Colonizing the Inner Solar System

In this epic, 2-part episode, we team up with Isaac Arthur to imagine how humans will colonize the inner Solar System, becoming a true spacefaring civilization.

The post Colonizing the Inner Solar System appeared first on Universe Today.

On The Origin Of Phobos’ Groovy Mystery

Phobos

Mars’ natural satellites – Phobos and Deimos – have been a mystery since they were first discovered. While it is widely believed that they are former asteroids that were captured by Mars’ gravity, this remains unproven. And while some of Phobos’ surface features are known to be the result of Mars’ gravity, the origin of its linear grooves and crater chains (catenae) have remained unknown.

But thanks to a new study by Erik Asphaug of Arizona State University and Michael Nayak from the University of California, we may be closer to understanding how Phobos’ got its “groovy” surface. In short, they believe that reaccretion is the answer, where all the material that was ejected when meteors impacted the moon eventually returned to strike the surface again.

Naturally, Phobos’ mysteries extend beyond its origin and surface features. For instance, despite being much more massive than its counterpart Deimos, it orbits Mars at a much closer distance (9,300 km compared to over 23,000 km). It’s density measurements have also indicated that the moon is not composed of solid rock, and it is known to be significantly porous.

Because of this proximity, it is subject to a great deal of tidal forces exerted by Mars. This causes its interior, a large portion of which is believed to consist of ice, to flex and stretch. This action, it has been theorized, is what is responsible for the stress fields that have been observed on the moon’s surface.

However, this action cannot account for another common feature on Phobos, which are the striation patterns (aka. grooves) that run perpendicular to the stress fields. These patterns are essentially chains of craters that typically measure 2o km (12 mi) in length, 100 – 200 meters (330 – 660 ft) in width, and usually 30 m (98 ft) in depth.

In the past, it was assumed that these craters were the result of the same impact that created Stickney, the largest impact crater on Phobos. However, analysis from the Mars Express mission revealed that the grooves are not related to Stickney. Instead, they are centered on Phobos’ leading edge and fade away the closer one gets to its trailing edge.

For the sake of their study, which was recently published in Nature Communications, Asphaug and Nayak used computer modelling to simulate how other meteoric impacts could have created these crater patterns, which they theorized were formed when the resulting ejecta circled back and impacted the surface in other locations.

As Dr. Asphaug told Universe Today via email, their work was the result of a meeting of minds that spawned an interesting theory:

“Dr. Nayak had been studying with Prof. Francis Nimmo (of UCSC), the idea that ejecta could swap between the Martian moons. So Mikey and I met up to talk about that, and the possibility that Phobos could sweep up its own ejecta. Originally I had been thinking that seismic events (triggered by impacts) might cause Phobos to shed material tidally, since it’s inside the Roche limit, and that this material would thin out into rings that would be reaccreted by Phobos. That still might happen, but for the prominent catenae the answer turned out to be much simpler (after a lot of painstaking computations) – that crater ejecta is faster than Phobos’ escape velocity, but much slower than Mars orbital velocity, and much of it gets swept up after several co-orbits about Mars, forming these patterns.”

Basically, they theorized that if a meteorite stuck Phobos in just the right place, the resulting debris could have been thrown off into space and swept up later as Phobos swung back around mars. Thought Phobos does not have sufficient gravity to reaccrete ejecta on its own, Mars’ gravitational pull ensures that anything thrown off by the moon will be pulled into orbit around it.

Once this debris is pulled into orbit around Mars, it will circle the planet a few times until it eventually falls into Phobos’ orbital path. When that happens, Phobos will collide with it, triggering another impact that throws off more ejecta, thus causing the whole process to repeat itself.

In the end, Asphaug and Nayak concluded that if an impact hit Phobos at a certain point, the subsequent collisions with the resulting debris would form a chain of craters in discernible patterns – possibly within days. Testing this theory required some computer modelling on an actual crater.

Using Grildrig (a 2.6 km crater near Phobos’ north pole) as an reference point, their model showed that the resulting string of craters was consistent with the chains that have been observed on Phobos’ surface. And while this remains a theory, this initial confirmation does provide a basis for further testing.

“The initial main test of the theory is that the patterns match up, ejecta from Grildrig for example.” said Asphaug. “But it’s still a theory. It has some testable implications that we’re now working on.”

In addition to offering a plausible explanation of Phobos’ surface features, their study is also significant in that it is the first time that sesquinary craters (i.e. craters caused by ejecta that went into orbit around the central planet) were traced back to their primary impacts.

In the future, this kind of process could prove to be a novel way to assess the surface characteristics of planets and other bodies – such as the heavily cratered moons of Jupiter and Saturn. These findings will also help us to learn more about Phobos history, which in turn will help shed light on the history of Mars.

“[It] expands our ability to make cross-cutting relationships on Phobos that will reveal the sequence of geologic history,” Asphaug added. “Since Phobos’ geologic history is slaved to the tidal dissipation of Mars, in learning the timescale of Phobos geology we learn about the interior structure of Mars”

And all of this information is likely to come in handy when it comes time for NASA to mount crewed missions to the Red Planet. One of the key steps in the proposed “Journey to Mars” is a mission to Phobos, where the crew, a Mars habitat, and the mission’s vehicles will all be deployed in advance of a mission to the Martian surface.

Learning more about the interior structure of Mars is a goal shared by many of NASA’s future missions to the planet, which includes NASA’s InSight Lander (schedules for launch in 2018). Shedding light on Mars geology is expected to go a long way towards explaining how the planet lost its magnetosphere, and hence its atmosphere and surface water, billions of years ago.

Further Reading: Nature Communications

The post On The Origin Of Phobos’ Groovy Mystery appeared first on Universe Today.

Time For NASA To Double Down On Journey To Mars

Artist concept of NASA’s Space Launch System (SLS) 70-metric-ton configuration launching to space. SLS will be the most powerful rocket ever built for deep space missions, including to an asteroid and ultimately to Mars. Credit: NASA/MSFC

Since the Authorization Act of 2010, NASA has been pushing ahead with the goal of sending astronauts to Mars by the 2030s. The latter part of this goal has been the subject of much attention in recent years, and for good reason. Sending crewed missions to the Red Planet would be the single-greatest initiative undertaken since the Apollo era, and the rewards equally great.

However, with the scheduled date for a mission approaching, and the upcoming presidential election, NASA is finding itself under pressure to show that they are making headway. Despite progress being made with both the Space Launch System (SLS) and the Orion Multi-Purpose Crew Vehicle, there are lingering issues which need to be worked out before NASA can mount its historic mission to Mars.

One of the biggest issues is that of assigned launched missions that will ensure that the SLS is tested many times before a crewed mission to Mars is mounted. So far, NASA has produced some general plans as part of it’s “Journey to Mars“, an important part of which is the use of the SLS and Orion spacecraft to send a crew beyond low-Earth orbit and explore a near-Earth asteroid by 2025.

This plan is not only intended to provide their astronauts with experience working beyond LEO, but to test the SLS and Orion’s capabilities, not to mention some vital systems – such as Solar Electric Propulsion (SEP), which will be used to send cargo missions to Mars. Another major step is  Exploration Mission 1 (EM-1), the first planned flight of the SLS and the second uncrewed test flight of the Orion spacecraft (which will take place on September 30th, 2018).

However, beyond this, NASA has only one other mission on the books, which is Exploration Mission 2 (EM-2). This mission will involve the crew performing a practice flyby of a captured asteroid in lunar orbit, and which is scheduled for launch in 2023. This will be the first crewed test of the Orion spacecraft, and also the first time American astronauts have left low-Earth orbit since the Apollo 17 mission in 1972.

While significant, these mission remain the only two assigned flights for the SLS and Orion. Beyond these, dozens more have been proposed as part of NASA’s three phase plan to reach Mars. For instance, between 2018 and the 2030s, NASA would be responsible for launching a total of 32 missions in order to send the necessary hardware to near-Mars space before making crewed landings on Phobos and then to Mars.

In accordance with the “Evolvable Mars Campaign” – which was presented last year by NASA’s Human Exploration and Operations Mission Directorate (HEOMD) – Phase One (the “Earth Reliant” phase) of this plan would involve two launches in 2028, which would be responsible for transporting a habitation module, an SEP module, and a exploration vehicle to cis-lunar space.

https://vimeo.com/31799422

This would be followed by two SLS flights in 2029, bringing the Trans-Earth Injection (TEI) stage to cis-lunar space, followed by a crew to perform the final checks on the Phobos Hab. By 2030, Phase Two (known as the “Proving Ground” phase) would begin with the last elements – the Earth Orbit Insertion (EOI) stage and taxi elements – being launched to cis-lunar orbit, and then all the equipment being sent to near-Mars space for pre-deployment.

By 2031, two more SLS missions would take place, where a Martian Hab would be launched, followed in 2032 by the launches of the Mars Orbit Insertion (MOI) and Trans-Mars Injection (TMI) stages. By 2033, Phase Three (the “Earth Independent” phase) would begin, where the Phobos crew would be transported to the Transit Hab, followed by the final crewed mission to the Martian surface.

Accomplishing all of this would require that NASA commit to making regular launches over the next few years. Such was the feeling of Bill Gerstenmaier – NASA’s Associate Administrator for Human Exploration and Operations – who recently indicated that NASA will need to mount launches at least once a year to establish a “launch cadence” with the SLS.

Mission proposals of this kind were also discussed at the recent Aerospace Safety Advisory Panel (ASAP) meeting – which meets annually to discuss matters relating to NASA’s safety performance. During the course of the meeting, Bill Hill – the Deputy Associate Administrator for Exploration Systems Development (ESD) in NASA’s Human Exploration and Operations Mission Directorate (HEOMD) – provided an overview of the latest developments in NASA’s planned mission.

By and large, the meeting focused on possible concepts for the Mars mission, which included using SEP and chemical propellants for sending hardware to cis-lunar space and near-Mars space, in advance of a mission to Phobos and the Martian surface. Two scenarios were proposed that would rely to these methods to varying extents, both of which called for a total of 32 SLS launches.

However, the outcome of this meeting seemed to indicate that NASA is still thinking over its long-term options and has not yet committed to anything beyond the mission to a near-Earth asteroid. For instance, NASA has indicated that it is laying the groundwork for Phase One of the Mars mission, which calls for flight testing to cis-lunar space.

However, according to Hill, NASA is currently engaged in “Phase 0” of the three phase plan, which involves the use of the ISS to test crew health via long duration space flight. In addition, there are currently no plans for developing Phases Two and Three of the mission. Other problems, such as the Orion spacecraft’s heatshield – which is currently incapable of withstanding the speed of reentry coming all the way from Mar – have yet to be resolved.

https://youtu.be/rx_dj8u3Pvg

Another major issue is that of funding. Thanks to the Obama administration and the passage of the Authorization Act of 2010, NASA has been able to take several crucial steps towards developing their plan for a mission to Mars. However, in order to take things to the next level, the US government will need to show a serious commitment to ensuring that all aspects of the plan get the funding they need.

And given that it is an election year, the budget environment may be changing in the near future. As such, now is the time for the agency to demonstrate that it is fully committed to every phase of its plan to puts boots on the ground of Mars.

On the other hand, NASA has taken some very positive strides in the past six years, and one cannot deny that they are serious about making the mission happen in the time frame it has provided. They are also on track when it comes to proving key concepts and technology.

In the coming years, with flight tests of the SLS and crewed tests of the Orion, they will be even further along. And given the support of both the federal government and the private sector, nothing should stand in the way of human boots touching red soil by the 2030s.

Further Reading: NASA Spaceflight.com

The post Time For NASA To Double Down On Journey To Mars appeared first on Universe Today.

How Many Moons Does Mars Have?

Many of the planets in our Solar System have a system of moons. But among the rocky planets that make up the inner Solar System, having moons is a privilege enjoyed only by two planets: Earth and Mars. And for these two planets, it is a rather limited privilege compared to gas giants like Jupiter […]

How Many Moons Does Mars Have?

Many of the planets in our Solar System have a system of moons. But among the rocky planets that make up the inner Solar System, having moons is a privilege enjoyed only by two planets: Earth and Mars. And for these two planets, it is a rather limited privilege compared to gas giants like Jupiter […]

How Many Moons Does Mars Have?

Many of the planets in our Solar System have a system of moons. But among the rocky planets that make up the inner Solar System, having moons is a privilege enjoyed only by two planets: Earth and Mars. And for these two planets, it is a rather limited privilege compared to gas giants like Jupiter […]

Dazzling Gallery From India’s MOM Mars Orbiter Camera

India’s first ever robotic explorer to the Red Planet, the Mars Orbiter Mission, more affectionately known as MOM, has captured an absolutely dazzling array of images of the fourth rock from the Sun. The Indian Space Research Organization (ISRO), India’s space agency, has recently published a beautiful gallery of images featuring a variety of picturesque […]

Weekly Space Hangout – May 15, 2015: Finding, Studying and Visiting Other Worlds!

Host: Fraser Cain (@fcain) Guests: Jolene Creighton (@jolene723 / fromquarkstoquasars.com) Brian Koberlein (@briankoberlein / briankoberlein.com) Dave Dickinson (@astroguyz / www.astroguyz.com) Morgan Rehnberg (cosmicchatter.org / @MorganRehnberg ) Alessondra Springmann (@sondy) (…)Read the rest of Weekly Space Hangout – May 15, 2015: Finding, Studying and Visiting Other Worlds! (501 words) © Fraser for Universe Today, 2015. | […]