Space Sunday: Ultima Thule, Dream Chaser and capsule leaks

An artist’s impression of New Horizons passing Ultima Thule on January 1st, 2019. Credit: Adrian Mann/All About Space

On July 14th, 2015, NASA’s New Horizons vehicle, the front-end of the mission of the same name, made its closest flyby of Pluto and Charon (see Perfectly Pluto for more). Before, during and after the point of closest approach, the vehicle gathered huge amounts of data about Pluto, Charon and their attendant moonlets. Much of the data is still being studied, but in the years since the encounter, New Horizons has revolutionised our thinking about dwarf planets.

Since that time, the space vehicle has been travelling on out into the solar system at a speed of around 49,600 km/h (31,000 mph), and almost as soon as the Pluto flyby had been completed, with New Horizons still having plenty of power thanks to its nuclear batteries, astronomers started looking along its route for a possible follow-up target for examination.

After due consideration of options, a suitable target was selected. officially designated (486958) 2014 MU69, the object is a trans-Neptunian body located in the Kuiper belt. Of an elongated, shape, it is estimated to be around 30 km (18.75 mi), and might be a binary system of objects orbiting one another, although this is currently in doubt.

Discovered by astronomers using the Hubble Space Telescope in June 2014, just over a year before New Horizons reached Pluto, the object was unofficially dubbed “Ultima Thule” (Thule, in Greek and Roman literature, being the farthest north you could go, and “Ultima” being used to indicate “beyond”).  It was selected because of its relative proximity to the probe’s projected course out through the Kuiper belt, allowing it to be reached with minimal course corrections using the probe’s orientation thrusters.

The New Horizons journey. Credit: JHU/APL

The Kuiper belt is a massive ring of stellar objects surrounding the solar system between 30 and 55 AU distance (1 AU – astronomical unit –  being the average distance between the Sun and Earth). It is often regarded as the “outer edge” of our solar system, but the truth is, the solar system extends much, much further. Pluto and Charon are themselves Trans-Neptunian objects within the Kuiper belt.

The region – which might be described more as a doughnut than a belt – contains tens of thousands of objects (with more being discovered on almost a weekly basis). However, such is the volume of space they occupy, most are separated from one another by at least the distance separating Earth from the Sun. They are of great interest to astronomers, as they represent pristine material dating back to the very birth of the solar system, so studying them could tell us a lot more about the place in which we live.

The [Kuiper] belt is analogous to the solar system’s attic. It’s an ancient region, very far from the sun, which has been preserved in a deep freeze. It’s the equivalent of an archaeological dig into the history and formation of the planets. So, scientifically it’s a gold mine, and by going there with a spacecraft and observing KBOs up close, like we’ll be doing with Ultima, we hope to learn a lot about how the early formation stages of the planets took place.

– Alan Stern, New Horizons principal investigator

However, New Horizons won’t have long to study Ultima Thule in detail. If all goes well, the vehicle will blaze past the object on New Year’s Day 2019, at 05:33 GMT), travelling far too fast to slow down. At its closest approach, the probe will be some 3,540 km (2,200 mi) from Ultima Thule, which will appear about as large to it as the full Moon does to observers on Earth. As currently takes 6 hours and 8 minutes for a signal to reach Earth from New Horizons, it means that – as with its Pluto encounter – the probe will be working on an automated basis and pre-programmed commands throughout the encounter.

Simulation of anticipated images the LORRI camera aboard New Horizons vehicle will capture during the close approach to Ultima Thule

Even so, astronomers around the world are eagerly awaiting the encounter, as very little in known about Ultima Thule, and what New Horizions has apparently discovered as it approaches this tiny rock – it is too small to even classify as a dwarf planet – has already piqued interest.

What we know of the trans-Neptunian region is that it’s the leftover remnants of the objects that didn’t make it into being planets. These little rocky and icy worlds were formed in the initial disc of material around the sun, the ones that never grew up into being planets in their own right. Since then, they’ve been sculpted by changes in the orbital positions of the giant planets, particularly Neptune. What we see there today are materials from that initial disc. Some of them are familiar, like water ice and rock, but some of them are unfamiliar, like kitchen cleaning chemicals you have under your sink, in solid form

– Michele Bannister, Outer Solar System Origins Survey, Queen’s University, Belfast

As noted earlier, it had been believed, from data gathered by Hubble, that Ultima Thule was an elongated, possibly binary, object. However, on December 20th, 2018, the New Horizons team reported that the light measured from 2014 MU69 is constant, as would be expected from a spherical body. This disparity between Hubble’s finding and those of New Horizons have yet to be explained.

One issue with the flyby has been the partial US Government shut-down that started on December 22nd, 2018, and which has impacted some of NASA’s public outreach feeds. To compensate, the Applied Physics Laboratory, responsible for designing and building New Horizons, and part of John Hopkins University, has taken over mission briefings and will provide live updates via the JHUAPL YouTube page for flyby events on Monday, December 31st 2018, and Tuesday January 1st, 2019. You can see a full schedule here.

Dream Chaser Cargo Production to Start

Sierra Nevada Corporation (SNC) received an early Christmas present from NASA just ahead of the US Government shut-down in December 2018, with the news that company’s Dream Chaser Cargo has passed its critical NASA Integrated Review 4. This means that SNC is now cleared to start work on constructing the first Dream Chaser Cargo vehicle intended to deliver supplies and equipment to the International Space Station (ISS), and which is pegged to fly in 2020.

Dream Chaser Cargo grew out of SNC’s bid to secure a contract to fly astronauts to and from the ISS as part of NASA’s Commercial Crew Transportation Programme, utilising a small spaceplane, launched atop a rocket but returning to Earth to make a conventional runway-style landing and capable of carrying up to 7 people. In 2014, NASA selected capsule designs by SpaceX and Boeing, earning SNC’s ire in the process, which resulted in a protest filed with the U.S. Government Accountability Office (GAO), pointing out that at the time, SNC’s work on Dream Chaser was significantly more advanced than Boeing’s work on the CST-100 capsule, and could be completed at a lower cost. As the protest was unsuccessful, SNC turned their attention to other potential uses for Dream Chaser and NASA approached them about using the vehicle in an uncrewed capacity to deliver cargoes to, and return experiments and equipment from, the ISS.

SNC’s uncrewed Dream Chaser Cargo spaceplane and the external cargo module, which will also supply electrical power to the vehicle. Credit: SNC

In 2016, NASA confirmed Dream Chaser Cargo had been selected to fly resupply missions to the ISS alongside SpaceX and Orbital ATK, allowing SNC to start work on re-developing the vehicle to carry cargo and operate almost on an entirely automated basis. In 2017, the company resumed drop tests on a test article to confirm the vehicle’s aero-handing and landing capabilities, and it was also announced that the United Nations had selected a Dream Chaser Cargo to fly the first-ever UN mission into space.

When operational, Dream Chaser Cargo will be launched atop the United Launch Alliance Atlas V, and will be capable of flying up to 5.5 tonnes of cargo to the International Space Station, both within the vehicle and in an external cargo module which sits between the Dream Chaser and its launcher, and which also includes a docking mechanism for berthing with the ISS. In addition to carrying supplies to the station, this external module can carrying up to 3.4 tonnes of waste from the station; on a return flight to Earth, the module is jettisoned by the spaceplane and  allowed to burn-up in the Earth’s atmosphere prior to Dream Chaser making a controlled re-entry and landing, bringing with it up to 1.85 tonnes of equipment and experiments with it.

Artist’s impression of Dream Chaser Cargo docked with the ISS. Credit: SNC

The United Nations mission will feature science missions from countries that have no space access or space programmes of their own and will last some 2 weeks, but will not feature any docking with the ISS. Beyond the ISS and UN mission, SNC is actively seeking other launch opportunities for Dream Chaser  – including a possible mission using the crewed variant to fly a Hubble Space Telescope.

News of this latter idea first surfaced in February 2017 as a suggestion from SNC, however, it appears the Trump Administration is considering the idea, despite such a mission having significant issues. For example, Hubble is designed to be serviced within the cargo bay of the much bigger space shuttle,, where it can be held within a special support frame and logistics as a whole are far easier to manage, with astronauts able to use suitable servicing platforms, including the shuttle’s own robotic arm. No only would a crew using Cream Chaser have to manage without any of these advantages (increasing the risk of damage to the telescope), they would also be limited in the equipment and parts they’d be able to carry aloft.

Soyuz Hole “Drilled From The Inside”

Back in August, the crew of aboard the ISS were informed by mission control that the station was suffering a slight loss of pressure due to a possible leak. The problem was ultimately traced to a 2mm hole puncturing the skin of one of the Soyuz vehicles docked at the station, and a fix for the hole was made.

Following the event, the rumour mill went into overdrive. Originally, it had been thought the hole in orbital module of Soyuz MS-09 was thought to be the result of a MMOD – a MicroMeteoroid (tiny piece of orbiting rock weighing less than a gramme but travelling at high-speed) or a piece of Orbital Debris (a tiny fragment from a space mission). But within days of the event, it was being claimed the hole might have been deliberately cut. These rumours grew as they were repeated by the director of the Russian space agency Roscosmos, Dmitry Rogozin, and by former cosmonaut turned politician, Maxim Suraev, who suggested that not only was the hole deliberate, it has been cut while the vehicle was in orbit, due to the “insanity” of one of the crew on the ISS. Such claims have since been walked back, but at the time, they were very unwelcome on the American side of the fence, with the (then) US mission commander making some very forthright comments during a broadcast from the station.

Soyuz MS-09 docked at the International Space Station. The hole that caused the leak was located in the spherical orbital module, which contains the docking mechanism and primary airlock of the vehicle. Soyuz MS-11 can also be seen docked with the ISS. Credit: Roscosmos / Oleg Artemyev

On December 11th, 2018, the damaged vehicle was due to return to Earth. However, while the repair posed no threat to any crew on the Soyuz – the hole was in the Orbital Module, designed to be jettisoned and left to burn-up in Earth atmosphere on a return to Earth – an EVA took place to allow cosmonauts to view the hole from the outside of the vehicle.

This space walk was completed by Oleg Kononenko and Sergei Prokopyev – who had been aboard the ISS at the time of the leak  – and involved them unsealing the thermal insulation and meteorite shield on the spacecraft to inspect the hole more closely, take digital images of it and gather samples from the surrounding skin of the module. Prolopyev then brought the images and samples back to Earth for examination aboard Soyuz MS-09.

Speaking at a conference on December 20th, 2018, the cosmonaut confirmed the hole appeared to have been drilled from inside the capsule. However, he dismissed any idea that it had been done while the vehicle was in space or that any of the crew on the ISS had been responsible. Instead, he indicated the matter was now in the hands of Russian law enforcement agencies for detailed investigation. In the meantime, and following the launch abort of Soyuz MS-10, crewed flights to and from the ISS have resumed.

 

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