Issued on: 25/09/2020 – 20:54Modified: 25/09/2020 – 20:52
As the US prepares to return humans to the Moon this decade, one of the biggest dangers future astronauts will face is space radiation that can cause lasting health effects, from cataracts to cancer and neurodegenerative diseases.
Though the Apollo missions of the 1960s and 1970s proved it was safe for people to spend a few days on the lunar surface, NASA did not take daily radiation measurements that would help scientists quantify just how long crews could stay.
This question was resolved Friday after a Chinese-German team published in the journal Science Advances the results of an experiment carried out by China’s Chang’E 4 lander in 2019.
“The radiation of the Moon is between two and three times higher than what you have on the ISS (International Space Station),” co-author Robert Wimmer-Schweingruber, an astrophysicist at the University of Kiel told AFP.
“So that limits your stay to approximately two months on the surface of the Moon,” he added, once the radiation exposure from the roughly week-long journey there, and week back, is taken into account.
There are several sources of radiation exposure: galactic cosmic rays, sporadic solar particle events (for example from solar flares), and neutrons and gamma rays from interactions between space radiation and the lunar soil.
Radiation is measured using the unit sievert, which quantifies the amount absorbed by human tissues.
The team found that the radiation exposure on the Moon is 1,369 microsieverts per day — about 2.6 times higher than the International Space Station crew’s daily dose.
The reason for this is that the ISS is still partly shielded by the Earth’s protective magnetic bubble, called the magnetosphere, which deflects most radiation from space.
Earth’s atmosphere provides additional protection for humans on the surface, but we are more exposed the higher up we go.
“The radiation levels we measured on the Moon are about 200 times higher than on the surface of the Earth and five to 10 times higher than on a flight from New York to Frankfurt,” added Wimmer-Schweingruber.
NASA is planning to bring humans to the Moon by 2024 under the Artemis mission and has said it has plans for a long term presence that would include astronauts working and living on the surface.
For Wimmer-Schweingruber there is one work-around if we want humans to spend more than two or three months: build habitats that are shielded from radiation by coating them with 80 centimeters (30 inches) of lunar soil.
© 2020 AFP
Trio returns to Earth after 6 months aboard International Space Station – CBC.ca
A trio of space travellers safely returned to Earth on Thursday after a six-month mission on the International Space Station.
The Soyuz MS-16 capsule carrying NASA astronaut Chris Cassidy, and Roscosmos’ Anatoly Ivanishin and Ivan Vagner landed on the steppes of Kazakhstan southeast of the town of Dzhezkazgan at 7:54 a.m. local time Thursday. After a brief medical checkup, the three will be taken by helicopters to Dzhezkazgan from where they will depart home.
The crew smiled as they talked to masked members of the recovery team, and NASA and Roscosmos reported that they were in good condition.
As part of additional precautions due to the coronavirus, the rescue team members meeting the crew were tested for the virus and the number of people involved in the recovery effort was limited.
Cassidy, Ivanishin and Vagner spent 196 days in orbit since arriving at the station on April 9.
NASA’s Kate Rubins and Roscosmos’ Sergey Ryzhikov and Sergey Kud-Sverchkov arrived at the orbiting outpost a week ago for a six-month stay.
Before the crew’s departure, Russian cosmonauts were able to temporarily seal the air leak they tried to locate for several months. The small leak has posed no immediate danger to the station’s crew, and Roscosmos engineers have been working on a permanent seal.
In November, Rubins, Ryzhikov and Kud-Sverchkov are expected to greet NASA’s SpaceX first operational Crew Dragon mission comprising NASA astronauts Mike Hopkins, Victor Glover and Shannon Walker, and Japan Aerospace Exploration Agency astronaut Soichi Noguchi. It follows a successful Demo-2 mission earlier this year.
Osiris-Rex: Nasa asteroid mission confident of success – BBC News
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.css-14iz86j-BoldTextfont-weight:bold;“We really did kind of make a mess.”
That was Dante Lauretta’s take after reviewing the first pictures to come down from .css-yidnqd-InlineLink:linkcolor:#3F3F42;.css-yidnqd-InlineLink:visitedcolor:#696969;.css-yidnqd-InlineLink:link,.css-yidnqd-InlineLink:visitedfont-weight:bolder;border-bottom:1px solid #BABABA;-webkit-text-decoration:none;text-decoration:none;.css-yidnqd-InlineLink:link:hover,.css-yidnqd-InlineLink:visited:hover,.css-yidnqd-InlineLink:link:focus,.css-yidnqd-InlineLink:visited:focusborder-bottom-color:currentcolor;border-bottom-width:2px;color:#B80000;@supports (text-underline-offset:0.25em).css-yidnqd-InlineLink:link,.css-yidnqd-InlineLink:visitedborder-bottom:none;-webkit-text-decoration:underline #BABABA;text-decoration:underline #BABABA;-webkit-text-decoration-thickness:1px;text-decoration-thickness:1px;-webkit-text-decoration-skip-ink:none;text-decoration-skip-ink:none;text-underline-offset:0.25em;.css-yidnqd-InlineLink:link:hover,.css-yidnqd-InlineLink:visited:hover,.css-yidnqd-InlineLink:link:focus,.css-yidnqd-InlineLink:visited:focus-webkit-text-decoration-color:currentcolor;text-decoration-color:currentcolor;-webkit-text-decoration-thickness:2px;text-decoration-thickness:2px;color:#B80000;Nasa’s Osiris-Rex probe following its bid to grab a sample from asteroid Bennu on Tuesday.
Dust and grit flew in all directions but that was good news, enthused the University of Arizona professor.
“Everything that we can see from these initial images indicates sampling success. So in case you can’t tell, I’m pretty excited.”
The principal investigator’s team now has to work out precisely how much material Osiris-Rex might have lifted from the surface of 500m-wide Bennu.
If it’s a kilo or more, it would represent the biggest extra-terrestrial sample cache since the Apollo astronauts gathered rocks from the Moon some 50 years ago.
But even a smaller amount would still be a great prize.
Bennu is a very primitive object, with chemistry preserved from the dawn of the Solar System more than 4.5 billion years ago. As such, it can tell us a great deal about how the Sun and the planets came into being.
Osiris-Rex used what had been described as a “reverse vacuum cleaner” to acquire its clutch of “soil”.
More properly called the Touch-and-Go Sample Acquisition Mechanism, or Tag-Sam, this device comprised a long boom with a ring-shaped collection chamber on the end.
The idea was to deliver a squirt of nitrogen when the Tag-Sam made contact with the asteroid.
The hope was this gas would stir up Bennu’s fragmented surface, leading to a considerable number of rocky pieces getting trapped inside the collection chamber.
The downlinked pictures certainly suggested the strategy was the right one.
Osiris-Rex may have been in contact with Bennu for only six seconds before retreating, but the sampling ring was flat and stable, and even pressing into the soil slightly. This should have maximised the chances of retaining material.
Rich Burns, Nasa’s project manager on the mission, lauded the the way his team managed to put the probe in just the right place on Bennu – almost exactly at the centre of the targeted sampling zone.
“We’re over 320 million km away from Earth at this point, and we touched this asteroid within a metre of where we intended to. So that’s extraordinary and a real credit to our team,” he told reporters.
On Thursday, engineers will command the spacecraft to take detailed pictures of the sampling ring to try to see what it contains.
And then on Saturday, they’ll make Osiris-Rex spin itself around with the Tag-Sam outstretched. Any extra mass on board will change the level of torque required to turn the probe, compared with the level that was needed to perform the same rotation exercise prior to sample acquisition.
“We are expecting a final sample mass measurement report on Monday,” explained Sandy Freund, the mission operations manager at Lockheed Martin, the company that manufactured Osiris-Rex.
It seems highly likely that Osiris-Rex has achieved its objective of taking at least 60g off Bennu. But if it hasn’t, there are two more nitrogen bottles still aboard the probe to facilitate further sampling bids. And there’s plenty of time, too.
The spacecraft is not scheduled to depart Bennu for Earth until April next year. A landing on Earth for any rock cache in this timeline would be late 2023.
Prof Lauretta once again on Wednesday’s paid tribute to the British scientist who conceived Osiris-Rex.
This was Bristol-born Michael Drake who held senior science positions at the University of Arizona in Tucson.
He worked up the concept for the mission but sadly died in 2011, aged 65, just months after Nasa had green-lit the project.
“I’m pleased to see that my dad’s legacy is being honoured at this exciting time in Osiris-Rex’s mission,” Michael Drake’s son, Matt Drake, told BBC News.
“My father’s idea to study near-Earth asteroids as a means of peering back in time to the birth of the Solar System finally came to fruition during [Tuesday’s] Tag event.
“As the principal investigator of this team from its inception until his passing almost 10 years later, he would have been incredibly proud of his team’s accomplishments.”
Osiris-Rex carries a plaque of remembrance to Michael Drake.
Rare 'blue moon' to appear on Halloween this year – Richmond News
The year 2020 has brought many surprises and this year’s Halloween is no different.
A rare “blue full moon” will be appearing on Halloween night this year.
While the moon will not look blue, the term “blue moon” is given when two full moons appear in a single month.
A full moon on Halloween occurs roughly once every 19 years – a pattern known as the Metonic Cycle.
The next illuminated Halloween full moon, says astronomers, after 2020 will be in the 2039, 2058, 2077 and 2096.
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