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When NASA astronauts return to the surface of the Moon in the Artemis III mission, the plan is to use a modified SpaceX Starship as their lunar lander. NASA announced last week that SpaceX has now demonstrated an important capability of the vacuum-optimized Raptor engine that will be used for the lander: an extreme cold start.  

A test last month successfully confirmed the engine can be started in the frigid conditions of space, even when the vehicle has spent an extended time in space, where temperatures will drop lower than a shorter low-Earth orbit mission. The Raptor vacuum engine was chilled to mimic conditions after a long coast period in space, and then was successfully fired.

SpaceX has a video on X (formerly Twitter) showing the test firing.

NASA said that one challenge that differentiates Artemis missions from those in low Earth orbit is that the landers may sit in space without firing for an extended period of time, “causing the temperature of the hardware to drop to a level below what they would experience on a much shorter low Earth orbit mission.”

SpaceX signed a $2.89 billion contract with NASA to develop a human landing system (HLS) for Artemis 3, currently scheduled to land astronauts on the Moon in 2025. Also, SpaceX signed another $1.15 billion contract last year for Artemis 4, which will tentatively take place 2028.

Artemis 2 is the second scheduled mission of NASA’s Artemis program and the first scheduled crewed mission of NASA’s Orion spacecraft, currently planned to be launched by the Space Launch System (SLS) in November 2024. However, several indications point to that flight being delayed.

Artemis II crew portrait
The Artemis II crew includes, clockwise from left, Christina Koch, Victor Glover, Jeremy Hansen and Reid Wiseman. (Credit: Josh Valcarcel / NASA)

The Starship HLS will be powered by two variants of the company’s Raptor engines—one optimized to operate in atmospheric pressure at sea-level and one optimized to operate in space, or in a vacuum, where there is no atmosphere.

SpaceX had previously tested that the engine could handle the descent portion of the mission, firing continuously for 281 seconds, the approximate amount of time for a descent burn to the lunar surface. That test, in November 2021 also showed Raptor’s ability to change the level of engine power over time, called the throttle profile, and for the engine to burn the full length of time of the powered descent phase. NASA said that successful test provided NASA “with early confidence in the company’s engine development.”

SX Throttle Test 768x436 1
The 281-second throttle test demonstrated the engine’s ability to meet the demands of a descent burn to the lunar surface. Credit: SpaceX

For Artemis III, the Starship HLS will land crew members at a region near the lunar South Pole to conduct moonwalks and survey the likely area of a future Moon base. SpaceX says on future missions, Starship will deliver supplies, equipment, and science payloads needed for extensive surface exploration.

Like any space hardware, testing critical technologies and hardware under simulated and actual flight conditions is key. On April 20, 2023, SpaceX conducted the first integrated launch of Starship and the Super Heavy booster, the most powerful rocket to ever launch. However, after liftoff, the vehicle experienced several anomalies including the loss of multiple first-stage engines. After the second stage failed to separate from the
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If Exoplanets Have Lightning, it’ll Complicate the Search for Life

TRAPPIST 1d artist impression 2018 jpg

Discovering exoplanets is almost routine now. We’ve found over 5,500 exoplanets, and the next step is to study their atmospheres and look for biosignatures. The James Webb Space Telescope is leading the way in that effort. But in some exoplanet atmospheres, lightning could make the JWST’s job more difficult by obscuring some potential biosignatures while amplifying others.

Detecting biosignatures in the atmospheres of distant planets is fraught with difficulties. They don’t advertise their presence, and the signals we receive from exoplanet atmospheres are complicated. New research adds another complication to the effort. It says that lightning can mask the presence of things like ozone, an indication that complex life could exist on a planet. It can also amplify the presence of compounds like methane, which is considered to be a promising biosignature.

The new research is “The effect of lightning on the atmospheric chemistry of exoplanets and potential biosignatures,” and it’s been accepted for publication in the journal Astronomy and Astrophysics. The lead author is Patrick Barth, a researcher from the Space Research Institute at the Austrian Academy of Sciences.

While we’ve discovered over 5,500 exoplanets, only 69 of them are in the potentially habitable zones around their stars. They’re rocky planets that receive enough energy from their stars to potentially maintain liquid water on their surfaces. Our search for biosignatures is focused on this small number of planets.

This is an artist's illustration of the exoplanet TRAPPIST-1d, a potentially habitable exoplanet about 40 light-years away. Planets like these are prime targets for JWST's spectrometry. Image Credit: By NASA/JPL-Caltech - Cropped from: PIA22093: TRAPPIST-1 Planet Lineup - Updated Feb. 2018, Public Domain, https://commons.wikimedia.org/w/index.php?curid=76364484
This is an artist’s illustration of the exoplanet TRAPPIST-1d, a potentially habitable exoplanet about 40 light-years away. Planets like these are prime targets for JWST’s spectrometry. Image Credit: By NASA/JPL-Caltech – Cropped from: PIA22093: TRAPPIST-1 Planet Lineup – Updated Feb. 2018, Public Domain, https://commons.wikimedia.org/w/index.php?curid=76364484

The important next step is to determine if these planets have atmospheres and then what the composition of those atmospheres is. The JWST is our most powerful instrument for these purposes. But in order to understand what the JWST shows us in distant atmospheres, we have to know what its signals tell us. Research like this helps scientists prepare for the JWST’s observations by alerting them to potential false positives and masked biosignatures.

This JWST spectra isn't part of this research, but it shows how the powerful space telescope can examine exoplanet atmospheres. It's a transmission spectrum of the hot gas giant exoplanet WASP-39 b, captured by Webb's Near-Infrared Spectrograph (NIRSpec.) It reveals the first definitive evidence of carbon dioxide in the atmosphere of a planet outside the Solar System. In the future, the JWST will bring its observation power to bear on more exoplanets as part of the search for biosignatures. Image Credit: NASA, ESA, CSA, and L. Hustak (STScI). Science: The JWST Transiting Exoplanet Community Early Release Science Team
This JWST spectra isn’t part of this research, but it shows how the powerful space telescope can
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Titan Probably Doesn’t Have the Amino Acids Needed for Life to Emerge

Possible liquid ocean beneath Titan s surface pillars 750 jpg

Does Saturn’s largest moon, Titan, possess the necessary ingredients for life to exist? This is what a recent study published in Astrobiology hopes to address as a team of international researchers led by Western University investigated if Titan, with its lakes of liquid methane and ethane, could possess the necessary organic materials, such as amino acids, that could be used to produce life on the small moon. This study holds the potential to help researchers and the public better understand the geochemical and biological processes necessary for life to emerge throughout the cosmos.

Along with its liquid lakes of methane and ethane, Titan is also strongly hypothesized to possess a subsurface liquid water ocean like Saturn’s icy moon, Enceladus, and Jupiter’s icy moon, Europa. For the study, the researchers used data from impact cratering from comets to estimate the number of organic molecules that could relocate from Titan’s surface to its subsurface liquid water ocean. The team hypothesized that when comets strike Titan’s surface, their icy materials would melt from the heat of the impact and mix with the surface organics, resulting in a unique mixture. However, the heavier liquid water would then sink to the subsurface, slowly filling the subsurface ocean over time.

Possible liquid ocean beneath Titan s surface pillars 750 1 jpg
Artist’s cutaway illustration displaying Titan’s subsurface ocean (blue). (Credit: NASA/JPL)

After accounting for a presumed annual number of cometary impacts on Titan’s surface throughout its billions of years of existence, the researchers then calculated how much water would make its way from the surface to the subsurface ocean. In the end, the team concluded that the amount of glycine, which is the most basic amino acid that forms the proteins to create life, was measured at no greater than 7,500 kilograms/year (16,530 pounds/year). This amount approximately equals the size of a smaller African forest elephant, hence indicating number of organic materials that exist on Titan is quite miniscule.

“One elephant per year of glycine into an ocean 12 times the volume of Earth’s oceans is not sufficient to sustain life,” said Dr. Catherine Neish, who is an associate professor in the Department of Earth Sciences at Western University and lead author of the study. “In the past, people often assumed that water equals life, but they neglected the fact that life needs other elements, in particular carbon.”

While Dr. Neish’s study presents somewhat dire implications for finding life on Titan, this study comes on the heels of a recent investigation into how organic hazes on ancient Earth could have contained the necessary building blocks of life, including nucleobases and amino acids, which could hold implications for finding life on Titan due to the moon’s hazy atmosphere. For this study, the researchers used laboratory experiments to determine that “warm little ponds” on ancient Earth could host nucleobases. Both studies offer profound insights into the processes responsible for both creating and sustaining life beyond Earth, and further research is undoubtedly required to better understand these processes.

One such research opportunity that could help solidify these studies could be NASA’s upcoming Dragonfly mission, which is a quadcopter designed to search Titan’s surface for signs of potential habitability with Dr. Neish assigned as a mission co-investigator. Dragonfly currently has a scheduled launch date of July 2028, arriving at Saturn’s largest moon sometime in 2034. While Dragonfly will not be the first aircraft on another world, as that honor goes to NASA’s Ingenuity Mars Helicopter, it will be the first aircraft to land and operate in the outer solar system. Dragonfly will launch more than 20 years after the European Space Agency’s Huygens probe landed on Titan in January 2005, beaming back images of rounded rocks that could have formed from liquid processes.

What new discoveries will scientists make about Titan and its potential for life in the coming years and decades? Only time will tell, and this is why we science!

As always, keep doing science & keep looking up!

The post Titan Probably Doesn’t Have the Amino Acids Needed for Life to Emerge appeared first on Universe Today
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Astronomers Discover a New Meteor Shower. The Source is Comet 46P/Wirtanen

1567215847897 Rosetta NavCam comet 67P 20150314 enhanced 625 jpg

Like many of you, I love a good meteor shower. I have fond memories of the Leonid meteor storm back in 1999 when several hundred per hour were seen at peak. Sadly meteor storms are not that common unlike meteor showers of which, there are about 20 major showers per year. Wait, there’s another one and this time it comes from the debris left behind from Comet 46P/Wirtanen with an expected peak on December 12. Last year, 23 meteors were seen on that night that matched the location of the comets trail. 

Comets (and some asteroids) leave a trail of debris behind them like a trail of celestial breadcrumbs. If the orbit of a comet crosses the orbit of the Earth then the particles from the debris (that are often no larger than grains of sand) collide with our atmosphere. At the immense speeds (of the order of 60 km per second, the particles falling through the atmosphere cause the gas to glow giving rise to the classic shooting star we see in the sky. Because the orbits of Earth and comets are relatively fixed, this process repeats itself every time we go through the same part of the orbit giving us the familiar annual meteor showers.

One such comet that it seems may become host to a new annual shower is Comet 46P/Wirtanen (46P). It nearly hit the headlines previously when it had been initially selected as the target for the Rosetta mission which, as you may recall, visited 67P/Churyumov-Gerasimenko instead.  46P is known as a short period comet taking 5.4 years to complete one orbit of the Sun. It is among the family of comets known as a Jupiter comet which has a most distant point from the Sun of between 5 and 6 astronomical units (1 AU is the average distance between the Sun and Earth). Observations have suggested it has a diameter of about 1.4km. 

1567215847897 Rosetta NavCam comet 67P 20150314 enhanced 625 1 jpg
Comet 67P/Churyumov-Gerasimenko from Rosetta mission (Credit – NASA)

Due to the high levels of ice present in comets, it’s not unusual for active areas on their surface to appear as the ices sublimate into gasses or pockets of gas escape. Observations using the TRAPPIST telescope (The Transiting Planets and Planetesimals Small Telescope) suggest 40% of the surface is active which is higher than the usual 5-10% for Jupiter family comets. A recent study found the presence of mm sized dust particles in the comet’s coma which should be visible upon entering Earth’s atmosphere.

The orbit of 46P has a very low minimum orbit intersection distance (MOID) to Earth of just 0.071AU. The MOID between two objects that orbit a common point is the distance between the closest points of their orbits. The low MOID and the mm sized particles mean there is a high liklihood it could be the source of a meteor shower. Previous observations however have revealed no positive confirmation of peaks in 2017 and 2019.

During the 2017 and 2019 predictions, it seems the low velocity of the particles coupled with the radiant (the point of apparent origin of the shower) below the horizon suggest that visibility may have been severely limited. The radiant of this predicted shower is in the constellation Sculptor and the shower has been dubbed the Lambda Sculptorids.

The prediction for the 2023 shower, which predicted an encounter from a stream of debris from an outburst in 1974, suggested an outburst of meteors on December 12 between 12:08 and 20:06. A further outburst was predicted between 17:05 and 06:26 on December 13. The team who presented their findings in Astronomy and Astrophysics reported meteor activity as predicted and detected 23 meteors from the new shower on the night of December 12 2023. The team are now looking at the models to see what we might expect to see this year and whether Lamba Sculptorids need to be added to our list of annual meteor showers.

Source : Observations of the new meteor shower from comet 46P/Wirtanen

The post Astronomers Discover a New Meteor Shower. The Source is Comet 46P/Wirtanen appeared first on Universe Today.

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