Astronomy

Fibres in wet wipes and clothes often make their way into soil - and natural versions could be more damaging than synthetic ones

Culture may play a role in how birds build collectively in the Kalahari Desert

You can save $300 on this early Black Friday VR headset deal as the HTC VIVE Pro 2 headset, the best high-resolution model out there, is on offer.

AstroForce has received a commercial license for operating and communicating with a mission headed to a near-Earth asteroid, the first to be granted for beyond Earth orbit.

Many people think of the James Webb Space Telescope as a sort of Hubble 2. They understand that the Hubble Space Telescope (HST) has served us well but is now old, and overdue for replacement. NASA seems to agree, as they have not sent a maintenance mission in over fifteen years, and are already preparing to wind down operations. But a recent paper argues that this is a mistake. Despite its age, HST still performs extremely well and continues to produce an avalanche of valuable scientific results. And given that JWST was never designed as a replacement for HST — it is an infrared (IR) telescope) — we would best be served by operating both telescopes in tandem, to maximize coverage of all observations.

Let’s not fool ourselves: the Hubble Space Telescope (HST) is old, and is eventually going to fall back to Earth. Although it was designed to be repairable and upgradable, there have been no servicing missions since 2009. Those missions relied on the Space Shuttle, which could capture the telescope and provide a working base for astronauts. Servicing missions could last weeks, and only the Space Shuttle could transport the six astronauts to the telescope and house them for the duration of the mission.

Without those servicing missions, failing components can no longer be replaced, and the overall health of HST will keep declining. If nothing is done, HST will eventually stop working altogether. To avoid it becoming just another piece of space junk, plans are already being developed to de-orbit it and send it crashing into the Pacific Ocean. But that’s no reason to give up on it. It still has as clear a view of the cosmos as ever, and mission scientists are doing an excellent job of working around technical problems as they arise.

The James Webb Space Telescope was launched into space on Christmas dat in 2021. Its system of foldable hexagonal mirrors give it an effective diameter some 2.7 times larger than HST, and it is designed to see down into the mid-IR range. Within months of deployment, it had already seen things that clashed with existing models of how the Universe formed, creating a mini-crisis in some fields and leading unscrupulous news editors to write headlines questioning whether the “Big Bang Theory” was under threat!

This image of NASA’s Hubble Space Telescope was taken on May 19, 2009 after deployment during Servicing Mission 4. NASA

The reason JWST was able to capture such ancient galaxies is that it is primarily an IR telescope: As the Universe expands, photons from distant objects get red-shifted until stars that originally shone in visible light can now only be seen in the IR. But these IR views are proving extremely valuable in other scientific fields apart from cosmology. In fact, many of the most striking images released by JWST’s press team are IR images of familiar objects, revealing hidden complexities that had not been seen before.

This is a key difference between the two telescopes: While HST’s range overlaps slightly with JWST, it can see all the way up into ultraviolet (UV) wavelengths. HST was launched in 1990, seven years late and billions of dollars over budget. Its 2.4 meter primary element needed to be one of the most precisely ground mirrors ever made, because it was intended to be diffraction limited at UV wavelengths. Famously, avoidable problems in the testing process led to it being very precisely figured to a slightly wrong shape, leading to spherical aberration preventing it from coming to sharp focus.

Fortunately the telescope was designed from the start to be serviceable, and even returned to Earth for repairs by the Space Shuttle if necessary. In the end though, NASA opticians were able to design and build a set of corrective optics to solve the problem, and the COSTAR system was installed by astronauts on the first servicing mission. Over the years, NASA sent up three more servicing missions, to upgrade or repair components, and install new instruments.

Illustration of NASA’s James Webb Space Telescope. Credits: NASA

HST could be one of the most successful scientific instruments ever built. Since 1990, it has been the subject of approximately 1200 science press releases, each of which was read more than 400 million times. The more than 46,000 scientific papers written using HST data have been cited more than 900,000 times! And even in its current degraded state, it still provided data for 1435 papers in 2023 alone.

JWST also ran over time and over budget, but had a far more successful deployment. Despite having a much larger mirror, with more than six times the collecting area of HST, the entire observatory only weighs half as much as HST. Because of its greater sensitivity, and the fact that it can see ancient light redshifted into IR wavelengths, it can see far deeper into the Universe than HST. It is these observations, of galaxies formed when the Universe was extremely young (100 – 180 million years), that created such excitement shortly after it was deployed.

As valuable as these telescopes are, they will not last forever. JWST is located deep in space, some 1.5 million kilometers from Earth near the L2 Lagrange point. When it eventually fails, it will become just another piece of Solar System debris orbiting the Sun in the vast emptiness of the Solar System. HST, however, is in Low Earth Orbit (LEO), and suffers very slight amounts of drag from the faint outer reaches of the atmosphere. Over time it will gradually lose speed, drifting downwards until it enters the atmosphere proper and crashes to Earth. Because of its size, it will not burn up completely, and large chunks will smash into the surface.

Because it cannot be predicted where exactly it will re-enter, mission planners always intended to capture it with the Space Shuttle and return it to Earth before this happened. Its final resting place was supposed to be in display in a museum, but unfortunately the shuttle program was cancelled. The current plan is to send up an uncrewed rocket which will dock with the telescope (a special attachment was installed on the final servicing mission for this purpose), and deorbit it in a controlled way to ensure that its pieces land safely in the ocean.

You can find the original paper at https://arxiv.org/abs/2410.01187

The post Hubble and Webb are the Dream Team. Don't Break Them Up appeared first on Universe Today.

Image: Moon waves goodbye to Hera

Dragon completed its docking at 10:04 a.m. EST.

On November 26th, 2018, NASA’s Interior Exploration using Seismic Investigations, Geodesy, and Heat Transport (InSight) mission landed on Mars. This was a major milestone in Mars exploration since it was the first time a research station had been deployed to the surface to probe the planet’s interior. One of the most important instruments InSight would use to do this was the Heat Flow and Physical Properties Package (HP3) developed by the German Aerospace Center (DLR). Also known as the Martian Mole, this instrument measured the heat flow from deep inside the planet for four years.

The HP3 was designed to dig up to five meters (~16.5 ft) into the surface to sense heat deeper in Mars’ interior. Unfortunately, the Mole struggled to burrow itself and eventually got just beneath the surface, which was a surprise to scientists. Nevertheless, the Mole gathered considerable data on the daily and seasonal fluctuations below the surface. Analysis of this data by a team from the German Aerospace Center (DLR) has yielded new insight into why Martian soil is so “crusty.” According to their findings, temperatures in the top 40 cm (~16 inches) of the Martian surface lead to the formation of salt films that harden the soil.

The analysis was conducted by a team from the Microgravity User Support Center (MUSC) of the DLR Space Operations and Astronaut Training Institution in Cologne, which is responsible for overseeing the HP3 experiment. The heat data it obtained from the interior could be integral to understanding Mars’s geological evolution and addressing theories about its core region. At present, scientists suspect that geological activity on Mars largely ceased by the late Hesperian period (ca. 3 billion years ago), though there is evidence that lava still flows there today.

The “Mars Mole,” Heat Flow and Physical Properties Package (HP³). Credit: DLR

This was likely caused by Mars’ interior cooling faster due to its lower mass and lower pressure. Scientists theorize that this caused Mars’ outer core to solidify while its inner core became liquid—though this remains an open question. By comparing the subsurface temperatures obtained by InSight to surface temperatures, the DLR team could measure the rate of heat transport in the crust (thermal diffusivity) and thermal conductivity. From this, the density of the Martian soil could be estimated for the first time.

The team determined that the density of the uppermost 30 cm (~12 inches) of soil is comparable to basaltic sand – something that was not anticipated based on orbiter data. This material is common on Earth and is created by weathering volcanic rock rich in iron and magnesium. Beneath this layer, the soil density is comparable to consolidated sand and coarser basalt fragments. Tilman Spohn, the principal investigator of the HP3 experiment at the DLR Institute of Planetary Research, explained in a DLR press release:

“To get an idea of the mechanical properties of the soil, I like to compare it to floral foam, widely used in floristry for flower arrangements. It is a lightweight, highly porous material in which holes are created when plant stems are pressed into it... Over the course of seven Martian days, we measured thermal conductivity and temperature fluctuations at short intervals.

“Additionally, we continuously measured the highest and lowest daily temperatures over the second Martian year. The average temperature over the depth of the 40-centimetre-long thermal probe was minus 56 degrees Celsius (217.5 Kelvin). These records, documenting the temperature curve over daily cycles and seasonal variations, were the first of their kind on Mars.”

NASA’s In­Sight space­craft land­ed in the Ely­si­um Plani­tia re­gion on Mars on 26 Novem­ber 2018. Credit: Credit: NASA-JPL/USGS/MOLA/DLR

Because the encrusted Martian soil (aka. “duricrust”) extends to a depth of 20 cm (~8 inches), the Mole managed to penetrate just a little more than 40 cm (~16 inches) – well short of its 5 m (~16.5 ft) objective. Nevertheless, the data obtained at this depth has provided valuable insight into heat transport on Mars. Accordingly, the team found that ground temperatures fluctuated by only 5 to 7 °C (9 to 12.5 °F) during a Martian day, a tiny fraction of the fluctuations observed on the surface—110 to 130 °C (230 to 266 °F).

Seasonally, they noted temperature fluctuation of 13 °C (~23.5 °F) while remaining below the freezing point of water on Mars in the layers near the surface. This demonstrates that the Martian soil is an excellent insulator, significantly reducing the large temperature differences at shallow depths. This influences various physical properties in Martian soil, including elasticity, thermal conductivity, heat capacity, the movement of material within, and the speed at which seismic waves can pass through them.

“Temperature also has a strong influence on chemical reactions occurring in the soil, on the exchange with gas molecules in the atmosphere, and therefore also on potential biological processes regarding possible microbial life on Mars,” said Spohn. “These insights into the properties and strength of the Martian soil are also of particular interest for future human exploration of Mars.”

What was particularly interesting, though, is how the temperature fluctuations enable the formation of salty brines for ten hours a day (when there is sufficient moisture in the atmosphere) in winter and spring. Therefore, the solidification of this brine is the most likely explanation for the duricrust layer beneath the surface. This information could prove very useful as future missions explore Mars and attempt to probe beneath the surface to learn more about the Red Planet’s history.

Further Reading: DLR

The post Scientists Have Figured out why Martian Soil is so Crusty appeared first on Universe Today.

Before Mesopotamian people invented writing, they used cylinder seals to press patterns into wet clay – and some of the symbols used were carried over into proto-writing

Before Mesopotamian people invented writing, they used cylinder seals to press patterns into wet clay – and some of the symbols used were carried over into proto-writing

Zinc nanoparticles, a common sunscreen ingredient, can make plants more resilient to climate change – in a surprising way

Zinc nanoparticles, a common sunscreen ingredient, can make plants more resilient to climate change – in a surprising way

Zinc nanoparticles, a common sunscreen ingredient, can make plants more resilient to climate change – in a surprising way

Zinc nanoparticles, a common sunscreen ingredient, can make plants more resilient to climate change – in a surprising way

India plans to launch astronauts to Earth orbit no sooner than 2026, roughly a year past the previously known timeline, following a series of uncrewed flight tests slated to begin in December.

A surprising reversal of our usual understanding of the second law of thermodynamics shows that it may be possible for heat to move in the “wrong” direction, flowing from a cold area to a warm one

A surprising reversal of our usual understanding of the second law of thermodynamics shows that it may be possible for heat to move in the “wrong” direction, flowing from a cold area to a warm one

In a rare show of openness about the X-37B, Boeing Space released a video detailing how the space plane's aerobraking maneuvers help change the spacecraft's orbit.

There are four Americans currently living in space, and each has had the opportunity to add their voice to the more than 160 million other Americans able to participate in the 2024 Presidential election.

Although the COP16 summit in Colombia ended with some important agreements, countries still aren’t moving fast enough to stem biodiversity loss