Recent Space Developments
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Written by: Miguel Rico, in collaboration with Suzanne Monir, EIS Education Team Members, January 2016
Title of Lesson: Recent Space Developments - SpaceX, CubeSats, Philae, Orbital Debris, How to Set Up Your Experiment
Topic: Engineering, Experiment Design, Orbital Mechanics, Rockets, Space Debris
Grade (Age) Level: High School (Ages 14-18), UniversityRecent Space Developments:
In recent times, there has been a great deal of development in space, arguably, after a period of space development stagnation lasting several decades. Some of the more recent developments will be summarized here to help guide you in creating potential microgravity experiments. In order to better understand where you believe your innovations will be the most useful, this course has been created to help you understand recent innovations and where our technology has taken us.-
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How to Brainstorm for Your Experiment:
Identify problems for Earth and/or space.
Identify the space environment factors (microgravity, radiation, vacuum) that could help you explore your chosen problem.
Determine how your experiment will contribute to a viable solution to the problem.
Identify the constraints of the experiment format.
Eliminate overly complex designs and make sure your experiment is subject to as few uncontrollable variables as possible.
Determine the data gathering and analysis methods that will be implemented.
Plan for possible contingency scenarios and be flexible in the experiment procedure.
- Optimize the experiment if needed.
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Written by: Miguel Rico and Suzanne Monir, EIS Education Team Members, January 2016
Title of Lesson: Recent Space Development
Topic: SpaceX,
Grade (Age) Level: High School (Ages 14-18), UniversityNote: for greater detail on rocket reusability and spacecraft design, please go to the Rocketry course.
SpaceX’s long-term goal is to make life multi-planetary. To achieve this, a large transfer of people and material to Solar System objects such as planets, moons and asteroids, will be necessary. It is not enough, however, to have the rockets to put large payloads into orbit. Economic viability is also a very important consideration. Arguably, cost is the single greatest obstacle to widespread space exploration and use.
Rockets, and by extension spaceflight, are expensive. At best, the current price per kg for current orbital launch systems lies at around $4000 [1,4]. But why? Refuelling the rocket, even when accounting for expensive fuels, costs less than 0.5% of the total rocket cost [3,4]. Flight operations for relatively high flight rates also do not make a significant contribution. In fact, most of the cost of a rocket can be attributed to the cost of the rocket hardware (i.e. rocket structure, engines, avionics, etc.). The reason spaceflight is so expensive is that, traditionally, multi-million rockets have been discarded after flights lasting fewer than 10 minutes [5]. This means that a great percentage of the $60 million [1,3,4] - at the current best - needed to build and launch a multi-ton payload rocket ends up crashing into oceans or deserts or burning up in the atmosphere. This is the equivalent of disposing of an aircraft or car after a single journey and needing to build another vehicle from scratch for the next. The conclusion that we can draw from this analysis is that reusability has the potential to drastically lower the costs of using a given transportation system.
There have been several proposed concepts to reuse rockets, ranging from rocket booster flyback [6] to mid-air engine recovery [7] and propulsive vertical landing [8].
Figure 1: This table by Raymond James shows 3 of the many reusability concepts currently under consideration
or
development.
Some other noteworthy mentions include Skylon, an air-breathing single-stage-to-orbit (SSTO) spaceplane that makes use of a novel engine cycle called SABRE [9]; the Baikal booster, a Russian proposal that would make use of wings for a horizontal landing [6]; and Escape Dynamics' recently discontinued microwave-powered SSTO vehicle [10,11]. Also, please note that 80-90% of targeted rocket cost savings for the Falcon 9 rocket is likely to be an overestimate, as the first stage of the rocket (the only one under serious consideration for reusability) costs approximately 75% of the total rocket hardware cost. Moreover, SpaceX's COO Gwynne Shotwell has said that it could offer a Falcon 9 rocket with a reused Falcon 9 stage for around $40 million.The problem with reusability is that the addition of recovery systems subtracts from the useful payload you can carry into orbit. Already, it is difficult to design a rocket that is able to withstand strong vibrations, aerodynamic loads and hundreds of degrees of temperature difference and that can put approximately 2% to
4% of rocket mass into orbit [12,13]*. Adding recovery systems such as landing systems, aerodynamic flight control surfaces and extra fuel might result in zero or even negative payload to orbit. The challenge for rocket reusability has therefore been to engineer a rocket that, even when outfitted with recovery systems, is able to carry useful payloads to orbit*.*To find out why rocket reusability is a somewhat easily achievable goal, check out the rocketry course!
SpaceX is one of the companies that has been pursuing rocket reusability. For now, the most easily recoverable part of the rocket, and also the most costly, is the first stage. It bears approximately 75% of the rocket's cost [14]. Through incremental steps, the propulsive landing recovery of SpaceX’s Falcon 9 first stage has become more and more likely. Firstly, there were the Falcon 9 Reusable Test and Grasshopper technology-demonstrator programs [15]. Modified Falcon 9 first stages were launched and subjected to different flight conditions, such as ascent to varying altitudes, hovering, diversion maneuvers, subsonic to supersonic speed transitions and landings.
Credit: SpaceX (click for greater resolution)
The insight gained during these tests was useful for the next stage of SpaceX’s reusability program: water landings (see above). After the first stage separated from the rocket, it performed a series of orientation maneuvers and burns needed to properly orient the rocket for atmospheric re-entry and to cancel out some of the velocity acquired during ascent [16]. Grid fins and one Merlin engine then guided the stage for its soft landing on the Atlantic Ocean [16].
These, partly successful experimental landings were then followed by landing attempts over stabilized, autonomous, floating landing platforms. During the first attempt, the first stage ran out of a hydraulic fluid needed to steer the grid fins and, as a result, the rocket impacted the barge in a forceful and uncontrolled manner [17,18,19].
The second attempt was marked by a thrust-controlling valve malfunction which resulted in the first stage tipping over after it descended with the incorrect attitude and excess lateral velocity [17,18].
The next rocket mission, which was intended to resupply the International Space Station, ended in an explosion (or a Rapid Unscheduled Disassembly (RUD) as SpaceX calls it) after a strut supporting a helium tank broke, leading to an overpressurization and subsequent disintegration of the second stage [19,20].
The next landing attempt occurred over land at SpaceX’s Landing Zone 1 complex. This mission marked the return to flight of SpaceX, the first flight of a significantly upgraded Falcon 9 rocket and the first successful landing and full recovery of an undamaged orbital-class first stage [19].
One of the more recent attempted landings on the autonomous barge platform resulted in failure when, due to ice buildup caused by fog condensation at the launch pad, a latch was unable to properly secure a landing leg [18,19]. This in turn caused the stage to tip over and explode.
As of late, however, two rocket stages were able to be recovered in the autonomous platform. The first of which occurred on April 8th, and was able to execute relatively comfortable recovery maneuvers as it came from Low Earth orbit (LEO), an orbit that does not require the rocket to reduce its available fuel margins to dangerously low levels. The second recent recovery, on the other hand, required a more demanding return flight profile. For example, to conserve fuel, the rocket used three rocket engines instead of the usual one to decelerate from supersonic speeds to touching down on the barge in just 15 seconds - 3 more seconds and it would have run out of propellant and crashed. The booster also dispensed with a boost-back burn, something that caused the booster to experience 8 times as much as heating as in previous recovery attempts.
April 8th mission's Falcon 9 first stage after landing on a ship in the Atlantic (high resolution) Credit: SpaceX
More such attempts are planned, and Elon Musk, co-founder and CEO of SpaceX, has said that a recovered stage may be reflow as soon as June of 2016. This would mark the first time any entity in the history of spaceflight has reflown an orbital-class rocket booster. Overall, Musk estimates that the success rate for rocket recovery will be about 70% for 2016 and rise to 90% in 2017 [21]. Second stage reusability should eventually follow suit (at least with future rocket designs), as will manned flights aboard the 7-crew Dragon V2, a spacecraft that will enable missions to the ISS in 2017, Mars in 2018 and possibly even the Jupiter moon Europa [22].
Hypothetical SpaceX rocket boosters landing on Earth, SHLV returning - Credit: Stanley Von Medvey
SpaceX Dragon V2 Mars Landing - Credit: ChrisMonson
SpaceX will continue to try to recover Falcon rocket first stages. While it is not the only company or government agency attempting to develop viable rocket reusability, currently, SpaceX is the company that can provide the highest potential launch cost savings in the shortest amount of time (see Rocket Reusability Initiatives above). Already, and even without reusability, SpaceX is at the forefront of lowering launch costs. With full, cost-effective and rapid reusability planned, launch costs should decline even further, low enough, in fact, to enable viable, long-term access to space, thus enabling greater space exploration and perhaps even a new, even more exciting, space age.
* SpaceX's upgraded reusable Falcon 9 v1.1 rocket has a payload fraction of 4.15% (payload 22800 kg and 549 054 kg total mass) while the Saturn V, the heaviest rocket to successfully reach orbit (flown in the 1960s and 70s), had a payload fraction of 4.71% (payload 140 000 kg and 2 970 000 kg total mass). How can two seemingly very different rockets with a more than 40 year age difference be so similar? Check out the rocketry course to find out!
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This section of the course serves to explore a very useful standard for remote experimentation, and to give you an overview of some of the most innovative projects that have been, or are intended to be, performed. Key to this experiment standard is the miniaturization of components, off-the-shelf technologies, and the use of automated systems for the handling of experiment materials. Such has been the success of CubeSats, that they can be used (among the many, many uses there exist) to explore planetary atmospheres and asteroids, test novel propulsion systems such as solar sails and miniaturized plasma thrusters, and perform experiments on dangerous biological samples.
Cube satellites, often called CubeSats, are miniaturized satellites made for space research. The advent of standardization and miniaturization in space equipment, as evidenced by the CubeSat standard, is lowering barriers to new forms of space research. These CubeSats are made up of multiples of 10×10×11 cm cubic units, and typically weigh less than 1.33 kilograms per unit. Their small, standard size, negligible weight and the fact that most of them are flown as auxiliary payloads, means that costs can greatly be lowered. Projects that can more cheaply monitor climate, outer space and perform experiments that could possibly be hazardous if there were any human interaction involved can thus be carried out relatively cheaply. In addition to the EIS spacecraft, EIS will launch CubeSats for experiments that are better suited to the CubeSat standard and protocol.
The video below explains what can be done with a CubeSat:
What can you do with a cubesat? Credit: DIY Space Exploration
Here are a few outstanding CubeSat projects:
A. The CubeSat Ambipolar Thruster
In the CubeSat Ambipolar Thruster (CAT), water is ionized into a plasma with the use of a Radio Frequency (RF) antenna which gets its energy from solar panels. The plasma is then guided by a magnetic nozzle using permanent magnets. This in turn produces thrust. While very small, minute thrust levels sustained over long periods of time enable spacecraft using such a type of electric propulsion to reach greater speeds than what would be possible by using an equivalent mass of chemical propellant. This means that, the payload can be maximized for a given weight, or that the cost can be minimized by employing less mass for the same payload.
For more information, see the sources below.
http://pepl.engin.umich.edu/thrusters/CAT.html
B. LightSail
LightSail is a three-unit CubeSat which is able to use the momentum imparted by photons to produce thrust. To do so, it employs 4 triangular pieces of 4.5 micron thick Mylar film which are extended by unwinding metal booms.
Deployed LightSail rendering - Credit: The Planetary Society
LightSail team members Alex Diaz and Riki Munakata preparing the
spacecraft for a sail deployment test - Credit: The Planetary Society
C. Mars Cube One (MarCO) CubeSats
Mars Cube One (MarCO) will be the first interplanetary CubeSat mission. It consists of two 6U CubeSats that, after separating from the Atlas V booster launching the InSight robotic lander, will fly under their own propulsion to Mars. These CubeSats will gather and transmit data during the few, critical minutes during which the InSight lander, the main payload, goes from atmospheric entry to landing on the Martian surface.
MarCO CubeSats providing an experimental relay to inform Earth of
the landing of of the InSight Mars Lander - Credits: NASA/JPL-Caltech
Sources for Mars Cube One:
http://www.nasa.gov/press-release/nasa-prepares-for-first-interplanetary-cubesats-on-agency-s-next-mission-to-mars NASA Prepares for First Interplanetary CubeSats on Agency's Next Mission to Mars
http://www.jpl.nasa.gov/cubesat/missions/marco.php Mars Cube One
http://www.jpl.nasa.gov/spaceimages/details.php?id=pia19388 Interplanetary CubeSat for Technology Demonstration at Mars (Artist's Concept)
D. Asteroid Impact Mission
The Asteroid Impact Mission would fly several CubeSats enclosed within a larger spacecraft to the Didymos asteroids, a binary asteroid system. This mission's objectives could include taking a "close-up look at the composition of the asteroid surface, measuring the gravity field, assessing the dust and ejecta plumes created during a collision, and landing a CubeSat for seismic monitoring" [1]. Thermal imaging and the use of low and high frequency radar could also be used to explore the thermal properties as well as the surface and interior structure of the asteroid(s) [2]. Laser optical communications are also expected to form part of the mission.
AIM (Asteroid Impact Mission) networking with CubeSats - Credit: ESA - ScienceOffice.org
Sources for AIM:
E. Skyfire, Lunar Ice Cube, Lunar Flashlight, LunaH-Map and other Exploration Mission-1 CubeSats
When NASA's Space Launch System makes its first flight (Exploration Mission-1) in 2018, it will be carrying 13 CubeSats of different purposes to various destinations. Skyfire will perform a flyby of the Moon and collect infrared sensor data, Lunar Ice Cube and Lunar Flashlight will search for water and other resources on the Moon from orbit, and LunaH-Map will map hydrogen within craters and other permanently shadowed regions throughout the moon's south pole. Other CubeSats include the Near-Earth Asteroid Scout (NEA Scout), which will do reconnaissance of an asteroid; BioSentinel, which will test the effects of prolonged deep space radiation on living organisms by using yeast; and CuSP, which will test the viability of a space weather monitoring network of spacecraft [1].
The Lunar Flashlight will examine the moon's surface for ice deposits and
identify locations where resources may be extracted - Credit: NASA
[1] http://www.jpl.nasa.gov/news/news.php?feature=4887 Six CubeSats with JPL Contributions Chosen for SLS Flight
Other CubeSat sources:
http://www.nasa.gov/mission_pages/cubesats/index.html
http://www.busek.com/cubesatprop__main.htm propulsion systems for CubeSats
http://amsat-uk.org/2013/11/29/firefly-cubesat-mission-to-study-lightning/ FireFly CubeSat Mission to Study Lightning
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Another recent accomplishment is the controlled landing of a man-made object on a comet. The achievement has lead to a better understanding of a comet's composition, structure and environment which will in turn help us understand how comets and other celestial objects have formed, how life may have originated, how we could extract resources from these objects and how we may be able to avoid an asteroid collision with our planet.
The $1.5 billion European Space Agency (ESA) comet lander mission consisted of a robotic laboratory lander (Philae) and the spacecraft (Rosetta) that carried it on an over 10-year, 6.5-billion-kilometre, multi-gravitational-slingshot-maneuver journey to the comet 67P/Churyumov-Gerasimenko. Once arrived at the comet, Rosetta released the ca. 100 kg Philae which, after descending for 7 hours, was intended to try execute a few maneuvers to anchor itself safely to the surface of the comet.
On November 11, 2014, however, things did not go as planned. Philae had to cope with a faulty thruster that was intended to counteract the bounce of the lander and the recoil of harpoons which weren't working either. This sent Philae on a tumbling path across the comet, impacting another 4 times over a 2 hour period.
Below you will find two videos. The first video shows the intended landing of Philae while the second displays a reconstruction of Philae's tumbling flight.
After coming to rest at a location approximately 1 km away from its intended landing spot (possibly in a shadowy crevasse), it became clear that the solar cells were not charging Philae's batteries, so a race began to make the most use of Philae before it entered hibernation some 60 hours after its landing. Incredibly, during those few hours, Philae managed to achieve over 80% of the planned scientific activities.
Here are some of the scientific contributions by Philae:
The lander's COSAC gas analyzer identified 16 different organic compounds, all of which are found in living things, and four of which (methyl isocyanate, acetone, propionaldehyde and acetamide) had never been detected on comets before (http://phys.org/news/2016-02-rocky-philae-comet-probe-raked.html).
Ptolemy, another instrument, detected water vapor, carbon monoxide, carbon dioxide and some organic compounds such as formaldehyde. Interestingly, some of the organic compounds detected by Philae's instruments play a key role in the formation of sugars, amino acids and nucleobases, which form the bases for known life.
The lander's ROLIS camera gathered data that allowed the surface characteristics of the intended landing site (Agilkia) and where it finally settled (Abydos). The latter's surface, for example, is composed of compacted dust and ice, while the former's surface is rather soft.
Surprisingly, the CONSERT radar instrument found that the consistency of the interior of the comet was that of a porous mix of dust and ice with a sufficiently low density to float on water on Earth.The magnetic properties of 67P/Churyumov-Gerasimenko were also determined. The ROMAP magnetometer could not identify a measurable magnetic field, which disputed the theory that magnetic forces could have played a key role in the accretion process of material in the photo-planetary disc.
While significant amounts of very valuable information were gathered, the ESA team hoped that when the comet approached perihelion, or its closest approach to the Sun, enough sunlight would reach Philae's solar panels to reestablish exploration of 67P/Churyumov-Gerasimenko. While Philae did awake on April 26th, 2015, it was unable to contact the Rosetta orbiter until June 13 and, following a series of sporadic communications caused by instrument complications, Philae communicated for the last time on July 9th, 2015. It is not known why the lander was unable to communicate. The transmitter and the communications antenna could be damaged or be pointing in the wrong direction. Philae could be buried by rubble or an ice cliff, or excessive sunlight may have damaged its electronics.
These theories may be proven or refuted around September of 2016, when the Rosetta orbiter descends for improved measurement-taking, effectively ending the mission. This is because, around that time, the temperatures will drop below the lander's and the orbiter's operational threshold and will mean that an awakening from hibernation will be considered extremely unlikely. However, until that time, Rosetta will continue to gather data on the composition and properties of 67P/Churyumov-Gerasimenko, perhaps reveal the final fate of Philae, and advance our knowledge of how the Solar System and life on Earth could have formed.
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Sending spacecraft, satellites, probes and other useful payloads into orbit produces space debris. Among others, it may be made up of the (abandoned) payloads themselves once they have reached the end of their useful life, spent rocket stages, and specks of paint or propellant. As of September 2015, more than 1300 active satellites orbit the Earth [1]. This number, however, represents only about a third of all satellites currently in orbit [2]. What is more, as of 2013, explosions of upper stages and spacecraft alone are estimated to have produced about 600 000 objects of around 1 cm in size [2].
The problem with these artificial, orbital objects is their potential for destruction. Collisions of relative velocities of more than 10km/s [3] with even a 1 cm large object can become a life hazard or put communications satellites out of service. In fact, the ISS has had to employ several collision avoidance maneuvers by firing onboard rocket engines to avoid damage to the orbital outpost and its crew. Even worse, the collision between two satellites can create thousands of pieces of debris, which then end up spreading out in their orbits. The generated debris in itself has the potential for rapidly increasing destruction. This scenario of runway debris generation, which could render space activities impractical, is known as the Kessler syndrome.
The best way to deal with such a problem is to stop exacerbating it. Placing unused satellites in a graveyard orbit at the end of their lifetime or redirecting them for atmospheric reentry and burn-up are easily implemented solutions, as is not testing anti-satellite weapons in space. Draining batteries and emptying fuel tanks to avoid explosions are also effective measures. However, given current levels of debris and space activities, such mitigation measures will not be enough to prevent a runaway scenario.
In fact, active debris removal (ADR) will be necessary to remove the debris already present in Earth orbit. By exerting forces on the debris, it is possible to move debris out of congested orbits into either a graveyard orbit or towards Earth, where a substantial increase in atmospheric drag will cause orbit decay and reentry of the space debris. The former could be accomplished by small, solar-powered orbital removal objects using highly fuel-efficient ion thrusters. The latter, bringing orbital debris closer to Earth, can be accomplished in several ways. One is to use physical capture mechanisms, whereby the orbital removal object physically comes in contact with the debris, either through nets, hooks, grapples or some other physical method. Once attached, a solar sail could increase the object’s drag, therefore accelerating the decay of the object. Small rocket motors, chemical or electrical, could also perform such tasks. Decreasing the kinetic energy of an object can also be accomplished by using pulses of atmospheric gases produced by high-altitude balloon platforms, lasers that ablate the surface of the debris, and even electrodynamic tethers that exert magnetic forces on the objects they are attached to as they pass through Earth’s magnetic field.
Space Debris - How it Got There, What To Do About It?
Space Debris: 1957 - 2015
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New Horizons is an interplanetary space probe.
