Comment

Although a major objective in Mars exploration is the search for life, there are many scenarios that could lead to the recovery of lifeless samples. What could lifeless samples tell us about Mars and its habitability?

South Africa is looking forward to hosting the IAU General Assembly in 2024 — the first on the African continent. The meeting will come at a time of burgeoning scientific prosperity for the growing community of indigenous South African and African astronomers.

The new generation of sample return missions from small bodies will deliver to us fresh witnesses from the early Solar System. In-depth laboratory analysis of retrieved samples will allow us to look in unprecedented detail at the formation and evolution of organic materials in asteroids.

On 27 June 2018 the Hayabusa2 spacecraft arrived at the carbonaceous asteroid Ryugu — a top-shaped asteroid with a very dark surface and many boulders. After a careful search for a safe and flat landing site, the first touchdown successfully took place on 22 February 2019.

Japanese and US missions returning samples from the carbon-rich asteroids Ryugu and Bennu are the latest steps in probing our Solar System’s smallest bodies, near and far, for clues to our own origins and directions for our future exploration.

After the return of Hayabusa from asteroid Itokawa in 2010, the Japanese space agency JAXA developed a plan to investigate how our planet became habitable. The Hayabusa2 spacecraft mission to the asteroid Ryugu is just one part of this exploration that aims to track water and organics throughout our Solar System.

Do black holes rotate, and if yes, how fast? This question is fundamental and has broad implications, but still remains open. There are significant observational challenges in current spin determinations, but future facilities offer prospects for precision measurements.

The PLOAD — Portuguese Language Office of Astronomy for Development — was established in 2015 by the International Astronomical Union (IAU) with the goal of promoting astronomy as a tool for sustainable development in Portuguese-speaking countries.

Both NASA and ESA hope their next Mars rovers will find evidence that life once thrived on Mars, but they have different strategies to reach this goal. Their landing site choices reflect this difference.

The existence of Earth’s Trojan asteroids is not well constrained and represents a major gap in our inventory of small bodies in near-Earth space. Their discovery would be of high scientific and human interest.

Scientific outreach involving people with disabilities does not require specific techniques for specific conditions. An inclusive approach involving complementary senses not only helps those with disabilities but everyone else as well.

Canadian astronomers and facilities have had a significant impact in wide-field astronomy. With community planning exercises underway this looks set to continue, with new capabilities and international collaborations in the near future.

The surface of Mars has been well mapped and characterized, yet the subsurface — the most likely place to find signs of extant or extinct life and a repository of useful resources for human exploration — remains unexplored. In the near future this is set to change.

The masses of supermassive black holes, key to many cosmological studies, are highly uncertain beyond our local Universe. The main challenge is to establish the spatial and kinematic structure of the broad-line emitting gas in active galactic nuclei.

The detection of a gravitational-wave background at nanohertz frequencies can tell us if and how supermassive black holes merge, and inform our knowledge of galaxy merger rates and supermassive black hole masses. All we have to do is time pulsars.

Intermediate-mass black holes (BHs) in local dwarf galaxies are considered the relics of the early seed BHs. However, their growth might have been impacted by galaxy mergers and BH feedback so that they cannot be treated as tracers of the early seed BH population.

There are efforts to establish a modern astronomical observatory on Timor Island, East Nusa Tenggara in Indonesia. This future observatory aims to answer fundamental astronomical questions and to strengthen the nation through education, research, science and technology.

The field of gamma-ray burst astronomy arguably went through three decades of growing pains before reaching maturity. What development lessons can be learned for the adolescent field of fast radio burst astronomy?

Fast radio bursts were discovered just over a decade ago, and their origin remains a mystery. Despite this disadvantage, astronomers have been using them to investigate the matter through which their bright, impulsive radiation travels.

To date, one repeating and many apparently non-repeating fast radio bursts have been detected. This dichotomy has driven discussions about whether fast radio bursts stem from a single population of sources or two or more different populations. Here we present the arguments for and against.