(MENAFN – The Conversation) There are many things humanity must overcome before any return journey to Mars is launched.
The two major players are NASA and SpaceX, which work together intimately on missions to the International Space Station but have competing ideas of what a crewed Mars mission would look like.
The biggest challenge (or constraint) is the mass of the payload (spacecraft, people, fuel, supplies etc) needed to make the journey.
We still talk about launching something into space being like launching its weight in gold.
The payload mass is usually just a small percentage of the total mass of the launch vehicle.
But it could launch only 140 tonnes (5% of its initial launch mass) to low Earth orbit, and 50 tonnes (less than 2% of its initial launch mass) to the Moon.
Mass constrains the size of a Mars spacecraft and what it can do in space. Every manoeuvre costs fuel to fire rocket motors, and this fuel must currently be carried into space on the spacecraft.
SpaceX’s plan is for its crewed Starship vehicle to be refuelled in space by a separately launched fuel tanker. That means much more fuel can be carried into orbit than could be carried on a single launch.
Another challenge, intimately connected with fuel, is time.
Missions that send spacecraft with no crew to the outer planets often travel complex trajectories around the Sun. They use what are called gravity assist manoeuvres to effectively slingshot around different planets to gain enough momentum to reach their target.
This saves a lot of fuel, but can result in missions that take years to reach their destinations. Clearly this is something humans would not want to do.
Both Earth and Mars have (almost) circular orbits and a manoeuvre known as the Hohmann transfer is the most fuel-efficient way to travel between two planets. Basically, without going into too much detail, this is where a spacecraft does a single burn into an elliptical transfer orbit from one planet to the other.
A Hohmann transfer between Earth and Mars takes around 259 days (between eight and nine months) and is only possible approximately every two years due to the different orbits around the Sun of Earth and Mars.
A spacecraft could reach Mars in a shorter time (SpaceX is claiming six months ) but — you guessed it — it would cost more fuel to do it that way.
Suppose our spacecraft and crew get to Mars. The next challenge is landing.
A spacecraft entering Earth is able to use the drag generated by interaction with the atmosphere to slow down. This allows the craft to land safely on the Earth’s surface (provided it can survive the related heating).
But the atmosphere on Mars is about 100 times thinner than Earth’s. That means less potential for drag, so it isn’t possible to land safely without some kind of aid.
A thruster landing on Mars. Life on Mars
A Martian day lasts 24 hours and 37 minutes but the similarities with Earth stop there.
The thin atmosphere on Mars means it can’t retain heat as well as Earth does, so life on Mars is characterised by large extremes in temperature during the day/night cycle.
Mars has a maximum temperature of 30℃, which sounds quite pleasant, but its minimum temperature is -140℃, and its average temperature is -63℃ . The average winter temperature at the Earth’s South Pole is about -49℃ .
So we need to be very selective about where we choose to live on Mars and how we manage temperature during the night.
The gravity on Mars is 38% of Earth’s (so you’d feel lighter) but the air is principally carbon dioxide (CO₂) with several percent of nitrogen, so it’s completely unbreathable. We would need to build a climate-controlled place just to live there.
Return to Earth
The final challenge is the return journey and getting people safely back to Earth.
Apollo 11 entered Earth’s atmosphere at about 40,000km/h, which is just below the velocity required to escape Earth’s orbit.
Spacecraft returning from Mars will have re-entry velocities from 47,000km/h to 54,000km/h, depending on the orbit they use to arrive at Earth.
They could slow down into low orbit around Earth to around 28,800km/h before entering our atmosphere but — you guessed it — they’d need extra fuel to do that.
If they just barrel into the atmosphere, it will do all of the deceleration for them. We just need to make sure we don’t kill the astronauts with G-forces or burn them up due to excess heating.
These are just some of the challenges facing a Mars mission and all of the technological building blocks to achieve this are there. We just need to spend the time and the money and bring it all together.
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SpaceX's first 'rideshare' mission will launch a record number of satellites – Engadget
The SpaceX Transporter-1 mission set to launch today will put 133 commercial and government spacecraft, as well as 10 more Starlink satellites, in orbit. SpaceX says that’s “the most spacecraft ever deployed on a single mission” — the previous record holder, an Indian Polar Satellite Launch Vehicle, ferried only 104 satellites to space. In addition to having a record-breaking payload, Transporter-1 is also the first dedicated launch under the SmallSat Rideshare Program SpaceX announced back in 2019.
Launching many small satellites for a wide range of customers tomorrow. Excited about offering low-cost access to orbit for small companies! https://t.co/NrXmBML747
— Elon Musk (@elonmusk) January 22, 2021
The SmallSat program offers companies and government agencies an affordable way to get their CubeSats, microsats and other small spacecraft to orbit. Its prices start at $2.5 million for payloads up to 150 kg (330 lbs). The program’s customers typically just hitch a ride on other Falcon 9 launches, and this is the first time they’re the main point of a mission. As for the Starlink satellites aboard the flight, they’ll be the first in the constellation to deploy to a polar orbit.
On Twitter, SpaceX chief Elon Musk said Transporter-1 “is getting even more scrutiny than a Starlink flight” because so many companies are depending on it to go off without a hitch.
Given so many other companies are depending on this mission, it is getting even more scrutiny than a Starlink flight
— Elon Musk (@elonmusk) January 23, 2021
SpaceX will open Transporter-1’s launch window later today, January 23rd, at 9:40AM Eastern. The mission will lift off from Space Launch Complex 40 at Cape Canaveral Space Force Station in Florida, and the company will livestream the event starting about 15 minutes before liftoff. You’ll be able to watch the launch as it happens in the video below:
SpaceX's first 'rideshare' mission will launch a record number of satellites – Yahoo Movies Canada
Swimming Australia has started discussions about a replacement domestic or virtual international competition for its athletes in case the Tokyo Olympics are cancelled, president Kieren Perkins said. Perkins, who won gold medals at the 1992 and 1996 Games, was delighted that Friday’s “little moment of panic” had been firmly quashed but felt he owed it to Australia’s swimmers to put a contingency plan in place. “If the worst happens and Tokyo is cancelled, for our athletes who have had the opportunity to prepare and work so hard for so long to get to this moment, I think it behoves us to give them the best chance to at least test themselves and see what that work has created,” he told the Australian newspaper.
Elon Musk's Starlink satellite service is being beta tested in BC – BC News – Castanet.net
It may come as a shock to some but only 36 per cent of rural households in British Columbia have access to reliable high-speed internet service.
That is changing, however, thanks to Elon Musk’s Starlink, satellite internet is now available, depending on where you live.
Starlink is a new high-speed internet service provided by U.S.-based SpaceX, which has launched nearly 900 satellites into a low-Earth orbit over the past year.
If you live within the right coordinates you can now apply to be part of Starlink’s satellite internet beta testing program.
- Province Latitudes (°N)
- Alberta 49.0 – 51.5
- British Columbia 48.4 – 51.7
- Manitoba 49.0 – 51.1
- New Brunswick 45.3 – 47.6
- Nova Scotia 45.0 – 46.0
- Ontario 43.1 – 51.0
- Saskatchewan 49.6 – 50.7
Once approved, users can purchase the necessary hardware which costs $649 for the satellite dish and $129 per month.
SpaceX began the public beta program in October and some subscribers are reporting service speeds of up to 150Mbps. The Canadian Radio-Television and Telecommunication Commission granted Starlink’s operator, SpaceX, a Basic International Telecommunications Service license in October 2020. The license allows SpaceX to provide telecommunication services in Canada but does not allow the company to operate as an internet service provider.
SpaceX has said it will cost U.S. $10 billion or more to build the network but industry analysts have estimated that Starlink could earn as much as $30 billion a year once it is fully operational.
The Starlink satellites float at low-Earth orbit, which cuts down on signal latency and allows the satellites to return to earth with greater ease once they’re decommissioned.
Stargazers have expressed concern that the satellites could obscure the view of the night sky.
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SpaceX's first 'rideshare' mission will launch a record number of satellites – Engadget
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