As 2013 draws to a close, I’ve been doing the strangest thing I can imagine. I’ve been writing a page on balloons and rockets into space. It is by no means one of my more favored topics. In fact, writing this up feels strange. But given some space-oriented discussion questions I had seen in the last days, I felt I needed to set the physics and math straight.
It should be easy for most chemists, physicists, and engineers. But I had to realize that there were a lot more people interested in space than just those fields.
I was also doing penance for not providing a short answer to people asking seemingly simple questions. For some reason, I hate simple yes or no. I have to get into the rationale behind the answer. The jury is still out on whether I did penance, or I compounded the sin.
Actually, this was the easy topic. There is another one involving geosynchronous transfer orbit (GTO). That came on the heels of the successful launch the SES-8 communications satellite by a SpaceX Falcon 9. Another launch, for Thaicom 6, is planned for this Friday, January 3, 2014.
I asked, what would be involved in putting a satellite in geosynchronous orbit (GSO) from Vandenberg AFB? In general you wouldn’t do that, particularly if the satellite is going to a geostationary orbit (GEO) just above the equator. But there might be cases where it is useful. I spent time working rudimentary trajectory numbers, and the penalty vs a launch from Cape Canaveral. I probably need to summarize the mechanics of GTO first before straying into my more exotic case. Hopefully, I will get to post the basic GTO case in the next few days.
This year, 2013, was an amazing year for space exploration and development. I had intended to create a list before the end of the year, but it kept mushrooming with things that were interesting in their own right. To have them all happen in one year was simply surprising. That list is in progress, but will take some time to settle down.
China launched its Chang’e 3 lunar probe atop a Long March 3B rocket on Dec 2, 2013 (Dec 1, US EST). It is actually two spacecraft — the Chang’e 3 lander and the Yutu rover.
Rather than try to explain the two spacecraft and their scientific mission, I refer you to Emily Lakadawalla of the Planetary Society, and her blog post on December 2. She does an amazingly good job of explaining how planetary science missions work, regardless of the country.
I am a flight vehicle and trajectories nut. I tend to look at how vehicles achieve orbit or other trajectory objectives. Before I go there, I need to get something out of my system… <frivolity>What unnerves me the most … is the pronunciation of the name of the rover, Yutu (玉兔), which means “jade rabbit”. It is NOT “you too”!! Don’t believe me? Then listen to it at translate.google.com!!</frivolity>
Here’s the launch of Chang’e 3 with English commentary:
I was so impressed by the quality of the video received from the flight vehicles that I decided to get the timeline down so I could make better sense of some of the pictures. The timing below is given in minutes and seconds (mm:ss) from the start of the video.
0:00 – final countdown
0:35 – 1st ignition, launch
2:27 – video from Long March rocket looking downward
2:55 – strap-on boosters discarded from 1st stage
3:12 – 1st stage separation, 2nd stage ignition
6:15 – 2nd stage separation, 3nd stage ignition
10:25 – 3rd stage engine cut-off, enter parking orbit
14:23 – 3rd stage re-ignition
17:57 – 3rd stage cut-off
18:50 – switch to forward camera looking at Chang’e 3 probe; rim of Earth is visible
19:35 – separation of probe from 3rd stage; most of Earth rim, previously obscured, is now visible
20:22 – probe starts a series of attitude correction burns
21:14 – probe engine ignition
29:40 – Earth coming into view of 3rd stage camera
30:00 – By this time, the probe is already on its trans-lunar trajectory.
Shortly after this, the video starts to repeat parts of the launch.
The English commentary is quite nice. There is one glitch, involving perigee and apogee. The technical commentator has them reversed; he talks about apogee as the closest point to the Earth in its parking orbit. In fact, the closest point is perigee; the highest point in the orbit is apogee.
Lander and rover design
Much has been made of the Yutu rover having the same basic shape as the Mars Exploration Rovers (the MERs, Spirit and Opportunity). The arrangement of the wheels is the same. Some observers claim this means they stole the MER rover designs. Actually, Mars Science Laboratory (MSL, Curiosity) has the same 6-wheel arrangement, and so do many other experimental designs. It turns out to be a good design for navigating irregular terrain.
I have not taken a close look at Yutu wheel base articulation, but have to assume it is similar in principle to the MER and MSL chassis designs.
Basically, the instrument chassis hangs on a crossbeam that attaches left and right sets of wheels; the two sets can twist independently of each other. On one side, a horizontal beam connects the middle and rear wheels. That beam and the front wheel connect to an inverted V; the vertex of the inverted V connects to the crossbeam going inside the instrument chassis. Each of these connection points can articulate.
Actually, the beams discussed above do not connect directly to the wheels. Rather, each connects to a pair of motors. One motor, with a vertical axis of rotation, can turn the wheel assembly left or right, allowing for turns of the rover. Another motor, with a vertical axis of rotation, makes the wheel itself spin, giving the rover longitudinal or lateral motion.
This is a popular arrangement. I have seen it in a couple of other independent rover projects. It’s possible that JPL laid the groundwork, and everyone is stealing that basic design.
The Chang’e 3 lander carries a plutonium-powered radioisotope thermoelectric generator (RTG). Why does it need this? Isn’t there an alternative? The reason for it is the lunar night, which is two weeks long. It is so cold that the electronics would not recover from the deep freeze. Solar panels are useless since there is no Sun. Batteries to carry sufficient charge to go all the way to the Moon would be prohibitively heavy and expensive. (And who knows if the batteries could survive the temperature drop.) So there currently is no alternative.
NASA is looking for an alternative through its Centennial Challenge program. The Night Rover competition is aimed at finding the best energy storage system for a lunar rover that could help the rover survive the lunar night. This challenge is offering $1.5 million in prize money.
(And there is so little plutonium-238 in the world that it would be best to keep it for outer planets missions.)
I typically stay out of discussions of the future of China in space and its implications for the United States. But with the launch of Chang’e-3 to the Moon with its rover Yutu, I sensed a lot of misinformation, tending toward public apprehension, which will lead to public policy positions based on shaky reasoning.
The Chinese space program is administered by the People’s Liberation Army (PLA), a military institution. As a result, many people see Chinese space as a military program. In the same line of thought, people incorporate espionage, spying on peoples’ Gmail accounts, the Chinese anti-satellite missile test of 2007, possible military attack on US space assets, etc. And then human rights gets added.
Of course, the anti-satellite test created a lot of space debris, fomenting a lot of international criticism. In my opinion, the right hand did not know what the left hand was doing (scientific vs military leadership). I suspect there was a lot of internal bickering and in-fighting in the leadership while this was sorted out.
Some people fear that China will take over the Moon and launch missiles from there toward targets on Earth. This is highly impractical, and the missiles would take several days to reach Earth. (One does not just drop a missile straight down; the Moon is rotating around the Earth. Any object leaving the Moon would start with its orbital angular momentum. To drop straight down, one would have to kill that momentum, that is fly the opposite direction from the Moon. The descent needs to be timed so that the missile ends up on your adversary’s head and not your head or your friend’s head. There’s more, but I’ll stop there.)
For some groups, all the possible justifications for not cooperating with China are brought to bear. It goes to the extent of any business that has contracts with businesses or the government in China cannot take part of US federal contracts. (I don’t know how large semiconductor and telecom companies get around this, if they do.) And the NASA administrator is not allowed to have direct talks with his counterpart in China, in spite of what his predecessor in the previous administration did.
And then there is the problem of presumably respectable media jumping to conclusions. A few days after the launch of Chang’e 3 and Yutu, I saw a post in LinkedIn titled, “Why does China want to militarize space?” The post cited an article in the Christian Science Monitor from October 2010. [article] In my opinion, the content of the article did not support that title. There was Pentagon analysis of the possibilities. But most of the article dealt with the just-launched Chang’e 2, and the other matters related to the emerging Asian space competition. In my view, someone wanted the article headline to sell papers.
In response to the poster’s question of “Why does China want to militarize space?”, I asked “What makes you think China is militarizing space any more than the US?” (We have recon satellites and the like, which I consider a valid use of space military assets. Now, why would a LinkedIn reader cite an article from over three years ago? I didn’t ask.
(In recent months, I’ve run into a lot of cases either in LinkedIn or Facebook where readers are citing articles which are years old, or do not really support their argument, or the headline doesn’t really represent the article. I fear we are being overrun by sound-bite culture.)
Does China want to establish a permanent human presence on the Moon? This idea has more credibility. Various groups see value in the Moon as the first step of human settlement for a space faring society. It does not matter what country you are from. Some claim that it doesn’t adequately represent Mars, that Mars has an easier environment to adjust to. In many respects, that may be true. But there is still basic development which can be done before pushing ahead to Mars. The fear some Mars advocates have is that focusing on the Moon will suck resources away from going to Mars; that is a valid fear.
There is political value in a society sending humans to the Moon to stay on a long-term basis. It is something the US has not done. Doing so would likely be considered a show of superior technology and intellectual capability. If you are a small nation and you are evaluating who you should have alliances with, this capability forms part of a convincing argument.
The grand prize may be how to mine and manufacture materials in space so that they don’t need to be brought from Earth. There is a potential for materials processed in space to have value on Earth. However, until manufacturing in space is actually proven, the value of this idea is unclear.
In establishing a settlement on the Moon, you can take members of your society and your value system, and establish them there along with representatives of your allies. But in large measure, if you are building the base, you establish the ground rules. When it comes time to spread humans throughout solar system, your values and trade system are the ones that spread with them.
Some number of world leaders probably understand this. I suspect the Chinese are among them.
With an adequate supply of Plutonium-238, and considering the current budget-constrained environment, NASA has decided to discontinue procurement of ASRG flight hardware. We have given direction to the Department of Energy, which manages the flight procurement, to end work on the flight units. The hardware procured under this activity will be transferred to the Glenn Research Center to continue development and testing of the Stirling technology.
Generators, power from Pu-238
The ASRG is the Advanced Stirling Radioisotope Generator. It was to improve the efficiency of energy conversion from isotope decay to electricity by a factor of 4. The existing system, the Multi-Mission Radioisotope Thermoelectric Generator (MMRTG), powers the Curiosity rover, providing about 125 watts of electrical power from 4.8 kg of Pu-238. [Curiosity specifications] The ASRG would provide about 140 watts from 0.8 kg. [ASRG Specifications] RTGs in space have been in use since the 1960s. The Stirling engine dates back to the early 1800s.
While the power output level is similar, the ASRG is also lighter (~20 kg) than the MMRTG (45 kg). But the ASRG is still in development; it would be a few years before it is ready for flight.
However, the overriding constraint on future outer planets missions (Jupiter and beyond) and heavy rovers like Curiosity is the amount of Plutonium-238 available. The Department of Energy will produce about 1.5-2.0 kg per year, paid for from the NASA Planetary Science budget. (This is a new cost item in the NASA budget, which gets no increase to cover it.) It would take 2-3 years to have enough for another Mars rover like Curiosity. In the meantime, no missions to the outer planets could be flown. By reducing the Pu-238 requirement to 0.8 kg, you could launch 1-2 outer planets explorers per year.
So the ASRG cancellation announcement got me upset.
The Planetary Society provided a standard form letter regarding the precarious state of funding for planetary science. (Follow Casey’s blogpost. The link is at the bottom.) I embellished it with my specific concerns about the ASRG program cancellation, but left the requested actions (“I strongly urge…”) the same as what the Planetary Society formulated to avoid mixed messages on action. The Planetary Society site is able to find your elected officials based on your zip code.
This letter was sent to my congressman (Mike Honda), two senators (Barbara Boxer, Dianne Feinstein), and the president (Barack Obama). (Some representatives, like Rep. Honda, require entry on a separate form their office provides. This requires a copy-n-paste, but an easy step. It is probably a decent first-level spam filter.)
Below is my letter, modified from the Planetary Society original, and sent off to my elected officials.
I am extremely concerned about the cancellation just announced of NASA’s Advanced Stirling Radioisotope Generator (ASRG) program. This program was going to vastly improve the capabilities of spacecraft exploring the outer planets when compared to current radioisotope thermoelectric generators (RTGs).
NASA’s Planetary Science Division (PSD), responsible for popular missions such as the Curiosity rover on Mars and the Cassini orbiter at Saturn, has suffered continuous budgetary attacks by the Office of Management and Budget for the past two years. As a result, we’ve seen missions delayed and cancelled, international partnerships broken, and an immeasurable loss of science.
In order to ensure any viability of any future outer planets missions, NASA PSD had to eat the cost to restart miniscule Pu-238 production WITH NO INCREASE in overall budget. This strikes me as both unfair and foolish.
I urge you to restore funding for NASA PSD to $1.5 billion per year, its recent historical average and the minimum required to maintain our edge in solar system exploration. Both the Senate and the House have recommended this level in their 2013 NASA Authorization bills.
I strongly urge the following:
* Restore funding for NASA’s Planetary Science Division to its historical average of $1.5 billion per year for the next five years.
* Ensure that NASA pursues a balanced program of planetary exploration as defined in the National Research Council’s “Decadal Survey” report, including storage of a sample to return from Mars and a mission to Europa.
* Maintain operations of existing spacecraft to ensure taxpayers get the highest science return on their fiscal investment.
I thank Congress for their efforts to restore funding to NASA’s Planetary Science Division in 2013. Before sequestration, Congress rejected the 20% cut proposed by the Office of Management and Budget in fiscal year 2013. Despite this, the OMB proposed further cuts in 2014.
Planetary science is one of the most successful parts of NASA.. These missions have consistently proven to be popular with the public, return an enormous amount of science, spur creative technological solutions within NASA and private industry, and foster strong international relationships. NASA’s planetary science program is one of the best investments the government can make.
There is bipartisan support for Planetary Science and exploration in both houses of Congress and across party lines. I strongly encourage you to join with your colleagues in government to restore funding to a minimum of $1.5 billion a year to maintain NASA’s leadership in space exploration.
One of the landmarks of the San Francisco bay area is Hangar One, located at Moffett Federal Airfield. It was built in the early 1930s to house lighter-than-air ships, specifically the USS Macon. The field started as Naval Air Station Sunnyvale, but was renamed in 1935 to NAS Moffett, in honor of Admiral William A. Moffett, who died in the crash of the airship USS Akron in 1933.
In its history, several federal agencies and military branches have been located there, including the Navy, Army Reserve, and the Air Force. It is also home to NASA Ames Research Center, which started there as the NACA Ames Aeronautical Laboratory in 1939, on recommendations of a committee chaired by Charles Lindbergh.
Crossroads for Moffett
The airfield and surrounding land are now at a crossroads. The General Services Adminstration and NASA have put out a request for proposal (RFP) to lease either just Hangar One, or the whole airfield, including Hangars One, Two, and Three. This particular post that you are reading started out as a reply to questions posed in the Mountain View Voice, the community newspaper of Mountain View, the town on the western border of NASA Ames. Mountain View is home to Google, and was once also home to Silicon Graphics, Sun Microsystems, Adobe, etc. To south of the field, right under the approach to the runway is Sunnyvale, current or former home to a variety of other tech companies. Hence the original name of the field, NAS Sunnyvale.
There is a lot of debate about the future use of the field and the hangars. A couple of years ago, one plan called for ripping out the runways and using the land to house World Expo 2020. This plan seems to no longer be viable.
Released in May, the RFP allows for a couple of two kinds of proposals: (1) just Hangar One, or (2) the airfield, including Hangars One, Two, and Three. In the first case, it seems NASA (via the California Air National Guard) would continue to operate the airfield. In both cases, the airfield would remain operational.
I have just started studying the RFP. There is nothing I see in it that allows the hangars to be torn down; if anything, there are varying levels of rehabilitation required. There may be reimbursable costs, but it is up to leasee to make the field financially viable. NASA Ames and the NASA Research Park in front of Hanger One are not part of the RFP, and remain under NASA control.
There appear to be four interested parties getting ready to submit proposals:
Google (presumably through its related company H211 LLC)
Of these groups, at least a couple of them seem intent on space entrepreneurship: ISDHub and SVSC. The Google founders have invested in space companies, but there is no indication of whether or not space entrepreneurship would factor into its proposal. Thus, what space entrepreneurship means for Moffett Field will depend on who wins the lease.
Among the key problems: Hangar One was stripped of its external skin, which showed evidence of asbestos. That job was performed by the Navy before it handed the airfield over to NASA. A protective coating has been applied to the skeleton. But the hangar need to be reskinned by whomever is the winning leasee of the property.
(Disclosure: For regular readers of this blog, it is no surprise that I am an SVSC member. I am not one of the key personnel on the SVSC/MFA Alliance proposal. However, I’ve worked with other SVSC members on projects, and have had opportunities to talk to the founders of companies being incubated through SVSC. I represent the AIAA SF side of the Small Payload Entrepreneur TechTalks which are co-sponsored with SVSC.)
The opinions below are mine. They reflect my current thinking on the future of Moffett Field. If/when the proposals are released for public consumption, I might change my mind on some aspects.
In my view, using Moffett Field for endeavors other than aerospace development activities would be a lost opportunity. There is collaboration that can come from pulling several complementary companies together in a single setting. There are suddenly a lot more potential users of products concentrated together; discovering common needs comes much more quickly. These users may be NASA or small companies in the area. In effect, as new economic supply chains emerge, participants are able to identify their current niches, and discover missing links and opportunities. [mod:0926]
To me, NASA Ames has demonstrated more interest and support for commercial applications in space than any other NASA center. It had the Space Portal long before the rest of NASA put such a priority on commercialization. The NASA Flight Opportunities program at Ames matches technology with research flights all across the country; it is helping to accelerate the maturity of hardware to be used in space. These programs stand to reduce the costs of space flight even faster if Moffett Field is dedicated to that kind of collaboration.
Mastering aerospace complexities
What about technologies other than aerospace? Would only aerospace companies reside in an aerospace entrepreneurial research park? There are two answers to this:
1. Concentrated aerospace. The unique value of Ames is to be able to pull developers of various parts of the aerospace ecosystem together in a single place. There are experts at Ames in various aerospace problems and technologies. The National Full-scale Aerodynamics Complex (NFAC) is at Ames. The Arc Jet Complex, used to test materials for atmospheric entry, is at Ames. The Lunar Science Institute is there. The Astrobiology Institute is there. The list goes on and on.
There are things that researchers at Ames want and entrepreneurs would like to offer. Rather than travel (which the GSA has managed to restrict), conference calls, and shipping intermediate deliverables around the country, which usually have to be highly focused activites, this opens up the ability to informally affect secondary and tertiary effects of technologies, leading to quicker feedback and optimization.
If you want to develop better computing technologies, or simply want to have a manufacturing line, there are other places in the Valley to do it. And close proximity to a flight line is not necessarily conducive to those activities, particularly if it is not a shipping port for manufactured goods.
2. The truly complex nature of aerospace. Ultimately, the goal of an aerospace enterprise is to design, construct, or integrate a flight vehicle that accomplishes a class of missions. For larger projects, the undertaking is so complex and has so many spin-offs that large aerospace companies sometimes identify themselves as systems companies. The complexity and resulting cash flow requirements are just too high for the vast majority of entrepreneurs. Starting with aeronautics, the field traditionally includes: aerodynamics, structures, propulsion, and controls. But when you get to satellites, the dominant discipline is electronics. This can be broken into power systems, sensors, computing, communications, and probably a few other things I’m forgetting. I expect to see boutique companies focusing on a single or a small cluster of disciplines. The integration of these disciplines makes aircraft or launch vehicles possible; this is virtually impossible for entrepreneurs to do, except for the most well-financed.
The smallest flight vehicle that an aerospace company might attempt is a small satellite or an autonomous unmanned aerial vehicle (UAVs). In such enterprises, an orchestrated solution for power, communications, sensors, attitude control, and overall resource management is being attempted. For serious UAVs, structures and mass are traded against propulsion, which may be traded against aerodynamics. Successful flight vehicles need expertise in all these areas. Concentrating so much intellectual power in an entrepreneurial company is a major challenge.
Thus, the most likely scenario is to see companies with highly focused products or activities which are able to occupy a niche in an aerospace supply chain.
As for museums, I don’t see an inherent conflict between space entrepreneurship and having part of Hangar One as a museum. If you go to the Computer History Museum, The Tech Museum, or the California Science Center down south, the exhibits show how technology works and what the potentials are for the future. The challenge would be how you cost-effectively add value above and beyond the other excellent venues that are already available in the region. Furthermore, NASA Ames has a Visitor Center at the entrance just off Highway 101. Would that continue as an independent venue, or be folded into a museum in Hangar One? Presumably, those who are proposing a museum in Hangar One are figuring that out.
If you dedicate a substantial part of Hangar One to a museum or other educational center, then you will need the rest of the airfield and its facilities if you also want to support space entrepreneurship. Some entrepreneurial work will involve chemicals, gasses, or other hazards which probably should not be present in a public venue. Otherwise, you need to accept from the outset that such activities cannot be pursued on the premises. (Since Hangar One is a historical site, they may not be allowed anyway.)
What is at stake
The decision on how to lease/manage Moffett Field has major repercussions for the future of space entrepreneurship. It is possible for it to struggle along in Silicon Valley, but increasingly, companies will find that it is more expedient to move out of California to Texas (home of the Johnson Space Flight Center), or Colorado (home to a lot of spacecraft design and construction), or other states that want space business.
The infusion of capital from Silicon Valley, where half of venture capital deals are made, is likely to accelerate the maturity of new commercial space operations. This is much more likely to happen when companies are located within easy access to venture firms. (Local residents understand the relationship between projects spun out from Stanford University and Sand Hill Road, which is just west of the campus.)
To be sure, a large portion of aerospace vehicle design and construction happens in southern California. That concentration of talent has allowed SpaceX to rise very quickly. The concentration of experimental flight vehicle talent around Mojave, just north of Los Angeles, makes possible Scaled Composites, XCOR Aerospace, Masten Space Systems, etc. However, some of these entrepreneurial companies are moving manufacturing and test operations to Texas (particularly, XCOR and SpaceX). Other states would certainly like to be home base to aerospace vehicle design and manufacturing, e.g., Alabama (Marshall Space Flight Center), Mississippi (Stennis Space Center) and Florida (Cape Canaveral and Kennedy Space Center), and even Virginia (Wallops Island). If companies don’t want to stay in California, there are welcome mats in a lot of other places.
The decision for the next phase of Moffett Field lies in the hands of NASA and the GSA. The residents of surrounding communities have their preferences on what they want to see, based on good and bad experiences with other local enterprises. Space entrepreneurs badly want to enable technology for humans returning to the Moon, reaching Mars, and settlements on both.
The next phase of Moffett Field is more than just the next side-effect of base realignment when the Navy and Air Force pulled out. It has potentially a major impact on how quickly a commercial space economy gets a foothold beyond Earth orbit, and how soon NASA’s limited resources can be freed up for more robust exploration missions.
[PostScript: Since I originally pushed this post out a few days ago, I’m making occasional small fixes, chiefly spelling or grammatical. Paragraphs that have such mods are marked with [mod:mmdd], where mmdd is obviously the month and day of modification. Given the readership I’m seeing, there may be a need to expand of a particular aspect of this article. But I’ll deal with that as a separate post at this time. –RSR]
Friday evening, September 6, 2013, the Lunar Atmosphere and Dust Environment Explorer (LADEE) was launched aboard a Minotaur rocket from Wallops Island, VA, on the mid-Atlantic seaboard. This mission is proving interesting in a lot of ways — some to do with the Moon, and some to do with how space missions are now executed.
The LADEE spacecraft was developed at NASA Ames Research Center, in Silicon Valley and sitting right on the edge of the San Francisco Bay. Ames is home to the NASA Lunar Science Institute. So it was fitting that Ames hosted a “science night” for thousands of enthusiasts, with the LADEE launch as the highlight.
Now, for my friends who were expecting to see me at the Ames event, I apologize. I had a major case of fatigue very early in the day, and did not think I would be able to drive home after the event. So I left work after the last meeting of the day, into a big traffic jam (sigh), and connected my laptop to the biggest screen in the house so that I could watch it.
In recent years, our understanding of the Moon has been rapidly evolving. After decades of neglect following the Apollo missions in the late 1960s-early 1970s, we were suddenly on the hunt for water. As a result of Apollo, we believed that the Moon is an exceedingly dry, barren place with no hope of supporting humans without a continual lifeline of supplies from Earth. So we stopped going. Even the first pictures from the surface of Mars, from Viking in the 1970s, showed a dry, barren place with hardly any atmosphere. A lot of people were probably wondering why governments were spending money on space at all. In fact, the reason was international prestige; with that in hand, further scientific understanding was hard to justify to government budget and oversight committees.
It turns out we were wrong. We now know water ice has been accumulating on the Moon, and Mars was once a very wet place. We suspect that Jupiter’s moon Europa has icy oceans below its surface. And comets, coming from the far reaches of the solar system, are an amalgamation of rock, dust, water ice, and frozen “gases” like carbon dioxide, methane, ammonia, etc. (At least, the latter would be gases at room temperature and pressure on Earth.)
The rocks from the Apollo missions did indeed contain faint traces of moisture, but it was felt these were probably contaminants brought from Earth. Indeed, the samples are pretty dry. Similarly sized samples of the Earth’s driest deserts have more water content.
In a nutshell, it now appears that water is virtually everywhere in the solar system. With some ingenuity, human settlements can be sustained as far from the Sun as the water goes. The Moon is the first step in figuring out how to do this.
The Moon’s exosphere
Like the Earth, the Moon is bombarded by a steady stream of atomic and subatomic particles from the Sun as well as meteorites from asteroids or other debris orbiting the Sun. With no atmosphere like the Earth to slow or disintegrate small objects before they hit, the Moon is littered with small impact fragments that retain their sharp edges for millennia. There is no erosion from abrasion against other fragments to round off the edges. There is extreme heat and cold which would drive out moisture, and perhaps produce cracks.
The molecules and gases driven out would follow ballistic trajectories, hardly ever hitting another molecule before hitting the Moon’s surface, and perhaps bouncing again until it ran out of energy. Protons from the Sun might ultimately combine with atomic oxygen, also from the Sun, first forming hydroxyl (one hydrogen, one oxygen), and later water (two hydrogens, one oxygen). [The Sun is about 78% hydrogen, 20% helium, and 0.86% oxygen, 0.4% carbon, etc..] Furthermore, the surface is bathed in ultraviolet, knocking electrons off some atoms, leaving positively charged dust on the Moon that also has sharp edges.
A funny thing happened on the Moon during the Apollo 17 mission. Astronaut Gene Cernan was set to observe the coronal and zodiacal light (CZL) of the Sun when it was hidden by the Moon. Indeed, he did see it, but there was more. There should have been just a small hump of light over the horizon, but in fact there were additional columns of light across the horizon as the Sun prepared to rise. It turned out there were similar sightings during Apollo 8, 10, and 15 during CZL observations. In fact, there was a lunar horizon glow (LHG) during the Surveyor missions preceding Apollo. The problem is, it wasn’t consistently seen; it was highly variable.
The LHG seen by Surveyor was from the surface of the Moon. To an extent, this can be explained by electrostatic charge on lunar dust. Ultraviolet radiation kicks electrons off the dust, leaving them positively charged, pushing away from each other, and rising off the Moon’s surface. This is expected a few meters up. But what the Apollo astronauts saw was at much higher altitudes.
It is possible that the electrostatic charge is propelling smaller particles faster, onto trajectories high above the lunar surface. It could also be from sodium atoms in the Moon’s exosphere.
Part of what LADEE will do is gather more information on the composition of this tenuous lunar atmosphere and dust environment. (Hence, the name.) What is learned here will undoubtedly shed light on what is happening on other small bodies elsewhere in the solar system. One has to imagine the moons of Mars, or for that matter, the moons of Pluto. (Pluto itself seems to have a very very faint atmosphere; New Horizons will be visiting soon and find out more.)
LADEE is built on a “modular common spacecraft bus” (MCSB); that is, a basic spacecraft framework (structure, propulsion, electrical buses). It is intended to be utilized for a variety of missions, thus reducing the overall cost of spacecraft and mission development.
In fact, the MCSB is being utilized by Moon Express, a team competing for the Google Lunar X Prize.
Modularity and commonality are not new concepts in the spacecraft business. Commercial satellites are often built on a common bus, with small incremental improvements from one spacecraft bus to the next. Exploratory spacecraft are often developed with pairs of hardware — one for the spacecraft to be launched, and a spare set for testing and backup. The spare set is often later used for a cheaper spacecraft. Venus Radar Mapper, aka Magellan, utilized spare components from Galileo. If the Galileo spacecraft was lost during launch or early in the mission, the spare set would have been appropriated to create the backup spacecraft, and there would have been no Magellan. (At least, that was the plan. Check the launch dates; you’ll see something else happened.)
In the emerging industry of asteroid mining, one can see the glimmer of a spacecraft production line, where perhaps hundreds of spacecraft will ultimately be manufactured for various stages of asteroid resource exploration. These are, so far, much smaller than the MCSB that LADEE uses. (Although once resource extraction begins, it seems impossible for the spacecraft to retain a small size.)
Having done the prototyping of the bus and adapting it to LADEE, it is hoped that other missions will see fit to utilize it. LADEE itself is a lunar orbiter. Moon Express is building a lander. A variety of other lander and rendezvous missions are possible using MCSB components.
Spaceports for small spacecraft
Wallops Island has been a flight facility for NASA or NACA, dating back to 1945. Sounding rockets have been launched from Wallops to study the upper atmosphere. A variety of aircraft and scientific balloon missions have originated from there as well.
However, it is emerging as a launch facility for orbital and lunar missions. This means payload integration, tracking range, etc. While larger payloads are launched from Cape Canaveral to destinations like the International Space Station, Wallops is focused on small payloads in the range of 4-400 pounds (1.8 to 180 kilograms).
Rather than hitching a ride as a secondary payload on a larger rocket, it gives the opportunity for small payloads to be primaries, thus giving mission teams more control and flexibility in what they can do.
This particular launch involved an Orbital Sciences Minotaur V rocket. A few months earlier, on April 21, Orbital launched an Antares rocket, carrying a few small payloads, including three copies of PhoneSat-1, developed at NASA Ames.
These are unmanned launches. There is also a trend toward utilizing hardware for manned suborbital launches for unmanned orbital as well.
XCOR Aerospace is building its Lynx rocketplane to take-off and land on a runway. As the vehicle matures, a version is planned to have a dorsal pod that extends from the fuselage. The pod will be able to hold a rocket stage that could put a small payload into orbit. (This would be a nanosatellite such as a CubeSat.)
Virgin Galactic, which is building SpaceShipTwo for tourists, is also building LauncherOne for small payloads. Both will utilize the WhiteKnightTwo aircraft as their launch platform. Currently, Virgin Galactic is planning commercial flights at New Mexico’s “Spaceport America.”
Thus, the options for payloads ranging from small to very small are gaining. Wallops and the state of Virginia undoubtedly hope to be a leading flight facility for launches of small payloads into orbit and beyond.
Putting it all together…
LADEE is a research and exploration mission built using a modular spacecraft design. It is intended to answer questions about the nature of the tenuous lunar atmosphere/exosphere. The lessons learned may be extrapolated to other small planetoids beyond Earth in the solar system. The launch from Wallops is part of an emerging trend to provide better options for smaller spacecraft.
How frequently do near Earth asteroids (NEAs) closely approach Earth? Usually, NEAs only show up in the news media if they are very close and very large, or they impact a populated area. There are, however, many more that make close approaches, but safely pass by the Earth. Some of these may be candidates for possible mining.
If we want to select asteroids for possible mining, then the ideal candidates are those that come close to Earth slowly, but don’t hit, and are sizable to allow for extensive mining. How frequently do candidate asteroids show up?
JPL maintains a table of NEO close approaches (NEO = near Earth object). The table describes close approaches for the next 60 days. I abstracted from the table today (August 23, 2013) to see how frequently these occur.
Here are some sizable asteroids that have velocity < 10.0 km/s relative to Earth, and < 20 LD (lunar distances) at close approach.
Aug 28, 2013
170 – 380
Aug 30, 2013
90 – 200
Aug 31, 2013
64 – 140
Sep 9, 2013
130 – 290
Sep 30, 2013
140 – 310
As a point of comparison, the velocity needed to reach low Earth orbit is about 7.9 km/s. Escape velocity is 11.2 km/s at the surface of the Earth. What this means is that a probe from Earth to one of these NEAs would spend the majority of its velocity change (delta V) just leaving the Earth.
The uncertainty of diameter is substantial, which means we don’t have a good handle on mass. Rendezvous/loiter near these objects would help determine mass and shed light on their make-up.
The relatively low close approach speeds means that these orbits are not highly elliptical. They are likely to be generally in the Venus-Earth-Mars system. Faster speeds would indicate more energetic orbits which might take them to the outer planets (or at least to the main asteroid belt).
There are a lot of asteroids which are farther or passing by much faster. Those would take more energy to reach than these, and thus I did not include them. There are also many that are smaller, and thus not much mining to be done. So, given the table for the next 60 days, these are the ones that might make prime candidates for rendezvous missions. Extrapolating to over a year’s time, there might be 50-60 asteroids each year that might be worth visiting as mining candidates.
As instruments such as image sensors get smaller, cheaper, and yet improve in performance, they open up possibilities for very small satellites. Of particular interest to me are nanosatellites (under 10 kg) and microsatellites (under 100 kg). To date, these have been launched as secondary payloads on rockets carrying extremely expensive primary payloads.
To simplify the integration of low-cost small satellites, Prof. Jordi Puig-Suari of Cal Poly Luis Obispo and Prof. Bob Twiggs of Stanford University came up with a standard framework known as a CubeSat. It is no understatement to say that it has revolutionized the design and deployment of low-cost small satellites.
Standard 1U CubeSat nanosatellites are exactly 1 liter in volume, 10 cm on a side, and have mass of up to 1.33 kg. A 2U CubeSat is 20x10x10 cubic cm, and up to 2.66 kg. A 3U is 30x10x10 and up to 4.0 kg. They typically fly in very low orbits, and may re-enter and burn up in a matter of weeks or a few years. Thus, their design life-times are adjusted accordingly.
Because they fly as secondary payloads, they are subject to the rules of the typically very expensive primaries. Launches can be anywhere from months to years away. But increasingly, they are first flown to the International Space Station, and then released into a trailing orbit behind it.
The case for nanosat launchers
I have previously posted my thoughts about the business case for a nanosat launcher. I believe the premises for a business case still hold. In fact, I am beginning to see increasing evidence of interest.
The purported benefits of a nanosat launcher include: better control over launch window, selection of orbital plane/trajectory, no risk to a more expensive primary payload, no risk to humans on the ISS, option to test exotic propulsion systems.
Current launch costs of payloads are fairly high. But in my view, the greater impediment to broader access to space is schedule. If launches can be arranged weeks or days in advance (instead of months or years), it then becomes possible to build an iterative research and development cycle where payloads are designed for a month or two, launched and monitored for a month, and then a new experiment is developed in another month or two while continuing to digest results from the current one in orbit. Researchers do not go off to another two or three projects while waiting for this one to launch again, and then come back and have to restart their research efforts. A company can conceivable fly 4-6 times a year, and dramatically shorten their research efforts.
(Who would do this? There are a variety of effects in microgravity or vacuum conditions which can be utilized. Going through these is a separate subject, and is more suited to those researchers who might benefit from them. So I won’t belabor those here.)
Why do we not hear more about these? The major media will not be reporting on nanosat launchers because the big space issue is how the US will launch its own people into space.
Among the trends quietly emerging is the use of the International Space Station as a launch platform for nanosatellites. All the requisite safety checks apply. But there is a regular schedule of launches to the ISS every two months, bringing food and other supplies. Payload integrator NanoRacks has effectively gotten the checks and procedures into a reliable business cycle. There are limits on what can be flown to the ISS. Even though a CubeSat is intended for launch from the station, it still needs to be handled by the crew, and there has to be iron-clad assurances that no small incident would precipitate a major emergency on the station. NanoRacks has been so successful at this that they have received an ISS Innovation Award from the American Astronautical Society. (The major innovation is really in bringing small experiments into the ISS on a regular basis. Nevertheless, the same principles apply to satellite deployment from the ISS.)
The ISS is not necessarily in the ideal orbit for deploying satellites. It occupies one orbital plane. It cannot handle orbits which are more polar or more equitorial. These still require separate launch vehicles.
A case is arising for asteroid mining, or at this stage, prospecting. The chances of a primary payload being aligned with a passing near-Earth asteroid are extremely slim. Companies like Deep Space Industries would like to fly lots of prospecting CubeSats to lots of asteroids. A launcher on which their probe is the primary payload can greatly simplify the logistics of prospective.
Who is working on nanosat launchers?
NASA released an SBIR Select topic for nano/microsatellite launch vehicles in 2012; these are expected to loft 20 kg into a circular (possibly polar) orbit at 400-450 km altitude. DARPA has selected teams to develop vehicle technology for an microsatellite (up to 45 kg, 100 lb-m) air-launch vehicle (ALASA: Airborne Launch Assist Space Access).
DARPA ALASA has now funding five companies’ research studies. In addition to them, Virgin Galactic is a non-funded ALASA participant, and is now working on LauncherOne, using the same launch platform as SpaceShipTwo.
US Army and NASA are working on SWORDS. A tactical nanosatellite launch due for flight test in 2014. Payloads will be up to 25 kg.
Small satellite company Microcosm spun off Scorpius to solely focus on rocket technology they had developed.
When XCOR matures the Lynx rocketplane to Mark III, its dorsal pod is intended to house a nanosatellite launcher.
There are also smaller efforts with varying degrees of hardware development. Among the notable is the Microlaunchers effort of Charles Pooley. Charles prefers a grassroots movement that is akin to the PC revolution. He believes in a cadre of people building skills from the ground up. He has at least done a propulsion test.
There’s also me, with no hardware, some conceptual designs, and a bit of simulation. I’ve spent too much time in recent years among pilots and aerodynamicists; they smile when I say air-launch. But then I tell them my design is premature; I am very direct about the holes that need to be filled in before a credible design optimization can be done.
My personal suspicion is that one of the dual-use plans, where the support infrastructure is also used in another business model, will be the one that succeeds. That means possibly XCOR, Virgin, or even my crazy air-launch scheme. However, Charles may win the award for lowest cost, if he can win the grassroots people over.
It was a year ago, on August 5, 2012, that Curiosity – a rover the size of an SUV – survived what its designers nicknamed “7 minutes of terror”, including a new landing technique known as the Skycrane maneuver. Prior to the landing, the world was introduced to the video which portrayed the complexity of the landing problem. Fundamentally, Curiosity was so much larger than previous rovers that it could not land using the same techniques, which often involved inflated thick-skinned balloons bouncing several times before coming to rest. Curiosity was just too large. A new series of engineering tricks had to be invented, and each trick had to work in succession until the rover was landed on the surface of the planet.
In some locations, NASA hosted gatherings for people who wanted to see the landing live. These sites had direct feeds from JPL. I attended the outdoor event at NASA Ames with 6,000 other people. The accompanying photos were shot of the big screen (about 20 feet tall) of the JPL video feed.
NASA Ames had a vested interest in the landing because the heat shield tiles were developed there. Once on the surface, the CheMin (Chemistry and Mineralogy) experiment from NASA Ames would analyze samples of the Martian soil. Assuming, of course, that all the parts of the automated complex landing process would actually work. While lots of testing was done on Earth, there are some conditions of a Martian landing that simply cannot be duplicated extensively.
The atmosphere on Mars is 1/100th the density of the atmosphere on Earth. Nevertheless, entry into the Martian atmosphere at interplanetary speeds (an equivalent of escape velocity, but in reverse) piles on combined heat and deceleration G forces for several minutes. On Earth, you can heat a sample of material for an extended period. You can generate G forces separately for the same period. But you can’t necessarily do both together. You hope that there is not a failure mode that only exists when the two work together.
The newest innovation in the landing was the Skycrane. After the heat shield was jettisoned, the Skycrane cradling the rover would deploy, and rocket off to the side. If it were to go straight down, chances are that the parachute and aeroshell that it had just separated from would continue down and impact the vehicle. Thus, the first order of business was a collision avoidance maneuver.
As it neared the surface, the rover was winched down, unwinding several meters of cable to provide a distance between the Skycrane and the rover. The objective was to minimize the blast of the rocket engines on soil and loose rocks of the Martian surface, thus minimizing potential damage to the rover. Once touchdown was detected, the rover had to disconnect the cables holding it to the Skycrane, leaving it to rocket away into the distance. All of the cables had to release, all at the same time. If one cable did not release, the unbalance would send the Skycrane gyrating into the ground, not far from the rover, probably destroying it in the process.
Understandably, for the designers of the EDL system (EDL = entry, descent, and landing), the time period from atmospheric entry to touchdown and release was sheer terror. After that, the designers of the instruments get to worry if their handiwork survived the trip.
If you don’t remember the seven minutes of terror, and what it represented, here is a video reminder.
As this writing, a year after landing, Curiosity has fired over 75,000 laser shots at the soil to facility spectrographic analysis. It is taken over 70,000 images, and has sent nearly 200 gigabytes of data back to Earth. The rover is on its way to Mount Sharp, a mountain that shows several geological layers, including ones that indicate a once wet environment.
Curiosity has been so successful, that a new rover of similar design will be launched in about 7-8 years. Meanwhile, a series of smaller spacecraft will be sent to Mars to study the planet.
Amazing images have shown up from the International Space Station (ISS) since the cupola. A structure of seven Earth-facing windows, its spectacular views draw the crew to it in their off hours.
One of the most inspiring personalities from the ISS has to be Dr. Don Pettit, an engineer turned astronaut and communicator. He performs really simple experiments, but does them in microgravity, and explains them in a way that the masses can understand. In total, he has spent nearly a year in space, spread across several missions on the ISS.
He has also taken his love of photography with him into orbit. This short film, Making the Invisible Visible, was crafted by Christopher Malin, and showcases amazing images from the ISS, interfaced with comments by Don Pettit himself.
It probably makes some people want to go to space just for the scenery.
Quite likely, most people in the US and around the world could care less about today’s fly-by of asteroid 2012 DA14. Today’s meteor burst over Russia is another story. It is important to state that these two events are completely unrelated. Purely coincidental that they should happen on the same day. One of them, we knew about in advance, and there is TV coverage to go with it. The other one completely took us by surprise.
If 2012 DA14 has any chance of hitting at all, the earliest opportunity will be in 2080. And the chances are 1 in 4,762,000. (Orbital and impact info) Today, around 11:25am PST (2:25pm EST / 19:25 UTC), it is making a close approach at 17,500 miles (27,600 km) above the Earth’s surface. Fortunately, it is well clear of the orbit of geosynchronous communication satellites. JPL has announced that NASA Television will cover the event. (Live coverage at: NASA TV and JPL Ustream)
A few hours before its arrival, a meteor hit the atmosphere of the Earth over Russia’s Urals region. A few hundred people were injured and there was some broken glass. The Earth’s atmosphere was thick enough to cause the meteor to burst before it could hit the ground. The resulting shock wave caused the injuries and property damaged that followed. (CNN story) Various sources report the original size of the rock to be about 10 tons.
Below is amateur video caught of the meteor entering the Earth’s atmosphere.
In fact, the Earth is swimming in a cosmic shooting gallery. How many bullets or pellets are swimming around with our planet’s name on them? Our catalog of asteroids has dramatically increased in recent years. Scott Manley, a hybrid of astronomer and game nut, has put the discoveries to music. Note the red dots are the ones that are potentially hazardous to Earth. The dots are very small. You may not be able to distinguish them on a small screen. You will notice a vast difference when you play the video on a screen with HD resolution.
Marcia Smith, a respected analyst who writes SpacePolicyOnline.com has posted her own commentary regarding the two events. She also provides a pointer to Phil Platt, of “Bad Astronomy” fame, who is collecting photos as fast as he can.
I’m continuing to collect notes about near Earth objects, particularly asteroids, and what we might do about it (as one of my spare time activities).
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