking phase”. Then all communications ceased.

ISRO issued a statement that the vehicle was performing nominally until around 2.1 km above the Moon, when the loss of communications occurred. However, images of the data received from the vehicle and released by ISRO appeared to suggest telemetry was being received when the lander was within 400 m of the lunar surface – and altitude at which it would be fully under its automatic guidance and landing software, and not reliant on commands from Earth. This seemed to suggest Vikram may have made a landing.

ISO stated communications with the Vikram lander were lost some 2.1 km above ground. However, a graphic of the vehicle’s descent towards the Moon (green above), appears to suggest telemetry was lost when the vehicle was between 300-400m above the lunar surface, and that it had drifted perhaps a mile from its planned descent track (red). If accurate, this suggests Vikram was in the fully automated terminal descent phase of its landing. Credit: ISRO

This idea gained ground as this article was being prepared, when an article published by Asia News international suggested Vikram has been spotted on the surface of the Moon, possibly 500m to 1 kilometre from its designated landing point. The article quotes ISRO’s director, Kailasavadivoo Sivan as saying:

We’ve found the location of Vikram Lander on lunar surface & orbiter has clicked a thermal image of Lander. But there is no communication yet. We are trying to have contact. It will be communicated soon.

Since then, the report has been repeated numerous times through various media (including an entirely UNofficial and unverified “ISRO Official Update” Twitter account) without (at the time of publication) official confirmation. This has made it hard to determine the veracity of the ANI report. Hopefully, the situation will become clearer in the coming days. One thing that could help define the lander’s condition would be an image captured by Chandrayaan-2’s main imaging camera. With a resolution of a third of a metre, it is the highest resolution camera in operation around the Moon.

The planned landing site for the Vikram lander. Credit: ISRO

But even though the lander and rover may have been lost, the mission is far from over; the orbiter continues to function perfectly. It also carries the bulk of the mission’s science experiments – eight of the 13 carried by the mission. he data gathered by these systems should enable scientists to compile detailed maps of the lunar surface, revealing key insights about the Moon’s elemental composition, formation and evolution, and potentially help in assessing the moon’s stores of water ice.

In this latter regard, the mission builds on work performed by Chandrayaan-1, which revealed water is present at the lunar poles, with subsequent studies suggesting much of this water is ice on the floors of polar craters, which have been in permanent shadow for billions of years. If this ice is easily accessible, it could be a critical enabling resource for the eventual human settlement of the moon, providing water, oxygen and fuel (hydrogen).

In all, Chandrayaan-2 is expected to operate for some 7 years.

Proxima Centauri: An Angry Star with Bad News for its Planet

In 2016, I wrote about Proixma b, a planet roughly 1.5 times the mass of Earth orbiting our nearest stellar neighbour, Proxima Centauri, 4.25 light years away (see: Exoplanets, dark matter, rovers and recoveries). Since then, and as a result of the planet being within the star’s zone of habitability, there has been a lot of debate about the potential for it to support life.

An artist’s impression of Proxima b with Proxima Centauri low on the horizon. The double star above and to the right of it is Alpha Centauri A and B. Credit: ESO

Numerical models have indicated that Proxima b probably lost a large amount of its water in its early life stages, possibly as much as one of Earth’s oceans. however, those models also suggest liquid water could have survived in warmer regions of the planet – such as on the side of the planet facing its star (Proxima b is potentially tidally locked with its parent star, always keeping the same face towards it). This means other factors that might affect habitability must be examined. Chief among these is the overall activity of the parent star – notably flares, coronal mass ejections and strong UV flux -, all of which can erode a planet’s atmosphere, rendering it uninhabitable in the long term.

That Proxima Centauri is very active with flares has been known for some time, as has been the star’s ability to generate “super-flares”, one of which in 2016 briefly raised the star’s brightness to the point of making it briefly visible to the naked eye from Earth. This activity has suggested that Proxima b is unlikely to support life (see: Curiosity’s 5th, Proxima b and WASP-121b). But the debate has remained.

Over the past year, a team of scientists at the Konkoly Observatory in Hungary have been using data from the Transiting Exoplanet Survey Satellite (TESS) to observe Proxima Centauri’s flare activity over a two month period, split between April and June 2019. They found that in the roughly 55-day period, the star pent around 7% of its time violently flaring, with a total of 72 relatively large-scale flares observed. In particular, the energy of the eruptions put them as not far below “super flare” status, suggesting the star could produce a super flare perhaps once every two years.

TESS data on flare activity on Proxima Centauri: yellow triangles indicate flare activity, green triangles show particularly violent flare events. Credit: Krisztián Vida / Konkoly Observatory

Such frequent, high-energy eruptions almost certainly have a severe impact on the atmosphere of Proxima Centauri b, disrupting it to a point where it cannot reach any steady state, leaving it continuously in a state of disruption and alteration, making the potential for the planet to support life even more remote. However, it also raises a curiosity about the star: the underlying magnetic frequency evidenced by Proxima Centaur. Such activity is normally associated with fast-rotating stars with periods of a few days. However, Proxima Centauri has a rotation period of ~80 days; so why it should be so active is now a subject for investigation.

Continue reading “Space Sunday: Lunar landers, and robots in space”

Advertisements

Butlers, enchanted lands, island living and pirates

Seanchai Library

It’s time to highlight another week of storytelling in Voice by the staff and volunteers at the Seanchai Library. As always, all times SLT, and events are held at the Library’s home at Holly Kai Park, unless otherwise indicated.

Sunday, September 8th 13:30: Tea Time with Jeeves

Just for summer, Seanchai Library takes a dive into the world of Reginald Jeeves, a well-educated, intelligent valets of indeterminate age who is employed by the amiable young man-about-town, Bertie Wooster, whom Jeeves routinely has to benignly rescue from the consequences of his idiocy.

Created by author, humorist, and lyricist (working with Guy Bolton and Jerome Kern) Pelham Grenville Wodehouse (October 1881 – February 1975), Jeeves and Wooster are perhaps his most iconic characters, their adventures eventually growing to 35 short stories and 11 novels, the majority of which are first-person narrated from the perspective of Bertie Wooster.

This week comes the fourth part of The Inimitable Jeeves.

A semi-novel published in the UK and the United States in 1923, The Inimitable Jeeves brings together 11 previously published stories structured as “chapters” rather than appearing as individual stories, giving the volume the appearance of being a novel something initially enhanced in early editions, which split the first five and final story into two chapters apiece, giving the impression the book was 18 chapters long (later editions reversed this, each story being just a single chapter for 11 in total).

The stories also add to the novel-like feel, as they each focused variously on a small group of characters throughout including Bertie’s Aunt Agatha, his somewhat inept friend Bingo, and his cousins Claude and Eustace, brought together with Jeeves and Wooster in some familiar Wodehouse themes.

Join Da5id Abbot, Kayden Oconnell, and Caledonia Skytower as they read this delightful series at Ceiliuradh Glen.

Monday, September 9th 19:00: Moonheart

Gyro Muggins reads Charles de Lint’s 1994 novel..

When Sara and Jamie discovered the seemingly ordinary artefacts, they sensed the pull of a dim and distant place. A world of mists and forests, of ancient magic, mythical beings, ageless bards – and restless evil.

Now, with their friends and enemies alike–Blue, the biker; Keiran, the folk musician; the Inspector from the RCMP; and the mysterious Tom Hengyr; Sara and Jamie are drawn into this enchanted land through the portals of Tamson House, that sprawling downtown edifice that straddles two worlds.

Sweeping from ancient Wales to the streets of Ottawa today, Moonheart will entrance you with its tale of this world and the other one at the very edge of sight and the unforgettable people caught up in the affairs of both. A tale of music, and motorcycles, and fey folk beyond the shadows of the moon. A tale of true magic; the tale of Moonheart.

Tuesday, September 10th 19:00: TBA

Check the Seanchai Library website for updates.

Wednesday, September 11th: Anne of Green Gables

As soon as Anne Shirley arrives at the white farmhouse called Green Gables, she is sure she wants to stay forever. The problem is, the owners of Green Gables, Matthew and Marilla Cuthbert wanted a boy to help Matthew with household chores; so at first it seems as if she will be returned to the orphanage from whence she came.

However, Anne is determined to stay, trying hard not to get into trouble or speaking out of turn, and the Cuthberts come to realise she is someone blessed with an enormous imagination. The latter is especially noticed by the quietly-spoken Matthew, who persuades his sister that young Anne should stay.

Thus we are drawn into Anne’s life and world as she settles into her first real home. Over the course of a five year period from her arrival in Bolingbroke at age 11 through until her move to Queen’s Academy at the age of 16, where she earns a university scholarship, we follow Anne’s adventures and ups and down within the close-knit community, making friends (and sometime enemies whom she is perhaps too stubborn to admit she’s long since forgiven for perceived wrongs) and her domestic trails and tribulations. The later, when tragedy strikes, we follow her back to Bollingbroke, where she indeed becomes Anne of Green Gables, and her story is left open.

Join Faerie Maven-Pralou as she reads L.M. Montgomery’s 1908 classic (and first of a series).

Thursday, September 12th 19:00: Jack Sparrow: The Siren Song, Part 1

Captain Jack Sparrow and his crew have suddenly fallen under a sinister spell. While continuing on their quest for the Sword of Corts, they find themselves entranced by an ethereal song which leads them away from their quarry.

With Shandon Loring, also Also in Kitely – teleport from the main Seanchai World grid.kitely.com:8002:SEANCHAI.